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The pathophysiologic basis for wound healing and cutaneous regeneration
Abstract
In this chapter, essential aspects of cutaneous wound repair/scar formation, including the early response and the cellular phase, will be covered. Fundamental differences between wound repair and regeneration, with emphasis on fibroblast and endothelial cell contribution to respective dermal architecture, will be discussed. 'Essential ingredients' for cutaneous regeneration will be explored in detail. Lastly, issues regarding stem cells, progenitors and cellular 'plasticity', as they relate to cutaneous wound healing, will be examined.
... As a fundamental part of innate immunity, neutrophils are the first to appear and are mainly responsible for invasion management and phagocytosis of microorganisms, capturing them through neutrophil extracellular traps (NETs) and destroying them through the secretion of reactive oxygen species (ROS) and antimicrobial peptides and proteases. Apoptotic neutrophils, additionally, produce important chemotactic cytokines and growth factors, such as IL-17 and vascular endothelial growth factor (VEGF), thus allowing the entrance of monocytes from the blood stream, that will later differentiate into macrophages [21]. In wound healing investigations, specifically, those concerning the role of the inflammatory response, both monocyte-derived and tissue-resident macrophages have been widely Upon injury, the tissue barrier properties are lost, thus initiating the finely tuned and controlled cascade of wound healing stages regulated by a sequence of biologically active species (grow factors, cytokines, chemokines) [17]. ...
... As a fundamental part of innate immunity, neutrophils are the first to appear and are mainly responsible for invasion management and phagocytosis of microorganisms, capturing them through neutrophil extracellular traps (NETs) and destroying them through the secretion of reactive oxygen species (ROS) and antimicrobial peptides and proteases. Apoptotic neutrophils, additionally, produce important chemotactic cytokines and growth factors, such as IL-17 and vascular endothelial growth factor (VEGF), thus allowing the entrance of monocytes from the blood stream, that will later differentiate into macrophages [21]. In wound healing investigations, specifically, those concerning the role of the inflammatory response, both monocyte-derived and tissue-resident macrophages have been widely studied since they are considered to be the key players in this complex repair mechanism. ...
... Anti-inflammatory macrophages with the help of transforming growth factor-β1 (TGF-β1), VEGF, FGF, and PDGF support inflammation suppression and drive new ECM synthesis, wound contraction, and angiogenesis [22,23]. Endless studies attempt to find an explanation for the presence of T lymphocytes even when no suspicious contamination is present [21,23,24]. Their role in wound healing is still defined as unknown or irrelevant but recent studies have shown that they are important for tissue remodeling and infection resolution. ...
The healing of deep skin wounds is a complex phenomenon evolving according with a fine spatiotemporal regulation of different biological events (hemostasis, inflammation, proliferation, remodeling). Due to the spontaneous evolution of damaged human dermis toward a fibrotic scar, the treatment of deep wounds still represents a clinical concern. Bioengineered full-thickness skin models may play a crucial role in this direction by providing a deep understanding of the process that leads to the formation of fibrotic scars. This will allow (i) to identify new drugs and targets/biomarkers, (ii) to test new therapeutic approaches, and (iii) to develop more accurate in silico models, with the final aim to guide the closure process toward a scar-free closure and, in a more general sense, (iv) to understand the mechanisms involved in the intrinsic and extrinsic aging of the skin. In this work, the complex dynamic of events underlaying the closure of deep skin wound is presented and the engineered models that aim at replicating such complex phenomenon are reviewed. Despite the complexity of the cellular and extracellular events occurring during the skin wound healing the gold standard assay used to replicate such a process is still represented by planar in vitro models that have been largely used to identify the key factors regulating the involved cellular processes. However, the lack of the main constituents of the extracellular matrix (ECM) makes these over-simplistic 2D models unable to predict the complexity of the closure process. Three-dimensional bioengineered models, which aim at recreating the closure dynamics of the human dermis by using exogenous biomaterials, have been developed to fill such a gap. Although interesting mechanistic effects have been figured out, the effect of the inflammatory response on the ECM remodelling is not replicated yet. We discuss how more faithful wound healing models can be obtained by creating immunocompetent 3D dermis models featuring an endogenous ECM.
... Wound healing is an intricate process in which the skin or any organ tissue repairs itself after injury [4]. Wound healing is a complex and dynamic process characterized by interaction of various cell types as lymphocytes, monocytes, epithelial cells and fibroblasts. ...
... Besides the fibroblast and macrophage activity, human wound associated lymphocyte populations are modulated during a healing process. [4] Polarized and non-polarized light from different sources in the spectral ranges of visible and near infrared (NIR) are widely used in clinical treatments and in medical research especially in the therapeutic field, such as Low Level Laser Therapy (LLLT), light phototherapy (lasers), quasi-monochromatic radiation (LEDs) and broadband light devices. [8] The most of laser types are polarized, where the electric field oscillates in a certain direction perpendicular to the propagation direction [9]. ...
Back ground and purpose: The ability of light to penetrate a tissue and deposit energy via the optical absorption properties of the tissue is the key to therapeutic applications. Birefringence which is an anisotropic property of dermal layer of skin, the blood flow in the tissue capillaries and the multi-scattering from the tissue static components affect the polarization of light. The goal of this study was to describe the healing process of deep partial thickness wound in pediatrics submitted (or not) to the excitation property or the polarization property of light. Subjects: Thirty children who suffered from deep partial thickness burn (20-30%) participated in this study (13 boys and 17 girls). Their ages ranged from 10 to18 years. They were classified randomly into two groups (study and control group) of equal numbers. Procedures: Group A (study) was treated using polarized light as an adjuvant therapy to the regular wound care (debridement, Local antimicrobial drug and beta dine) 5 sessions per week for 3 weeks. Group B (control) was treated using the regular wound care (debridement, Local antimicrobial drug and beta dine). Wound surface areas were measured before and after the treatment period by using wound tracing method. Results: The study showed a significant reduction in burn wound surface areas in both groups (P < 0.05) while there was no significant difference between both groups. Conclusion: it was concluded that polarized light has a limited effect as an adjuvant therapy on healing process of deep partial thickness burn wounds in children.
... A wound is defined as the disruption of the anatomical and functional continuity of living tissue (Nguyen et al. 2009). Wounds are classified as acute and chronic wounds. ...
... The post-injury healing phenomenon occurs in five stages; inflammation, neovascularisation, granulation tissue formation, reepithelisation of the new extracel-Veterinarni Medicina, 68, 2023 https://doi.org/10.17221/101/2021-VETMED lular matrix and tissue remodelling (Evans 1980;Nguyen et al. 2009;Rieger et al. 2015). Since ancient times, humans have used various parts of plants for prophylactic and therapeutic purposes against diseases including wounds and burns (Principe 2005;Chah et al. 2006;Alam et al. 2011). ...
In this study, the effects of Aloe vera gel and coconut oil on wound healing were investigated and compared in rats. Forty-two Wistar albino rats were used during the experiment, in which they were operated on under general anaesthesia to create two full-thickness open skin wounds (created with a 0.5 cm diameter punch biopsy apparatus) on both back sides of the median line. A total of 42 rats were divided into three groups of 14 animals each to receive the topical application of Aloe vera gel (AV group - n = 14), coconut oil (CO group - n = 14) and cold cream (CONT group - n = 14). The medical applications were performed twice a day in all the groups. The wound borders were marked on a transparent sheet every day. Afterwards, this sheet was transferred to the millimetre graph paper. On days 0, 7, and 14, the unhealed wound area was measured in all the groups. On days 7 and 14, seven rats in each group were euthanised. Then, skin samples including the intact skin were taken from the wound sites for histopathological and biochemical evaluations. The topical application of Aloe vera gel showed a significant increase in the healing process of the open wounds in terms of the clinical evaluation, histopathological and biochemical data averages when compared with the coconut oil and cold cream groups of rats (P < 0.05). The results obtained in the present study demonstrate that Aloe vera gel may provide a good alternative for the treatment of open wounds.
... Left untreated, the skin may break open and become infected. Moist skin is more sensitive to tissue ischemia and necrosis and is also more likely to get infected, 5,6,5,15,17,25,27,30 . ...
... Another needle was placed at the highest point of the ulcer to allow air to escape. The volume of solution required to fill the ulcer was recorded to indicate the volume of the ulcer, 4,13,15,20,27,30 . ...
Purpose: to evaluate the effect of Gallium Arsenide laser versus pulsed electromagnetic field on healing of pressure ulcers. Methods of evaluation: - (Measurement of the ulcer surface area (USA), ulcer volume measurement (UVM) and the colony count (CC). Methods: 40 diabetic patients with pressure ulcers grade II, their ages ranged from 40 – 60 years, were divided randomly into two equal groups in number. Group (A) Gallium arsenide (Ga-As) laser group: This group was consisted of 20 patients who received the Gallium arsenide (Ga-As) laser therapy 3 times per week for 2 months in addition to the routine conventional treatment (dressing – manage bacterial contamination – relieve pressure, friction, and shear – remove necrotic debris – correct nutritional deficits). Group (B) PEMFT group: 20 patients who received the Pulsed electromagnetic field therapy (PEMFT) 3 times per week for 2 months in addition to the routine conventional treatment (dressing – manage bacterial contamination – relieve pressure, friction, and shear – remove necrotic debris – correct nutritional deficits). Results: Results showed that both the Ga-As laser and the PEMFT, were significantly effective in improving healing of pressure ulcers as manifested by the highly decreased USA, UVM and CC in both groups.
... Wound healing replaces damaged or damaged tissue with tissue newly generated by a living organism [7]. The healing process involves four stages: hemostasis, inflammation, proliferation, and tissue remodeling [8,9]. ...
... In this study, we demonstrated that heat-killed probiotics GMNL-6 and GMNL-653 preparations help to heal skin injuries in the in vitro model of TGF-β stimulated Hs68 human fibroblast cells and in the in vivo model of experimental tail wounds in mice. Wound healing refers to the process of replacing destroyed or damaged tissue with newly produced tissue [7]. The wound-healing process can be broadly distinguished into four stages: (1) TGF-β upregulation-induced inflammatory effects in the wound area, (2) fibroblast migration, (3) extracellular matrix (ECM) production, accumulation in the remodeling phase, and finally (4) cross-talk between fibroblasts and other cell types in injury neighborhood areas. ...
Probiotics are defined as microorganisms with beneficial health effects when consumed by humans, being applied mainly to improve allergic or intestinal diseases. Due to the increasing resistance of pathogens to antibiotics, the abuse of antibiotics becomes inefficient in the skin and in systemic infections, and probiotics may also provide the protective effect for repairing the healing of infected cutaneous wounds. Here we selected two Lactobacillus strains, L. plantarum GMNL-6 and L. paracasei GMNL-653, in heat-killed format to examine the beneficial effect in skin wound repair through the selection by promoting collagen synthesis in Hs68 fibroblast cells. The coverage of gels containing heat-killed GMNL-6 or GMNL-653 on the mouse tail with experimental wounds displayed healing promoting effects with promoting of metalloproteinase-1 expression at the early phase and reduced excessive fibrosis accumulation and deposition in the later tail-skin recovery stage. More importantly, lipoteichoic acid, the major component of Lactobacillus cell wall, from GMNL-6/GMNL-653 could achieve the anti-fibrogenic benefit similar to the heat-killed bacteria cells in the TGF-β stimulated Hs68 fibroblast cell model. Our study offers a new therapeutic potential of the heat-killed format of Lactobacillus as an alternative approach to treating skin healing disorders.
... Wound healing is an intricate process in which tissues are repaired after injury [1]. Normal skin consists of the epidermis (outermost layer) and dermis (inner or deeper layer) which form a protective barrier against the external environment. ...
Histopathological assessment of tissue reactions in surgically induced skin wounds of rabbits sutured with cotton hair thread (CHT) and silk suture was investigated. Twenty four (24) clinically healthy male rabbits of New Zealand breed; aged 6-8 months with a weight range of 1.5-1.8 kg were used for the study. Following acclimatization for a period of two weeks, they were randomly assigned into two groups A and B of twelve (12) rabbits each. A 6 cm paralumber skin incision was aseptically performed on rabbits in both groups using xylazine (0.5 mg/kg body weight) and ketamine (22 mg/kg body weight) as pre-medicant and anesthetic respectively. The incised skin in group A was apposed with conventional silk suture while the incised skins in group B were approximated with CHT. Surgical sites in both groups were excised from two rabbits each for histopathological evaluation at post-operative days (pds) 1, 7, 10, 14, and 21. The histopathological wound healing markers such as re-epithelialization, polymorphonuclear leucocytes (PMNLs) and tissue macrophages infiltrations, fibroblasts, collagenization and neovascularization were evaluated and scored semi-quantitatively thus, none = 0, few = 0.5, moderate = 1, many = 2 and marked = 3. The semi-quantitative data of the wound healing markers when tested statistically, showed no significant difference (p > 0.05) in both groups A and B throughout the study. The results showed that cotton hair thread elicited similar histopathological reactions with the conventional silk suture. Therefore CHT is biocompatible after sterilization and could be used as skin suture in rabbits.
... During this phase, fibroblasts proliferate and collagen was deposited. Concurrently, vascular endothelial cells assemble to form micro vascular structures [5]. Fibroblast proliferation, collagen deposition and angiogenesis were the important processes for wound healing [6]. ...
Nauclea officinalis, as a Chinese medicine in Hainan province, had the effect of treating lower limb ulcers, burn infections. In this paper, we studied the effect of Strictosamide (STR), the main bioactive compound in Nauclea officinals, on wound healing and explored its internal mechanism. Firstly, the wound healing potential of STR was evaluated in a rat model, demonstrating its ability to expedite wound healing, mitigate inflammatory infiltration, and enhance collagen deposition. Additionally, immunofluorescence analysis revealed that STR up-regulated the expression of CD31 and PCNA. Subsequently, target prediction, protein-protein interaction (PPI), gene ontology (GO), and pathway enrichment analyses were used to obtain potential targets, specific biological processes, and molecular mechanisms of STR for the potential treatment of wound healing. Furthermore, molecular docking was conducted to predict the binding affinity between STR and its associated targets. Additionally, in vivo and in vitro experiments confirmed that STR could increase the expression of P-PI3K, P-AKT and P-mTOR by activating the PI3K/AKT signaling pathway. In summary, this study provided a new explanation for the mechanism by which STR promotes wound healing through network pharmacology, suggesting that STR may be a new candidate for treating wound.
