The effect of disodium cromoglycate on the skin wound healing and collagen content in the wounds of rats

The effect of disodium cromoglycate on skin wound healing and collagen formation in the wounds was studied. Disodium cromoglycate (a mast cell stabilizer) administered to the rats in a dose of 2 mg/animal was found to retard wound healing and markedly increased wound surface in all examined days (3rd, 5th, 7th, 10th, 14th day of healing). The mast cell stabilizer injected directly into wounds decreased collagen content, especially on 10th and 14th day of the healing process.     

Evidence That Mast Cells Are Not Required for Healing of Splinted Cutaneous Excisional Wounds in Mice

Wound healing is a complex biological process involving the interaction of many cell types to replace lost or damaged tissue. Although the biology of wound healing has been extensively investigated, few studies have focused on the role of mast cells. In this study, we investigated the possible role of mast cells in wound healing by analyzing aspects of cutaneous excisional wound healing in three types of genetically mast cell-deficient mice. We found that C57BL/6-Kit^W-sh/W-sh, WBB6F₁-Kit^W/W-v, and Cpa3-Cre; Mcl-1^fl/fl mice re-epithelialized splinted excisional skin wounds at rates very similar to those in the corresponding wild type or control mice. Furthermore, at the time of closure, scars were similar in the genetically mast cell-deficient mice and the corresponding wild type or control mice in both quantity of collagen deposition and maturity of collagen fibers, as evaluated by Masson’s Trichrome and Picro-Sirius red staining. These data indicate that mast cells do not play a significant non-redundant role in these features of the healing of splinted full thickness excisional cutaneous wounds in mice.     

Activity of mesenchymal stem cells in therapies for chronic skin wound healing

Chronic or non-healing skin wounds present an ongoing challenge in advanced wound care, particularly as the number of patients increases while technology aimed at stimulating wound healing in these cases remains inefficient. Mesenchymal stem cells (MSCs) have proved to be an attractive cell type for various cell therapies due to their ability to differentiate into various cell lineages, multiple donor tissue types, and relative resilience in ex-vivo expansion, as well as immunomodulatory effects during transplants. More recently, these cells have been targeted for use in strategies to improve chronic wound healing in patients with diabetic ulcers or other stasis wounds. Here, we outline several mechanisms by which MSCs can improve healing outcomes in these cases, including reducing tissue inflammation, inducing angiogenesis in the wound bed, and reducing scarring following the repair process. Approaches to extend MSC life span in implant sites are also examined.     

Stimulation of growth factor synthesis in skin wounds using tissue extract (G-90) from the earthworm Eissenia foetida

Growth factors are biologically-active mediators that bind to specific receptors on target cells and regulate genes involved in cell growth, wound healing and regeneration. In the case of wound healing, a proper wound dressing is needed to cover the wound area, protect the damaged tissue, and if possible to activate cell proliferation and stimulate the healing process. In this study we examined the efficacy of a glycolipoprotein tissue homogenate extract from Eisenia foetida (G-90) to activate signal transduction pathways, leading to wound healing. We measured the activation of EGF and FGF in healthy skin, in wounds with physiological healing and in wounds treated with G-90. The activation of EGF and FGF was measured during the first 24 h of wound healing under both physiological conditions and treatment with G-90. In both cases an increased concentration of EGF and FGF was observed 6 h after wounding. In comparison with healthy skin, the concentration of EGF increased 10-fold and FGF five-fold in wounds treated with G-90 (10 ng ml(-1)). Healing in physiological conditions resulted in a two-fold increase of EGF and 1.5-fold of FGF.     

Multipotent adult progenitor cells: their role in wound healing and the treatment of dermal wounds

The use of cellular therapy in the treatment of dermal wounds is currently an active area of investigation. Multipotent adult progenitor cells (MAPC) are an attractive choice for cytotherapy because they have a large proliferative potential, the ability to differentiate into different cell types and produce a variety of cytokines and growth factors important to wound healing. Whole bone marrow (BM) was one of the initial attempts to treat impaired wounds. While it has shown some promise, the low frequency of progenitor cell populations in BM and the large number of inflammatory cells make it less attractive. Multipotent mesenchymal stromal cells (MSC) and endothelial progenitor cells are populations of BM-derived progenitor cells that have been isolated and used to treat chronic wounds with some success. Skin-derived MAPC are another heterogeneous population of progenitor cells present in the skin with the potential to differentiate into skin elements and participate in wound healing. All of these progenitor cell populations are potential sources for cytotherapy of wounds. This review focused on the contribution of adult progenitor cell populations to dermal wound healing and their potential for use in cytotherapy.     

