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Low molecular weight hyaluronic acid prevents free radical damage to granulation tissue during wound healing
Abstract
Hyaluronic acid protects granulation tissue from oxygen free radical damage and stimulates wound healing, but its molecular weight prevents it from permeating the epidermal barrier A low molecular weight hyaluronic acid preparation is able to permeate the skin, but it is unknown whether or not it retains the scavenging effects of oxygen free radicals in granulation tissue. Our experiments were conducted in rats with excisional or incisional wounds. Wound contraction over 11 days and breaking strength on the fifth day were measured. Oxygen free radical production was induced by intraperitoneal administration of two different xenobiotics: phenazine methosulfate and zymosan. The wounds were treated topically with low molecular weight hyaluronic acid (0.2%) cream or placebo. In the incisional wound group, the effects of superoxide dismutase were also determined. Absolute controls received wounds and placebo but no xenobiotics. Wound healing was significantly slower in the xenobiotic group than in the control groups. These effects were strongly reduced by topical administration of low molecular weight hyaluronic acid (0.2%) cream and in incisional wounds by topically injected superoxide dismutase. Low molecular weight hyaluronic acid is effective as the native compound against oxygen free radicals. Its pharmacological effects through transdermal administration should be tested in appropriate models.
... In the initial stage of wound healing, i.e., homeostasis, HMM HA (~2000 kDa) accumulates in the extracellular matrix and binds to fibrinogen to form a clot. Thereafter, in the inflammatory phase, HMM HA is fragmented into LMM HA (80-800 kDa) by hyaluronidase for subsequent usage in healing [69]. A major function of HA is the modulation of inflammatory cells and dermal fibroblast activities, e.g., cellular migration, proinflammatory cytokine synthesis and the phagocytosis of invading microbes. ...
... Therefore, the most important mechanism of HA in tissue regeneration is its ability to serve as a free radical scavenger, which happens in the process of granulation of the tissue [71]. It was found that LMM HA prevented damage of the granulation tissue by ROS and increased the self-defense of skin epithelium by inducing various skin-repair-related genes during the healing process [69]. Wound dressings are traditionally used to protect the wound site from contamination, but they can be exploited as materials to deliver bioactive molecules to wound sites. ...
Hyaluronan (HA) is a natural glycosaminoglycan present in many tissues of all vertebrates. HA has various biological functions, which are dependent on its molar mass. High-molar-mass HA has anti-angiogenic, immunosuppressive and anti-inflammatory properties, while low-molar-mass HA has opposite effects. HA has also antioxidative properties, however on the other hand it can be readily degraded by reactive oxygen species. For many years it has been used in treatment of osteoarthritis, cosmetics and in ophthalmology. In the last years there has been a growing interest of HA to also be applied in other fields of medicine such as skin wound healing, tissue engineering, dentistry and gene delivery. In this review we summarize information on modes of HA administration, properties and effects of HA in various fields of medicine including recent progress in the investigation of HA.
... Moreover, HA and its fragments have been shown to reduce the amount of lipid peroxidation secondary products on liposomal skin lipid models [29]. Additionally, low molecular-weight hyaluronic acid can prevent oxygen free radical damage to granulation tissue during wound healing and is therefore effective as a native compound against oxygen free radicals [30]. These antifibrotic characteristics correspond to our histopathological results for Group C, in which liver fibrosis The imbalance between the cellular pro-oxidant and antioxidant redox favoring the pro-oxidant state can result in oxidative stress and cause potential cellular damage [23]. ...
... Moreover, HA and its fragments have been shown to reduce the amount of lipid peroxidation secondary products on liposomal skin lipid models [29]. Additionally, low molecular-weight hyaluronic acid can prevent oxygen free radical damage to granulation tissue during wound healing and is therefore effective as a native compound against oxygen free radicals [30]. These antifibrotic characteristics correspond to our histopathological results for Group C, in which liver fibrosis residues can be observed but fibrosis and hepatocyte swelling severity were clearly decreased. ...
Astaxanthin (Asta), a xanthophyll carotenoid, has been reported to be a strong antioxidative agent and has anti-inflammatory, antitumor and free radical-scavenging activities. However, inadequate stability and water solubility results in its low bioavailability. This study incorporated Asta into hydrophilic hyaluronan nanoparticles (HAn) to produce Asta-HAn aggregates (AHAna) using an electrostatic field system and investigated the restorative effects of AHAna on retrorsine-CCl₄-induced liver fibrosis in rats in vivo. Transmission electron microscopy (TEM) revealed that the prepared HAn were approximately 15 ± 2.1 nm in diameter and after the incorporation of Asta into HAn, the size increased to 210-500 nm. The incorporation efficiency of Asta was approximately 93% and approximately 54% of Asta was released after incubation for 18 h. Significant reductions in alanine aminotransferase and aspartate aminotransferase levels were observed after the rats were intraperitoneally injected with AHAna. Histopathological findings revealed the greatest reduction in hepatic fibrosis and hepatocyte necrosis in the rats after 2 weeks of intraperitoneal injection with AHAna, which is consistent with the data acquired from serum biochemical analysis. The restorative effects on liver damage displayed by AHAna in vivo demonstrated that Asta aggregated through HAn incorporation exerts therapeutic effects on liver fibrosis and necrosis.
... A potential functional significance in the turnover of HA fragments during wound repair has also been suggested in vitro [15][16][17]. For example, the importance of L-HA in propagating an inflammatory response (through activation of macrophages and induction of chemokines) has been well described by McKee and co-authors [18]. ...
... We can speculate that hyaluronidases produced by the cells degraded H-HA in this specific time frame thus decreasing viscosity. This biocatalytic process leads to a great amount of hyaluronic fragments in the solution, accelerating the future reparative action (Fig. 2) [10,14,15,17,31]. ...
Recent studies have reported the roles of Hyaluronic acid (HA) chains of diverse length in wound repair, especially considering the simultaneous occurrence in vivo of both high- (H-HA) and low-molecular weight (L-HA) hyaluronan at an injury site. It has been shown that HA fragments (5 ≤ MW ≤ 20 kDa) usually trigger an inflammatory response that, on one hand, is the first signal in the activation of a repair mechanism but on the other, when it's overexpressed, it may promote unwanted side effects. The present experimental research has aimed to investigate H-HA, L-HA and of a newly developed complex of the two (H-HA/L-HA) for stability (e.g. hyaluronidases digestion), for their ability to promote wound healing of human keratinocytes in vitro and for their effect on cellular biomarker expression trends.
Time-lapse video microscopy studies proved that the diverse HA was capable of restoring the monolayer integrity of HaCat. The H-HA/L-HA complex (0.1 and 1%w/v) proved faster in regeneration also in co-culture scratch test where wound closure was achieved in half the time of H-HA stimulated cells and 2.5-fold faster than the control. Gene expression was evaluated for transformation growth factor beta 1 (TGF-β1) proving that L-HA alone increased its expression at 4 h followed by restoration of similar trends for all the stimuli. Depending on the diverse stimulation (H-HA, L-HA or the complex), metalloproteinases (MMP-2, -9, -13) were also modulated differently. Furthermore, type I collagen expression and production were evaluated. Compared to the others, persistence of a significant higher expression level at 24 h for the H-HA/L-HA complex was found.
The outcomes of this research showed that, both at high and low concentrations, hybrid complexes proved to perform better than HA alone thus suggesting their potential as medical devices in aesthetic and regenerative medicine.
... This parallels the elaboration of TSG-6 that limits the severity of inflammatory arthritis. 108,109 The superoxide dismutases (SODs) also have an ameliorating role in wound inflammation. 85 The SODs are present in the ECM, inside cells, and also in mitochondria that catalyze the dismutation of superoxide (O2 − ) into oxygen and hydrogen peroxide. ...
... The complex of TSG-6, IαI, and HA appears to function as a negative-feedback control on the inflammatory reaction, stabilizing the healing process and doing so in part by its hyaluronidase inhibitor activity. 108,109,122 The TSG-6-IαI complex provides a two-pronged effect on wound healing, the TSG-6 component functioning as an anti-inflammatory molecule and the IαI portion serving as a hyaluronidase inhibitor. ...
Wound healing involves a series of carefully modulated steps, from initial injury and blood clot to the final reconstituted tissue or scar. A dynamic reciprocity exists throughout between the wound, blood elements, extracellular matrix, and the cells that participate in healing. Multiple cytokines and signal transduction pathways regulate these reactions.A major component throughout most of the process is hyaluronan, a straight-chain carbohydrate extracellular matrix polymer.Hyaluronan occurs in multiple forms, chain length being the only distinguishing difference between these sugar chains.Levels of hyaluronan in its high molecular weight form are prominent in the earliest stages of wound repair.Progressively more fragmented forms occur in a manner not previously appreciated.We outline here steps in the wound-healing cascade in which hyaluronan participates, as well as provide a review of its metabolism. Although described by necessity in a series of quantum steps, the healing process is constituted by a smooth continuum of overlapping reactions. The prevalence of hyaluronan in the wound, particularly in its early stages, termed initially as hexosamine-containing mucopolysaccharides, was pointed out over half a century ago by the Harvard surgeon, J. Engelbert Dunphy. It appears we are now returning to where we started.
... High molecular weight HA (HMWHA) with average molecular weight of 5400 kDa and 2000 kDa attenuated DNA damage in leukocytes during oxidative burst via reducing intracellular level of reactive oxidants [89]. The antoxidant ability of low molecular weight HA (LMWHA, 200-230 kDa) seems to be related to their ability to penetrate the skin preventing ROS damage in granulation tissue and promoting incisional wound healing in a rat experimental model [90,91]. The administration of LMWHA increased the activity of SOD, catalase, glutathione peroxidase, and total antioxidant capacity in cyclophosphamide-induced immunosuppressed mice [92]. ...
Objective: Haemorrhoidal disease (HD) is a very diffuse anorectal condition that involves a large part of the population, both male and female of every age. Among the procedures proposed to treat HD, conventional excisional surgery remains one of the most performed. Milligan-Morgan (MM) technique is one of the most used haemorrhoidectomy techniques. In this technique, the wounds are left open and re-epithelialization requires almost 3-5 weeks, in which patients generally experience pain and intense discomfort improving over the weeks. Methods: The aim of this study was to evaluate the effect of topic administration of Benebeo Gel®, mainly composed by bergamot-derived flavonoids and hyaluronic acid, on post-operative wound healing after open MM haemorrhoidectomy. An observational prospective study was carried out, involving 205 patients aged between 18 and 75. Results and Conclusion: The results after 2 weeks of treatment seem to be promising with a very good clinical outcome and patient satisfaction within 1 month.
