Chapter

Stem Cell and Stem Cell-Derived Molecular Therapies to Enhance Dermal Wound Healing

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Abstract

Chronic wounds that do not heal with standard wound care are a growing public healthcare concern. Wound care costs associated with lower extremity ulcers, such as venous leg ulcers, pressure ulcers, and diabetic foot ulcers, place a signifi cant burden on healthcare systems and severely lower the quality of life for patients. Advanced wound care therapies are needed to promote wound closure in recalcitrant wounds. Exogenous mesenchymal stem cell delivery and endogenous bone marrow stem cell recruitment have been investigated as advanced wound therapies, and have demonstrated promising potential for enhancing wound closure in preclinical and clinical studies. The aim of this book chapter is to review the wound healing process and pathobiology of chronic wounds, and discuss the current state of stem cell therapies as advanced wound therapies. The potential role of nano- and micro-scale technologies in addressing current limitations of stem cell therapies will also be explored. © Springer International Publishing Switzerland 2016. All right reserved.

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... Stem cells (SCs) have impressive self-renewal properties and the ability to differentiate into a wide range of cell types. Miscellaneous types of SCs have been utilized for skin regeneration and wound healing such as embryonic SCs [40], adult SCs [41], induced pluripotent SCs [42], mesenchymal stem cells (MSCs) [43], adiposederived stem cells [44], human umbilical cord derived SCs [45] and melanocyte SCs [46]. Applying MSCs into the wound area increased re-epithelization and helped angiogenesis [47]. ...
... Embedded adipose-derived stem cells within an acellular dermal matrix applied onto the wound led to increased wound healing and better vascularization [44]. Human-induced melanocyte SCs produce hair follicles and epidermal pigment [45]. Skin-derived SCs were utilized for regenerating the neural cells in the skin that could be damaged in burn wounds [48]. ...
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Data from registries can be especially useful in the evaluation of healthcare effectiveness. Thus, the goal of this study was to report on use of the US Wound Registry to investigate the outcomes of a broad population of patients undergoing treatment. Using a 5-year slice of de-identified data from electronic health records originating from 59 hospital-based outpatient wound centers in 18 states, outcomes, pa- tient and wound variables, and costs for facility and physician fees and procedures were analyzed for 5240 patients with 7099 wounds. Mean patient age was 61.7 years with 52.3% being male and the majority Caucasian (73.1%) and Medicare beneficiaries (52.6%). The mean number of serious comorbid conditions per patient was 1.8, with the most common being diabetes (46.8%), obese or overweight (71.3%), and having cardiovascular or peripheral vascular disease (51.3%). More than 1.6% of patients died in service or within 4 weeks of the last visit. Almost two thirds of wounds healed (65.8%) with an aver- age time to heal of 15 weeks and 10% of wounds taking 33 weeks or more to heal. The average wound surface area was 19.5 cm2. Half of wounds that healed did so with only the use of moist wound care (50.8%) and without the need for advanced therapeutics. Mean cost to heal per wound was $3927 with jeopardized flaps and grafts the most expensive ($9358). This Registry would seem ideal for comparative effectiveness research in wound care, as it includes patients often ex- cluded from randomized controlled trials and reflects actual practice.
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Background: Chronic wounds represent a worldwide problem. For laboratory and clinical research to adequately address this problem, a common language needs to exist. Observation: This language should include a system of wound classification, a lexicon of wound descriptors, and a description of the processes that are likely to affect wound healing and wound healing end points. Conclusions: The report that follows defines wound, acute wound, chronic wound, healing and forms of healing, wound assessment, wound extent, wound burden, and wound severity. The utility of these definitions is demonstrated as they relate to the healing of a skin wound, but these definitions are broadly applicable to all wounds.