EGF and TGF-alpha in wound healing and repair

Wound healing is a localized process which involves inflammation, wound cell migration and mitosis, neovascularization, and regeneration of the extracellular matrix. Recent data suggest the actions of wound cells may be regulated by local production of peptide growth factors which influence wound cells through autocrine and paracrine mechanisms. Two peptide growth factors which may play important roles in normal wound healing in tissues such as skin, cornea, and gastrointestinal tract are the structurally related peptides epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha). EGF/TGF-alpha receptors are expressed by many types of cells including skin keratinocytes, fibroblasts, vascular endothelial cells, and epithelial cells of the GI tract. In addition, EGF or TGF-alpha are synthesized by several cells involved in wound healing including platelets, keratinocytes, and activated macrophages. Healing of a variety of wounds in animals and patients was enhanced by treatment with EGF or TGF-alpha. Epidermal regeneration of partial thickness burns on pigs or dermatome wounds on patients was accelerated with topical application of EGF or TGF-alpha, and EGF treatment accelerated healing of gastroduodenal ulcers. EGF also increased tensile strength of skin incisions in rats and corneal incisions in rabbits, cats, and primates. Additional research is needed to better define the roles of EGF, TGF-alpha and their receptor in normal wound healing, to determine if alterations have occurred in the EGF/TGF-alpha system in chronic wounds, and optimize vehicles for effective delivery of peptide growth factors to wounds.     

The effect of finger millet feeding on the early responses during the process of wound healing in diabetic rats

In the present study, the role of finger millet feeding on skin antioxidant status, nerve growth factor (NGF) production and wound healing parameters in healing impaired early diabetic rats is reported. Hyperglycemic rats received food containing 50 g/100 g finger millet (FM). Non-diabetic controls and diabetic controls received balanced nutritive diet. Full-thickness excision skin wounds were made after 2 weeks prior feeding of finger millet diet. The rate of wound contraction, and the levels of collagen, hexosamine and uronic acid in the granulation tissue were determined. The skin antioxidant status and lipid peroxide concentration were also monitored during the study. In hyperglycemic rats fed with finger millet diet, the healing process was hastened with an increased rate of wound contraction. Skin levels of glutathione (GSH), ascorbic acid and alpha-tocopherol in alloxan-induced diabetic rat were lower as compared to non-diabetics. Altered activities of superoxide dismutase (SOD) and catalase (CAT) were also recorded in diabetics. Interestingly, thiobarbituric acid reactive substances (TBARS) were elevated in the wound tissues of all the groups, when compared to normal (unwounded) skin tissues. However, in diabetic rats the TBARS levels of both normal and wounded skin tissues were significantly elevated (P < 0.001) when compared with control (non-diabetic) and diabetics fed with FM. Impaired production of NGF, determined by ELISA, in diabetic rats was improved upon FM feeding and further confirmed by immunocytochemical observations reflects the increased expression of NGF in hyperglycemic rats supplemented with FM-enriched diet. Histological and electron microscopical evaluations revealed the epithelialization, increased synthesis of collagen, activation of fibroblasts and mast cells in FM-fed animals. Thus, increased levels of oxidative stress markers accompanied by decreased levels of antioxidants play a vital role in delaying wound healing in diabetic rats. However, FM feeding to the diabetic animals, for 4 weeks, controlled the glucose levels and improved the antioxidant status, which hastened the dermal wound healing process.     

Mast cells: an unexpected finding in the modulation of cutaneous wound repair by charged beads