... Moreover, cell death can be rescued by adding HA to chondrocytes exposed to various concentrations of H2O2 [64]. HA antioxidant properties have similarly been shown in other cell types [65][66][67][68]. Therefore, we set out to determine if HA could limit the oxidative stress in NPC, resulting from DMSO, to increase the potency of a potential off-the-shelf transplantation product. ...
To develop an off-the-shelf therapeutic product for intervertebral disc (IVD) repair using nucleus pulposus cells (NPCs), it is beneficial to mitigate dimethyl sulfoxide (DMSO)-induced cytotoxicity caused by intracellular reactive oxygen species (ROS). Hyaluronic acid (HA) has been shown to protect chondrocytes against ROS. Therefore, we examined the potential of HA on mitigating DMSO-induced cytotoxicity for the enhancement of NPC therapy. Human NPC cryo-preserved in DMSO solutions were thawed, mixed with equal amounts of EDTA-PBS (Group E) or HA (Group H), and incubated for 3-5 h. After incubation, DMSO was removed, and the cells were cultured for 5 days. Thereafter, we examined cell viability, cell proliferation rates, Tie2 positivity (a marker of NP progenitor cells), and the estimated numbers of Tie2 positive cells. Fluorescence intensity of DHE and MitoSOX staining, as indicators for oxidative stress, were evaluated by flow cytometry. Group H showed higher rates of cell proliferation and Tie2 expressing cells with a trend toward suppression of oxidative stress compared to Group E. Thus, HA treatment appears to suppress ROS induced by DMSO. These results highlight the ability of HA to maintain NPC functionalities, suggesting that mixing HA at the time of transplantation may be useful in the development of off-the-shelf NPC products.
... In the absence of these ions, highly reactive hydroxyl radicals with DNA cannot be generated [61]. In addition, studies have reported that HA treatment promotes the protection of granulation tissue from damage caused by oxygen-free radicals [62]. ...
This study aimed to investigate the effects of iontophoresis and hyaluronic acid (HA) combined with a gold nanoparticle (GNP) solution in an excisional wound model. Fifty Wistar rats (n = 10/group) were randomly assigned to the following groups: excisional wound (EW); EW + MC; EW + MC + HA; EW + MC + GNPs; and EW + MC + HA + GNPs. The animals were induced to a circular excision, and treatment started 24 h after injury with microcurrents (300 µA) containing gel with HA (0.9%) and/or GNPs (30 mg/L) in the electrodes (1 mL) for 7 days. The animals were euthanized 12 h after the last treatment application. The results demonstrate a reduction in the levels of pro-inflammatory cytokines (IFNϒ, IL-1β, TNFα, and IL-6) in the group in which the therapies were combined, and they show increased levels of anti-inflammatory cytokines (IL-4 and IL-10) and growth factors (FGF and TGF-β) in the EW + MC + HA and EW + MC + HA + GNPs groups. As for the levels of dichlorofluorescein (DCF) and nitrite, as well as oxidative damage (carbonyl and sulfhydryl), they decreased in the combined therapy group when compared to the control group. Regarding antioxidant defense, there was an increase in glutathione (GSH) and a decrease in superoxide dismutase (SOD) in the combined therapy group. A histological analysis showed reduced inflammatory infiltrate in the MC-treated groups and in the combination therapy group. There was an increase in the wound contraction rate in all treated groups when compared to the control group, proving that the proposed therapies are effective in the epithelial healing process. The results of this study demonstrate that the therapies in combination favor the tissue repair process more significantly than the therapies in isolation.
... 64 Studies report that HA improves the healing process by protecting granulation tissue from damage caused by oxygen free radicals. 65,66 It happens because HA forms a cytoprotective coating on the cell membrane and, as a result, protects the cell from oxidative damage and consequent cell death. In addition, by binding to CD44 on the surface of lymphocytes, HA is endocytosed and capable of neutralizing intracellular ROS, attenuating DNA damage during the respiratory pump. ...
Objectives: This article aimed to investigate the effects of the association between photobiomodulation and hyaluronic acid incorporated in lipid nanoparticles in an epithelial lesion model in inflammatory parameters and oxidative stress. Methods: Eighty Wistar rats were randomly assigned to the following groups: epithelial lesion group (EL); EL+PBM; EL+HA; EL+SLNs; EL+SLNs-HA; EL+PBM+HA; EL+PBM+SLNs; EL+PBM+SLNs-HA. The animals were anesthetized with 4% isofluorane after shaving and induced to an epithelial lesion. Topical treatment with a gel containing HA (0.9%) and/or SLNs (10 mg/mL) and with laser irradiation occurred daily for 1 week. Results: The results showed an increase in wound contraction on the seventh day in the LE + LBM + AH-NPL group, a reduction in pro-inflammatory cytokines (IL-6, IL-1β, and TNF-α), an increase in anti-inflammatory cytokines (IL- 4 and IL-10) and TGF-β. The levels of pro-inflammatory cytokine IL-4 and TGF-β also showed an increase in the LE + NPL-AH, LE + FBM + AH, LE + FBM + NPL and LE + FBM + NPL-AH groups. Regarding oxidative stress parameters, the levels of DCF and nitrite decreased in the combined therapy group when compared to the control group, as well as oxidative damage (carbonyl and sulfhydryl). In the antioxidant defense, there was an increase in GSH and SOD in the combination therapy group. Histological analysis showed a reduction in inflammatory infiltrate in the combination therapy group. The number of fibroblasts and the compaction of collagen fibers did not obtain significant responses. Conclusions: Results analyzed together showed that the combined therapy favored the repair process, and that studies can be carried out to enhance the histological analysis therapy favored the tissue repair process and that studies can be carried out to enhance the histological analysis.
... Though the reasons for this rapid metabolism are still unknown, the intrinsic ability of Hy to act as a scavenger of ROS represents a key factor in this rapid turnover [93]. Hy reduces levels of ROS [95], inducing protective effects in different cellular systems [96][97][98], tissues [99] and pathological conditions [38,95,100], while the polymer injection increases the endogenous synthesis in patients affected by inflammatory and oxidative injuries [101]. ...
Hyaluronic acid (Hy) is a natural linear polymer that is widely distributed in different organisms, especially in the articular cartilage and the synovial fluid. During tissue injury due to oxidative stress, Hy plays an important protective role. All the beneficial properties of Hy make the polymer attractive for many biomedical uses; however, the low stability and short biological half-life limit Hy application. To overcome these problems, the addition of small antioxidant molecules to Hy solution has been employed to protect the molecular integrity of Hy or delay its degradation. Carnosine (β-alanyl-L-histidine, Car) protects cells from the damage due to the reactive species derived from oxygen (ROS), nitrogen (RNS) or carbonyl groups (RCS). Car inhibits the degradation of hyaluronan induced by free radical processes in vitro but, like Hy, the potential protective action of Car is drastically hampered by the enzymatic hydrolysis in vivo. Recently, we conjugated Hy to Car and the derivatives (HyCar) showed protective effects in experimental models of osteoarthritis and rheumatoid arthritis in vivo. Here we report the antioxidant activity exerted by HyCar against ROS, RNS and RCS. Moreover, we tested if the covalent conjugation between Hy and Car inhibits the enzymatic hydrolysis of the polymer and the dipeptide backbone. We found that the antioxidant properties and the resistance to the enzymatic hydrolysis of Hy and Car are greatly improved by the conjugation.
... HA possesses antioxidant activity, which imparts a resistance to ROS degradation that enables HA to maintain its biological properties, and also accelerates wound healing and reduces arthritis symptoms (Campo et al., 2003a;Presti and Scott 1994;Sato et al., 1988;Trabucchi et al., 2002). Therefore, HA has received much attention as a functional natural product with utility as an exogenous antioxidant. ...
Hyaluronan (HA) possesses radical scavenging properties. The low molecular weight HA (LHA)-containing drink (PL) is a dietary supplement that consists of several antioxidants in addition to LHA. The aim of this study is to characterize the hydroxyl radical scavenging activity of LHA through the interactions between the components of PL in in vitro assays. Moreover, the efficacy of LHA toward oxidative stresses (ultraviolet C irradiation, oxidative DNA damage) was evaluated. LHA revealed the following hydroxyl radical-scavenging properties: 1) LHA directly scavenges hydroxyl radicals, 2) LHA activity is enhanced in the presence of other PL components, thereby enabling protection against oxidative damage to DNA, and 3) exposure to UVC-radiation temporarily attenuated the antioxidant activity of PL, which is recovered in an LHA-dependent process. These results suggest that LHA is an excellent material because its antioxidative activity is enhanced in the presence of other antioxidants, which ultimately increases resistance to oxidative stress.
... 39,40 Low-molecular weight HA however is able to function as an antioxidant scavenger, and promotes wound healing through ROS quenching. 41,42 HA is able to facilitate the movement of Langerhans cells through the epidermis by binding CD44 found on the surface of these cells, and therefore may help promote immune homeostasis given the well-known immune tolerance functions of Langerhans cells. 43 Ligation of keratinocyte-associated CD44 by HA is reported to promote epidermal differentiation and increase barrier function, 44 although the precise role for HA in epidermal differentiation remains controversial with suggestions that only with very low or high HA levels (e.g. as imparted by exogenous HA administration) is epidermal differentiation increased. ...