... Immediately following a burn injury, haemostasis is induced, a process that is characterised by platelet activation and aggregation, which subsequently results in the formation of a transient fibrin clot, providing a provisional or temporary matrix to allow the subsequent recruitment of inflammatory cells [15]. Neutrophils and monocytes, the precursors of macrophages, are recruited to the injury site to orchestrate the eradication of pathogenic microbial agents, clearance of extracellular matrix (ECM), and perpetuation of the inflammatory response. ...
Burn injuries are among the most common types of injuries worldwide, with devastating long-term physical and psychological effects. Recently, adipose-derived stem cells (ADSCs) have shown promise as a potential therapeutic approach for reversing fibrosis, promoting wound healing, and remodeling scars in various types of injuries. ADSCs possess unique features such as multipotency, immunomodulation, and the ability to secrete regenerative factors. These characteristics position them as attractive candidates for enhancing tissue regeneration and reducing inflammation in burn injuries. This overview discusses the current understanding of the biological properties of fat grafts, focusing on ADSCs, in relation to burn injury mechanisms and its clinical manifestations. We examine the role of ADSCs in burn injury and recovery, exploring potential mechanisms of action and future research directions. The aim is to facilitate the clinical application of ADSCs in treating burns and to address the challenges of their clinical use highlighting areas for further research.
Level of evidence: Not ratable
... Wound healing refers to a living system's replacement of destroyed or damaged tissue by newly produced tissue. 1 Wound healing is a complex biological process that consists of hemostasis, inflammation, proliferation, and remodeling Many types of cells include neutrophils, macrophages, lymphocytes, keratinocytes, fibroblasts, and endothelial cells-these all are involved in the wound healing process. Several elements can cause reduced wound healing by affecting single or multiple phases of the process and are divided into local and systemic factors. ...
... Wound healing is a complex biological process that involves the restoration of tissue and occurs through various sequential phases [159]. An ideal wound dressing should have the capability to absorb exudate from the wound while simultaneously allowing for the permeation of oxygen. ...
... In healthy skin, the outermost layer, also known as the epidermis, and the innermost layer, the dermis, are in a constant state of balance with one another and provide a defence against the environment. Upon piercing the protective barrier, the body's natural healing mechanisms kick in [2]. ...
Aim: An essential medicinal plant, Echhornia crassipes is a member of the Pontederiaceae family and is used to treat a wide range of disorders. Using various animal models, this study sought to investigate the anti-inflammatory and wound-healing benefits of an ethanolic extract of E. crassipes. Study Design: This study engaged in vivo studies to investigate the wound healing and anti-inflammatory studies of the extract when compare with standard treatment. Place and Duration of Study: Department of Pharmacology, Gokaraju Rangaraju College of Pharmacy, Bachupally, Hyderabad, Telangana, India. Methodology: The optimal dosage of MEEC (Methanolic Extract of Eichhornia crassipes) was established by conducting acute toxicity tests. The efficacy of wound healing was assessed in this study by means of excision and incision wound models. For the purpose of inducing paw oedema and testing the anti-inflammatory efficacy, we utilised carrageenan and formalin, respectively. Results: Experiments on acute toxicity indicated that the extract was acceptable at doses up to 2000 mg/kg. Two gel concentrations of the extract, 5% and 10%, were applied topically. Wounds healed significantly faster with 10% MEEC gel than with the conventional 10% povidone iodine ointment. Similar to the gold standard drug diclofenac, MEEC at doses of 200 mg/kg b.w. and 400 mg/kg b.w. demonstrated strong anti-inflammatory effects in the two animal models. Conclusion: The benefits of MEEC on wound healing and inflammation may be attributed to its chemical components, which include alkaloids, flavonoids, triterpenoids, and sterols.
... that, the remodelling phase occurs by collagen fiber maturation, migration of epithelial cells from the wound edge, and, ultimately, wound closure [36]. The immune system is the primary investigator in wound healing, where it participates in homeostasis following skin injury through collaboration between diverse pro-angiogenic cells such as leuckocytes, monocytes, macrophages, fibroblasts, endothelial and epidermal cells, as well as a series of cross-cellular reactions such as hemostasis, inflammation, proliferation, and remodelling to promote cell differentiation, ECM deposition, and predispose secretion of growth factors [37]. Our study was the first to elucidate the topical application of TQcp on the rat wound model. ...
Wound healing is a series of coordinated events that involve tissue repair and regeneration. Cold atmospheric plasma approach sheds the light on the mechanism that initiates the inflammatory responses throughout the healing cascade. The present study was planned to assess the effect of thymoquinone treated with cold plasma (TQcp) on the rat wound model compared to thymoquinone (TQ). To assess the wound healing potential of TQcp, a full-thickness wound model was used. The induced wound was smeared, starting just after excision, twice daily with TQcp and TQ for 7 days. Our findings revealed that TQcp improved the skin healing potential by augmenting the skin regeneration indices as evidenced by enhancing the new production of hyaluronic acid and collagen type I. TQcp significantly reduced the skin content of tumor necrosis factor- α and inhibited the hypertrophic scarring by up-regulating the skin content of transforming growth factor-beta. Furthermore, TQcp enhanced the levels of interleukin-10, alpha smooth muscle actin and vascular endothelial growth factor, demonstrating a great potential for wound healing that also reflected in the histopathological and ultra-structural picture of the skin. Finally, our results demonstrated that TQcp revealed a significant potential for wound healing than TQ alone.
... Angiogenesis and keratinocyte migration are important factors in this phase, with VEGF and FGF playing a critical role in regulating angiogenesis 33 . Fibroblasts also play a crucial role in this phase by transforming into myofibroblasts, which contract and contribute to wound closure 34 . The MSCs play a vital role in this stage by manipulating macrophages to recruit keratinocytes and fibroblasts to the wound site and promote their migration and proliferation 35 . ...
Skin is the largest organ in the human and animal body and serves as the first line of defense against the external environment. The present study aimed to summarize the mechanisms underlying the effect of MSCs on wound healing and describe the latest strategies to enhance their therapeutic efficacy. Wounds caused by cuts, abrasions, or burns can disrupt the skin integrity, leading to severe consequences, such as infections, scarring, and reduced mobility. Therefore, effective wound healing therapies are essential to reduce the risk of complications and improve the quality of life for patients. In recent years, mesenchymal stem cells (MSCs) have emerged as promising therapy for wound healing due to their unique properties. The MSCs are found in various tissues, including the bone marrow, and can differentiate into multiple cell types, including skin cells. Additionally, MSCs can secrete substances with anti-inflammatory, anti-fibrotic, and pro-angiogenic properties, which play a critical role in the wound healing process. The MSCs can release these substances as soluble molecules, such as growth factors and cytokines, or enclosed within membrane vesicles like microparticles and exosomes. By releasing these substances, MSCs can reduce inflammation, prevent excessive scarring, and promote the growth of new blood vessels, which are crucial for effective wound healing. The MSC-based therapies have indicated promising results for wound healing. However, the optimal dosage, route of administration, and timing of MSC-based treatments for wound healing applications are yet to be determined. Despite the great potential of bone marrow-derived MSCs to improve the healing process of damaged skin caused by wounds and burns, more research is needed to fully understand how MSCs enhance wound healing and optimize their use in clinical settings.
... However, it was found that linearly shaped wounds have significantly different dynamics from, e.g., circular wounds (3). Although there have long been efforts by clinicians to explore better ways to manage surgical cuts [e.g., zigzag incisions to improve scarring (4)], scientific studies based on molecular and cellular biology have only been pursued recently (5). The last stage of wound healing involves reepithelialization-the wound gap closure by epithelial cells (6). ...
Wound healing through reepithelialization of gaps is of profound importance to the medical community. One critical mechanism identified by researchers for closing non-cell-adhesive gaps is the accumulation of actin cables around concave edges and the resulting purse-string constriction. However, the studies to date have not separated the gap-edge curvature effect from the gap size effect. Here, we fabricate micropatterned hydrogel substrates with long, straight, and wavy non-cell-adhesive stripes of different gap widths to investigate the stripe edge curvature and stripe width effects on the reepithelialization of Madin-Darby canine kidney (MDCK) cells. Our results show that MDCK cell reepithelization is closely regulated by the gap geometry and may occur through different pathways. In addition to purse-string contraction, we identify gap bridging either via cell protrusion or by lamellipodium extension as critical cellular and molecular mechanisms for wavy gap closure. Cell migration in the direction perpendicular to wound front, sufficiently small gap size to allow bridging, and sufficiently high negative curvature at cell bridges for actin cable constriction are necessary/sufficient conditions for gap closure. Our experiments demonstrate that straight stripes rarely induce cell migration perpendicular to wound front, but wavy stripes do; cell protrusion and lamellipodia extension can help establish bridges over gaps of about five times the cell size, but not significantly beyond. Such discoveries deepen our understanding of mechanobiology of cell responses to curvature and help guide development of biophysical strategies for tissue repair, plastic surgery, and better wound management.
... The condition and quality of the skin is a key sign of overall health, wellness, and beauty; however, as a protective shield, the skin is repeatedly subjected to multiple injuries and complaints that affect humans at all ages and cause harm in intricate ways (Abbasi et al., 2010). Of these, wounds are major skin disorders brought about by surgical, abrasive or infectious causes that alter the integrity of outer skin tissues and have therefore become a point of clinical, dermatologic, and cosmetic concern (Nguyen et al., 2009;Udegbunam et al., 2015;Chopra et al., 2022). Today, many wound types are known to produce skin damage or dysfunction, e.g. ...
Narcissus plants have long been recognized as a source of natural cosmetics and skincare botanicals since ancient times. Among them, Narcissus pseudonarcissus L. was commonly used for a plethora of skin disorders, e.g. abscesses, sores, burns, bruising, freckles, and wounds; however, no previous scientific reports have deliberated its wound curative properties. Therefore, this study was designed to explore the wound healing potential of the total extract of N. pseudonarcissus bulbs and its derived fractions (I-IV) on normal lung fibro-blast (WI-38) cells using the wound scratch assay. Firstly, the possible cytotoxic effects of N. pseudonarcissus total ethanol extract and fractions towards WI-38 cells were examined using the MTT assay and the most appropriate concentrations (either non-toxic or showing the least toxicity) were selected for the wound healing assay accordingly. Overall, WI-38 cells treated with 31.25 and 62.50 mg/mL of the petroleum ether fraction (I) exhibited both negligible cytotoxicity (IC 50 = 1207.96 mg/mL) and the highest wound closure and migration rates after 24 and 48 h compared to either the untreated control cells as well as those treated with the other fractions. Additionally, phytochemical analysis of fraction (I) led to the isolation of varied metabo-lites, e.g. hydrocarbons, monoglycerides, pyrrolidines, and steroids that were first described herein in either the genus Narcissus or the family Amaryllidaceae. Finally, molecular docking analysis of the identified metab-olites revealed their possible interaction with a group of enzymes that affect different stages of wound healing , particularly steroidal metabolites, of which sitosterol 3-O-b-glucopyranoside-6ꞌ-O-hexadecanoate (7) showed noteworthy binding affinities to TGF-b, GSK-3, TNF-a, and IL-1b proteins. These findings could therefore endorse the traditional use of N. pseudonarcissus for wounds and its potential to develop alternative plant-derived cosmeceuticals for skin repair.
... Besides this, there is not a single synthetic drug formulation in the market which can claim for its wound healing properties. The drugs available are either bacteriostatic or bactericidal and in these cases healing is by a natural phenomenon only (Nguyen et al., 2009). ...
To achieve the purpose of this study 40 male college level volleyball players who were in various colleges of tehsil Devsar of district Kulgam, Jammu and Kashmir were randomly selected as subjects. The age ranged from 17-23. The selected subjects were divided into two groups and each group consists of 20 subjects, that is 20 subjects for experimental group and 20 subjects for control group.
... Therefore our results suggest a more direct role of MPs in SSc pathophysiology, however it will be of great importance to analyze MPs content in our patients and seek any association with clinical parameters in order to shed light on mechanisms of MPs profibrotic properties. A previous study has described that EMPs from idiopathic pulmonary fibrosis patients stimulated the migration of normal human lung fibroblast (32) and other reports suggest direct implication of MP in fibrosis genesis, through their content or their surface markers [DAMPs, metabolite implied in the ROS production or nuclear factor B pathway, plasmin expression etc.; (33)]. Another recent observation, provided by Wermuth et al., show the profibrotic effect of exosomes from SSc patients (34). ...
La sclérodermie systémique est une maladie auto-immune rare. Ses atteintes à la fois cutanées et viscérales peuvent impacter durablement la qualité de vie des patients, voir présenter un pronostic sombre. Bien que nous sachions que cette maladie associe vasculopathie, fibrose et dysimmunité, sa physiopathologie reste encore mal comprise, compliquant sa prise en charge. Depuis quelques années, la recherche s’intéresse à un nouveau médiateur pouvant aider à mieux comprendre cette pathologie : les microparticules. Ces dernières sont des structures vésiculaires dont la taille est comprise entre 100 nm et 1 µm et qui dérivent de sources cellulaires multiples telles que les plaquettes, les cellules endothéliales, les leucocytes, etc. Elles expriment et contiennent toute une variété de molécules pouvant réguler l'inflammation et jouer sur la fibrose. Plusieurs travaux ont mis en lumière la présence de concentrations anormalement élevées en microparticules dans plusieurs pathologies inflammatoires, dont notamment la sclérodermie systémique.Dans ce travail nous avons montré que les patients sclérodermiques présentaient des taux en microparticules, notamment d’origine plaquettaire, plus élevés que les sujets sains. Parmi ces mêmes patients, nous avons montré que ce sont ceux atteints de fibrose pulmonaire et d’ulcères digitaux actifs qui ont les plus forts taux en microparticules. De plus, nous avons également montré l’effet profibrotique de ces microparticules de patients sclérodermiques sur des fibroblastes de sujets sains.Par la suite, nous avons cherché à savoir quels pouvaient être les effets immunologiques des microparticules. Nous avons focalisé notre attention sur une composante essentielle de la réparation tissulaire : l’efferocytose. Cette fonction comprend à la fois la prise en charge des cellules apoptotiques, pour limiter la formation de corps nécrotique secondaire, et la production de facteurs en faveur de la résolution de l’inflammation. Il a récemment été montré que les macrophages de patients sclérodermiques présentaient une efferocytose altérée, via la diminution de plusieurs récepteurs à leur surface. Nous avons donc cherché s’il pouvait exister un lien entre défaut d’efferocytose et microparticules, notamment plaquettaires. Nous avons observé que les plaquettes de patients sclérodermiques agissaient sur les macrophages en diminuant leur capacité d’efferocytose. Nous avons pu voir également que de fortes concentrations en microparticules plaquettaires avaient un impact sur l’expression du récepteur MerTK impliqué dans l’efferocytose.Ainsi, nos observations permettent de renforcer l’impact des plaquettes sur la physiopathologie de la sclérodermie systémique. De plus, nos résultats montrent que les microparticules semblent être des médiateurs impliqués dans les liens entre dysimmunité, fibrose et vasculopathie.