Increased numbers of mast cells are affiliated with a broad spectrum of pathologic skin conditions, including ulcers, atopic dermatitis, neurofibromatosis, hemangiomas, keloids, and hypertrophic scars. It has been proposed that mast cells play a primary pathophysiologic role in these disorders and that their presence represents not merely a secondary event. While investigating their recent hypothesis that positively charged cross-linked diethylaminoethyl dextran (CLDD) beads potentiate cutaneous wound healing, the authors serendipitously observed increased numbers of mast cells in the deep dermis of wounds treated with CLDD beads. The authors propose that mast cells may play an important role in the modulation of healing seen with CLDD beads. Incisional wounds were studied in 30 Sprague-Dawley rats partitioned into two groups that were killed 7 or 14 days after wounding. The wounds were treated with positively, negatively, or neutrally charged CLDD beads. Physiologic saline served as a control. At the designated times after incisional wounding, biopsy specimens were tested for wound breaking strength or processed for histologic testing, fixed in 4% paraformaldehyde, and stained with Giemsa and Goldner-Masson trichrome. Mast cells were counted under light microscopy in a blinded fashion and were expressed as the number of cells per millimeter squared. Significant increases in the number of mast cells were observed in the deep dermis of incisional wounds after implantation with positively or negatively charged CLDD beads. In contrast, neutrally charged beads had no effect on mast cell numbers. At 7 days, the incisions treated with positively charged beads averaged 2.1 times more mast cells compared with those treated with physiologic saline or neutrally charged beads, whereas the incisions treated with negatively charged beads displayed 3.2 times more mast cells. By day 14, the incisions treated with positively charged beads averaged 2.5 times more mast cells than those wounds treated with saline or neutrally charged beads; the incisions treated with negatively charged CLDD beads had 3.4 times more mast cells. The 7-day tensiometric data indicated that wounds treated with negatively charged CLDD beads had increased breaking strength compared with wounds treated with neutrally charged beads or saline (1.8 and 1.7 times, respectively; p = 0.01 and p = 0.02). Wounds treated with positively charged beads also showed increased breaking strength compared with wounds treated with neutrally charged beads or saline (1.5 and 1.4 times greater); however, this did not reach statistical significance. There was no apparent difference in breaking strength when neutrally charged beads were compared with those treated with saline. At 14 days, there was no statistically significant difference in wound breaking strength between different treatments. These findings are clinically germane to the assessment of proposed therapeutic applications of CLDD beads for a variety of impaired wound-healing states. Furthermore, if increased mast cell populations are intimately linked to hypertrophic scar and keloid formation, the results of the authors' study suggest that CLDD bead therapy of cutaneous wounds may lead to pathologic wound healing in humans.     

Electron microscopic immunochemical localization of actin in fibroblasts in healing skin and palate wounds of beagle dog

Wound contraction in soft tissue has been attributed to the activity of contractile fibroblasts containing actin microfilaments. Immunochemical staining at the electron microscopic level was used to demonstrate the presence of such cells in healing wounds from skin and oral mucosa. Biopsies of granulation tissue from 10 and 16 day old excision wounds in beagle palate mucoperiosteum and skin were fixed and 10 micrometer sections were treated with antiactin serum, peroxidase-anti peroxidase (PAP) and then incubated to reveal the localization of actin. Controls were prepared using non-immune serum or preabsorbed immune serum. Thin sections examined with the electron microscope revealed the presence of PAP particles associated with microfilament bundles beneath the plasma membrane and in processes of fibroblasts. Reaction was also associated with micropinocytotic vesicles at the cell surface. More reactive cells were seen in 16 day than in 10 day old wounds and there were greater numbers of these cells in skin than in oral mucoperiosteum. The results indicate that actin containing cells with the ultrastructural characteristics of contractile fibroblasts (myofibroblasts) are present in the granulation tissue of healing skin and oral mucosal wounds. Such cells may be responsible for the wound contraction observed clinically in the healing palatal mucoperiosteum.     

Skin repair and scar formation: the central role of TGF-beta

Wound healing is a complex process that we have only recently begun to understand. Central to wound repair is transforming growth factor beta (TGF-beta), a cytokine secreted by several different cell types involved in healing. TGF-beta has diverse effects, depending upon the tissue studied. This review focuses on healing in skin, particularly the phases of cutaneous wound repair and the role of TGF-beta in normal and impaired wound-healing models. It also explores TGF-beta activity in scarless foetal wound healing. Knowledge of TGF-beta function in scarless repair is critical to improving healing in clinical scenarios, such as diabetic wounds and hypertrophic scars.     