Siew Tein Wang, Boon Hoe Neo, Richard J Betts L’Oréal Research & Innovation, L’Oréal Singapore, SingaporeCorrespondence: Richard J Betts Email richard.betts@rd.loreal.comAbstract: Glycosaminoglycans (GAGs) are long, linear polysaccharides comprised of repeating disaccharide units with pleiotropic biological functions, with the non-sulfated GAG hyaluronic acid (HA), and sulfated GAGs dermatan sulfate, chondroitin sulfate, heparan sulfate, keratan sulfate, and to a lesser extent heparin all being expressed in skin. Their ability to regulate keratinocyte proliferation and differentiation, inflammatory processes and extracellular matrix composition and quality demonstrates their critical role in regulating skin physiology. Similarly, the water-binding properties of GAGs and structural qualities, particularly for HA, are crucial for maintaining proper skin form and hydration. The biological importance of GAGs, as well as extensive evidence that their properties and functions are altered in both chronological and extrinsic skin aging, makes them highly promising targets to improve cosmetic skin quality. Within the present review, we examine the cutaneous biological activity of GAGs alongside the protein complexes they form called proteoglycans and summarize the age-related changes of these molecules in skin. We also examine current topical interventional approaches to modulate GAGs for improved skin quality such as direct exogenous administration of GAGs, with a particular interest in strategies targeted at potentiating GAG levels in skin through either attenuating GAG degradation or increasing GAG production.Keywords: proteoglycan, growth factor, retinoic acid, hyaluronic acid, C-xyloside
... It plays a role in ECM of several tissues and is involved in every step of wound healing since it has a fundamental role in promoting extracellular matrix secretion, reducing inflammation by inhibiting immune cell migration and maintaining homeostasis in healthy tissue. Moreover HA degradation increases tissue permeability and HA fragments further enhance angiogenesis and promote tissue healing processes [192]. Hyaluronic acid mediates receptor-driven detachment, mitosis and migration via interactions with CD44, RHAMM and ICAM-1 cell receptors. ...
Tissue repair and regeneration is an interdisciplinary field focusing on developing bioactive substitutes aimed at restoring pristine functions of damaged, diseased tissues. Biomaterials, intended as those materials compatible with living tissues after in vivo administration, play a pivotal role in this area and they have been successfully studied and developed for several years. Namely, the researches focus on improving bio-inert biomaterials that well integrate in living tissues with no or minimal tissue response, or bioactive materials that influence biological response, stimulating new tissue re-growth. This review aims to gather and introduce, in the context of Italian scientific community, cutting-edge advancements in biomaterial science applied to tissue repair and regeneration. After introducing tissue repair and regeneration, the review focuses on biodegradable and biocompatible biomaterials such as collagen, polysaccharides, silk proteins, polyesters and their derivatives, characterized by the most promising outputs in biomedical science. Attention is pointed out also to those biomaterials exerting peculiar activities, e.g., antibacterial. The regulatory frame applied to pre-clinical and early clinical studies is also outlined by distinguishing between Advanced Therapy Medicinal Products and Medical Devices.
... In the initial stage of wound healing, HA with a molecular weight reaching 2000 kDa only accumulates in the extracellular matrix and combines with fibrinogen to form a clot. However, L-HA with molecular weight ranging from 80 to 800 kDa influences the inflammatory response and activates macrophages [17], resulting in accelerated wound repair [18,19]. Although previous in vitro cellular studies have reported that L-HA exhibits a positive effect on bone healing, the effect of L-HA combined with hydroxyapatite/β-TCP bone graft on the healing of bone defects is still unclear [15,20,21]. ...
Osteoconduction is an important consideration for fabricating bio-active materials for bone regeneration. For years, hydroxyapatite and β-calcium triphosphate (β-TCP) have been used to develop bone grafts for treating bone defects. However, this material can be difficult to handle due to filling material sagging. High molecular weight hyaluronic acid (H-HA) can be used as a carrier to address this problem and improve operability. However, the effect of H-HA on bone formation is still controversial. In this study, low molecular weight hyaluronic acid (L-HA) was fabricated using gamma-ray irradiation. The viscoelastic properties and chemical structure of the fabricated hybrids were evaluated by a rheological analysis nuclear magnetic resonance (NMR) spectrum. The L-MH was mixed with H-HA to produce H-HA/L-HA hybrids at ratios of 80:20, 50:50 and 20:80 (w/w). These HA hybrids were then combined with hydroxyapatite and β-TCP to create a novel bone graft composite. For animal study, artificial bone defects were prepared in rabbit femurs. After 12 weeks of healing, the rabbits were scarified, and the healing statuses were observed and evaluated through micro-computer tomography (CT) and tissue histological images. Our viscoelastic analysis showed that an HA hybrid consisting 20% H-HA is sufficient to maintain elasticity; however, the addition of L-HA dramatically decreases the dynamic viscosity of the HA hybrid. Micro-CT images showed that the new bone formations in the rabbit femur defect model treated with 50% and 80% L-HA were 1.47 (p < 0.05) and 2.26 (p < 0.01) times higher than samples filled with HA free bone graft. In addition, a similar tendency was observed in the results of HE staining. These results lead us to suggest that the material with an H-HA/L-HA ratio of 50:50 exhibited acceptable viscosity and significant new bone formation. Thus, it is reasonable to suggest that it may be a potential candidate to serve as a supporting system for improving the operability of granular bone grafts and enhancing new bone formations.
... Furthermore, hyaluronic acid affects the proliferation and differentiation of cells and immobilizes water in tissues (Weindl et al., 2004). Hyaluronic acid also accelerates the healing process via its antioxidant activity (Trabucchi et al., 2002). The considerable therapeutic activity of exogenous hyaluronic acid on wounds including, preserving moisture in wound sites, promoting migration of epithelial cells, regeneration, and remodeling processes, encourage its large scale production (Anilkumar et al., 2011). ...
Age and diabetes related slow-healing or chronic wounds may result in morbidity and mortality through persistent biofilms infections and prolonged inflammatory phase. Nano-materials [metal/metal oxide NPs (39%), lipid vehicles (21%), polymer NPs (19%), ceramic nanoparticles (NPs) (14%), and carbon nanomaterials (NMs) (7%)] can be introduced as a possible next-generation therapy because of either their intrinsic wound healing activity or via carrying bioactive compounds including, antibiotics, antioxidants, growth factor or stem cell. The nanomaterials have been shown to implicate in all four stages of wound healing including hemostasis (polymer NPs, ceramic NPs, nanoceria-6.1%), inflammation (liposome/vesicles/solid lipid NPs/polymer NPs/ceramic NPs/silver NPs/gold NPs/nanoceria/fullerenes/carbon-based NPs-32.7%), proliferation (vesicles/liposome/solid lipid NPs/gold NPs/silver NPs/iron oxide NPs/ceramic NPs/copper NPs/self-assembling elastin-like NPs/nanoceria/micelle/dendrimers/polymer NPs-57.1%), remodeling (iron oxide NPs/nanoceria-4.1%). Natural compounds from alkaloids, flavonoids, retinoids, volatile oil, terpenes, carotenoids, or polyphenolic compounds with proven antioxidant, anti-inflammatory, immunomodulatory, or antimicrobial characteristics are also well known for their potential to accelerate the wound healing process. In the current paper, we survey the potential and properties of nanomaterials and microbial compounds in improving the process of wound and scar healing. Finally, we review the potential biocompounds for incorporation to nano-material in perspective to designate more effective or multivalent wound healing natural or nano-based drugs.
... It was also reported that low molecular weight hyaluronic acid (LMWHA, 200-230 kDa) that is able to penetrate the skin prevents ROS damage in granulation tissue and promotes incisional wound healing in a rat experimental model [132,133]. Irradiation of gamma rays to the native hyaluronic acid increased its antioxidant activity by reducing the molecular weight [134]. Two LMWHAs, LMWHA-1 (145 kDa) and LMWHA-2 (45.2 kDa), inhibit lipid peroxidation and scavenge hydroxyl radical 1,1-diphenyl-2-picryldydrazyl radical superoxide anion in vitro [135]. ...
Antioxidants may modulate the microenvironment of epidermal stem cells by reducing the production of reactive oxygen species or by regulating the expression of extracellular matrix protein. The extracellular membrane is an important component of the stem cell niche, and microRNAs regulate extracellular membrane-mediated basal keratinocyte proliferation. In this narrative review, we will discuss several antioxidants such as ascorbic acid, plant extracts, peptides and hyaluronic acid, and their effect on the epidermal stem cell niche and the proliferative potential of interfollicular epidermal stem cells in 3D skin equivalent models.
... It has either anti-inflammatory or pro-inflammatory properties, in relation to its molecular weight [73]. Specifically, HA binds CD44 keratinocyte receptors, leading to their differentiation and increasing their motility [74,75]. For these and many other well-known properties (excellent biocompatibility, biodegradability, durability and absence of toxicity) [76,77] researchers in recent years have focused their interest on the application of some HA-based products, such as Hyaff-11 ® , in skin tissue engineering and regenerative medicine. ...
The discovery of several unexpected complex biological roles of hyaluronic acid (HA) has promoted new research impetus for biologists and, the clinical interest in several fields of medicine, such as ophthalmology, articular pathologies, cutaneous repair, skin remodeling, vascular prosthesis, adipose tissue engineering, nerve reconstruction and cancer therapy. In addition, the great potential of HA in medicine has stimulated the interest of pharmaceutical companies which, by means of new technologies can produce HA and several new derivatives in order to increase both the residence time in a variety of human tissues and the anti-inflammatory properties. Minor chemical modifications of the molecule, such as the esterification with benzyl alcohol (Hyaff-11® biomaterials), have made possible the production of water-insoluble polymers that have been manufactured in various forms: membranes, gauzes, nonwoven meshes, gels, tubes. All these biomaterials are used as wound-covering, anti-adhesive devices and as scaffolds for tissue engineering, such as epidermis, dermis, micro-vascularized skin, cartilage and bone. In this review, the essential biological functions of HA and the applications of its derivatives for pharmaceutical and tissue regeneration purposes are reviewed.
... Although HNa is a fragile molecule that can be degraded by chemical processes such as free radicals, functional maturation of dendritic cells during inflammation, inhibition of anchorage-independent growth of tumor cells, and protection of granulation tissue from oxygen free radical damage have been ascribed to HA fragments (61)(62)(63). However, the retention of antioxidant capabilities is essential to ensure the role of the protective barrier which limits the action of free radicals on cartilage (1). ...