Article
Keratins K14 and K5 have long been considered to be biochemical markers of the stratified squamous epithelia, including epidermis (Moll, R., W. Franke, D. Schiller, B. Geiger, and R. Krepler. 1982. Cell. 31:11-24; Nelson, W., and T.-T. Sun. 1983. J. Cell Biol. 97:244-251). When cells of most stratified squamous epithelia differentiate, they downregulate expression of mRNAs encoding these two keratins and induce expression of new sets of keratins specific for individual programs of epithelial differentiation. Frequently, as in the case of epidermis, the expression of differentiation-specific keratins also leads to a reorganization of the keratin filament network, including denser bundling of the keratin fibers. We report here the use of monospecific antisera and cRNA probes to examine the differential expression of keratin K14 in the complex tissue of human skin. Using in situ hybridizations and immunoelectron microscopy, we find that the patterns of K14 expression and filament organization in the hair follicle are strikingly different from epidermis. Some of the mitotically active outer root sheath (ORS) cells, which give rise to ORS under normal circumstances and to epidermis during wound healing, produce only low levels of K14. These cells have fewer keratin filaments than basal epidermal cells, and the filaments are organized into looser, more delicate bundles than is typical for epidermis. As these cells differentiate, they elevate their expression of K14 and produce denser bundles of keratin filaments more typical of epidermis. In contrast to basal cells of epidermis and ORS, matrix cells, which are relatively undifferentiated and which can give rise to inner root sheath, cuticle and hair shaft, show no evidence of K14, K14 mRNA expression, or keratin filament formation. As matrix cells differentiate, they produce hair-specific keratins and dense bundles of keratin filaments but they do not induce K14 expression. Collectively, the patterns of K14 and K14 mRNA expression and filament organization in mitotically active epithelial cells of the skin correlate with their relative degree of pluripotency, and this suggests a possible basis for the deviation of hair follicle programs of differentiation from those of other stratified squamous epithelia.
Article
The cellular and molecular mechanisms underpinning tissue repair and its failure to heal are still poorly understood, and current therapies are limited. Poor wound healing after trauma, surgery, acute illness, or chronic disease conditions affects millions of people worldwide each year and is the consequence of poorly regulated elements of the healthy tissue repair response, including inflammation, angiogenesis, matrix deposition, and cell recruitment. Failure of one or several of these cellular processes is generally linked to an underlying clinical condition, such as vascular disease, diabetes, or aging, which are all frequently associated with healing pathologies. The search for clinical strategies that might improve the body's natural repair mechanisms will need to be based on a thorough understanding of the basic biology of repair and regeneration. In this review, we highlight emerging concepts in tissue regeneration and repair, and provide some perspectives on how to translate current knowledge into viable clinical approaches for treating patients with wound-healing pathologies. © 2014, American Association for the Advancement of Science. All rights reserved.
Article
The American College of Physicians (ACP) developed this guideline to present the evidence and provide clinical recommendations based on the comparative effectiveness of risk assessment scales and preventive interventions for pressure ulcers. This guideline is based on published literature on this topic that was identified by using MEDLINE (1946 through February 2014), CINAHL (1998 through February 2014), the Cochrane Library, clinical trials registries, and reference lists. Searches were limited to English-language publications. The outcomes evaluated for this guideline include pressure ulcer incidence and severity, resource use, diagnostic accuracy, measures of risk, and harms. This guideline grades the quality of evidence and strength of recommendations by using ACP's clinical practice guidelines grading system. The target audience for this guideline includes all clinicians, and the target patient population is patients at risk for pressure ulcers. ACP recommends that clinicians should perform a risk assessment to identify patients who are at risk of developing pressure ulcers. (Grade: weak recommendation, low-quality evidence). ACP recommends that clinicians should choose advanced static mattresses or advanced static overlays in patients who are at an increased risk of developing pressure ulcers. (Grade: strong recommendation, moderate-quality evidence). ACP recommends against using alternating-air mattresses or alternating-air overlays in patients who are at an increased risk of developing pressure ulcers. (Grade: weak recommendation, moderate-quality evidence).
Article
The paucity of cellular and molecular signals essential for normal wound healing makes severe dermatological ulcers stubborn to heal. The novel strategies of skin regenerative treatments are focused on the development of biologically responsive scaffolds accompanied by cells and multiple biomolecules resembling structural and biochemical cues of the natural extracellular matrix (ECM). Electrospun nanofibrous scaffolds provide similar architecture to the ECM leading to enhancement of cell adhesion, proliferation, migration and neo tissue formation. This Review surveys the application of biocompatible natural, synthetic and composite polymers to fabricate electrospun scaffolds as skin substitutes and wound dressings. Furthermore, the application of biomolecules and therapeutic agents in the nanofibrous scaffolds viz growth factors, genes, antibiotics, silver nanoparticles, and natural medicines with the aim of ameliorating cellular behavior, wound healing, and skin regeneration are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Article
A great deal of emphasis, clinical and financial, is placed on limb salvage efforts in diabetic patients suffering from lower extremity ulceration. This is because of the impression that amputation in such patients may be a proximal cause of death. While amputation is certainly a negative clinical outcome, it is not entirely clear that it causes death. In this systematic review, we examine the available literature to attempt to understand the role that the ulceration itself may play in mortality. In brief, we searched for human studies in OVID, CINAHL and the COCHRANE CENTRAL DATABASE from 1980 to 2013, looking for articles related to ulcer or wound of the foot, in patients with diabetes or peripheral vascular disease, and death. We looked for articles with 5 years of follow-up, or Kaplan-Meier estimates of 5-year mortality, and excluded reviews and letters. Articles were assessed for quality and potential bias using the Newcastle-Ottawa scale. We find that while the patient populations studied varied widely in terms of demographics and comorbidities, limiting generalisability, 5-year mortality rates after ulceration were around 40%. Risk factors for death commonly identified were increased age, male gender, peripheral vascular disease and renal disease. © 2015 Medicalhelplines.com Inc and John Wiley & Sons Ltd.