... In healthy skin, the epidermis and dermis can protect the skin and act as a barrier to the external environment. Once the barrier is broken, a controlled sequence of organic chemical events is triggered to repair the damage [133,134]. Human skin wound healing consists of four dynamic overlapping stages hemostatic, inflammation, proliferation, and remodeling [135]. The wound is difficult and fragile to heal, it is believed that once interrupted or failed, leading to the formation of chronic non-healing wounds such as diabetes, vascular disease, infection, and metabolic disease [136]. ...
Essentially cell forming and vigorous conjunctive tissues such as skin, joints, ligaments, and bones are expressed as fibril forming the most abundant protein collagen in the human body substantially about one-quarter by weight. Additionally, amongst the biopolymers, the collagen macromolecule is serving humanity in myriad ways. Although it has been used in cosmetics for a long time, nowadays its biological characteristics like nontoxic, biocompatible, biodegradable, structural integrity, cellular affinity and weak antigenicity have encouraged using of it significantly in biomedical and pharmaceutical applications. Its excellent biodegradability and notable bioactivity by endogenous collagenases enzyme convert exogenous collagen for biomedical use. Triple helix 29 collagen composed of three α-chain characteristic variants, type I is the most suitable extracellular matrix (ECM) macromolecule gradually consumed thickness and strength with time being, can be correlated with skin aging phenomena. This review focuses on the sources, structures, extractions, and properties (e.g., bioactive, mechanical, viscoelastic, tensile, etc.) of collagen proteins for use in biomedical applications. The abundance of collagen protein from a natural source can be effectively used in human tissue scaffolds, cardiac implantation, wound healin g, cornea membranes, dental membrane, dermal filler, cosmetic surgery, etc. as highlighted in this review. The application-based advantages and disadvantages of body-suits collagen are also discussed with prospects.
... Wound healing is a complex mechanism in which an organ's tissue recovers itself after trauma. 32 DFUs do not heal in a predictable or organized manner. 31 Multiple factors, including bacterial infection, might cause wound healing to be delayed in DFUs. ...
Background: Diabetic foot ulcer (DFU) complications are the most common cause of morbidity in diabetic patients. Bioptron light therapy is a new adjuvant therapy for wound healing. This study aimed to investigate the effect of polarized light therapy on the healing and microbial nature of DFUs. Methods: Forty type 2 diabetic patients with Wagner grade 1 or 2 DFUs were randomly assigned to one of two groups: the light therapy group, which received Bioptron light therapy using the Bioptron lamp for 12 min three times per week, plus standard wound care, or the control group, which received standard wound care only. Both interventions were given over a 2-month period. Wound surface area, volume, and ulcer microbial cultures were all measured before and after the study period. Results: There was a significant reduction in ulcer surface area between groups in favor of the light therapy group, with a relative ulcer size reduction of 51.44% ± 23.76% compared with 24.5% ± 9.6% in the control group (p < 0.001). Besides, a significant difference was observed between groups in the microbial cultures (p = 0.02); by the end of the 8th week, the number of patients with negative ulcer culture was 12 (60%) in the light therapy group compared with 3 (15%) in the control group. Conclusions: Bioptron light therapy seems to be an effective therapeutic intervention combined with standard care in decreasing wound size and reducing ulcer microbiota for DFUs. It reduces ulcer bacterial infection and speeds up ulcer healing. Trial registration: ClinicalTrials.gov: NCT04446767.
... Macrophages are essential for wound healing. [1] They replace PMNs as the predominant cells in the wound by two days after injury. [2] Attracted to the wound site by growth factors released by platelets and other cells, monocytes from the bloodstream enter the area through blood vessel walls. ...
Cicatrisation, is an intricate process in which the skin repairs itself after injury. Considerable effort has been devoted to understanding the physical relationships governing wound healing and subsequent scarring with simulation developed to elucidate these relationships. Particularly, Rosa indica linn were used in the management of many infections and diseases. During study of wound healing in normal rats following results were obtained: Acute toxicity studies showed that drug was found to be safe up to maximum dose of 2g/Kg body weight of the animal. In studies using excision wound model, the latex treated group III showed significantly greater wound healing as compared to control animals. The standard drug treated in normal animals were showed significantly greater wound closure as compared to control and latex treated animal. In the inflammatory phase, bacteria and debris are phagocytosed and removed, and factors are released that cause the migration and division of cells involved. Fibrin and fibronectin cross-link together and form a plug that traps proteins and particles and prevents further blood loss. This fibrin-fibronectin plug is also the main structural support for the wound until collagen is deposited. The plant Rosa indica have wide ethnomedicinal use. The literatures revealed that there is lack of scientific reports on its leaves. So it is important to provide scientific means in a systematic manner. The findings from this research indicates that the extract of Rosa indica linn are effective in inhibiting the growth of wound and faster the process of wound healing.It is estimated that surgical wound infections result in an increased length of hospital stay by about 7-10 days. Hence the prevention and management of wound infections has a major impact on both patient health and health economics.
... There is a significant interaction between the cells and the extracellular matrix. Wound healing is also influenced by the action of growth factors, chemokines, cytokines, chemokines, receptors, etc. [18,19]. ...
Most commercialized wound dressings are polymer-based. Synthetic and natural polymers have been utilized widely for the development of wound dressings. However, the use of natural polymers is limited by their poor mechanical properties, resulting in their combination with synthetic polymers and other materials to enhance their mechanical properties. Natural polymers are mostly affordable, biocompatible, and biodegradable with promising antimicrobial activity. They have been further tailored into unique hybrid wound dressings when combined with synthetic polymers and selected biomaterials. Some important features required in an ideal wound dressing include the capability to prevent bacteria invasion, reduce odor, absorb exudates, be comfortable, facilitate easy application and removal as well as frequent changing, prevent further skin tear and irritation when applied or removed, and provide a moist environment and soothing effect, be permeable to gases, etc. The efficacy of polymers in the design of wound dressings cannot be overemphasized. This review article reports the efficacy of wound dressings prepared from a combination of synthetic and natural polymers.
... Wound healing or wound repair is an intricate process in which the skin remodels itself after injury [3]. Cutaneous wound healing is an essential pathophysiological process envisaging the combined involvement of certain angiogenic and Vasculogenic markers i.e. ...
Present study was conducted to undermine the wound healing potential of mangiferin vis a vis its molecular dynamics in immunocompromised excisional rat model. 120 rats were randomly and equally divided into five groups viz. group I (Healthy control), group II (Immunocompromised control), group III (Immunocompromised group treated with silver sulphadiazine), group IV (Immunocompromised group treated with 2.5 %Mangiferin) and group V (Immunocompromised group treated with 5 %Mangiferin). Immuno compromised state was achieved following intramuscular injection of Hydrocortisone @ 80 mg/kg body weight. Study was conducted for a period of 28 days. Six animals from each group were humanely sacrificed at weekly interval till day 28th of study. Planimetric analysis, biochemical studies viz. hydroxyproline assay, total protein and DNA content, antioxidative potential through LPO assay was done along with molecular studies involving expression profiling of IL1β, TNFα and COX-2 and Immunohistochemistry of angiogenic marker i.e. VEGF was performed to undermine the pharmacodynamics of mangiferin. Histopathological studies including H&E and Masson’s Trichome was also performed to study histoarchitectural changes in wound healing and reparative process following application of mangiferin ointment. Study revealed significant (P ≤ 0.05) reduction in wound area measurement and significant (P ≤ 0.05) increase in wound contraction (%) following mangiferin administration in immunocompromised rats. Hydroxyproline, DNA and total protein showed significant (P ≤ 0.05) increase in skin tissues of mangiferin treated immunocompromised rats. LPO assay revealed significant (P ≤ 0.05) reduction in mangiferin treated animals. Histopathological studies of skin tissues revealed complete restoration advocating grade III of healing in 2.5% mangiferin treated group. Higher expression and strong signal intensity of VEGF was noticed in 2.5% mangiferin treatment group along with significant (P ≤ 0.05) upregulation IL1β and TNFα on day 7 in 2.5% mangiferin treatment group with significant (P ≤ 0.05) down regulation of COX-2 in mangiferin treatment group as compared to other groups i.e. group II and III. It is concluded from our study that mangiferin facilitates wound healing through improved wound closure, organized deposition of collagen deposition and granulation matrix formation.
... Wound healing is a normal biological process in the human body in which the skin and the tissue repair themselves after injury [21]. Wound healing is a vital process that consists of four uninterrupted overlapping and programmed phases such as hemostasis, inflammation, proliferation, and tissue resolution [15]. ...
Background
Diabetes is a chronic disease, affecting more than 8.5 % adults population in the world. Among various issues caused by diabetes, wound healing is a major cause of concern.
Objective
Injuries are most common, can be caused normally like abrasion, laceration (cuts), injury, etc. But in diabetes, they do not heal so easily and cause problems. It can be due to compromised immune system, neuropathy, poor circulation, infections etc., which could lead to amputation or even death. Current therapies, for the treatment of wound healing in diabetic patients, have side effects of their own as there is no particular drug for the healing of wounds
Methods
Numerous survey in Literature was carried out to reveal the obstacles in diabetic wound healing and current approaches to its management with emphasis on alternative therapies. Relevant peer-reviewed research publications were searched through various online bibliographic databases such as ScienceDirect, PubMed, Scopus, Google Scholar, and ResearchGate (all English-language articles).
Results
Repurposed drugs include a class of statin, phenytoin, estrogen, DPP4 inhibitors. Plants with wound healing activity include Rosmarinus officinalis, Radix Rehmannia, Carica papaya, Aloe vera, Catharanthus roseus, Punica granatum, etc. have been explored in Pre-clinical studies. Besides these studies, a lot of other studies including clinical trials have been performed for wound healing in diabetes by using different procedures like Honey-dressing, Royal Jelly, Extracorporeal Shock wave therapy, Manuka honey-impregnated dressing, LeucoPatch system, etc.
Conclusion
In this review, an approach was made to study wound healing in diabetes and various options that could be best suited for the treatment of wounds in Diabetes.
... For the tissue to regain its integrity, the damaged tissue begins the orderly process of wound healing immediately an injury occurs [4,5]. Hemostasis, inflammation, proliferation, and remodeling are some of the mechanisms involved in wound healing [6,7]. In general, wound contraction, epithelialization, and granulation tissue formation are the measurable phenomena involved in wound healing [7], with the individual contributions depending on the category of wound in question. ...
Lannea barteri Oliv. (Anacardiaceae) gained popularity in traditional medicinal practice in the treatment of neurological disorders (madness, epilepsy and paralysis). It is mostly used to treat wounds, sores and leprosy in the western and middle belts of Nigeria. The L. barteri leaf extract (LBLE) and fractions were assessed for their wound healing and antimicrobial potentials. In incision wound model, 10, 20 and 40%w/w of extract and fractions were used. Gentamicin ointment (1%) and sterile soft white paraffin served as positive and negative controls respectively. The antimicrobial activity was evaluated in vitro using broth dilution method. The extract and fractions caused a dose-dependent significant (p < 0.05) increase in the wound breaking strength with 40% n-hexane fraction exhibiting the highest wound breaking strength of 650 g. All tested microorganisms were sensitive to the methanol extract. Most of the organisms were susceptible to the fractions. E. faecalis ATCC 29219 was resistant to the fractions. The minimal inhibitory concentrations (MICs) and minimal biocidal concentrations (MBCs) of the methanol extract and fractions against susceptible pathogens were in the range 1.67 to 100 mg/ml while the minimal fungicidal concentrations (MFCs) of the fractions against A. fumigatus (Af293) and A. fumigatus (Ku80) was 100 mg/ml. This study established that the methanol leaf extract and fractions of L. barteri potentiated wound healing and inhibited the growth of pathogenic microorganisms. The study thus, validated the folkloric use of L. barteri for the treatment of skin and wound infections and forms a strong basis for further exploration of the plant.
... Wound is a break in the normal continuity of the skin which results in disruption in the cellular, anatomic and functional continuity of the body (Heydrari et al., 2011). Toxins resulting from surgical sepsis, infections and immune-suppressive agents have been incriminated in cutaneous wounds formation (Nguyen et al., 2009). Wound healing is a complex self-initiated process by which a disrupted organ/tissue repairs itself after injury (Nilani et al., 2011). ...
Background: Stephania dinklagei Diels (Engl.) is used in folkloric medicine in Southeastern Nigeria for treatment of wounds and some bacterial-associated infections. This study evaluated the wound healing and antibacterial potential of Stephania dinklagei to validate or invalidate its folkloric use. Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of methanolic extract of S. dinklagei root (MESDR) against Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Klebsiella spp. was determined by macrobroth dilution. The extract at 20% and 10% concentrations were dosed orally to rats at 300mg/kg body weight (bw) in incision and dead space wound healing model to determine wound tensile strength and granulation tissue weight, respectively. Same extract concentrations were applied topically in excision wound model to determine the rate of wound contraction and epithelialization. Activities of superoxide dismutase (SOD), catalase (CAT), and the levels of total protein (TP), malondialdehyde (MAL), hydroxyproline (HYP) and hexosamine (HEX) in excision wound biopsies were determined at days 7 and 14 post wounding (pw). In the excision wound model, the extract concentrations were compared with gentamicin sulphate. Results: The MIC of S. dinklagei extract against P. aeruginosa, S. aureus, B. subtilis, E. coli and Klebsiella spp. were 8mg/ml, 3 mg/ml, 5mg/ml, 6mg/ml and 7mg/ml, respectively, while the corresponding MBC were 10 mg/ml, 5 mg/ml, 7mg/ml, 8mg/ml, and 9 mg/ml, respectively. The 20% extract concentration gave significantly (P0.05) at day 14 pw. HYP level of the extract-treated groups significantly (P
... Traditional plant medicines or herbal formulations might offer a natural key to managing diabetic complications. Wound healing, or cicatrisation, is an intricate process in which the skin (or another organ-tissue) repairs itself after injury (Murphy et al, 2009). When tissue is first wounded, blood comes in contact with collagen, triggering blood platelets to begin secreting inflammatory factors. ...