The present work attempts to develop and optimize the formula of a lipidic nanoemulsion (NE) containing sodium hyaluronate (HNa) and indomethacin (Ind) as HNa–Ind for enhanced transdermal antiarthritic activity. NEs were prepared by the spontaneous emulsification method and characterized by Fourier-transform infrared (FTIR) spectroscopy. The composition of the optimal formulation was statistically optimized using Box–Behnken experimental design method with three independent factors and was characterized for particle size, polydispersity index, and percent transmittance. The selected formula was tested for its in vitro antioxidant activity and in vivo anti-inflammatory activity. The optimized HNa–Ind NE formula was characterized and displayed a particle size of 12.87 ± 0.032 nm, polydispersity index of 0.606 ± 0.082, and 99.4 ± 0.1 percentage of transmittance. FTIR showed no interaction between HNa and Ind as a physical mixture. In addition, the optimized HNa–Ind NE was able to preserve the antioxidant ability of the two drugs, as evidenced through a 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition assay used to assess free radical scavenging ability. The cell viability was increased while the free radical scavenging activity was decreased (94.28% inhibition at higher concentrations compared with vitamin C as a reference with an inhibition of 100%). Moreover, the pharmacological anti-inflammatory potential of the optimized HNa–Ind NE formulation was assessed using an in vivo model. Compared with reference drugs (ibuprofen gel 5%), the remarkable activity of the optimized formulation was established using xylene-induced ear edema in mice model, in which the inflamed region reduced by 92.5% upon treatment. The optimized HNa–Ind NE formulation showed considerably higher skin permeation and drug deposition capability compared with the HNa–Ind solution. HNa–Ind NE was demonstrated to be a successful carrier with enhanced antioxidant and anti-inflammatory potential while showing better skin penetration, thus being a promising vehicle for transdermal drug delivery.
... These effects allow macrophages to move to the wound site to phagocytose debris and clean infectious matter [16]. Several investigations also found that LMWHA prevented oxygen free radical damage to granulation tissue [19] and increased the selfdefense of skin epithelium by inducing various skin-repair-related genes [20] during the wound healing process. ...
In this study, we prepared low-molecular-weight hyaluronic acid (LMWHA) powder by γ-irradiation. The chemical and physical properties of γ-irradiated LMWHA and the in vitro cellular growth experiments with γ-irradiated LMWHA were analyzed. Then, hyaluronic acid exposed to 20 kGy of γ-irradiation was used to fabricate a carboxymethyl cellulose (CMC)/LMWHA fabric for wound dressing. Our results showed that γ-irradiated LMWHA demonstrated a significant alteration in carbon–oxygen double bonding and can be detected using nuclear magnetic resonance and ultraviolet (UV)-visible (Vis) spectra. The γ-irradiated LMWHA exhibited strain rate-dependent Newton/non-Newton fluid biphasic viscosity. The viability of L929 skin fibroblasts improved upon co-culture with γ-irradiated LMWHA. In the in vivo animal experiments, skin wounds covered with dressings prepared by γ-irradiation revealed acceleration of wound healing after two days of healing. The results suggest that γ-irradiated LMWHA could be a potential source for the promotion of skin wound healing.
... 16 Excessive free radicals not only impair local wound healing but can also produce negative neurological outcomes in an injured brain. [17][18][19] Free radicals also inhibit the healing metabolic function of keratinocytes in wound healing. 20 Poorly controlled diabetes further impairs healing of fractures, which can affect neurosurgery patients with traumatic injuries to the skull and spine. ...
Surgically accessing pathological lesions located within the central nervous system (CNS) frequently requires creating an incision in cosmetic regions of the head and neck. The biggest factors of surgical success typically tend to focus on the middle portion of the surgery, but a vast majority of surgical complications tend to happen towards the end of a case, during closure of the surgical site incisions. One of the most difficult complications for a surgeon to deal with is having to take a patient back to the operating room for wound breakdowns and, even worse, wound or CNS infections, which can negate all the positive outcomes from the surgery itself. In this paper, we discuss the underlying anatomy, pharmacological considerations, surgical techniques and nutritional needs necessary to help facilitate appropriate wound healing. A successful surgery begins with preoperative planning regarding the placement of the surgical incision, being cognizant of cosmetics, and the effects of possible adjuvant radiation therapy on healing incisions. We need to assess patient's medications and past medical history to make sure we can optimise conditions for proper wound reepithelialisation, such as minimizing the amount of steroids and certain antibiotics. Contrary to harmful medications, it is imperative to optimise nutritional intake with adequate supplementation and vitamin intake. The goals of this paper are to reinforce the mechanisms by which surgical wounds can fail, leading to postoperative complications, and to provide surgeons with the reminder and techniques that can help foster a more successful surgical outcome.
... 3,27 In addition, it has been proposed that HA can protect the granulation tissue from damage caused by oxygen free radicals by its ability to eliminate reactive oxygen species. 28 The HA molecule probably interacts with CD44 or RHAMM on the surface of endothelial cells, although the contribution of each receptor is controversial. 29 Evaluation of bone formation using CBCT is done using various methods without standardization, making it difficult to compare studies. ...
This study evaluated the effects of hyaluronic acid (HA) on bone repair of human dental sockets. Thirty-two lower first premolars were extracted from 16 patients (2 per patient) for orthodontic reasons. Following the extractions, one socket was randomly filled with 1% HA gel, while the other was allowed to naturally fill with blood clot. After 30 and 90 days of surgery, patients underwent cone beam computed tomography. Five central orthoradial slices were captured from each socket. The gray intensity was measured in each image and results were reported as mean percentage of bone formation. The buccolingual alveolar ridge width was measured and dimensional changes were compared between the postoperative intervals. The pattern of alveolar trabecular bone was evaluated through the fractal dimension. Treated sockets showed a higher percentage of bone formation and fractal dimension values (58.17% and 1.098, respectively) compared with controls (48.97% and 1.074, respectively) in the 30-day postoperative period (p < 0.05). After 90 days, there was no significant difference between groups. Additionally, no significant difference was found between groups regarding the alveolar dimensions (p > 0.05). Use of 1% HA gel after tooth extraction accelerates bone repair in human dental sockets.
... A similar effect cannot be ruled out in the present study since whole-body of the animal was irradiated. Furthermore, ionizing radiation are known to produce cytotoxic effects by generating oxygen-derived free radicals and the overproduction of free radical results in oxidative stress, producing negative effect on wound healing [78]. ...
... The process by which HA fragments promote granulation tissue formation is associated with higher collagen deposition and protection from the deleterious effects of oxygen free radicals [167,211,212]. In addition, HA has been shown to activate the host innate immune response [213], control the angiogenic process, and stimulate collagen production in endothelial cells [194][195][196]. ...
Cutaneous wound healing in adult mammals is a complex multi-step process involving overlapping stages of blood clot formation, inflammation, re-epithelialization, granulation tissue formation, neovascularization, and remodelling. Re-epithelialization describes the resurfacing of a wound with new epithelium. The cellular and molecular processes involved in the initiation, maintenance, and completion of epithelialization are essential for successful wound closure. A variety of modulators are involved, including growth factors, cytokines, matrix metalloproteinases, cellular receptors, and extracellular matrix components. Here, we focus on cellular mechanisms underlying keratinocyte migration and proliferation during epidermal closure. Inability to re-epithelialize is a clear indicator of chronic non-healing wounds, which fail to proceed through the normal phases of wound healing in an orderly and timely manner. This review summarizes the current knowledge regarding the management and treatment of acute and chronic wounds, with a focus on re-epithelialization, offering some insights into novel future therapies.
... These findings suggest greater ability of LMW-HA-based biomaterials in promoting healing of incisional and excisional wounds. 94 Several other experimental models reported that LMW-HA significantly promotes angiogenesis during wound healing processes compared to MMW-HA and HMW-HA. 95,96 In contrast, a recent study conducted by Ghazi et al. 89 revealed that the application of medium molecular weight HA (MMW-HA, 100-300 kDa) significantly enhanced wound healing compared to low molecular weight HA (LMW-HA, 50-100 kDa) and high molecular weight HA (HMW-HA, 1000-1400 kDa). ...
Wound healing is a multipart and dynamic process of replacing devitalized and damaged cellular structures and tissue layers. Numerous conventional wound dressings are employed for the management of wounds but there is a lack of absolute and versatile choice. An ideal wound healing modality should provide a moist environment, offer protection from secondary infections, eliminate wound exudate, and stimulate tissue regeneration. Hyaluronic acid (HA) has been known to promote angiogenesis, granulation tissue formation, remodeling of extracellular matrix (ECM), and wound healing. Accumulation and turnover of ECM is a hallmark of tissue injury, repair, and remodeling in wound healing. HA is a major component of ECM and plays an important role in regulating tissue injury, accelerating tissue repair, and controlling disease outcomes. A wide range of in vitro, in vivo, and clinical studies have demonstrated the wound healing efficacy of HA-based biomaterials not only in the treatment of wound in the tympanic membrane, skin, and articular cartilage but also in tracheal and corneal wound healing. Recent progress and improved therapeutic efficacy achieved through partial modification and formation of HA-based biomaterials, including HA-scaffolds, sponge-like hydrogels, anti-adhesive sheets, cultured dermal substitutes, thin membranes, and dermal matrix grafts, have been discussed. The current review summarizes the evidence for the therapeutic effectiveness of HA-based biomaterials in the treatment of traumatic, surgical, and chronic wounds and tissue regeneration.
... Hyaluronic acid cream is one of the topical treatment methods of RISD. It has been shown that hyaluronic acid reduces the incident of dermatitis and improves the healing of wounds [40,42]. Steroid creams and vitamin E solutions were ineffective in RISD [43,44]. ...
Aim:
This study is aimed to evaluate the effects of boron on radiation-induced skin reactions (RISR) in breast cancer patients.
Material and methods:
After 47 patients with invasive ductal carcinoma underwent radiotherapy, 23 (49%) received a boron-based gel, and 24 (51%) received placebo. Assessments were performed according to the Radiation Therapy Oncology Group (RTOG) skin scale and a Five-Point Horizontal Scale (FPHS).
Results:
At the end of the fifth week of radiotherapy, the RTOG scores in the boron group were significantly lower than those in the placebo group (p = .024). The FPHS score was higher in the placebo group than in the boron group, and this difference was not statistically significant (p = .079).
Conclusion:
Using the RTOG scoring system, we revealed that the application of a boron-based gel diminished RISR. The mechanism of action is unclear but may be related to antioxidant, wound healing, and thermal degradation effects of boron.
... Also expressed in placental membranes are immunosuppressive factors and antibacterial peptides that contribute to the reduced risk of rejection of placental membranes (Park et al., 2008;Mamede et al., 2010). Large amounts of the ECM glycosaminoglycan hyaluronan (HA) are also present in placental membranes, which has been shown to function as a free radical scavenger to remove reactive oxygen species (Trabucchi et al., 2002;Lockington et al., 2014). However, different processing methods impact the composition and functionality of these materials (von Versen-Hoeynck et al., 2008). ...