Article
Background: Chronic wounds represent a worldwide problem. For laboratory and clinical research to adequately address this problem, a common language needs to exist. Observation: This language should include a system of wound classification, a lexicon of wound descriptors, and a description of the processes that are likely to affect wound healing and wound healing end points. Conclusions: The report that follows defines wound, acute wound, chronic wound, healing and forms of healing, wound assessment, wound extent, wound burden, and wound severity. The utility of these definitions is demonstrated as they relate to the healing of a skin wound, but these definitions are broadly applicable to all wounds.(Arch Dermatol. 1994;130:489-493)
Article
In 2007, the treatment of diabetes and its complications in the United States generated at least $116 billion in direct costs; at least 33% of these costs were linked to the treatment of foot ulcers. Although the team approach to diabetic foot problems is effective in preventing lower-extremity amputations, the costs associated with implementing a diabetic-foot–care team are not well understood. An analysis of these costs provides the basis for this report. Diabetic foot problems impose a major economic burden, and costs increase disproportionately to the severity of the condition. Compared with diabetic patients without foot ulcers, the cost of care for those with foot ulcers is 5.4 times higher in the year after the first ulcer episode and 2.8 times higher in the second year. Costs for treating the highest-grade ulcers are 8 times higher than are those for treating low-grade ulcers. Patients with diabetic foot ulcers require more frequent emergency department visits and are more commonly admitted to the hospital, requiring longer lengths of stay. Implementation of the team approach to manage diabetic foot ulcers in a given region or health-care system has been reported to reduce long-term amputation rates 62% to 82%. Limb salvage efforts may include aggressive therapy such as revascularization procedures and advanced wound-healing modalities. Although these procedures are costly, the team approach gradually leads to improved screening and prevention programs and earlier interventions and, thus, seems to reduce long-term costs. To date, aggressive limb preservation management for patients with diabetic foot ulcers has not usually been paired with adequate reimbursement. It is essential to direct efforts in patient-caregiver education to allow early recognition and management of all diabetic foot problems and to build integrated pathways of care that facilitate timely access to limb salvage procedures. Increasing evidence suggests that the costs of implementing diabetic foot teams can be offset in the long term by improved access to care and reductions in foot complications and amputation rates. (J Am Podiatr Med Assoc 100(5): 335–341, 2010)
Article
Research has shown that nitric oxide (NO) provides an enhancement in wound healing. The incorporation of NO into polymers for medical materials and surgical devices has potential benefits for many wound healing applications. In this work, acrylonitrile (AN)-based terpolymers were electrospun to form non-woven sheets of bandage or wound dressing type materials. NO is bound to the polymer backbone via formation of a diazeniumdiolate groups. In a 14 day NO release study, the dressings released 79 μmol NO/g polymer. The NO-loaded dressings were tested for NO release in vivo, which demonstrate upregulation of NO-inducible genes with dressing application compared to empty dressings. Studies were also conducted to evaluate healing progression in wounds with dressing application performed weekly and daily. In two separate studies, excisional wounds were created on the dorsum of 10 mice. Dressings with NO loaded on the fibers or empty controls were applied to the wounds and measurements of the wound area were taken at each dressing change. The data show significantly enhanced healing progression in the wounds with weekly NO application, which is more dramatic with daily application. Further, the application of daily NO bandages results in improved wound vascularity. These data demonstrate the potential for this novel NO-releasing dressing as a valid wound healing therapy.