Background: This study was designed to ascertain this claim and to investigate the possible mechanism of action in relation to their phytochemical contents, using crude extracts of N. latifolia and M. esculenta leaves on topical wound in a rat model of Type 1 diabetes. Methods and Materials: The leaves were air-dried under shade and subjected to cold extraction in 95% ethanol. Normoglycaemic male Wistar rats were subjected to 2-month high-energy diet/ fat emulsion manipulation and injected with alloxan (150 mg/kg BW/day, i. p.). Fasting plasma glucose was determined after 7 days and rats with values exceeding 200 mg/dl were selected. 16 diabetic rats (120 – 180 g) were randomly assigned to four groups of four animals each. Wound was inflicted on the back of each rat by excision method. The crude extracts were topically applied over a period of 21 days. The scar tissues were removed at 7 days interval for collagen quantification and wound margin reduction was also monitored using tracing paper. Results: The crude extracts showed efficient wound healing activity as revealed by increased collagen content (scar tissues versus fresh wound tissues ab initio). Percentage wound closure also progressed significantly (p< 0.05) upon topical application of the extracts. Conclusion: The crude extract of N. latifolia leaves has proven to be more potent than that of M. esculenta in wound healing in Type I diabetic rats. It stimulated wound contraction and collagen formation, making it a promising natural product for further screening in search of new chemical entities that can be useful in diabetic wound management.
... 3. Реорганизация рубца и эпителизация, 15 дней -6 мес. [23][24][25]. ...
Introduction. Literature review search did not show enough information to answer the question concerning the need to remove hair in the external auditory canal as a part of preoperative preparation of the surgical field in middle ear surgery with endaural and transcanal approaches.
Aim of the study. To substantiate the removal of hair from the external auditory canal during transcanal and endaural otosurgery.
Materials and methods. A prospective randomized study included 2 groups. In the first group, tympanoplasty and stapedoplasty were performed via endaural approach with and without hair removal in the external auditory canal. The effect on the intraoperative overview and postoperative wound healing was assessed. Shunting of the tympanic cavity in the second group, with transcanal approach, have been performed under the control of a microscope and endoscope. The evaluation was done via a questionnaire, it was given to the doctor before and after hair removal separately. Postoperative inflammatory reaction was also assessed.
Results. Postoperative wound healing of the external auditory canal in the first group were considered comparable between the main and the control group, and had no complications. In the second group, inflammation was absent in all patients. Hair removal significantly improve the visibility in endaural and transcanal approach.
Conclusions. Hair removal from the external auditory canal increases the visibility of the surgical field and facilitates the work of an otosurgeon. It is especially recommended as a preoperative preparation, especially for transcanal surgical interventions on the middle ear under endoscope control.
... Melanocyte stem cells Bulge and bulb [13] Maintenance of periodic cycles of hair pigmentation [14] 4 ...
Purpose of Review
In this article, we summed up the different types of stem cells which are present in the skin and the role of adipose-derived stem cells (ADSCs) in providing various anti-aging properties.
Recent Findings
Adipose-derived stem cells (ADSCs) can be utilised in numerous unbelievable ways like in skin regeneration, soft tissue augmentation, anti-aging therapy, curing wrinkled skin and even in skin whitening. ADSCs prove to be useful even in cosmetic surgeries where it increases the success rate dramatically with the fusion of fat grafts and lipo-injections.
Summary
We sum up the various other related properties of ADSCs like angiogenesis, plastic surgery and cancer treatment and their applications in curing skin diseases.
... While discharging their various functions in the body, which range from homeostasis to inflammation and tissue regeneration, these cells encounter diverse microenvironmental cues that are thought to impact their function by altered cellular shape, spread, focal adhesion, and force generation [6][7][8][9]. Macrophages are among the early responders to injury sites, appearing between 24 and 48 h after injury [10], and often encountering a compliant microenvironment in the form of a fibrin clot [11]. External wounds are accompanied by the presence of invading pathogens and neutrophil signaling, which provoke a proinflammatory phenotype in macrophages, unleashing free radicals and phagocytosis-mediated immunity. ...
Macrophages are innate immune cells that help wounds heal. Here, we study the potential immunomodulatory effects of negative-pressure wound therapy (NPWT) materials on the macrophage inflammatory response. We compared the effects of two materials, Granufoam™ (GF) and Veraflo Cleanse™ (VC), on macrophage function in vitro. We find that both materials cause reduced expression of inflammatory genes, such as TNF and IL1B, in human macrophages stimulated with bacterial lipopolysaccharide (LPS) and interferon-gamma (IFNγ). Relative to adherent glass control surfaces, VC discourages macrophage adhesion and spreading, and may potentially sequester LPS/IFNγ and cytokines that the cells produce. GF, on the other hand, was less suppressive of inflammation, supported macrophage adhesion and spreading better than VC, and sequestered lesser quantities of LPS/IFNγ in comparison to VC. The control dressing material cotton gauze (CT) was also immunosuppressive, capable of TNF-α retention and LPS/IFNγ sequestration. Our findings suggest that NPWT material interactions with cells, as well as soluble factors including cytokines and LPS, can modulate the immune response, independent of vacuum application. We have also established methodological strategies for studying NPWT materials and reveal the potential utility of cell-based in vitro studies for elucidating biological effects of NPWT materials.
... Wound healing or wound repair is an intricate process in which the skin repairs itself after injury (Nguyen et al., 2009). In normal skin, the epidermis and dermis exist in steady-state equilibrium, forming a protective barrier against the external environment. ...
The aim of this study was to investigate the anti-diabetic and wound healing properties of Cissus multistriata leaf extract. Diabetes mellitus was induced with alloxan and graded doses of methanol leaf extract of Cissus multistriata were administered orally to the experimentally diabetic rats for 28 days at 400, 800 and 1600mg/kg b.w for groups. Administration of the methanol extract elicited a statistically significant (P<0.05) reduction in blood glucose level in alloxan induced diabetic rats. The reduction was dose dependent. There was reduction in blood haemoglobin and increase in body weights of animals which were statistically significant (P<0.05) when compared with the control. Three groups of male rats each consisting of four rats were used for the evaluation of wound healing potential of the extract. Groups 1, 2 and 3 were treated topically with C. multistriata, Povidone iodine (drug) and paraffin base (negative control), respectively. The extract significantly (P<0.05) accelerated wound healing process compared to standard povidone iodine used. It could be stated that Cissus multistriata possesses hypoglycemic and wound healing properties.
... Wound healing is a complex physiological process that occurs in the skin and the tissues under it (Nguyen et al., 2009). The wound healing process depends on cellular and molecular mechanisms and divided into three overlapping and interdependent phases, including inflammatory phase (consisting of homeostasis and inflammation), proliferative phase (consisting of granulation, contraction and epithelialization) and remodelling phase (Ximenes et al., 2013). ...
Background
Ferula persica is one of the most important traditional medicinal plants that is used to treat various diseases such as diabetes, backache and rheumatism. The aim of the present study was to evaluate the anti‐inflammatory and wound healing potential of F. persica using stereological and molecular methods in experimental models.
Methods
In the present study, two wound models (circular excision and linear incision) were used. Male Wistar rats were divided into four groups (n = 16), including control, vehicle treated, treated with F. persica extract ointment (5% w/w) and treated with the reference drug (Madecassol). All the animals were treated topically once a day. The circular and linear wounds were treated for 9 and 17 days, respectively. At the end of the study, samples from wounds area were harvested for histology, stereology, immunohistochemistry and molecular assessments to determine the in vivo healing potential and anti‐inflammatory activity.
Results
We observed significant recovery in macroscopic evaluation of wound healing in the F. persica extract treated group compared with the control and vehicle treated groups (p < 0.05). Histological and stereological assessments showed complete repair of the epidermal layer, increasing fibroblast cells and collagen density, decreasing inflammatory cells and a remarkable degree of neovascularization by determining length density of blood vessels in the extract group, which were significant as compared to the control and vehicle treated groups (p < 0.05). Expressions of TNF‐α and TGF‐β were found to be decreased and increased (p > 0.05, p < 0.05, respectively), in the extract treated group as compared to the control and vehicle treated groups. Also, greater COX‐2 expression could be detected in the control and vehicle treated groups, which was significantly attenuated in the extract group.
Conclusion
Our results confirm that the F. persica extract is a valuable source of antioxidant and anti‐inflammatory activity and can allow damaged tissue in wounds to recover markedly.
The content of this book covers new developments in applications of mathematics in science and engineering, with an emphasis on mathematical and computational modeling. Topics range from the use of differential equations to the employ of number theory in the development of information security and ryptography. Educational issues of mathematical competencies by engineering and science students at all university levels are also touched on. Researchers, practitioners, and university students can significantly benefit from this book, especially those seeking advanced methods for applying mathematics to various contexts and fields.
Introduction: The leaves of Saraca asoca (the Ashoka tree), a member of Caesalpinioideae family, have been used widely in Traditional medicines; however, their wound healing ability in diabetic condition is not investigated yet. The aim of present study was to investigate the anti-diabetic and wound healing potential of Saraca asoca leaves extract in various streptozocin induces diabetic animal models. Methods: Antidiabetics activity was evaluated in streptozocin induced rat models and wound healing potential was determined using excision and incision wound models. Results: The aqueous and ethanolic extracts induced hypoglycemia and improved glucose tolerance in normal rats, despite the presence of counter-regulatory mechanisms aimed at preventing a decrease in blood glucose levels. This suggests that the hypoglycemic action of the aqueous and ethanolic extracts may be attributed to extra-pancreatic processes or by stimulating the remaining cells to produce more insulin. Conclusion: The present study suggests that the extracts of Saraca asoca leave have significant anti-diabetic and wound healing potential.
Uncontrolled hemorrhage from wounds is a significant cause of morbidity, highlighting the need for rapid and effective hemostatic interventions. Wound dressings play a crucial role in managing blood loss and fluid exudation while supporting the dynamic wound-healing process. This process involves hemostasis, inflammation, proliferation, angiogenesis, and remodeling to restore the skin's barrier function. Among available options, dry absorbable local hemostats offer practical advantages by absorbing wound exudates and promoting healing. Gelatin sponges, known for their hemostatic properties, biocompatibility, and biodegradability, are excellent candidates for wound dressings. They effectively stop bleeding and support tissue repair. However, gelatin’s inherent sensitivity to environmental conditions limits its direct application. To address these challenges, cross-linking techniques are employed to improve mechanical strength, hydrolysis resistance, and stability while refining the pore morphology of gelatin sponges for enhanced biomedical applications. Various cross-linkers, such as aldehydes, carbodiimides, reducing sugars, genipin, and acyl azides, have been investigated for gelatin modification. While glutaraldehyde achieves effective cross-linking, its high cytotoxicity restricts its use in biocompatible products. Alternatives like 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and genipin offer reduced cytotoxicity, though genipin's cost poses a limitation. Reducing sugars, such as glucose and fructose, provide a promising, non-toxic, and cost-effective solution for commercial-scale production. Optimizing cross-linking methods is essential for developing safe, effective, and affordable gelatin-based wound dressings. Addressing cross-linker toxicity remains critical to advancing their clinical applicability.
Connexin 43 (Cx43) protein forms hemichannels (connexons) and gap junctions, with hemichannels consisting of six Cx43 molecules and gap junctions formed by two hemichannels. While gap junctions are prevalent in organs like the heart and liver, hemichannels are found in specific cell types, such as astrocytes and osteocytes. They allow the passage of small molecules (<1.5 kDa) between the cytoplasm and extracellular matrix. Cx43 hemichannels have emerged as potential therapeutic targets in various diseases, including central nervous system disorders, bone-related diseases, diabetic complications, wound healing, and cancers. Aberrant hemichannel opening can worsen conditions by releasing inflammatory elements, such as causing gliosis in neuronal cells. Conversely, functional hemichannels may inhibit cancer cell growth and metastasis. Recent studies are revealing new mechanisms of Cx43 hemichannels, broadening their therapeutic applications and highlighting the importance of regulating their activity for improved disease outcomes.
Attention to nanoemulsions has significantly grown in recent years as a result of their unique features like better stability, special appearance, higher performance, and sensorial merits. Chronic injuries are the consequence of a disturbance in the extremely coordinated cataract of wound healing actions. Nevertheless, correlated with variations in the timescales of various physical methods embroiled in tissue renewal, the aggression of the tumor microenvironment, rich in decaying enzymes, as well as its increased pH, demands the use of efficient drug delivery applications. This chapter summarizes that the various stages of wound healing include four phases: hemostatic stage, inflammation, proliferation, and remodeling process, respectively. Moreover, the major reported classes of lipid-based elements were either vesicular (liposome, permeation increased vesicle, etc.), emulsion-based behavior (nano-emulsion and micro-emulsion), or comprise a solid-based liquid matrix in the wound-healing process.
Background
Wounds continue to be a difficult clinical problem, with early and late consequences causing significant morbidity and death. As a result, proper wound management is critical. In addition to contemporary medicine, medicinal herbs serve an essential role in the treatment of wounds and bacterial infections. Z. scabra is a medicinal plant that has traditionally been used to treat wounds. However, there are no scientific reports on solvent fraction wound healing activities. As a result, the current study presents a scientific assessment of the wound healing ability of the solvent fractions of Z. scabra leaves.