Skin regeneration requires the coordinated integration of concomitant biological and molecular events in the extracellular wound environment during overlapping phases of inflammation, proliferation, and matrix remodeling. This process is highly efficient during normal wound healing. However, chronic wounds fail to progress through the ordered and reparative wound healing process and are unable to heal, requiring long-term treatment at high costs. There are many advanced skin substitutes, which mostly comprise bioactive dressings containing mammalian derived matrix components, and/or human cells, in clinical use. However, it is presently hypothesized that no treatment significantly outperforms the others. To address this unmet challenge, recent research has focused on developing innovative acellular biopolymeric scaffolds as more efficacious wound healing therapies. These biomaterial-based skin substitutes are precisely engineered and fine-tuned to recapitulate aspects of the wound healing milieu and target specific events in the wound healing cascade to facilitate complete skin repair with restored function and tissue integrity. This mini-review will provide a brief overview of chronic wound healing and current skin substitute treatment strategies while focusing on recent engineering approaches that regenerate skin using synthetic, biopolymeric scaffolds. We discuss key polymeric scaffold design criteria, including degradation, biocompatibility, and microstructure, and how they translate to inductive microenvironments that stimulate cell infiltration and vascularization to enhance chronic wound healing. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic, biopolymeric scaffolds as tunable treatment modalities for chronic wounds will be considered.
... Several studies suggest that HA has a central role in skin regeneration , scarless wound healing and wrinkles reduction due to viscoelastic properties and regulation of water content [99,101,102]. It is also as a free radicals scavenger in the skin and, therefore has a protective role in the epidermis [103]. Topical treatment of in vitro skin model that contains 8–12 cell layers with 2% GlcNAc and 4% niacinamide (as precursor to NAD(P), an essential cofactor for hyaluronic acid synthesis) led to increase of HA amount that improves skin hydration and reduces wrinkles [104]. ...
Glucosamine and its acetylated derivative, N-acetyl glucosamine, are naturally occurring amino sugars found in human body. They are important components of glycoproteins, proteoglycans and glycosaminoglycans. Scientific studies have supported that glucosamine has the beneficial pharmacological effects to relieve osteoarthritis symptoms. Glucosamine can also be as a promising candidate for the prevention and/or treatment of some other diseases due to its anti-oxidant and anti-inflammatory activities. Most of its function is exerted by modulation of inflammatory responses especially through Nuclear Factor-κB (NF-κB) that can control inflammatory cytokine production and cell survival. In this review, we present a concise update on additional new therapeutic applications of glucosamine including treatment of cardiovascular disease, neurological deficits, skin disorders, cancer and the molecular mechanistic rationale for these uses. This article will also examine safety profile and adverse effects of glucosamine in human.
... The preparation of low-molecular-weight glycosamino-glycans are gaining increased attention. Some types of glycosaminoglycans with low-molecular-weight can effectively inhibit free radicals (Trabucchi et al., 2002), prevent lipid peroxidation (Trommer et al., 2003), and protect against DNA damage (Zhao et al., 2008). However, the anti-oxidant properties of low-molecularweight chondroitin sulfate were unclear. ...
Low-molecular-weight chondroitin sulfate was obtained by degradation of chondroitin sulfate using hyaluronidase. Then, separated with sephadex G25, DEAE-52, and finally purified with AKATA superpeptide separation system and fluorescence-assisted carbohydrate electrophoresis. The main compo-nents detected by high performance gel-filtration chromatography were disaccharide, tetrasaccharide, hexasaccharide with molecular weight of 521, 1024 and 1527 Da, respectively. The anti-oxidant activity of these three oligosaccharides in vitro showed that the reducing power (maximum value at 10 mg/mL) and superoxide anion radical scavenging abilities were increased (maximum value at 4 mg/mL) with an increased in their concentration. There were no significant differences of the anti-oxidant properties between those three oligosaccharides.
... The rapid turnover of HA also helps to remove and clear the harmful substances from the injured cells. 25 Thus, HA can alleviate the apoptosis of keratinocytes. ...
To compare the cytotoxicities and efficacy of hyaluronan (HA), carbomer, and sodium alginate on repairing thermal-injured cells and promoting cell migration.
The 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetra-zoliumromide method was used to evaluate the cytotoxicities of HA, carbomer, and sodium alginate on L929 mouse fibroblasts and their repairing ability to thermal-injured HaCaT keratinocytes. A scratch test was used to observe the effects of the 3 materials on cell migration.
Hyaluronan with different molecular weights were nontoxic, even at the concentration of 0.5%, whereas carbomer and sodium alginate showed mild or moderate cytotoxicities when their concentrations were higher than 0.1%. Cell viability and cell density of the thermal-injured keratinocytes treated with HA (600, 1070, and 1500 kDa) were increased significantly compared with that of model control (P < .05), whereas carbomer aggravated cell injury, and sodium alginate had no obvious repairing ability. Hyaluronan promoted cell migration significantly with higher cell density in the scratch area, compared with the control after culture for 48 hours; both carbomer and sodium alginate inhibited the cell migration, and carbomer altered the cell morphology completely.
Hyaluronan can repair cell injury and promote cell migration and proliferation. It also has good biocompatibility. As a new type of hydrogel matrix, HA is superior to carbomer and sodium alginate if it is used in wound caring preparations.
... Furthermore, HA and its related low molecular weight products modulate the expression of fibroblast genes involved in remodeling and repair of extracellular matrix (David-Raoudi et al., 2008) and play a role in the control of angiogenesis (West, Hampson, Arnold, & Kumar, 1985). HA may also protect granulation tissue from the deleterious effects of oxygen free radical due to its scavenging activity (Trabucchi et al., 2002). ...
... A separate study also showed improved age-related skin function, when HA was administered to patients with skin atrophy in a CD44-dependent manner (151). Topical administration of LMW-HA also acts as a scavenging agent following xenobiotic treatment (and ROS generation), promoting wound healing in excisional and incisional wound models (152). In the lung, LMW-HA protected against porcine pancreatic elastase-induced bronchoconstriction (153). ...
Transition from homeostatic to reactive matrix remodeling is a fundamental adaptive tissue response to injury, inflammatory disease, fibrosis, and cancer. Alterations in architecture, physical properties, and matrix composition result in changes in biomechanical and biochemical cellular signaling. The dynamics of pericellular and extracellular matrices, including matrix protein, proteoglycan, and glycosaminoglycan modification are continually emerging as essential regulatory mechanisms underlying cellular and tissue function. Nevertheless, the impact of matrix organization on inflammation and immunity in particular and the consequent effects on tissue healing and disease outcome are arguably under-studied aspects of adaptive stress responses. Herein, we review how the predominant glycosaminoglycan hyaluronan (HA) contributes to the structure and function of the tissue microenvironment. Specifically, we examine the evidence of HA degradation and the generation of biologically active smaller HA fragments in pathological settings in vivo. We discuss how HA fragments versus nascent HA via alternate receptor-mediated signaling influence inflammatory cell recruitment and differentiation, resident cell activation, as well as tumor growth, survival, and metastasis. Finally, we discuss how HA fragmentation impacts restoration of normal tissue function and pathological outcomes in disease.
... Variations were found in the dimensions of the wounds. Only a few studies used the same size wound in the same location with the same wounding technique, which was a 4-cm incision wound on the dorsum of the rats [50,51,52,53] . Because the numbers of studies using similar techniques is so small, no meaningful statements can be made to illustrate consistent findings in the data. ...
___________________________________________________________________________ SUMMARY Wound is defined as the loss of breaking cellular and functional continuity of the living tissues and management of wounds is frequently encountered with different problems. Drug resistance and toxicity hindered the development of synthetic antimicrobial agents with wound healing activity. Many factors should be considered before selecting a wound healing model for a specific study. A wide variety of models have been developed for examining different aspects of the repair response thus many animal models are used for the evaluation of wound healing activities. Rats and mice have been widely used in the study of skin wound healing and efficacy of different treatment modalities. These particular species are mostly selected because of its availability, low cost and small size. In this review, we discussed about the wound and types of wound models that can be used along with the topics like wound location, where it is feasible to create the wound, wound size, strain and sex of rat, weight and age range as well as anaesthetics and analgesics and analytical measures that are used in wound healing studies. The present review will be helpful for the evaluation of drugs having potential for wound healing activity. KEYWORDS
... The high-molecular-weight hyaluronan is readily degraded into small molecules after tissue injury (22), primarily by increased levels of hyaluronidases (HYALs) and reactive oxygen species (ROS) (23). The degraded hyaluronan fragments play important roles in inflammation, innate immunity, cell proliferation, and wound healing through its antioxidant properties and through interacting with its primary cell surface receptors, CD44, RHAMM, and toll-like receptor 4 (TLR-4) (24)(25)(26). The increased fragmentation of HA in the early stages of injury could exert antioxidant effect against ROS and stimulate white blood cells-mediated immune response by up-regulating CD44 (27,28). ...
Traumatic brain injury (TBI) triggers many secondary changes in tissue biology, which ultimately determine the extent of injury and clinical outcome. Hyaluronan [hyaluronic acid (HA)] is a protective cementing gel present in the intercellular spaces whose degradation has been reported as a causative factor in tissue damage. Yet little is known about the expression and activities of genes involved in HA catabolism after TBI. Young adult male Sprague-Dawley rats were assigned to three groups: naïve control, craniotomy, and controlled-cortical impact-induced TBI (CCI-TBI). Four animals per group were sacrificed at 4 h, 1, 3, and 7 days post-CCI. The mRNA expression of hyaluronan synthases (HAS1-3), hyaluronidases (enzymes for HA degradation, HYAL 1-4, and PH20), and CD44 and RHAMM (membrane receptors for HA signaling and removal) were determined using real-time PCR. Compared to the naïve controls, expression of HAS1 and HAS2 mRNA, but not HAS3 mRNA increased significantly following craniotomy alone and following CCI with differential kinetics. Expression of HAS2 mRNA increased significantly in the ipsilateral brain at 1 and 3 days post-CCI. HYAL1 mRNA expression also increased significantly in the craniotomy group and in the contralateral CCI at 1 and 3 days post-CCI. CD44 mRNA expression increased significantly in the ipsilateral CCI at 4 h, 1, 3, and 7 days post-CCI (up to 25-fold increase). These data suggest a dynamic regulation and role for HA metabolism in secondary responses to TBI.
... Day/night cycle was 12/12 [18]. All animals were divided into two groups: group A with full thickness excisional round cutting wounds [19][20][21] and group B with full thickness round burn wound [22][23][24][25][26]. Both groups were divided into two sub-groups. ...