Article
Mammalian skin research represents the convergence of three complementary disciplines: cell biology, mouse genetics, and dermatology. The skin provides a paradigm for current research in cell adhesion, inflammation, and tissue stem cells. Here, I discuss recent insights into the cell biology of skin. Single-cell analysis has revealed that human epidermal stem cells are heterogeneous and differentiate in response to multiple extrinsic signals. Live-cell imaging, optogenetics, and cell ablation experiments show skin cells to be remarkably dynamic. High-throughput, genome-wide approaches have yielded unprecedented insights into the circuitry that controls epidermal stem cell fate. Last, integrative biological analysis of human skin disorders has revealed unexpected functions for elements of the skin that were previously considered purely structural. Copyright © 2014, American Association for the Advancement of Science.
Article
The novel strategies of skin regenerative treatment are aimed at the development of biologically responsive scaffolds capable of delivering multiple bioactive agents and cells to the target tissues. In this study, nanofibers of poly (lactic-co-glycolic acid) (PLGA) and gelatin were electrospun and the effect of parameters viz polymer concentration, acid concentration, flow rate and voltage on the morphology of the fibers were investigated. PLGA nanofibers encapsulating epidermal growth factor were also prepared through emulsion electrospinning. The core-sheath structure of the nanofibers was verified by transmission electron microscopy. The hemostatic attributes and the biocompatibility of the scaffolds for human fibroblast cell were scrutinized. Furthermore, gene expression of collagen type I and type III by the cells on the scaffolds was quantified using real-time RT-PCR. The results indicated desirable bioactivity and hemostasis of the scaffolds with the capability of encapsulation and controlled release of the protein which can be served as skin tissue engineering scaffolds and wound dressings.
Article
Great challenges in transplantation of mesenchymal stem cells (MSCs) for treating ischemic diabetic ulcers (IDUs) are to find a suitable carrier and create beneficial microenvironment. Brain-derived neurotrophic factor (BDNF), a member of neurotrophin family, is considered angiogenic and neuroprotective. Given that IDUs are caused by vascular disease and peripheral neuropathy, we used BDNF as a stimulant, and intended to explore the role of new biomaterials complex with MSCs in wound healing. BDNF promoted the proliferation and migration of MSCs using MTT, transwell and cell scratch assays. The activity of human umbilical vein endothelial cells (HUVECs) was also enhanced by the MSC-conditioned medium in the presence of BDNF, via a VEGF-independent pathway. Because proliferated HUVECs in the BDNF group made the microenvironment more conducive to endothelial differentiation of MSCs, by establishing co-culture systems with the two cell types, endothelial cells derived from MSCs increased significantly. A new biomaterial made of polylactic acid, silk and collagen was used as the carrier dressing. After transplantation of the BDNF-stimulated MSC/biomaterial complex, the ulcers in hindlimb ischemic mice healed prominently. More blood vessel formation was observed in the wound tissue, and more MSCs were co-stained with some endothelial-specific markers such as CD31 and von Willebrand Factor (vWF) in the treatment group than in the control group. These results demonstrated that BDNF could improve microenvironment in the new biomaterial, and induce MSCs to differentiate into endothelial cells indirectly, thus accelerating ischemic ulcer healing.
Article
Novel therapeutic tools to accelerate wound healing would have a major impact on the overall burden of skin disease. Lin et al. demonstrate in mice that endogenous bone marrow stem cell mobilization, produced by a pharmacologic combination of AMD3100 and tacrolimus, leads to faster and better-quality wound healing, findings that have exciting potential for clinical translation.
Article
The skin protects mammals from insults, infection and dehydration and enables thermoregulation and sensory perception. Various skin-resident cells carry out these diverse functions. Constant turnover of cells and healing upon injury necessitate multiple reservoirs of stem cells. Thus, the skin provides a model for studying interactions between stem cells and their microenvironments, or niches. Advances in genetic and imaging tools have brought new findings about the lineage relationships between skin stem cells and their progeny and about the mutual influences between skin stem cells and their niches. Such knowledge may offer novel avenues for therapeutics and regenerative medicine.