Methods
The leaves were crushed and macerated three times in 80% methanol. Chloroform, ethyl acetate, and aqueous fractions of simple ointment at 5% w/w and 10 percent w/w strengths were prepared using the fusion technique based on the British Pharmacopoeia. Excision and incision wound models were used to assess the solvent fractions’ wound healing activities. The anti-inflammatory efficacy of crude and solvent fractions was tested in mice utilizing a carrageenan-induced hindpaw edema model.
Results
In rats, a test dose of 2000 mg/kg of the 10% w/w crude extract ointment was found to be safe. Groups treated with the 5% and 10% ethyl acetate fractions of the extract experienced significant (p<0.05 and p<0.01) wound reduction in the excision wound model. When compared to the negative control, the length of epithelization in groups treated with 10% ethyl acetate fraction and aqueous fractions of Z. scabra was statistically significant (p 0.001). By lowering the amount of carrageenan-induced paw edema, the leaf extract and the chloroform fraction of Z. scabra demonstrated a dose-dependent anti-inflammatory effect.
Conclusion
The extract showed remarkable wound healing and anti-inflammatory activity and might be recommended for the treatment of many types of human wounds.
Soft robotics has opened a unique path to flexibility and environmental adaptability, learning from nature and reproducing biological behaviors. Nature implies answers for how to apply robots to real life. To find out how we learn from creatures to design and apply soft robots, in this Review, we propose a classification method to summarize soft robots based on different functions of biological systems: self-growing, self-healing, self-responsive, and self-circulatory. The bio-function based classification logic is presented to explain
why
we learn from creatures. State-of-art technologies, characteristics, pros, cons, challenges, and potential applications of these categories are analyzed to illustrate
what
we learned from creatures. By intersecting these categories, the existing and potential bio-inspired applications are overviewed and outlooked to finally find the answer, that is,
how
we learn from creatures.
Understanding wound healing at multiple levels – biochemical, physiologic, cellular and molecular provides the surgeon with basic clinical decisions. This review article describes the classification of wounds, wound healing, phases of wound, factors, wound dressing.
Macrophages, the key player in innate immune response, are originated from yolk sac and the fetal liver during embryogenesis. They are also recruited from blood and bone marrow under proliferative inflammatory conditions. Macrophages have powerful ability to phagocytose pathogens or foreign matter and play vital role in immune regulation, wound healing and tissue homeostasis. The cells can polarize into two major phenotypes, classically activated M1-type, which are derived from monocyte and alternatively activated M2-type, which are mostly tissue-resident. The chapter summarizes the recent findings of macrophage regulation, dysregulation, and therapy during wound healing process. Many research support the application of macrophage in early wound cases. However, it has been reported that dysregulated and altered macrophage phenotypes impair healing process of chronic wound. Further research has to focus on details signaling mechanisms of macrophages phenotypes to evaluate the application of macrophage therapy in chronic wound.
Daphne mucronata (DM) has regenerative features. Alginate hydrogel (Alg), as a natural scaffold, acts as a drug delivery system. This study aimed to assess the probable regenerative effects of DM encapsulated in Alg dermal scaffold on skin wound healing. Seventy-two male mice were grouped as: control (normal skin with no experimental treatments), sham (only punched skin), margarine (only margarine ointment administration), Alg group (Alg hydrogel with no DM), margarine-DM (margarine-based ointment with DM), and Alg-DM (DM encapsulated in Alg scaffold). DPPH assay was applied for phytochemical screening of DM. Cranial and cranial incisions of back were conducted for histological and gene expression evaluations, respectively. Alg scaffold was placed on wound and supported by a dressing pad. Tissue sampling was applied on 3, 7, 12, and 22 days of treatments. Collagen deposition, regeneration rate, angiogenesis and granulation, respectively, were assessed through hydroxyproline assay, caliper instrument, CD31 immunohistochemistry staining, and ImageJ software. Also, gene expression of MMP13, EGF, and bFGF was evaluated by real-time PCR. Data were analyzed using SPSS (V. 16), and graphs were drawn by GraphPad Prism (V.9, 2020) software. Antioxidant agents of DM were approved by the DPPH assay. Besides, it was found that DM restored the damaged dermal tissue and increased the expression of genes involved in wound healing significantly (p < 0.05) in 7 and 12 days of experiment in both groups of margarine-DM and Alg-DM than control. Application of hydroalcoholic extract of DM encapsulated in alginate hydrogel scaffold can accelerate skin tissue regeneration by induction of genes expression and histological tissue indices in dermal injuries. It is believed that the drug delivery system can increase the effectiveness of a drug. Application of dermal scaffold leads to the early expression of genes involved in wound healing and changes of histopathological factors. This study found that the Daphne mucronata extract encapsulated in alginate gel can accelerate wound healing by modulation of the expression of genes and tissue factors. This technique can be used in other pathologic skin-related conditions like diabetes or other non-skin injuries like musculoskeletal disorders.
Aim
Determining the relationship between diabetes and delayed wound healing from the literature. Research literature search from 2010-2020, research on various medicinal plants and their phytoconstituents that are effective in treating wound associated with diabetes. Determining potentially medicinal plants that are used to treat wound and can be used to treat diabetes.
Methodology
Research and review articles from 2010 - 2020 have been researched on a variety of topics such as PubMed, Scopus, Mendeley, Google Scholar, Indian traditional medicine system, Ayurvedic treatment program using different words such as "diabetes", treatment of diabetes "," " Plants in the treatment of diabetes "," wound healing "," wound healing plants ".
Conclusion
Other herbs are also traditionally used to treat wounds. In this study, the main focus is on medicinal plants that are used specifically to treat wounds in diabetic conditions. Although quite a few medicinal florae for wound restoration may be observed in the literature, there's a need for the isolation and characterization of the bioactive compounds chargeable for the wound restoration properties. Also, cytotoxicity research needs to be executed at promising agents or bioactive fractions or extracts.
Wound healing is a process that consists of hemostasis, inflammation, proliferation, and maturation following acute wounds. These processes are disrupted and the inflammation phase is extended in chronic wounds. Local, systemic, and external factors and microbial agents can alter these processes, the cells, and other factors. Hypertrophic scar, keloid, and contracture are complications of wound healing.
Background— Endothelial progenitor cells (EPCs) have been isolated from peripheral blood and can enhance angiogenesis after infusion into host animals. It is not known whether the proangiogenic effects are a result of such events as endothelial differentiation and subsequent proliferation of EPCs or secondary to secretion of angiogenic growth factors.
Methods and Results— Human EPCs were isolated as previously described, and their phenotypes were confirmed by uptake of acetylated LDL and binding of ulex-lectin. EPC proliferation and surface marker expression were analyzed by flow cytometry, and conditioned medium was assayed for growth factors. The majority of EPCs expressed monocyte/macrophage markers such as CD14 (95.7±0.3%), Mac-1 (57.6±13.5%), and CD11c (90.8±4.9%). A much lower percentage of cells expressed the specific endothelial marker VE-cadherin (5.2±0.7%) or stem/progenitor-cell markers AC133 (0.16±0.05%) and c-kit (1.3±0.7%). Compared with circulating monocytes, cultured EPCs showed upregulation of monocyte activation and macrophage differentiation markers. EPCs did not demonstrate any significant proliferation but did secrete the angiogenic growth factors vascular endothelial growth factor, hepatocyte growth factor, granulocyte colony–stimulating factor, and granulocyte-macrophage colony–stimulating factor.
Conclusions— Our findings suggest that acetylated LDL(+)ulex-lectin(+) cells, commonly referred to as EPCs, do not proliferate but release potent proangiogenic growth factors. The majority of acetylated LDL(+)ulex-lectin(+) cells are derived from monocyte/macrophages. The findings of low proliferation and endothelial differentiation suggest that their angiogenic effects are most likely mediated by growth factor secretion. These findings may allow for development of novel angiogenic therapies relying on secreted growth factors or on recruitment of endogenous monocytes/macrophages to sites of ischemia.
There are two types of excessive scarring, keloid and hypertrophic scar. Contrary to hypertrophic scars, keloids do not regress with time, are difficult to revise surgically, and do not provoke scar contractures. These two lesions require different therapeutic approaches but are often confused because of an apparent lack of morphological differences. We have investigated the collagen organization and the possible presence of alpha-smooth muscle (SM) actin-expressing myofibroblasts in these conditions. Keloids contain large, thick collagen fibers composed of numerous fibrils closely packed together. In contrast hypertrophic scars exhibit modular structures in which fibroblastic cells, small vessels, and fine, randomly organized collagen fibers are present. We confirm that such nodular structures are always present in hypertrophic scar and rarely in keloid. Furthermore, only nodules of hypertrophic scars contain alpha-SM actin-expressing myofibroblasts. Electron microscopic examination supports the above-mentioned differences in collagen organization and in fibroblastic features and shows the presence of an amorphous extracellular material surrounding fibroblastic cells in keloid. The presence in hypertrophic scar myofibroblasts of alpha-SM actin, the actin isoform typical of vascular SM cells, may represent an important element in the pathogenesis of contraction. Interestingly, when placed in culture fibroblasts from hypertrophic scars and keloid express similar amounts of alpha-SM actin, suggesting that local microenvironmental factors influence in vivo the expression of this protein. Thus several morphological and immunohistochemical differences exist between hypertrophic scar and keloid that are useful for the biological and pathological characterization of the two lesions.
The stimulation of the human umbilical vein endothelial cell (HUVEC) with recombinant human monocyte-derived colony-stimulating factor (MCSF) increased the gene expression of monocyte chemotactic protein (MCP-1). Northern blot analysis indicated that 50 U/ml of MCSF is the optimal concentration for this effect. The elevation of MCP-1 mRNA started as early as 1 h after stimulation and was maintained for at least 8 h. An increased MCP-1 level in MCSF-treated HUVEC was also demonstrated at the protein level by immunocytochemical staining using a polyclonal MCP-1-specific antibody. HUVEC activated by 50 U/ml of MCSF for 5 h showed a stronger immunofluorescence staining than control cells. Micropipette separation of THP-1 monocytes from HUVEC showed that the activation of both THP-1 and endothelium by MCSF led to an increase in the separation force by more than three times (36.2 +/- 6.7 x 10(-4) vs. 9.6 +/- 3.6 x 10(-4) dyn). An increased adhesiveness was also observed after MCSF activation of peripheral blood monocytes and HUVEC (16.7 +/- 2.7 x 10(-4) vs. 5.2 +/- 0.9 x 10(-4) dyn). The increased adhesive force in both systems was blocked by the use of anti-MCP-1 (5.5 +/- 0.8 x 10(-4) and 6.8 +/- 1.1 x 10(-4) dyn). Similar results were obtained in experiments in which only HUVEC, but not monocytes, were activated by MCSF. This increased adhesion of untreated monocytes to MCSF-activated HUVEC was also blocked by the addition of anti-MCP-1. In contrast, experiments in which only THP-1 or peripheral blood monocytes, but not HUVEC, were treated with MCSF did not show a significant increase of adhesion between these cells. These results indicate that MCSF augments monocyte-endothelium interaction primarily by its action on the endothelial cell and that this function is probably mediated through an increased expression of MCP-1. The MCSF/MCP-1-dependent adhesive mechanism might be operative in the arterial wall in vivo to lead to the trapping of the infiltrated monocyte-macrophage in the subendothelial space during atherogenesis.
The Journal of Investigative Dermatology publishes basic and clinical research in cutaneous biology and skin disease.
Recent studies have identified a novel population of blood-borne cells, termed fibrocytes, that have a distinct cell surface phenotype (collagen+/CD13(+)/CD34(+)/CD45(+)), rapidly enter sites of tissue injury, and synthesize connective tissue matrix molecules. We found by flow cytometry that purified human fibrocytes express each of the known surface components that are required for antigen presentation, including class II major histocompatability complex molecules (HLA-DP, -DQ, and -DR), the costimulatory molecules CD80 and CD86, and the adhesion molecules CD11a, CD54, and CD58. Human fibrocytes induced antigen-presenting cell-dependent T cell proliferation when cultured with specific antigen and this proliferative activity was significantly higher than that induced by monocytes and nearly as high as that induced by purified dendritic cells. Mouse fibrocytes also were found to express the surface components required for antigen presentation and to function as potent APCs in vitro. Mouse fibrocytes pulsed in vitro with the HIV-proteins p24 or gp120 and delivered to a site of cutaneous injury were found to migrate to proximal lymph nodes and to specifically prime naive T cells. These data suggest that fibrocytes play an early and important role in the initiation of antigen-specific immunity.
An unresolved question in wound contraction concerns the identity of integrins mediating the attachment of tissue myofibroblasts
to matrix in the injury site. Previous studies with cell lines have focussed on α1β1 and α2β1, the principal collagen-binding
integrins, but have yielded conflicting data. We have examined this issue in wound healing in the liver, isolating the myofibroblast
population (activated stellate cells) and quantitating expression of the α1 and α2 integrin subunits during the in vivo injury. Normal stellate cells displayed α1 but no detectable α2. During injury, α1 expression was maintained; α2 became detectable
at the mRNA level but at all times was <8% of α1 mRNA. Contraction of collagen lattices, studied with 24-h cultured cells
and initiated by endothelin 1, was blocked 70% by anti-α1 and 30% by anti-α2 (both significant, p< 0.05). The inhibition by anti-α2, which was unexpected, was attributable to culture-induced change in integrin expression;
both the mRNA and protein for α2 increased strikingly within 24 h of plating stellate cells on a collagen gel. We conclude
that α1β1 is the sole integrin utilized by contracting myofibroblasts in vivo. Although α2β1 is capable of mediating contraction, its expression by myofibroblasts occurs largely, if not exclusively,
in response to culture.
Human mesenchymal stem cells are thought to be multipotent cells, which are present in adult marrow, that can replicate as
undifferentiated cells and that have the potential to differentiate to lineages of mesenchymal tissues, including bone, cartilage,
fat, tendon, muscle, and marrow stroma. Cells that have the characteristics of human mesenchymal stem cells were isolated
from marrow aspirates of volunteer donors. These cells displayed a stable phenotype and remained as a monolayer in vitro.
These adult stem cells could be induced to differentiate exclusively into the adipocytic, chondrocytic, or osteocytic lineages.
Individual stem cells were identified that, when expanded to colonies, retained their multilineage potential.