Natural-synthetic blend nanofibres have recently attracted more interest because of the ability of achieving desirable properties. Poly(Ε-caprolactone) (PCL)-chitosan (Cs)-poly(vinyl alcohol) (PVA) blend nanofibrous scaffolds were electrospun in 2:1:1.33 mass ratio of PCL:Cs:PVA. The presence of PCL in the blend leads to improvement in web hydrophobicity and helped the web to retain its integrity in aqueous media. The scaffolds were used in two forms of acellular and with mesenchymal stem cells. They were applied on burn (n = 12) and excisional cutting (n = 12) wounds on dorsum skin of rats. Macroscopic investigations were carried out to measure the wounds areas. It was found that the area of wounds that were treated with cell-seeded nanofibrous scaffolds were smaller compared to other samples. Pathological results showed much better healing performance for cell-seeded scaffolds followed by acellular scaffolds compared with control samples. All these results indicate that PCL:Cs:PVA nanofibrous web would be a proper material for burn and cutting wound healing.
... For all these reasons, the main role of HA in tissue repair processes consists in facilitating the entry of a large number of cells into the injured area and in orientating the deposition of ECM fibrous components [26][27][28][29][30] . Furthermore, HA seems to protect directly the granulation tissue from oxygen-free radicals that impair the wound healing, possibly acting as a molecular scavenger 32,33 . ...
Bed debridement is important to treat chronic wounds. Effective agents should remove the necrosis but protect the granulation tissue. We evaluated the performance and tolerability of a new composite ointment containing collagenase and hyaluronic acid for chronic venous ulcers.
Subjects with class 6 venous ulcers (CEAP classification) of at least 6 months duration were prospectively recruited. The ointment was administered daily and follow-up visits were conducted on the fifth, 10th, 15th and 20th days. On each visit the necrotic area was measured with a grid. The moisture balance, odour, viability of non-necrotic areas and the presence of erythema were also assessed. Primary outcome was the percentage of subjects with complete debridement, secondary outcomes the time to complete healing, reduction of the lesion area, absence of necrotic tissue, presence of odor, erythema, hydration, any adverse events.
One hundred subjects were enrolled in four centres. All patients achieved complete debridement of the necrotic area and a significant reduction of the total ulcer area by day 20, while other parameters improved significantly over time. Only two patients experienced a transient leg oedema.
The combination of collagenase and hyaluronic acid is safe and effective for chronic venous ulcers.
... In recent years, several reports described that HA has anti-ageing effect with potential antioxidant properties both in vitro and in vivo (Balogh, Illes, Szekely, Forrai, & Gere, 2003;Campo et al., 2004;Halicka, Mitlitski, Heeter, Balazs, & Darzynkiewicz, 2009). During inflammation, inhibition of tumor cells and protection of tissue from free radical damage have also been attributed to a mixture of hyaluronic acid fragments (Termeer et al., 2000;Trabucchi et al., 2002;Ghatak, Misra, & Toole, 2002). So far, many unique compounds of marine origin with different biological activities have been isolated and a number of them were investigated and/or being developed as new pharmaceuticals (Ely, Supriya, & Naik, 2004). ...
The concept of wound microenvironment has been discussed for a long time. However, the mechanism of the internal microenvironment is relatively little studied. Here, we present a systematic discussion on the mechanism of natural polymer materials such as chitosan, cellulose, collagen and hyaluronic acid through their effects on the internal wound microenvironment and regulation of wound healing, in order to more comprehensively explain the concept of wound microenvironment and provide a reference for further innovative clinical for the preparation and application of wound healing agents.
Convergent advances in the field of soft matter, macromolecular chemistry, and engineering have led to the development of biomaterials that possess autonomous, adaptive, and self-healing characteristics similar to living systems. These rationally designed biomaterials could surpass the capabilities of their parent material. Herein, we describe the modification of hyaluronic acid (HA) to exhibit self-healing properties and studied its physical and biological function both in vitro and in vivo. Our in vitro findings showed that self-healing HA designed to undergo self-repair improved lubrication, enhanced free radical scavenging, and attenuated enzymatic degradation compared to unmodified HA. Longitudinal imaging following intraarticular injection of self-healing HA showed improved in vivo retention despite its low molecular weight. Concomitant with these functions, intraarticular injection of self-healing HA mitigated anterior cruciate ligament injury-mediated cartilage degeneration in rodents. This proof-of-concept study shows how incorporation of functional properties like self-healing can be used to surpass the existing capabilities of biolubricants.
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Probiotics are advantageous microbes, considered to have many positive outcomes on human well-being, predominantly in the fight against harmful microbes. The probiotics have been linked with enhanced intestinal ulcer recovery and mending of skin wounds (infection). This book chapter discusses the most recent probiotics investigations associated with their wound healing characteristics on skin and gut epithelium. The competitive displacement of pathogenic microorganisms, direct elimination of pathogens, fibroblasts induction and migration, strengthening of epithelial barrier, and function of epithelial cells are the established processes by which probiotic microorganisms exert their advantageous effects. Advantageous immune-modulatory impacts of probiotic microorganisms are associated with activation and modulation of macrophages, natural killer cells, and intraepithelial lymphocytes through triggering of cytokines production. Also discussed are the systemic implications of beneficial microorganisms and the relation between the immune system, gut microbiome, and cutaneous health. Considering the enhanced antibiotic resistance by the disease-causing microbes, the antibiotic’s use is becoming less efficient for the treatment of systemic and cutaneous infection. The emphasis of this chapter is on the innovative knowledge and advantageous pharmaceutical probiotic microorganisms’ potential as an innocuous alternative solution to the cure of patients suffering from various skin-related infections and wound healing disorders.
Hyaluronic acid (HA) is a naturally formed acidic mucopolysaccharide, with excellent moisturising properties and used widely in the medicine, cosmetics, and food industries. The industrial production of specific molecular weight HA has become imperative. Different biological activities and physiological functions of HA mainly depend on the degree of polymerisation. This article reviews the research status and development prospects of the green biosynthesis and molecular weight regulation of HA. There is an application-based prerequisite of specific molecular weight of HA that could be regulated either during the fermentation process or via a controlled HA degradation process. This work provides an important theoretical basis for the downstream efficient production of diversified HA, which will further accelerate the research applications of HA and provide a good scientific basis and method reference for the study of the molecular weight regulation of similar biopolymers.
Hyaluronate lyases have received extensive attention due to their application in medical science, drug and biochemical engineering. However, little thermotolerant and pH-stable hyaluronate lyase has been found. In this study, hyaluronate lyase TcHly8B from Thermasporomyces composti DSM22891 was expressed in Escherichia coli BL21(DE3), purified, and characterized. Phylogenetic analysis revealed that TcHly8B belonged to a new subfamily in PL8. The molecular mass of recombinant TcHly8B determined by SDS-PAGE was approximately 86 kDa. It exhibited the highest activities at 70 °C, which was higher than previously reported hyaluronate lyases. TcHly8B was very stable at temperatures from 0 to 60 °C. The optimal pH of TcHly8B was 6.6. It could retain more than 80% of its original enzyme activity after incubation for 12 h in the pH range of 3.0–10.6. TcHly8B degraded hyaluronic acid into unsaturated disaccharides as the end products. The amino acid sequence and structure analysis of TcHly8B demonstrated that the amino acid composition and salt bridges might contribute to the thermostability of TcHly8B. Overall, this study provides an excellent example for the discovery of thermotolerant hyaluronate lyases and can be applied to the industrialized production and basic research of hyaluronate oligosaccharides.
Wound care and tissue regeneration is a global challenge and affects millions of populations. The process of wound healing and tissue repair is inherently complex in nature. Lifestyle and anthropogenic factors increase the risk in wound care and management. Even after advancements in medicine, chronic wounds and risk of sepsis continue to remain major concerns in healthcare with a high mortality rate. The application of biocomposites and biomaterials derived from silk, cellulose, alginate, chitin, hyaluronate, collagen, and gelatin is gaining popularity owing to attributes like bioactive nature, biocompatibility, antimicrobial, immunomodulatory, and angiogenic effects. Recently, application of bioactive glass in wound healing and blood clotting process is also being explored exclusively. With the current knowledge in the material science, nanotechnology, and regenerative medicine, these properties can be enhanced to improve efficacy in wound care like tissue repair, restoration of lost tissue integrity, and scar less healing. In this direction, the progress in regenerative medicine will continue to provide a platform for cellular therapy, growth factor delivery, and fabrication of extracellular matrix alternatives. In this chapter, we have discussed in quite detail, the key challenges in wound healing and tissue engineering highlighting the contemporary nanotechnology based solutions to address current limitations in biomaterial fabrication and scaffold designing.
Hyaluronic acid (HA) plays an important role promoting the wound contraction increase and epidermal proliferation, cytokines regulation and adhesion molecules, collagen deposition increase, and neovascularization stimulus. Its function is associated with the molecular weight and its rheological properties. HA changes in the skin can be observed due to aging, wound healing, and degenerative disease. Traditionally, the native HA was extracted from animal tissues, but nowadays it is mainly produced by microbial fermentation. Microbial HA is recommended for human therapeutic products for medical, pharmaceutical, and cosmetic application because this one does not present risk of cross-species viral and other adventitious agent infection. In clinical medicine, HA and its derivatives have showed great potential in treatment of different types of wounds as burns. This chapter describes the HA properties, microbial polymer production, its function in the wound stages, and discusses the current trends of its utilization on wound healing treatment either as component of topical formulations or as scaffold.
Cutaneous radiation damage, commonly referred to as radiation dermatitis, is a finding of considerable concern. The exposure is often from radiation therapy, a double-edged sword, removing malignant cancer cells and improving the lives of countless patients, yet being locally destructive and potentially premalignant. Among its negative consequences and complications, radiation dermatitis, a potentially severe skin reaction that occurs after the receipt of radiation therapy, presents a clinical challenge today. There are two types of cutaneous radiation dermatitis: acute and chronic. Acute radiation dermatitis manifests within 90 days after the induction of radiation therapy while chronic radiation dermatitis develops beyond 90 days of radiation. There are many risk factors associated with radiation dermatitis which can be characterized as intrinsic, extrinsic, or both. Intrinsic risk factors include concurrent chemotherapy and targeted therapy, connective tissue and skin disorders, genetic and personal factors such as age, sex, smoking habits, and nutritional status. Extrinsic factors are mainly related to the type and dose of the radiation received. Treatment options have been enhanced in the last decade, providing patients with better outcomes and improved quality of life. Such treatments include topical ointments and therapies, oral enzymes, wound dressings and surgical treatments. This article aims to review the current medical understanding of radiation dermatitis, its risk factors, pathophysiology, and treatment options.