Article
Silk fibroin (SF) and poly (lactide-co-glycolic acid) (PLGA) have been proved to be invaluable polymers in the field wound healing. This study aims at optimizing the electrospinning process of those polymers to make a hybrid membrane as a chronic wounds dressing. After characterizing the scaffolds, PLGA/SF (2:1) and PLGA scaffolds were selected for further study according to their superior tensile mechanical properties. The attachment and proliferation of mouse fibroblasts (L929) on scaffolds were measured using colorimetric assay and scanning electron microscopy. Furthermore, to evaluate the wound healing effect of the scaffolds in comparison with gauze and Comfeel(®) dressings, an excision wound model was conducted on diabetic rats. On the postoperative days of 3, 6, 9, 12 and 15, residual wound area was calculated using macroscopic data. In vitro results showed that the attachment and proliferation of L929 were significantly increased on PLGA/SF (2:1) hybrid scaffold. Animal study and histopathological evaluation outcomes confirmed the in vitro results as well. On day 15, the residual wound area in PLGA/SF (2:1) hybrid membrane group was significantly smaller than PLGA and control groups. This promising scaffold has the potential to be used for the upcoming development of wound dressings with or without biological drugs.
Article
Aims/Hypothesis Although the initial healing stage involves a re-epithelialization in humans, diabetic foot ulceration (DFU) has been investigated using rodent models with wounds on the thigh skin, in which a wound contraction is initiated. In this study, we established a rodent model of DFU on the plantar skin and evaluated the therapeutic efficacy of bone-marrow-derived mesenchymal stem cells (BM-MSCs) in this model. Methods The wounds made on the hind paws or thighs of streptozotocin induced diabetic or control rats were treated with BM-MSCs. Expression levels of phosphorylated focal adhesion kinase (pFAK), matrix metaroprotease (MMP)-2, EGF, and IGF-1, were evaluated in human keratinocytes, which were cultured in conditioned media of BM-MSCs (MSC-CM) with high glucose levels. Results Re-epithelialization initiated the healing process on the plantar, but not on the thigh, skin. The therapy utilizing BM-MSCs ameliorated the delayed healing in diabetic rats. In the keratinocytes cultured with MSC-CM, the decreased pFAK levels in the high glucose condition were restored, and the MMP2, EGF, and IGF-1 levels increased. Conclusions/Interpretation Our study established a novel rat DFU model. The impaired healing process in diabetic rats was ameliorated by transplantation of BM-MSCs. This amelioration might be accounted for by the modification of keratinocyte functions.
Article
The objective of this research study is to develop collagen (Col) and hyaluronic acid (HA) inter-stacking nanofibrous skin equivalent substitute with programmable release of multiple angiogenic growth factors (VEGF, PDGF, bFGF and EGF) either directly embedded in the nanofibers or encapsulated in the gelatin nanoparticles (GN) by electrospinning technology. The delivery of EGF and bFGF in early stage is expected to accelerate epithelialization and vasculature sprouting, while release of PDGF and VEGF in late stage is aimed for the induction of blood vessels maturation. The physiochemical characterizations report that the Col-HA-GN nanofibrous membrane possesses mechanical property similar to human native skin. The design of particle-in-fiber structure allows growth factors for slow controlled release up to one month. Cultured on biodegradable Col-HA membrane with four kinds of growth factors (Col-HA w/4GF), endothelial cells not only increase in growth rate but also form better network of thread-like tubular structure. Therapeutic effect of Col-HA w/4GF membrane on STZ-induced diabetic rats reveal accelerated wound closure rate, elevated collagen deposition, and enhanced mature vessels by Masson's trichrome stain and immunohistochemical analysis, respectively. From the above, the electrospun Col-HA-GN composite nanofibrous skin substitute with stage-wise release pattern of multiple angiogenic factors could be a promising bioengineered construct for the chronic wound healing in skin tissue regeneration.
Article
Stem cell therapy has shown promise in treating a variety of pathologies including skin wounds, but practical applications remain elusive. Here we demonstrate that endogenous stem cell mobilization produced by AMD3100 and low-dose Tacrolimus is able to reduce by 25% the time of complete healing of full-thickness wounds created by surgical excision. Equally important, healing was accompanied by reduced scar and regeneration of hair follicles. Searching for mechanisms, we found that AMD3100 combined with low-dose Tacrolimus mobilized increased number of lineage-negative c-Kit+, CD34+ and CD133+ stem cells. Low-dose Tacrolimus also increased the number of SDF-1 bearing macrophages in the wounds sites amplifying the "pull" of mobilized stem cells into the wound. Lineage tracing demonstrated the critical role of CD133 stem cells in enhanced capillary and hair follicle neogenesis contributing to more rapid and perfect healing. Our findings offer a significant therapeutic approach to wound healing and tissue regeneration.Journal of Investigative Dermatology accepted article preview online, 28 March 2014; doi:10.1038/jid.2014.162.