Endothelial progenitor cells (EPCs) have been isolated from circulating mononuclear cells in human peripheral blood and shown to be incorporated into foci of neovascularization, consistent with postnatal vasculogenesis. We determined whether endogenous stimuli (tissue ischemia) and exogenous cytokine therapy (granulocyte macrophage-colony stimulating factor, GM-CSF) mobilize EPCs and thereby contribute to neovascularization of ischemic tissues. The development of regional ischemia in both mice and rabbits increased the frequency of circulating EPCs. In mice, the effect of ischemia-induced EPC mobilization was demonstrated by enhanced ocular neovascularization after cornea micropocket surgery in mice with hindlimb ischemia compared with that in non-ischemic control mice. In rabbits with hindlimb ischemia, circulating EPCs were further augmented after pretreatment with GM-CSF, with a corresponding improvement in hindlimb neovascularization. There was direct evidence that EPCs that contributed to enhanced corneal neovascularization were specifically mobilized from the bone marrow in response to ischemia and GM-CSF in mice transplanted with bone marrow from transgenic donors expressing beta-galactosidase transcriptionally regulated by the endothelial cell-specific Tie-2 promoter. These findings indicate that circulating EPCs are mobilized endogenously in response to tissue ischemia or exogenously by cytokine therapy and thereby augment neovascularization of ischemic tissues.
Various in vitro models have been described that emulate one or more of the processes involved in angiogenesis in vivo. In the present study endothelial cells were cultured in three-dimensional type I collagen lattices in the presence of a mixture of basic fibroblast growth factor, vascular endothelial cell growth factor, and phorbol myristate acetate. Under these conditions, the endothelial cells rapidly assemble into an interconnected network of tube-like structures with a high frequency of intercellular canals or lumens. The formation of the networks and lumens was completely blocked by cycloheximide and by actinomycin D. Monoclonal antibodies directed against CD31 or vascular endothelial cadherin (VE-cadherin) inhibited the formation of endothelial tubes. A subtle difference in the morphology of cells treated with anti-CD31 versus anti-VE-cadherin was noted; namely, cells incubated in the presence of CD31 antibodies were rounded or formed attenuated tube-like structures, both of which were characterized by a single, large intra- or intercellular vacuole. In contrast, tube formation by cells incubated in the presence of VE-cadherin antibodies was also impaired and, most notably, demonstrated a reduction in either vacuole formation or vacuole fusion, depending upon the monoclonal antibody used. We suggest that the two endothelial-junction-associated proteins, CD31 and VE-cadherin, play different roles in the process of tube formation. CD31 appears to be required for cell elongation, migration, and/or invasion in the gels as well as for cell-cell association to form the network structures. VE-cadherin also appears to be required for cell-cell association, but additionally appears to play some role in the process of vacuolization or vacuole fusion leading to intercellular lumen formation.
During angiogenesis, anastomosing capillary sprouts align to form complex three-dimensional networks of new blood vessels. Using an endothelial cell spheroid model that was developed to study endothelial cell differentiation processes, we have devised a novel collagen gel-based three-dimensional in vitro angiogenesis assay. In this assay, cell number-defined, gel-embedded endothelial cell spheroids act as a cellular delivery device, which serves as a focal starting point for the sprouting of lumenized capillary-like structures that can be induced to form complex anastomosing networks. Formation of capillary anastomoses is associated with tensional remodeling of the collagen matrix and directional sprouting of outgrowing capillaries towards each other. To analyze whether directional sprouting is dependent on cytokine gradients or on endothelial cell-derived tractional forces transduced through the extracellular matrix, we designed a matrix tension generator that enables the application of defined tensional forces on the extracellular matrix. Using this matrix tension generator, causal evidence is presented that tensional forces on a fibrillar extracellular matrix such as type I collagen, but not fibrin, are sufficient to guide directional outgrowth of endothelial cells. RGD peptides but not control RAD peptides disrupted the integrity of sprouting capillary-like structures and induced detachment of outgrowing endothelial cells cultured on top of collagen gels, but did not inhibit primary outgrowth of endothelial cells. The data establish the endothelial cell spheroid-based three-dimensional angiogenesis technique as a standardized, highly reproducible quantitative assay for in vitro angiogenesis studies and demonstrate that integrin-dependent matrix tensional forces control directional capillary sprouting and network formation.
Emerging data suggest that a subset of circulating human CD34(+) cells have phenotypic features of endothelial cells. Whether these cells are sloughed mature endothelial cells or functional circulating endothelial precursors (CEPs) is not known. Using monoclonal antibodies (MoAbs) to the extracellular domain of the human vascular endothelial receptor-2 (VEGFR-2), we have shown that 1.2 +/- 0.3% of CD34(+) cells isolated from fetal liver (FL), 2 +/- 0.5% from mobilized peripheral blood, and 1.4 +/- 0.5% from cord blood were VEGFR-2(+). In addition, most CD34(+)VEGFR-2(+) cells express hematopoietic stem cell marker AC133. Because mature endothelial cells do not express AC133, coexpression of VEGFR-2 and AC133 on CD34(+) cells phenotypically identifies a unique population of CEPs. CD34(+)VEGFR-2(+) cells express endothelial-specific markers, including VE-cadherin and E-selectin. Also, virtually all CD34(+)VEGFR-2(+) cells express the chemokine receptor CXCR4 and migrate in response to stromal-derived factor (SDF)-1 or VEGF. To quantitate the plating efficiency of CD34(+) cells that give rise to endothelial colonies, CD34(+) cells derived from FL were incubated with VEGF and fibroblast growth factor (FGF)-2. Subsequent isolation and plating of nonadherent FL-derived VEGFR-2(+) cells with VEGF and FGF-2 resulted in differentiation of AC133(+ )VEGFR-2(+) cells into adherent AC133(-)VEGFR-2(+)Ac-LDL(+ )(acetylated low-density lipoprotein) colonies (plating efficiency of 3%). In an in vivo human model, we have found that the neo-intima formed on the surface of left ventricular assist devices is colonized with AC133(+)VEGFR-2(+) cells. These data suggest that circulating CD34(+) cells expressing VEGFR-2 and AC133 constitute a phenotypically and functionally distinct population of circulating endothelial cells that may play a role in neo-angiogenesis.
Fibrocytes are a distinct population of blood-borne cells that display a unique cell surface phenotype (collagen I+/CD11b+/CD13+/CD34+/CD45RO+/MHC class II+/CD86+) and exhibit potent immunostimulatory activities. Circulating fibrocytes rapidly enter sites of tissue injury, suggesting an important role for these cells in wound repair. However, the regulatory processes that govern the differentiation of blood-borne fibrocytes and the mechanisms that underlie the migration of these cells to wound sites are currently not known. We report herein that ex vivo cultured fibrocytes can differentiate from a CD14+-enriched mononuclear cell population and that this process requires contact with T cells. Furthermore, we demonstrate that TGF-beta1 (1-10 ng/ml), an important fibrogenic and growth-regulating cytokine involved in wound healing, increases the differentiation and functional activity of cultured fibrocytes. Because fibrocytes home to sites of tissue injury, we examined the role of chemokine/chemokine receptor interactions in fibrocyte trafficking. We show that secondary lymphoid chemokine, a ligand of the CCR7 chemokine receptor, acts as a potent stimulus for fibrocyte chemotaxis in vitro and for the homing of injected fibrocytes to sites of cutaneous tissue injury in vivo. Finally, we demonstrate that differentiated, cultured fibrocytes express alpha smooth muscle actin and contract collagen gels in vitro, two characteristic features of wound-healing myofibroblasts. These data provide important insight into the control of fibrocyte differentiation and trafficking during tissue repair and significantly expand their potential role during wound healing.
The role of artificial skin substitutes in burn surgery and the treatment of chronic wounds is constantly evolving. New products are regularly being produced and approved for clinical use. Studies on existing products clarify their efficacy and effectiveness in different clinical scenarios. This review is aimed at busy clinicians in order to bring them up to date with the latest developments in the field of artificial skin substitutes. It examines the components, structure, performance and comparative costs of the main commercial skin substitutes, and reviews briefly technologies under development that have not yet become widely available.
Contraction plays a major role in wound healing and is inevitably mediated through the mechanical interaction of fibroblast cytoskeleton and integrins with their extracellular matrix ligands. Cell-matrix attachment is critical for such events. In human dermal fibroblasts most such interactions are mediated by the beta1-type integrins. This study investigated the role played by key components in this system, notably fibronectin, vitronectin, and integrin subcomponents alpha2 and alpha5, which recognize collagen and fibronectin. Inhibition of adhesion through these ligands was studied either by antibody blocking or with fibronectin and/or vitronectin depletion. Functional effects of inhibition were monitored as force generation in collagen-glycosaminoglycan (IntegraTM) sponges, over 20 hours using a culture force monitor. Dose and time-course inhibition studies indicated that initial attachment and force generation (approx. 0-5 hours postseeding) was through fibronectin receptors and this was followed by vitronectin ligand and receptor utilization (4 hours onward). Utilization of the collagen integrin subcomponent alpha2 appeared to be increasingly important between 6 and 16 hours and dominant thereafter. Additionally, there was evidence for functional interdependence between the three ligand systems fibronectin, vitronectin, and collagen. We propose that there is a short cascade of sequential integrin-ligand interactions as cells attach to, extend through, and eventually contract their matrix. (WOUND REP REG 2002;10:-408)
This chapter focuses on morphological aspects, phenotype, and functions of the population of Langerhans cells and dendritic cells (DCs) resident in the skin. Langerhans cells (LCs) and dermal dendritic cells (DDCs) are leukocytes, originated from bone marrow progenitors that colonize the skin after leaving the peripheral blood circulation. Upon entering the skin, resident epidermal LCs and DDCs remain as resting cell populations until a “danger signal” induces their activation and mobilization to draining lymph nodes. LCs and DDCs constitute migratory cell populations. They arrive in the dermis possibly as an immature precursor from peripheral blood and reside as immature cells in the epidermis or in dermis until a stimulatory signal is able to induce their migration. During this migratory cycle, LCs differentially modulate adhesion molecules that allow their interaction with other cells or with extracellular matrix proteins. DCs or their precursors need to attach to endothelial cells and then migrate through the endothelial wall to migrate from peripheral blood into the skin. Some adhesion molecules such as ICAM-2 are expressed constitutively by endothelial cells, but most of the molecules related to leukocyte migration are upregulated by proinflammatory cytokines.
Keloid and hypertrophic scars have affected patients and frustrated physicians for centuries. Keloid and hypertrophic scars result from excessive collagen deposition, the cause of which remains elusive. Clinically, these scars can be disfiguring functionally, aesthetically, or both. A thorough understanding of the pathophysiology and clinical nature of the scar can help define the most appropriate treatment strategy.
Although many articles have been published on the management of hypertrophic and keloid scars, there is no universally accepted treatment protocol. Prevention of keloid and hypertrophic scars remains the best strategy; therefore, those patients with a predisposition to develop excessive scar formation should avoid nonessential surgery. Once a scar is present, there are many treatments from which to choose. Hypertrophic scars and keloids have been shown to respond to radiation, pressure therapy, cryotherapy, intralesional injections of corticosteroid, interferon and fluorouracil, topical silicone or other dressings, and pulsed-dye laser treatment. Simple surgical excision is usually followed by recurrence unless adjunct therapies are employed. Biologic agents that are directed towards the aberrant collagen proliferation that characterizes keloid and hypertrophic scars might be an important addition to the current armamentarium of modalities in the near future.
objective. To investigate the role of macrophages in the development of laser-induced choroidal neovascularization (CNV) by selective depletion with liposomal clodronate (Cl2MDP-LIP).
methods. Laser photocoagulation was used to induce CNV in wild-type C57BL/6J mice. Animals were treated with intravenous (IV) and/or subconjunctival (SC) Cl2MDP-LIP or PBS-LIP at the following time points: 2 days before, immediately after, 2 days before and immediately after, or 2 days after laser injury. CNV responses were compared on the basis of en masse volumetric measurements and fluorescein angiography after laser photocoagulation. Macrophages were identified by immunostaining for F4/80, and vascular endothelial growth factor (VEGF) expression was quantified by ELISA.
results. Macrophages invaded the site of laser injury within 1 day of photocoagulation and peaked at 3 days. IV Cl2MDP-LIP significantly decreased the volume of CNV and angiographic leakage when administered 2 days before and/or immediately after laser injury, but not when administered 2 days after injury. SC Cl2MDP-LIP significantly decreased lesion volume when coadministered with IV PBS-LIP but not IV Cl2MDP-LIP. IV Cl2MDP-LIP was significantly more beneficial when administered 2 days before laser injury than immediately after, but combining SC Cl2MDP-LIP with IV treatment eliminated this difference. Reduction in CNV volume correlated with VEGF protein levels and number of infiltrating macrophages.
conclusions. Generalized macrophage depletion reduced the size and leakage of laser-induced CNV and was associated with decreased macrophage infiltration and VEGF protein. These findings define the role of the macrophage as a critical component in initiating the laser-induced CNV response.
The CD34 positive (CD34+) spindle cells constitute a special population of spindle cells which show a unique distribution in the skin. So far, however, the functional role of CD34+ spindle cells and the regulation of CD34 expression on dermal spindle cells are totally unknown. We examined immunohistologically the pattern of the expression of CD34 and proline‐4‐hydroxylase, a marker for the fibroblasts that participate in active collagen synthesis, on dermal spindle cells at various stages of scar and keloidal tissues.
Dermal spindle cells in the lesions of hypertrophic scar and those at inflammatory expanding borders of keloids totally lost CD34 expression, but they strongly expressed proline‐4‐hydroxylase. On the other hand, they expressed CD34, together with decreased immunoreactivity to anti‐proline‐4‐hydroxylase antibody, in non‐inflammatory scars or in a non‐inflammatory central portion of keloid. In two cases of scars, in which inflammation began to subside, double immunofluorescence demonstrated that both CD 34 and proline‐4‐hydroxylase were expressed on the same spindle cells.
CD34 expression, once disappeared from the lesions of hypertrophic scar or keloid, seems to return on CD34–proline‐4‐hydroxylase+ cells, when the initial inflammatory changes begin to regress. There is a reverse correlation between CD34 expression on spindle cells and the synthesis of type I collagen in the skin.