Defects in skin gamma delta T cell function contribute to delayed wound repair in rapamycin-treated mice

Disruptions in the normal program of tissue repair can result in poor wound healing, which perturbs the integrity of barrier tissues such as the skin. Such defects in wound repair occur in transplant recipients treated with the immunosuppressant drug rapamycin (sirolimus). Intraepithelial lymphocytes, such as gammadelta T cells in the skin, mediate tissue repair through the production of cytokines and growth factors. The capacity of skin-resident T cells to function during rapamycin treatment was analyzed in a mouse model of wound repair. Rapamycin treatment renders skin gammadelta T cells unable to proliferate, migrate, and produce normal levels of growth factors. The observed impairment of skin gammadelta T cell function is directly related to the inhibitory action of rapamycin on mammalian target of rapamycin. Skin gammadelta T cells treated with rapamycin are refractory to IL-2 stimulation and attempt to survive in the absence of cytokine and growth factor signaling by undergoing autophagy. Normal wound closure can be restored in rapamycin-treated mice by addition of the skin gammadelta T cell-produced factor, insulin-like growth factor-1. These studies not only reveal that mammalian target of rapamycin is a master regulator of gammadelta T cell function but also provide a novel mechanism for the increased susceptibility to nonhealing wounds that occurs during rapamycin administration.     

Role of caveolin-1 in epidermal stem cells during burn wound healing in rats

Local transplantation of stem cells has therapeutic effects on skin damage but cannot provide satisfactory wound healing. Studies on the mechanisms underlying the therapeutic effects of stem cells on skin wound healing will be needed. Hence, in the present study, we explored the role of Caveolin-1 in epidermal stem cells (EpiSCs) in the modulation of wound healing. We first isolated EpiSCs from mouse skin tissues and established stable EpiSCs with overexpression of Caveolin-1 using a lentiviral construct. We then evaluated the epidermal growth factor (EGF)-induced cell proliferation ability using cell counting Kit-8 (CCK-8) assay and assessed EpiSC pluripotency by examining Nanog mRNA levels in EpiSCs. Furthermore, we treated mice with skin burn injury using EpiSCs with overexpression of Caveolin-1. Histological examinations were conducted to evaluate re-epithelialization, wound scores, cell proliferation and capillary density in wounds. We found that overexpression of Caveolin-1 in EpiSCs promoted EGF-induced cell proliferation ability and increased wound closure in a mouse model of skin burn injury. Histological evaluation demonstrated that overexpression of Caveolin-1 in EpiSCs promoted re-epithelialization in wounds, enhanced cellularity, and increased vasculature, as well as increased wound scores. Taken together, our results suggested that Caveolin-1 expression in the EpiSCs play a critical role in the regulation of EpiSC proliferation ability and alteration of EpiSC proliferation ability may be an effective approach in promoting EpiSC-based therapy in skin wound healing.     

Involvement of notch signaling in wound healing

The Notch signaling pathway is critically involved in cell fate decisions during development of many tissues and organs. In the present study we employed in vivo and cell culture models to elucidate the role of Notch signaling in wound healing. The healing of full-thickness dermal wounds was significantly delayed in Notch antisense transgenic mice and in normal mice treated with gamma-secretase inhibitors that block proteolytic cleavage and activation of Notch. In contrast, mice treated with a Notch ligand Jagged peptide showed significantly enhanced wound healing compared to controls. Activation or inhibition of Notch signaling altered the behaviors of cultured vascular endothelial cells, keratinocytes and fibroblasts in a scratch wound healing model in ways consistent with roles for Notch signaling in wound healing functions all three cell types. These results suggest that Notch signaling plays important roles in wound healing and tissue repair, and that targeting the Notch pathway might provide a novel strategy for treatment of wounds and for modulation of angiogenesis in other pathological conditions.     

創傷癒合和組織再生的研究——Ⅰ.白鼠皮膚切除創傷癒合過程中創口的收縮

一.引言在高等動物的皮膚創傷癒合過程中,創口的收縮是很顯著的現象,使它所形成的疤痕往往小於當初創傷的部分。因此,創口的收縮作用,對於創傷癒合來說,是具有極大意義的。最早Carrel(1910)在研究狗的皮膚創傷癒合工作中,即已指出這個創口收縮的重要性;並且提出是由於肉芽的收縮作用(granulous retrac-     

微小RNA miR-21在皮肤创伤愈合中的研究进展

微小RNA是一类真核细胞中广泛存在的内源性转录后调控分子,其在细胞的增殖、分化、凋亡、迁移等过程中发挥了重要的调控作用。皮肤创伤修复涉及复杂的细胞与分子的相互作用网络。近年来研究表明micro RNAs在皮肤创伤修复中发挥调控作用,引人关注。miR-21作为重要的癌基因是目前研究的最多的miRNAs分子之一,其在皮肤创伤修复中的作用研究也越来越受到重视。研究表明miR-21参与了细胞增殖与迁移、炎症反应、血管生成和细胞外基质合成等重要修复相关事件的调控。因此,阐明miR-21分子在正常皮肤创伤愈合中的作用,厘清miR-21表达失调在修复不足和修复过度中的功能,将深化我们对于皮肤创伤愈合基本理论的认识,并为促进创面愈合与防治修复不足和过度提供潜在的治疗靶点。本文就miR-21分子在正常皮肤创伤修复、慢性难愈性创面和增生性瘢痕中作用的研究进展进行综述展望。     