Wound is a growing healthcare challenge affecting several million worldwide. Lifestyle disorders such as diabetes increases the risk of wound complications. Effective management of wound is often difficult due to the complexity in the healing process. Addition to the conventional wound care practices, the bioactive polymers are gaining increased importance in wound care. Biopolymers are naturally occurring biomolecules synthesized by microbes, plants and animals with highest degree of biocompatibility. The bioactive properties such as antimicrobial, immune-modulatory, cell proliferative and angiogenic of the polymers create a microenvironment favorable for the healing process. The versatile properties of the biopolymers such as cellulose, alginate, hyaluronic acid, collagen, chitosan etc have been exploited in the current wound care market. With the technological advances in material science, regenerative medicine, nanotechnology, and bioengineering; the functional and structural characteristics of biopolymers can be improved to suit the current wound care demands such as tissue repair, restoration of lost tissue integrity and scarless healing. In this review we highlight on the sources, mechanism of action and bioengineering approaches adapted for commercial exploitation.
Efficient wound healing requires the coordinated integration of associated biological and chemical events in the wound bed. Chronic wounds fail to follow this ordered remodeling cascade, requiring long-term, active intervention usually in the form of high-cost wound dressings. Studies show that no treatment significantly outperforms the others, leading researchers to focus on developing innovative and more efficacious wound healing technologies. This chapter will provide a brief overview of chronic wound healing with a focus on recent engineering approaches that regenerate skin. We discuss various design challenges plaguing chronic wound healing, explore the mechanisms of action for products currently in clinical use, and describe design strategies used in recent developments, such as the use of novel polymers, growth factor release, and cell loading. As healthcare moves toward precision medicine-based strategies, the potential and therapeutic implications of synthetic biomaterials as tunable treatment modalities for chronic wounds will be considered.
Ketamine-induced ulcerative cystitis (KIC) initially damaged the bladder mucosa and induced contracted bladder thereafter. Hyaluronan (hyaluronic acid; HA) instillation to the bladder has been used to treat KIC. The present study investigated bladder injury by urothelial defect and HA degeneration and bladder repair by urothelium proliferation and differentiation. This work was based on the hypothesis that HA treatment altered the bladder urothelial layer and the expression of hyaluronan-metabolizing enzymes and/or HA receptors in KIC. Cystometrogram study and tracing analysis of voiding behavior revealed that the ketamine-treated rats exhibited significant bladder hyperactivity with an increase in micturition frequency and a decrease in bladder capacity. The expression of inflammatory and fibrosis markers was also increased in the ketamine-treated group. Moreover, ketamine administration decreased the expression of urothelial barrier–associated protein, altered HA production, and induced abnormal urothelial differentiation, which might attribute to urothelial lining defects. However, HA instillation ameliorated bladder hyperactivity, lessened bladder mucosa damage, and decreased interstitial fibrosis. HA instillation also improved the level of HA receptors (CD44, Toll-like receptor-4, and receptor for HA-mediated motility) and HA synthases 1 to 3 and decreased the expression of hyaluronidases in the urothelial layer of bladder, resulting in enhanced mucosal regeneration. These findings suggested that HA could modulate inflammatory responses, enhance mucosal regeneration, and improve urothelial lining defects in KIC.
Background:
Hydrolifting is a newly developed modality of skin rejuvenation which enhances overall facial volume augmentation and recovers skin thickness through multi-pass HA injection. Although it is commonly performed, only a few articles have reported on the rejuvenating effects of hydrolifting. Moreover, clear protocols and possible mechanisms of the procedure have not been elucidated.
Objective:
To define a novel technique for injecting HA and to clarify how to choose an appropriate HA filler based on the procedural purpose.
Methods:
This article is based on a review of the medical literature and the authors' clinical experience in investigating and treating skin wrinkles with the hydrolifting method.
Results:
In hydrolifting, HA filler serves as a hydration source, dermal volumizer and stimulator of dermal collagen and antioxidants. Hydrolifting is frequently indicated in minor wrinkles, minor volume depletion and rough skin texture.
Conclusion:
The hydrolifting method is a newly introduced anti-aging treatment modality. It effectively covers the blind spots of conventional HA injection, such as infraorbital, perioral and hand dorsal wrinkles. However, further investigations are needed to reach a consensus on the basic concepts of treatment, choice of appropriate fillers and optimal technique in hydrolifting.
Radiation therapy has been a commonly employed modality for a variety of ailments, including cancer. Patients undergoing radiation often experience acute and/or chronic skin changes that can be detrimental to their quality of life. Many topical agents and specialized wound dressings are being used for the prevention and management of radiation-induced skin changes. However, no single therapeutic option has been found to be consistently effective.
Introduction
Treatment of musculoskeletal injuries is still demanding, because most of these tissues have low healing capability and are under different forces during healing and regeneration. Tissue engineering is one of the new approaches aimed to solve these difficulties. Simply, tissue engineering could be divided into three parts: scaffolds, healing promotive factors and stem cells. Healing promotive factors such as growth factors and a wide variety of glycosaminoglycans have major roles in the healing process of connective tissues; however, most of the tissue-engineered products are expensive and may not be available at the time of treatment. Synovial fluid is an available option, and it contains different healing promotive factors mainly glycosaminoglycans and lubricin. The major glycosaminoglycans that have been found in synovial fluid of different species are hyaluronic acid and chondroitin sulphate that have been shown to be effective in reducing peritendinous adhesion and inflammation. They also can modulate different stages of wound healing by motivating the healing cells to deposit more matrix and collagen fibres and have some antioxidant and protective effects, which promote efficient wound healing. This review has focused on the roles of these glycosaminoglycans on different musculoskeletal injuries in vitro, in vivo and in clinical situations. Due to the availability of hyaluronic acid and chondroitin sulphate in normal synovial fluid, it is reasonable to suggest the synovial fluid as a new treatment strategy in musculoskeletal medicine and surgery. Synovial fluid can be obtained from auto-, allo- and xenogeneic bases. The xenogeneic-based synovial fluid is more available than the other two forms. It is recommended to make some processing such as acellularization, sterilization and purification before application of the synovial fluid. Based on this evidence, it seems the exogenous synovial fluid could be considered as a popular therapeutic agent in the near future. The aim of this review was to discuss exogenous synovial fluid as a new option in tissue engineering.
Conclusion
Glycosaminoglycans such as hyaluronic acid and chondroitin sulphate make up the synovial fluid. Hyaluronic acid is beneficial in reducing peritendinous adhesion and signs of osteoarthrosis and in improving bone tunnel healing, tendon and bone regeneration. Exogenous synovial fluid looks to be a good method of providing glycosaminoglycans to the site of injury. We call on further studies to increase our understanding of synovial fluid and the effectiveness of its compounds in different injured tissues.
Preparative chromatographic fractions of human umbilical cord hyaluronic acid (HA) of a molecular weight of 10(6) were subjected to graded oxygen-derived free radical (oxy radical) fluxes produced by: (a) the autoxidation of ferrous ions; (b) the action of xanthine oxidase (XO) on hypoxanthine (HX); and (c) by peripheral blood polymorphonuclear leucocytes that had been stimulated by phorbol myristate acetate (PMA). Analysis by gel chromatography of the products obtained with each of the oxy radical generating systems showed polydispersity in size. The smallest molecules detected had a molecular weight of 10(4). This limiting size was not reduced further by exposure to a second oxy radical flux. The relative proportions of large, medium, and small degradation products were established for various levels of oxy radical flux. Consistently a relatively rapid transition from large to small material was seen on Sepharose 2B chromatography, suggesting an ordered element to the breakdown process. Although the decrease in molecular weight after oxy radical exposure was confirmed by analytical ultracentrifugation, this procedure showed that those samples of lowest viscosity did not have the lowest sedimentation values, possibly reflecting oxy radical-induced repolymerisation. If the size and possibly the conformational characteristics of HA are altered, oxy radical exposure might be expected to alter its biological properties.
Oxygen-derived free radicals (ODFR) appear to be involved in the pathogenesis of arthritic disorders. In order to gain new insight on their role in the phenomenon and as a basis for a therapeutic approach, the effect of ODFR (produced by the xanthine oxidase-hypoxantine system) on hyaluronic acid, on two HA ester derivatives, and on pig articular chondrocytes was investigated. High M(r) HA (1.1 x 10(6)) and low M(r) HA (16 x 10(4)) were depolymerized by ODFR but the methyl and hydrocortisone esters of HA (HYAFF 2P50 and HYC13) turned out to be nearly unaffected. When articular chondrocytes were treated with ODFR, a rapid nucleoside triphosphate (NTP) depletion, a transient appearance of pyrophosphate (PPi), and an increase of phosphomonoester and diphosphodiester concentrations have been observed. The NTP depletion and the DPDE increase are related to the concentration of free radicals. Glyceraldehyde-3-phosphate accumulation during ODFR treatment suggests that ATP depletion can occur as a consequence of the blockage of glycolysis at the level of glyceraldehyde-3-P dehydrogenase. The hypothesis is presented that PPi can be produced from the pathway of the FAD-NAD (DPDE) biosynthesis and then either hydrolyzed by endogenous pyrophosphatases or precipitated in the form of insoluble calcium salts. Long-term treatment (16 h) with ODFR causes a loss of chondrocyte membrane integrity which can be revealed both by an increased free LDH activity and by the characteristic signal of free phospholipids in the 31P-NMR spectra. While high M(r) HA shows a significant protective activity for chondrocytes against ODFR action, low M(r) HA and ester derivatives do not. It is suggested that the therapeutic activity of HA ester derivatives can be ascribed to their in vivo hydrolysis products.