Background/Purpose: In a noncontractile fetal rabbit model, the authors recently have shown the induction of excisional wound contraction with sustained-release cellulose implants formulated with transforming growth factor (TGF)-β. The purpose of this study was to test the hypothesis that the excisional wound contraction in this model is associated with the induction of myofibroblasts in the surrounding dermis, demonstrated by the presence of α-smooth muscle actin.Methods:Cellulose discs were formulated with either 1.0 μg of TGF-β1 (n = 6); 1.0 μg of TGF-β3 (n = 9); 10 μg of TGF-β3 (n = 6); or their carrier protein, bovine serum albumin (BSA; n = 9), for sustained-release over 5 days. Each disc was implanted into a subcutaneous pocket on the back of a fetal New Zealand White rabbit in utero on day 24 of gestation (term, 31 days). A full-thickness, 3-mm excisional wound (7.4 mm2) was then made next to the implanted cellulose disc. All fetuses were harvested at 3 days. The amount of α-smooth muscle (SM) actin in the dermis around the implants and wounds was determined using immunohistochemical techniques.Results: Excisional wounds exposed to 1.0 jig of TGF-β1 (5.6 ± 2.0 mm2), 1.0 μg of TGF-β3 (6.9 ± 1.0 mm2), and 10 μg of TGF-β3 (2.7 ± 1.0 mm2) were significantly smaller when compared with the BSA control group (12.8 ± 1.1 mm2; P < .05). Furthermore, there was a significant increase in staining for α-SM actin in the TGF-β1, (1.8 ± 0.5) and 10 μg TGF-β3 (2.8 ± 0.2) groups in comparison with the scant staining in the BSA control group (0.5 ± 0.2; P < .05).Conclusions:, TGF-β2 and −β3 induce α-SM actin and contraction of cutaneous excisional wounds in a fetal noncontractile model. This model of inducible cutaneous excisional wound contraction may be useful in further determining the role of the myofibroblast in wound contraction and the physiology underlying this poorly understood aspect of wound healing.
The rate of in vitro enzymatic degradation of various materials based on collagen has been determined by a novel mechanochemical method, and has been compared with the extent of degradation resulting from subcutaneous implantation in guinea pigs. In vitro data correlate well with in vivo data. It is suggested that the simple in vitro method described is an effective means of screening a large number of materials based on collagen for their ability to resist degradation during implantation in animals.
Keratinocytes of stratified squamous epithelium can be grown serially in culture and retain the various markers typical of their form of differentiation. In order to form colonies at each transfer, the keratinocytes must be suitably supported by fibroblasts. Established keratinocyte lines of teratomal origin show this dependence, as do diploid strains of finite culture life derived from human skin. For at least some keratinocyte lines, this requirement can be satisfied by soluble products elaborated by the fibroblasts. It is suggested that epithelial cells in general may not be independent cell types and that their poor cultivability may be due to failure to provide suitable fibroblast support. The existence of a number of established lines of epithelial origin that can grow without such support and of lines of fibroblastic origin which cannot support keratinocytes suggests that both epithelial dependence and the fibroblast supporting function can sometimes be lost in established cell lines.
Human diploid epidermis epidermal cells have been successfully grown in serial culture. To initiate colony formation, they require the presence of fibroblasts, but proliferation of fibroblasts must be controlled so that the epidermal cell population is not overgrown. Both conditions can be achieved by the use of lethally irradiated 3T3 cells at the correct density. When trypsinized human skin cells are plated together with the 3T3 cells, the growth of the human fibroblasts is largely suppressed, but epidermal cells grow from single cells into colonies. Each colony consists of keratinocytes ultimately forming a stratified squamous epithelium in which the dividing cells are confined to the lowest layer(s). Hydrocortisone is added to the medium, since in secondary and subsequent subcultures it makes the colony morphology more oderly and distinctive, and maintains proliferation at a slightly greater rate. Under these culture conditions, it is possible to isolate keratinocyte clones free of viable fibroblasts. Like human diploid fibroblasts, human diploid keratinocytes appear to have a finite culture lifetime. For 7 strains studied, the culture lifetime ranged from 20-50 cell generations. The plating efficiency of the epidermal cells taken directly from skin was usually 0.1-1.0%. On subsequent transfer of the cultures initiated from newborns, the plating efficiency rose to 10% or higher, but was most often in the range of 1-5% and dropped sharply toward the end of their culture life. The plating efficiency and culture lifetime were lower for keratinocytes of older persons.
We have sequentially documented the early morphologic events that result in partial regeneration of the adult guinea pig dermis. This phenomenon occurs when a full-thickness skin wound is grafted with a highly specific collagen-glycosaminoglycan (CG) copolymer which has been seeded with autologous dermal and epidermis cells (Yannas IV, Lee E, Orgill DP, Skrabut EM, Murphy GF, Proc Natl Acad Sci USA 86:933-937, 1989). By day 7, ultrastructural analysis disclosed highly organized associations between mononuclear cells and CG fibers involving prominent extension of pseudopod-like processes toward the fiber surface. Spatial organization of cells was not evident in ungrafted wounds. By day 10, more than 50% of the CG grafts had been degraded and extensive neovascularization was observed in various stages of formation. By day 14, dermal fibroblasts in the graft site demonstrated random alignment of long axes, and a minor fraction (less than 10%) exhibited features of myofibroblasts. A majority (greater than 50%) of dermal fibroblasts in ungrafted wounds were identified as myofibroblasts at this time, and their axes were regularly aligned in parallel with the overlying epidermal layer. Scattered CG copolymer fragments were engulfed by macrophages by day 14, and complete dissolution occurred by day 21. Dermal blood vessels formed a discrete, subepidermal plexus oriented parallel to the epidermal plane by days 14 to 17 in grafted wound beds but not in ungrafted ones. Progressive, randomly oriented collagen deposition occurred at graft sites during the 1st year, whereas collagen fibers in ungrafted wounds were aligned in a horizontal plane atypical of a forming scar. By 1 year, the graft sites resembled normal dermis, with well-defined dermal papillae, normal anastomosing superficial vasculature, nerve fibers, and random collagen fiber morphology. Wound sites at this juncture resembled a mature scar, with a flattened dermal-epidermal interface; rare and disorganized vessels and nerves; and collagen fibers parallel to the epidermis. This investigation demonstrates the critical importance of highly specific extracellular matrix in induction of dermal morphogenesis.
Bovine hide collagen dispersions were swollen in the pH range 1.6-7.0, treated with glutaraldehyde, and dialyzed to neutral pH. The intensity with which these collagens reacted with human platelets in plasma was studied by aggregometry and scanning electron microscopy. Collagen swollen at a pH below 4.25 +/- 0.30 and treated with glutaraldehyde exhibited greatly reduced platelet aggregating ability after restoration of neutral pH. In addition, the state of supramolecular order in these collagens was investigated by transmission electron microscopy and infrared spectroscopy. Native, insoluble collagen fibrils were found to lose their banded structure, as observed by transmission electron microscopy, reversibly when exposed to low ionic strength aqueous solutions below pH 4.25 +/- 0.30. During the disorder transition, which occurred by time dependent swelling of fibrils, but without their disaggregation, the packing order in the fibrils was largely abolished while the triple helical structure of individual collagen molecules was retained. Chemical modification of collagen by glutaraldehyde treatment was found to prevent recrystallization of collagen during dialysis to neutral pH but did not otherwise affect the collagen-platelet reaction. The results of altering collagen mass dose (concentration) demonstrated the critical importance of traces of banded fibrils which resisted disordering below pH 4.25. The data suggest that collagen preparations which are free of significant traces of banded fibrils, but which are made up of collagen molecules possessing triple helical structure do not induce platelet aggregation, irrespective of dose.
Regeneration of the dermis does not occur spontaneously in the adult mammal. The epidermis is regenerated spontaneously provided there is a dermal substrate over which it can migrate. Certain highly porous, crosslinked collagen-glycosaminoglycan copolymers have induced partial morphogenesis of skin when seeded with dermal and epidermal cells and then grafted on standard, full-thickness skin wounds in the adult guinea pig. A mature epidermis and a nearly physiological dermis, which lacked hair follicles but was demonstrably different from scar, were regenerated over areas as large as 16 cm2. These chemical analogs of extracellular matrices were morphogenetically active provided that the average pore diameter ranged between 20 and 125 microns, the resistance to degradation by collagenase exceeded a critical limit, and the density of autologous dermal and epidermal cells inoculated therein was greater than 5 x 10(4) cells per cm2 of wound area. Unseeded copolymers with physical structures that were within these limits delayed the onset of wound contraction by about 10 days but did not eventually prevent it. Seeded copolymers not only delayed contraction but eventually arrested and reversed it while new skin was being regenerated. The data identify a model extracellular matrix that acts as if it were an insoluble growth factor with narrowly specified physiochemical structure, functioning as a transient basal lamina during morphogenesis of skin.
Prompt and long-term closure of full-thickness skin wounds is guinea pigs and humans is achieved by applying a bilayer polymeric
membrane. The membrane comprises a top layer of a silicone elastomer and a bottom layer of a porous cross-linked network of
collagen and glycosaminoglycan. The bottom layer can be seeded with a small number of autologous basal cells before grafting.
No immunosuppression is used and infection, exudation, and rejection are absent. Host tissue utilizes the sterile membrane
as a culture medium to synthesize neoepidermal and neodermal tissue. A functional extension of skin over the entire wound
area is formed in about 4 weeks.
We have developed a living skin equivalent, which serves as a skin substitute in experimental animals. On application it is rapidly vascularized, it inhibits wound contraction, and it is immunologically tolerated and persists for as long as it is allowed to remain in place. It comes to resemble normal skin, although it lacks secondary derivatives, the cells for which may in time be available for incorporation into the fabricated tissue.
Monocyte chemotactic protein-1 (MCP-1), a potent monocyte chemoattractant secreted by endothelial cells (ECs), is believed to play a key role in the early events of atherogenesis. Since vascular ECs are constantly subjected to mechanical stresses, we examined how cyclic strain affects the expression of the MCP-1 gene in human ECs grown on a flexible membrane base deformed by sinusoidal negative pressure (peak level, -16 kPa at 60 cycles per minute). Northern blot analysis demonstrated that the MCP-1 mRNA levels in ECs subjected to strain for 1, 5, or 24 hours were double those in control ECs (P < .05). This strain-induced increase was mainly serum independent, and MCP-1 mRNA level returned to its control basal level 3 hours after release of strain. Culture media from strained ECs contained approximately twice the MCP-1 concentration and more than twice the monocyte chemotactic activity of media from control ECs (P < .05). Pretreatment of collected media with anti-MCP-1 antibody suppressed such activity. Monocyte adhesion to ECs subjected to strain for 12 hours was 1.8-fold greater than adhesion to unstrained control ECs (P < .05). A protein kinase C inhibitor, calphostin C, abolished the strain-induced MCP-1 gene expression. In addition, cAMP- or cGMP-dependent protein kinase inhibitors (KT5720 and KT5823, respectively) partially inhibited such expression. Pretreatment with EGTA or the intracellular Ca2+ chelator BAPTA/AM strongly suppressed the strain-induced MCP-1 mRNA. Verapamil, a Ca2+ channel blocker, greatly reduced MCP-1 mRNA levels in both strained and unstrained ECs.(ABSTRACT TRUNCATED AT 250 WORDS)
The marsupial Monodelphis domestica provides a versatile model for the study of "fetal" wound healing. The pouch young of this species have been used to perform a systematic histological study of wound healing and skin development throughout pouch life; from Pouch Day 0 to Pouch Day 30 with comparisons drawn against adults. We have demonstrated that pouch young heal without macroscopic scars if wounded before Pouch Day 9 and that a transition into a scarring healing phenotype occurs around the ninth pouch day. The inflammatory reaction of wounds and aspects of skin differentiation such as dermal collagen organisation, adipose layer development, hair follicle growth, and epithelial maturation have been documented using simple ranking scales to highlight trends through pouch life. Inflammation was noted to become prominent after Pouch Day 9. There was also a general temporal correlation between the other aspects of differentiation and the transition into a scarring phenotype. It is concluded that although fetal wounds may have different cytokine profiles due to the differences of inflammatory reaction compared to adults, other aspects of skin development play a role in determining the healing phenotype.
This review updates the surgeon about the cellular, matrix, and growth factor components of scarless fetal wound repair.
Fetal skin wound healing is characterized by the absence of scar tissue formation. This unique repair process is not dependent on the sterile, aqueous intrauterine environment. The differences between fetal and adult skin wound healing appear to reflect processes intrinsic to fetal tissue, such as the unique fetal fibroblasts, a more rapid and ordered deposition and turnover of tissue components, and, particularly, a markedly reduced inflammatory infiltrate and cytokine profile. Scarless fetal wounds are relatively deficient in the inflammatory cytokine, transforming growth factor beta (TGF-beta). In contrast, the fibrosis characteristic of adult wound repair may be associated with TGF-beta excess. Recent experimental studies suggest that specific anti-TGF-beta therapeutic strategies can ameliorate scar formation in adult wound repair and fibrotic diseases. Inhibitors of TGF-beta may be important future drugs to control scar.
Based on the scarless fetal wound repair model, a number of ways in which the matrix and cellular response of the healing adult wound might be manipulated to reduce scarring are reviewed.
This study investigated the influence of the fetal environment on the healing characteristics of adult skin.
The remarkable ability of the fetus to heal without scarring is poorly understood. The unique qualities of fetal wound healing may be caused by the fetal environment, the fetal tissues, or a combination of both. There are numerous differences between the prenatal and postnatal environments that may play a role in the unique fetal response to injury.
Full-thickness adult sheep skin was transplanted onto the backs of 60-day-gestation fetal lambs (term, 145 days of gestation). The adult skin grafts were thus perfused by fetal blood and bathed in amniotic fluid. Previous work has demonstrated that, before midgestation, fetal lambs do not reject allogenic skin grafts. Forty days later (100 days of gestation), incisional wounds were made on both the adult skin graft and the adjacent fetal skin. The wounds were harvested 14 days postwounding and analyzed by both light microscopy and immunohistochemical testing using antibodies to collagen types I, III, and VI.
The wounds in the adult skin grafts healed with scar formation. This observation contrasts strongly with the scarless healing of the incisional fetal skin wounds.