Article
The epidermis is maintained by epidermal stem cells (ESCs) that reside in distinct niches and contribute to homeostasis and wound closure. Keratinocytes at the nonhealing edges of venous ulcers (VUs) are healing-incompetent, hyperproliferative, and nonmigratory, suggesting deregulation of ESCs. To date, genes which regulate ESC niches have been studied in mice only. Utilizing microarray analysis of VU nonhealing edges, we identified changes in expression of genes harboring regulation of ESCs and their fate. In a prospective clinical study of 10 VUs, we confirmed suppression of the bone morphogenetic protein receptor (BMPR) and GATA binding protein 3 (GATA3) as well as inhibitors of DNA-binding proteins 2 and 4 (ID2 and ID4). We also found decreased levels of phosphorylated glycogen synthase kinase 3 (GSK3), nuclear presence of β-catenin, and overexpression of its transcriptional target, c-myc, indicating activation of the Wnt pathway. Additionally, we found down-regulation of leucine-rich repeats and immunoglobulin-like domains protein 1 (LRIG1), a gene important for maintaining ESCs in a quiescent state, and absence of keratin 15 (K15), a marker of the basal stem cell compartment suggesting local depletion of ESCs. Our study shows that loss of genes important for regulation of ESCs and their fate along with activation of β-catenin and c-myc in the VU may contribute to ESC deprivation and a hyperproliferative, nonmigratory healing incapable wound edge.
Article
Innovative approaches are needed to accelerate the healing of human chronic wounds not responding to conventional therapies. An evolving and promising treatment is the use of stem cells. Our group has previously described the use of expanded (in vitro) autologous stem cells aspirated from human bone marrow and applied topically in a fibrin spray to human acute and chronic wounds. More recently, we have sought ways to mobilize stem cells directly from the bone marrow, without in vitro expansion. In this report, we show that systemic injections of granulocyte colony-stimulating factor (GCSF) can mobilize stem cells from bone marrow into the peripheral blood and then to the wound site. Our objectives were to optimize parameters for this method by using mouse models and proof of principle in a human chronic wound situation. Mice were injected for 5 days with 2 different formulations of GCSF and compared to control saline. To monitor stem cell mobilization, flow cytometric measurements of Sca-1 and c-Kit and colony-forming cell assays were performed. Full-thickness tail wounds in mice were created and monitored for healing, and polyvinyl alcohol sponges were implanted dorsally to assess collagen accumulation. To determine bone marrow stem cell homing to the wound site, chimeric mice transplanted with Green Fluorescent Protein bone marrow cells were scanned by live imaging. Additionally, as proof of principle, we tested the systemic GCSF approach in a patient with a nonhealing venous ulcer. Our findings lay the ground work and indicate that the systemic administration of GCSF is effective in mobilizing bone marrow stem cells into the peripheral blood and to the wound site. These findings are associated with an increased accumulation of collagen and promising results in terms of wound bed preparation and healing.
Article
Wound healing is a major problem in diabetic patients and current methods of treatment have met with limited success. Since skin cell renewal is under the control of mesenchymal stem cells (MSCs) treatment of wounds has been attempted with the application of exogenous bone marrow MSCs (hBMMSCs). However, hBMMSCs have the limitations of painful harvest, low cell numbers and short-lived stemness properties unlike MSCs from the Wharton's jelly of human umbilical cords (hWJSCs). Since nanoscaffolds provide three dimensional architectural patterns that mimic in vivo stem cell niches and aloe vera has antibacterial properties we evaluated the use of an aloe vera-polycaprolactone (AV/PCL) nanoscaffold impregnated with green fluorescent protein (GFP)-labeled hWJSCs (GFP-hWJSCs + AV/PCL) or its conditioned medium (hWJSC-CM + AV/PCL) for healing of excisional and diabetic wounds. In skin fibroblast scratch-wound assays exposed to GFP-hWJSCs + AV/PCL or hWJSC-CM + AV/PCL, fibroblasts migrated significantly faster from edges of scratches into vacant areas together with increased secretion of collagen I and III, elastin, fibronectin, superoxide dismutase and metalloproteinase-1 (MMP-1) compared to controls. After one application of GFP-hWJSCs + AV/PCL or hWJSC-CM + AV/PCL excisional and diabetic wounds in mice showed rapid wound closure, reepithelialization and increased numbers of sebaceous glands and hair follicles compared to controls. The same wounds exposed to GFP-hWJSCs + AV/PCL or hWJSC-CM + AV/PCL also showed positive keratinocyte markers (cytokeratin, involucrin, filaggrin) and increased expression of ICAM-1, TIMP-1 and VEGF-A compared to controls. AV/PCL nanoscaffolds in combination with hWJSCs appear to have synergistic benefits for wound healing. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.