Degradation of hyaluronic acid by oxidants such as HO· and HOCl/ClO− is believed to be important in the progression of rheumatoid arthritis. While reaction of hyaluronic acid with HO· has been investigated extensively, reaction with HOCl/ClO− is less well defined. Thus, little is known about the site(s) of HOCl/ClO− attack, the intermediates formed, or the mechanism(s) of polymer degradation. In this study reaction of HOCl/ClO− with amides, sugars, polysaccharides, and hyaluronic acid has been monitored by UV-visible (220–340 nm) and EPR spectroscopy. UV-visible experiments have shown that HOCl/ClO− reacts preferentially with N-acetyl groups. This reaction is believed to give rise to transient chloramide (R—NCl—C(O)—R′) species, which decompose rapidly to give radicals via either homolysis (to produce N· and Cl·) or heterolysis (one-electron reduction, to give N· and Cl−) of the N—Cl bond. The nature of the radicals formed has been investigated by EPR spin trapping. Reaction of HOCl/ClO− with hyaluronic acid, chondroitin sulphates A and C, N-acetyl sugars, and amides gave novel, carbon-centered, spin adducts, the formation of which is consistent with selective initial attack at the N-acetyl group. Thus, reaction with hyaluronic acid and chondroitin sulphate A, appears to be localized at the N-acetylglucosamine sugar rings. These carbon-centered radicals are suggested to arise from rapid rearrangement of initial nitrogen-centered radicals, formed from the N-acetyl chloramide, by reactions analogous to those observed with alkoxyl radicals. The detection of increasing yields of low-molecular-weight radical adducts from hyaluronic acid and chondroitin sulphate A with increasing HOCl/ClO− concentrations suggests that formation of the initial nitrogen-centered species on the N-acetylglucosamine rings, and the carbon-centered radicals derived from them, brings about polymer fragmentation.
Synovial fluid is a approximately 0.15% (w/v) aqueous solution of hyaluronic acid (HA), a polysaccharide consisting of alternating units of GlcA and GlcNAc. In synovial fluid of patients suffering from rheumatoid arthritis, HA is thought to be degraded either by radicals generated by Fenton chemistry (Fe2+/H2O2) or by NaOCl generated by myeloperoxidase. We investigated the course of model reactions of these two reactants in physiological buffer with HA, and with the corresponding monomers GlcA and GlcNAc. meso-Tartaric acid, arabinuronic acid, arabinaric acid and glucaric acid were identified by GC-MS as oxidation products of glucuronic acid. When GlcNAc was oxidised, erythronic acid, arabinonic acid, 2-acetamido-2-deoxy-gluconic acid, glyceric acid, erythrose and arabinose were formed. NaOCl oxidation of HA yielded meso-tartaric acid; in addition, arabinaric acid and glucaric acid were obtained by oxidation with Fe2+/H2O2. These results indicate that oxidative degradation of HA proceeds primarily at glucuronic acid residues. meso-Tartaric acid may be a useful biomarker of hyaluronate oxidation since it is produced by both NaOCl and Fenton chemistry.
The reactive superoxide radical, O2-, formerly of concern only to radiation chemists and radiobiologists, is now understood
to be a normal product of the biological reduction of molecular oxygen. An unusual family of enzymes, the superoxide dismutases,
protect against the deleterious actions of this radical by catalyzing its dismutation to hydrogen peroxide plus oxygen.
Using a model of 'reperfusion injury' as a mechanism of oxygen radical (OR) production in vivo, we have demonstrated that superoxide (O2-) is the major source of damage. Inhibition of its production from polymorphonuclear leucocytes (PMNs) by aprotinin, a protease inhibitor, or by scavenging with superoxide dismutase (SOD), resulted in reduced oxidation of of tissue glutathione (P less than 0.002). Colonic healing after anastomosis was also improved by aprotinin as measured by histology (P less than 0.05), breaking energy (P less than 0.001), breaking strength (P = 0.02), and by hydroxyproline content (P = 0.01). Allopurinol, although inhibiting glutathione oxidation, had no effect on PMN leucocyte OR production and did not protect against histological damage. These data demonstrate that PMNs endogenous to the tissue or attracted there as a result of trauma are the source of OR production in 'reperfusion'. Their inhibition improves colonic healing.
A model is presented outlining the molecular and cellular events that occur during the early stages of the wound healing process. The underlying theme is that there is a specific binding interaction between fibrin, the major clot protein, and hyaluronic acid (HA), a constituent of the wound extracellular matrix. This binding interaction, which could also be stabilized by other cross-linking components, provides the driving force to organize a three-dimensional HA matrix attached to and interdigitated with the initial fibrin matrix. The HA-fibrin matrix plays a major role in the subsequent tissue reconstruction processes. We suggest that HA and fibrin have both structural and regulatory functions at different times during the wound healing process. The concentration of HA in blood and in the initial clot is very low. This is consistent with the proposed interaction between HA and fibrin(ogen), which could interfere with either fibrinogen activation or fibrin assembly and cross-linking. We propose that an activator (e.g. derived from a plasma precursor, platelets or surrounding cells) is produced during the clotting reaction and then stimulates one or more blood cell types to synthesize and secrete HA into the fibrin matrix of the clot. We predict that HA controls the stability of the matrix by regulating the degradation of fibrin. The new HA-fibrin matrix increases or stabilizes the volume and porosity of the clot and then serves as a physical support, a scaffold through which cells trapped in the clot or cells infiltrating from the peripheral edge of the wound can migrate. The HA-fibrin matrix also actively stimulates or induces cell motility and activates and regulates many functions of blood cells, which are involved in the inflammatory response, including phagocytosis and chemotaxis. The secondary HA-fibrin matrix itself is then modified as cells continue to migrate into the wound, secreting hyaluronidase and plasminogen activator to degrade the HA and fibrin. At the same time these cells secrete collagen and glycosaminoglycans to make a more differentiated matrix. The degradation products derived from both fibrin and HA are, in turn, important regulatory molecules which control cellular functions involved in the inflammatory response and new blood vessel formation in the healing wound. The proposed model generates a number of testable experimental predictions.
The reduction of nitro blue tetrazolium (NitroBT) with NADH mediated by phenazine methosulfate (PMS) under aerobic conditions was inhibited upon addition of superoxide dismutase. This observation indicated the involvement of superoxide aninon radical (O2−) in the reduction of NitroBT, the radical being generated in the reoxidation of reduced PMS. Similarly, the reduction of NitroBT coupled to D-amino acid oxidase-PMS system under aerobic conditions was also inhibited by superoxide dismutase. A simple method for detecting superoxide dismutase is described.
The contribution of free radical-mediated reperfusion injury to the ischemic damage caused by total venous occlusion of island skin flaps was investigated in a standardized rat model. Control flaps subjected to 8 hours of total venous occlusion showed complete, full thickness necrosis when followed for 7 days following release of the vascular occlusion. Treatment with superoxide dismutase, a scavenger of superoxide radicals, prior to and immediately following the onset of reperfusion, significantly enhanced island flap survival from 0/11 (0%) to 8/15 (53%), p less than 0.005, and from 0/9 (0%) to 6/12 (50%), p less than 0.02, respectively. These findings are consistent with the hypothesis that oxygen free radicals generated at the time of reperfusion following a period of ischemia contribute significantly to the ultimate damage caused by ischemic injury. Such findings are consistent with similar reported observations on other tissues and suggest a means by which ischemic tissue injury might be therapeutically modified, even after the period of ischemia.
HO. attack on hyaluronic acid, related polymers and monomers has been studied by both direct, rapid-flow, EPR (ESR) and EPR spin trapping using a variety of traps. Evidence has been obtained, with the monomers, for essentially random hydrogen-atom abstraction at all the ring C -- H bonds with glucuronic acid, and at all sites except the N-acetyl side chain and C(2) with N-acetylglucosamine. The initial radicals do not undergo rapid rearrangement reactions at pH 4; however at both lower and higher pH values, acid- and base-catalysed rearrangement process, respectively, result in the loss of these species. The rate of loss of these species is dependent on the substrate, with those derived from N-acetylglucosamine undergoing slowed acid-catalysed rearrangement than the glucuronic acid-derived species. This is rationalised in terms of a rearrangement reaction of 1.2-dihydroxyalkyl(1.2-dio) radicals involving an electron-deficient radical-cation intermediate; the formation of this species would be disfavoured by the electron-withdrawing N-acetyl substituent. The base-catalysed process, which is believed to involve a radical-anion intermediate, occurs rapidly at pH 7.4, and appears to be less substrate dependent. In the case of glucuronic acid- (but not N-acetylglucosamine-) derived species this latter process results in the detection of ring-opened semidione species. With equimolar mixtures of the two monomers essentially random attack occurs on the two rings. However with chondroitin sulphate A, attack appears to be much more selective, with a radical generated at C(5) on the glucuronic acid ring present at highest concentration. The initial radicals obtained with this polysaccharide also undergo base- and acid-catalysed rearrangements; this leads to strand-breakage and the formation of low-molecular-weight material. Spin-trapping experiments carried out with hyaluronic acid, and a number of other polysaccharides, resulted in the detection of a number of novel spin adducts, the formation of which are consistent with attack on both the sugar rings in the polymer. The pH dependence of the observed spectra, and the detection of additional species at some pH values, suggest that at least some of the initial radicals undergo base-catalysed rearrangement reactions which result in strand-breakage and the formation of low-molecular-weight fragments. The extent of fragmentation at a particular pH, is also affected by the radical flux, with high radical yields giving more low-molecular-weight material. These observations suggest that pH-independent processes also contribute to strand-cleavage; this may be due to beta-cleavage of the radicals formed at C(1) on either ring, C(3) on N-acetylglucosamine or C(4) on the glucuronic acid ring.
Hyaluronan is a major carbohydrate component of the extracellular matrix and can be found in skin, joints, eyes and most other organs and tissues. It has a simple, repeated disaccharide linear copolymer structure that is completely conserved throughout a large span of the evolutionary tree, indicating a fundamental biological importance. Amongst extracellular matrix molecules, it has unique hygroscopic, rheological and viscoelastic properties. Hyaluronan binds to many other extracellular matrix molecules, binds specifically to cell bodies through cell surface receptors, and has a unique mode of synthesis in which the molecule is extruded immediately into the extracellular space upon formation. Through its complex interactions with matrix components and cells, hyaluronan has multifaceted roles in biology utilizing both its physicochemical and biological properties. These biological roles range from a purely structural function in the extracellular matrix to developmental regulation through effects of cellular behavior via control of the tissue macro- and microenvironments, as well as through direct receptor mediated effects on gene expression. Hyaluronan is also thought to have important biological roles in skin wound healing, by virtue of its presence in high amounts in skin. Hyaluronan content in skin is further elevated transiently in granulation tissue during the wound healing process. In this review, the general physicochemical and biological properties of hyaluronan, and how these properties may be utilized in the various processes of wound healing: inflammation, granulation and reepithelization, are presented.