Roles of lactoferrin on skin wound healing

Skin wound healing is a complex biological process that requires the regulation of different cell types, including immune cells, keratinocytes, fibroblasts, and endothelial cells. It consists of 5 stages: hemostasis, inflammation, granulation tissue formation, re-epithelialization, and wound remodeling. While inflammation is essential for successful wound healing, prolonged or excess inflammation can result in nonhealing chronic wounds. Lactoferrin, an iron-binding glycoprotein secreted from glandular epithelial cells into body fluids, promotes skin wound healing by enhancing the initial inflammatory phase. Lactoferrin also exhibits anti-inflammatory activity that neutralizes overabundant immune response. Accumulating evidence suggests that lactoferrin directly promotes both the formation of granulation tissue and re-epithelialization. Lactoferrin stimulates the proliferation and migration of fibroblasts and keratinocytes and enhances the synthesis of extracellular matrix components, such as collagen and hyaluronan. In an in vitro model of wound contraction, lactoferrin promoted fibroblast-mediated collagen gel contraction. These observations indicate that lactoferrin supports multiple biological processes involved in wound healing.     

Accelerated healing of full-thickness skin wounds in a wet environment

Full-thickness skin wounds are preferably allowed to heal under controlled hydration dressings such as hydrocolloids. It was hypothesized that a wet (liquid) environment rather than a dry or moist one would accelerate the wound healing process. We compared skin repair by secondary intention in full-thickness skin wounds in wet (saline), moist (hydrocolloid), and dry (gauze) conditions in an established porcine wound healing model. The study included three animals with a total of 70 wounds layered in a standardized fashion on the back of young Yorkshire pigs. Twelve days after wounding, 0 percent of dry, 20 percent of moist, and 86 percent of saline-treated wounds were completely reepithelialized (p values = 0.0046 and 0.027 for saline wounds compared with dry and moist wounds, respectively). The accelerated healing was caused at least in part by faster contraction in wet wounds (p value < 0.005 compared with that of other groups 9 and 12 days after wounding). Development of granulation tissue was faster in moist conditions than it was for dry and wet wounds. The thickness and number of cell layers of the newly formed epidermis were greater in dry and wet wounds than in moist ones. It was concluded that these full-thickness porcine skin wounds healed faster in a wet environment than in a moist one. Dry wounds healed more slowly than moist wounds. The basic mechanisms of skin wound repair were influenced by the treatment modality as demonstrated by the observed differences in granulation tissue formation, reepithelialization, and rate of wound contraction.     

Immunohistochemical localization of growth factors in fetal wound healing

Fetal wound healing occurs rapidly, in a regenerative fashion, and without scar formation, by contrast with adult wound healing, where tissue repair results in scar formation which limits tissue function and growth. The extracellular matrix deposited in fetal wounds contains essentially the same structural components as that in the adult wound but there are distinct differences in the spatial and temporal distribution of these components. In particular the organization of collagen in the healed fetal wound is indistinguishable from the normal surrounding tissue. Rapidity of healing, lack of an inflammatory response, and an absence of neovascularization also distinguish fetal from adult wound healing. The mechanisms controlling these differing processes are undefined but growth factors may play a critical role. The distribution of growth factors in healing fetal wounds is unknown. We have studied, by immunohistochemistry, the localization of platelet-derived growth factor (PDGF), transforming growth factor beta (TGF beta), and basic fibroblast growth factor (bFGF), in fetal, neonatal, and adult mouse lip wounds. TGF beta and bFGF were present in neonatal and adult wounds, but were not detected in the fetal wounds, while PDGF was present in fetal, neonatal, and adult wounds. This pattern correlates with the known effects in vitro of these factors, the absence of an inflammatory response and neovascularization in the fetal wound, and the patterns of collagen deposition in both fetal and adult wounds. The results suggest that it may be possible to manipulate the adult wound to produce more fetal-like, scarless, wound healing.