Article
Wounds are one of the most frequently occurring medical complication. Stem cells were recently highlighted as a novel therapeutic approach to treating wounds, although some negative aspects of allogenic stem cell transplantation were observed, such as cellular source limitations and unknown side effects in vivo. To address and eliminate these side effects, we examined the wound healing effect of secretory factors released from human cord blood-derived stem cells (hCB-SCs) and human umbilical vascular endothelial cells (HUVECs) on cutaneous excisional wound models. The hCB-SCs retained endothelial progenitor cell characteristics and expressed MSC markers such as CD73, CD105, and CD44. Analysis of hCB-SC-conditioned medium (CM) indicated that hCB-SCs secrete distinctly unique cytokines and chemokines such as TGF-β, PDGF, bFGF, EGF, KGF, and VEGF, which are well known to be important in normal angiogenesis and wound healing. Furthermore, hCB-SCs also secreted stem cell-recruiting factors such as G-CSF and GM-CSF, whereas HUVECs did not. When CB-SC-CM was applied to wound sites, hCB-SC-CM accelerated the wound healing rate compared with HUVEC-CM- and control medium-treated groups. In addition, hCB-SC-CM treatment caused a more rapid re-formation of granulation tissue and re-epithelialization of wounds, which indicates that the therapeutic effect of hCB-SC-CM is due to secreted stem cell-recruiting factors from stem cells, not just from endothelial lineage cells. Taken together, these results suggest that secretory factors released from stem cells, not just from endothelial cells, could be an important mediator of stem cell therapy in ischemic tissue diseases.
Article
Introduction: Close to 5 million people in the USA are affected by chronic wounds, and billions of dollars are spent annually for their treatment. Despite advances in chronic wound management over the past decades, many patients afflicted with chronic wounds fail to heal or their ulcers recur. There is emerging evidence that the use of bone marrow-derived mesenchymal stem cells (BM-MSCs) can offset this situation of impaired healing. Areas covered: This article provides a review of the use of BM-MSC for the treatment of chronic wounds, the current development of stem cell delivery to chronic wounds and related challenges are also described in this manuscript. Expert opinion: Numerous animal studies and a few pilot studies in human wounds have shown that BM-MSC can augment wound closure. Still, the primary contribution of mesenchymal stem cells (MSCs) to cutaneous regeneration and the long-term systemic effects of MSCs are yet to be established. In addition, we need to determine whether other types of stem/progenitor cells will be more effective. Therefore, more randomized controlled clinical trials need to be undertaken. It is of importance to remember that even with the most advanced and sophisticated therapeutic approaches, proper wound care and adherence to basic principles remain critical.
Article
The objective of this research is to develop a dual-growth factor releasing nanoparticle-innanofiber system for wound healing applications. In order to mimic and promote the natural healing procedure, chitosan and poly(ethylene oxide) were electrospun into nanofibrous meshes as mimics of extracellular matrix. Vascular endothelial growth factor (VEGF) was loaded within nanofibers to promote angiogenesis in short term. In addition, platelet-derived growth factor-BB (PDGF-BB) encapsulated poly(lactic-co-glycolic acid) nanoparticles were embedded inside nanofibers to generate a sustained release of PDGF-BB for accelerated tissue regeneration and remodeling. In vitro studies revealed that our nanofibrous composites delivered VEGF quickly and PDGF-BB in a relayed manner, supported fibroblast growth, and exhibited anti-bacterial activities. Preliminary in vivo study performed on normal full thickness rat skin wound models demonstrated that nanofiber/nanoparticle scaffolds significantly accelerated the wound healing process through promoting angiogenesis, increasing re-epithelialization, and controlling granulation tissue formation. For later stages of healing, evidence also showed quicker collagen deposition and earlier remodeling of the injured site to achieve a faster full regeneration of skin compared to the commercial Hydrofera Blue® wound dressing. These results suggest that our nanoparticle-in-nanofiber system could provide a promising treatment for normal and chronic wound healing.