This study suggests that scarless fetal skin healing properties are intrinsic to fetal skin and are not primarily the result of the fetal environment.
The host response to tissue injury requires a complex interplay of diverse cellular, humoral, and connective tissue elements. Fibroblasts participate in this process by proliferating within injured sites and contributing to scar formation and the longterm remodeling of damaged tissue. Fibroblasts present in areas of tissue injury generally have been regarded to arise by recruitment from surrounding connective tissue; however this may not be the only source of these cells.
Long-term culture of adherent, human, and murine leukocyte subpopulations was combined with a variety of immunofluorescence and functional analyses to identify a blood-borne cell type with fibroblast-like properties.
We describe for the first time a population of circulating cells with fibroblast properties that specifically enter sites of tissue injury. This novel cell type, termed a "fibrocyte," was characterized by its distinctive phenotype (collagen+/vimentin+/CD34+), by its rapid entry from blood into subcutaneously implanted wound chambers, and by its presence in connective tissue scars.
Blood-borne fibrocytes contribute to scar formation and may play an important role both in normal wound repair and in pathological fibrotic responses.
The healing of an adult skin wound is a complex process requiring the collaborative efforts of many different tissues and
cell lineages. The behavior of each of the contributing cell types during the phases of proliferation, migration, matrix synthesis,
and contraction, as well as the growth factor and matrix signals present at a wound site, are now roughly understood. Details
of how these signals control wound cell activities are beginning to emerge, and studies of healing in embryos have begun to
show how the normal adult repair process might be readjusted to make it less like patching up and more like regeneration.
Deep skin wounds in the adult mammal close spontaneously by epithelialization, wound contraction, and scar synthesis. In previous wound healing studies, it has been unsuccessfully attempted to separate from each other the natural processes that close wounds. In this study, we attempted to isolate skin regeneration from spontaneous processes of wound closure using "island" grafts. A porous analog of the extracellular matrix, composed of a graft copolymer of type I collagen and chondroitin 6-sulfate, was seeded with uncultured autologous keratinocytes and served to induce regeneration of the dermis and the epidermis. Grafts of the copolymer, measuring 1 x 2 cm, were placed in the center of 5 x 6-cm wounds in guinea pigs. By day 14, the edges of the island grafts were clearly separated from the host epidermis and dermis by a distinct bed of granulation tissue. Histologic study of island grafts on day 14 showed that the copolymer grafts had largely degraded and that a new epidermis and dermis had been synthesized in its place. The thickness of the new epidermis increased as the density of cells seeded into the graft increased. No synthesis of epidermis or dermis was observed in the granulation tissue outside the perimeter of the island grafts. We conclude that island grafting allows the study of early events in skin regeneration in isolation from epithelialization, contraction, and scar synthesis.
Excess scar formation secondary to traumatic or surgical injuries can have devastating consequences, ranging from body disfigurement to organ dysfunction. Hypertrophic scars and keloids are skin fibrotic conditions that can be caused by minor insults to skin, such as acne or ear piercing, or by severe injuries such as burns. Differences between keloids, hypertrophic scars and normal scars include distinct scar appearance, histologic morphology and cellular function in response to growth factors. Recent advances in our understanding of the wound healing process reveal possible causes for hypertrophic scars and keloids. This information might assist in the development of efficacious treatment for hypertrophic scar and keloid formation.
Methods for serial cultivation of human keratinocytes can provide large quantities of epidermal cells, which have the potential of restoring the vital barrier function of the epidermis in extensive skin defects such as burns. To investigate the value of combining an epidermis with a dermal component, fibroblasts originated from the superficial dermis were used to seed a collagen lattice as described by E. Bell (dermal equivalent). Beginning in 1981, we grafted 18 patients (burns and giant nevi) using 35 grafts 10 x 10 cm in size. In the course of this work, the original technique was modified and improved as experience was gained. We began by using small skin biopsy samples as a source of keratinocytes cultured on a dermal equivalent before grafting in a one-step procedure, but this gave poor cosmetic results, because of a nonhomogeneous epidermalization. We then chose to cover the graft bed using a two-step procedure. The first step consisted of grafting a dermal equivalent to provide a dermal fibroblast-seeded substrate for subsequent in vivo epidermalization by cultured epidermal sheets. Whatever the epidermalization technique used, a living dermal equivalent applied to the graft bed was found to reduce pain, to provide good hemostasis, and to improve the mechanical and cosmetic properties of the graft. A normal undulating dermal-epidermal junction reappeared by 3 to 4 months after grafting and elastic fibers were detectable 6 to 9 months after grafting. As a result of the biosynthesis of these products, the suppleness (e.g., elasticity) of the grafts was closer to that of normal skin than the cicatricial skin usually obtained with epidermal sheets grafted without the presence of living dermal cells. This rapid improvement of the mechanical properties of the graft could be attributed to the presence of fibroblasts cultured from the dermis and seeded into the collagen matrix.
Nanomechanical properties of biological fibers are governed by the morphological features and chemically heterogeneous constituent subunits. However, very little experimental data exist for nanoscale correlation between heterogeneous subunits and their mechanical properties. We have used keratin-rich wool fibers as a model of composite biological fibers; a wool fiber is a simple two component cylindrical system consisting of a core cellular component surrounded by an outer cell layer and their ultrastructure and chemical composition are well-characterized. The core is 16-40 micrometer in diameter and rich in axially aligned keratin microfibrils. Outer cells have multiple laminar layers, 60-600 nm thick and distinctly rich in disulfide bonds. We used an atomic force microscope (AFM) to examine the nanomechanical properties of various structural components using complementary techniques of force-volume imaging and nano-indentation. AFM images of transverse sections of fibers were obtained in ambient environment, and the mechanical properties of several identified regions were examined. The outer cell layer showed a significantly higher mechanical stiffness than the internal cellular core region. Chemical reduction of disulfide bonds eliminated such dichotomy of mechanical strengths, indicating that the higher rigidity of the outer layer is attributed primarily to the presence of extensive disulfide bonding in the exo-cuticle. This is the first detailed correlative study of nano-indentation and regional elasticity measurements in composite biological systems, including mammalian biological fibers.
In a noncontractile fetal rabbit model, the authors recently have shown the induction of excisional wound contraction with sustained-release cellulose implants formulated with transforming growth factor (TGF)-beta. The purpose of this study was to test the hypothesis that the excisional wound contraction in this model is associated with the induction of myofibroblasts in the surrounding dermis, demonstrated by the presence of alpha-smooth muscle actin.
Cellulose discs were formulated with either 1.0 microg of TGF-beta1 (n = 6); 1.0 microg of TGF-beta3 (n = 9); 10 microg of TGF-beta3 (n = 6); or their carrier protein, bovine serum albumin (BSA; n = 9), for sustained-release over 5 days. Each disc was implanted into a subcutaneous pocket on the back of a fetal New Zealand White rabbit in utero on day 24 of gestation (term, 31 days). A full-thickness, 3-mm excisional wound (7.4 mm2) was then made next to the implanted cellulose disc. All fetuses were harvested at 3 days. The amount of alpha-smooth muscle (SM) actin in the dermis around the implants and wounds was determined using immunohistochemical techniques.
Excisional wounds exposed to 1.0 microg of TGF-beta1 (5.6+/-2.0 mm2), 1.0 microg of TGF-beta3 (6.9+/-1.0 mm2), and 10 microg of TGF-beta3 (2.7+/-1.0 mm2) were significantly smaller when compared with the BSA control group (12.8+/-1.1 mm2; P<.05). Furthermore, there was a significant increase in staining for alpha-SM actin in the TGF-beta1 (1.8+/-0.5) and 10 microg TGF-beta3 (2.8+/-0.2) groups in comparison with the scant staining in the BSA control group (0.5+/-0.2; P<.05).
TGF-beta1 and -beta3 induce alpha-SM actin and contraction of cutaneous excisional wounds in a fetal noncontractile model. This model of inducible cutaneous excisional wound contraction may be useful in further determining the role of the myofibroblast in wound contraction and the physiology underlying this poorly understood aspect of wound healing.
Angiogenesis is an important event for embryonic organogenesis as well as for tissue repair in the adult. Here, we show that hematopoietic stem cells (HSCs) play important roles for angiogenesis during embryogenesis. To investigate the role of HSCs in endothelial cell (EC) development, we analyzed AML1-deficient embryos, which lack definitive hematopoiesis. These embryos showed defective angiogenesis in the head and pericardium. Para-aortic splanchnopleural (P-Sp) explant cultures on stromal cells (P-Sp culture) did not generate definitive hematopoietic cells and showed defective angiogenesis in the AML1 null embryo. Disrupted angiogenesis in P-Sp cultures from AML1 null embryos was rescued by addition of HSCs or angiopoietin-1 (Ang1). HSCs, which express Ang1, directly promoted migration of ECs in vivo and in vitro. These results indicate that HSCs are critical for angiogenesis.
Granulation tissue formation is an example of new tissue development in an adult. Its rich vascular network has been thought to derive via angiogenic sprouting and extension of preexisting vessels from the surrounding tissue. The possibility that circulating cells of hematopoietic origin can differentiate into vascular endothelial cells (ECs) in areas of vascular remodeling has recently gained credibility. However, no quantitative data have placed the magnitude of this contribution into a physiological perspective. We have used hematopoietic chimeras to determine that 0.2% to 1.4% of ECs in vessels in control tissues derived from hematopoietic progenitors during the 4 months after irradiation and hematopoietic recovery. By contrast, 8.3% to 11.2% of ECs in vessels that developed in sponge-induced granulation tissue during 1 month derived from circulating hematopoietic progenitors. This recruitment of circulating progenitors to newly forming vessels would be difficult to observe in standard histological studies, but it is large enough to be encouraging for attempts to manipulate this contribution for therapeutic gain.
Recent studies have advanced our understanding that the regulation of immune responses is not only confined to immunocompetent cells. Upon stimulation, keratinocytes are capable of releasing various factors and expressing receptors that are significantly involved in immunoregulation. Dysregulation and the abnormal production of cytokines and other inflammatory mediators as well as their receptors can be observed in various skin diseases. An understanding of keratinocytes as important regulators of the skin immune system opens new opportunities for the treatment of various skin diseases.
Great advances have been made in the identification of the soluble angiogenic factors, insoluble extracellular matrix (ECM) molecules, and receptor signaling pathways that mediate control of angiogenesis--the growth of blood capillaries. This review focuses on work that explores how endothelial cells integrate these chemical signals with mechanical cues from their local tissue microenvironment so as to produce functional capillary networks that exhibit specialized form as well as function. These studies have revealed that ECM governs whether an endothelial cell will switch between growth, differentiation, motility, or apoptosis programs in response to a soluble stimulus based on its ability to mechanically resist cell tractional forces and thereby produce cell and cytoskeletal distortion. Transmembrane integrin receptors play a key role in this mechanochemical transduction process because they both organize a cytoskeletal signaling complex within the focal adhesion and preferentially focus mechanical forces on this site. Molecular filaments within the internal cytoskeleton--microfilaments, microtubules, and intermediate filaments--also contribute to the cell's structural and functional response to mechanical stress through their role as discrete support elements within a tensegrity-stabilized cytoskeletal array. Importantly, a similar form of mechanical control also has been shown to be involved in the regulation of contractility in vascular smooth muscle cells and cardiac myocytes. Thus, the mechanism by which cells perform mechanochemical transduction and the implications of these findings for morphogenetic control are discussed in the wider context of vascular development and cardiovascular physiology.
The early-gestation fetus heals dermal wounds rapidly and scarlessly. This phenomenon appears to be intrinsic to fetal skin and independent of the intrauterine environment. Unique properties of fetal cells, extracellular matrix, cytokine profile, and gene expression contribute to scarless repair. An intensive research effort has focused on unraveling the mechanisms that underlie scarless fetal wound healing in an attempt to improve the quality of healing in both children and adults.
Keloid and hypertrophic scars have affected patients and frustrated physicians for centuries. Keloid and hypertrophic scars result from excessive collagen deposition, the cause of which remains elusive. Clinically, these scars can be disfiguring functionally, aesthetically, or both. A thorough understanding of the pathophysiology and clinical nature of the scar can help define the most appropriate treatment strategy. Although many articles have been published on the management of hypertrophic and keloid scars, there is no universally accepted treatment protocol. Prevention of keloid and hypertrophic scars remains the best strategy; therefore, those patients with a predisposition to develop excessive scar formation should avoid nonessential surgery. Once a scar is present, there are many treatments from which to choose. Hypertrophic scars and keloids have been shown to respond to radiation, pressure therapy, cryotherapy, intralesional injections of corticosteroid, interferon and fluorouracil, topical silicone or other dressings, and pulsed-dye laser treatment. Simple surgical excision is usually followed by recurrence unless adjunct therapies are employed. Biologic agents that are directed towards the aberrant collagen proliferation that characterizes keloid and hypertrophic scars might be an important addition to the current armamentarium of modalities in the near future.
Bone marrow has long been known to be a source of stem cells capable of regeneration of the hematopoeitic system. Recent reports, however, have indicated that bone marrow might also contain early stem cells that can differentiate into other organ tissues such as skin. While these studies have illustrated that bone marrow stem cells could find their way to the skin, they have not addressed the dynamics of how bone marrow stem cells might participate in the homeostatis and regeneration of skin. In this report we followed green fluorescent protein (GFP) labeled bone marrow transplanted into non-GFP mice in order to determine the participation of bone marrow stem cells in cutaneous wounds. Our results indicate that there are a significant number of bone marrow cells that traffic through both wounded and non-wounded skin. Wounding stimulated the engraftment of bone marrow cells to the skin and induced bone marrow derived cells to incorporate into and differentiate into non-hematopoietic skin structures. This report thus illustrates that bone marrow might be a valuable source of stem cells for the skin and possibly other organs. Wounding could be a stimulus for bone marrow derived stem cells to travel to organs and aid in the regeneration of damaged tissue.
Adult human stem cells that are intrinsic to various tissues have been described and characterized, some only recently. Analysis of recent data suggests that adult stem cells can generate differentiated cells beyond their own tissue boundaries, a process termed “developmental stem-cell plasticity.” This review focuses on in vivo models of adult stem cells derived from bone marrow and peripheral blood and their potentially novel therapeutic applications.