Exercise accelerates cutaneous wound healing and decreases wound inflammation in aged mice

The purpose of this study was to determine the effect of exercise on wound healing and inflammation in young (3 mo) and old (18 mo) female BALB/cByJ mice. Mice were assigned to either exercise or sedentary control (control) groups. The exercise group mice were run on a motorized treadmill at a moderate intensity 30 min/day for 8 days. All mice were given four full-thickness dermal wounds, and the rate of wound closure was assessed daily for 10 days. Four months later, the aged mice were rerandomized to treatment, wounded again in different locations, and wounds were harvested at 1, 3, or 5 days postwounding. Wound tissue was analyzed for IL-1beta, IL-6, keratinocyte chemoattractant (KC), monocyte chemoattractant protein-1 (MCP-1), and TNF-alpha protein. Myeloperoxidase (MPO) activity and F4/80 mRNA were assessed as an indirect measure of neutrophil and macrophage content, respectively. There was a trend (P = 0.10) for exercise to reduce wound size in young mice, and exercise significantly (P < 0.05) decreased wound size in old mice. TNF-alpha, KC, and MCP-1 were significantly (P < 0.05) lower in wounds from exercised old mice compared with control. No group differences were found for wound IL-1beta or IL-6, MPO activity, or F4/80 mRNA. Our data suggest that exercise accelerates the wound healing process in old mice. This improved healing response in the old mice may be the result of an exercise-induced anti-inflammatory response in the wound.     

Effects of CD100 promote wound healing in diabetic mice

Diabetes is a condition that causes delayed wound healing and results in chronic wounds. CD100 has been reported to promote and induce potent and obvious angiogenesis both in vivo and in vitro studies, the absence of which are a main cause of the diabetic chronic wound. In the present study, we investigated the effects of application of soluble CD100 on wound healing in diabetic mice. Four 5-mm full-thickness dermal wounds were made on each male db/db mouse. 12 mice from CD100 group were subcutaneously injected with 250 ng of CD100 (50 µl) per wound, in addition, 12 mice were injected with the same volume phosphate-balanced solution as the control. The animals were treated every other day until the wounds healed completely. Images were obtained to calculate the area ratio of the original area. HE and Masson’s trichrome staining were used for histological examination. Collagen remodeling, angiogenesis and wound bed inflammation were evaluated by immunohistochemical staining and western blot. We demonstrated that CD100 had distinct functions during the wound healing process. Histological and western blotting analysis showed a more organized epithelium and dermis, more collagen fibers, higher angiogenesis and lower inflammation in the CD100 group than in the PBS group. These findings suggest that CD100 may accelerate wound healing in diabetic mice by promoting angiogenesis in the wound and by reducing the inflammatory response.     

Biodegradable collagen from Scomberomorus lineolatus skin for wound healing dressings and its application on antibiofilm properties

The major resolution of the study was to develop a dynamic form of natural biopolymer material to improve the wound healing by inhibition of biofilm formation on the surface. The extraction of collagen was effectively prepared from Scomberomorus lineolatus fish skin. Lyophilized collagen sheet was liquefied in 0.5M acetic acid to form acidic solubilized collagen (ASC) for further analysis. Physicochemical characterization of ASC was performed by various techniques using a standard protocol. The yield of ASC form S.lineolatus is higher (21.5%) than the previous reported studies. The effect of collagen solubility is gradually decreases with increasing concentration of NaCl and collagen is mostly soluble in acidic pH conditions. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of ASC contains α chain composition of α₁ and α₂ subunits and was characterized as type I collagen. Ultraviolet absorption was regulated as the appropriate wavelength to optimize the collagen. Fourier-transform infrared spectroscopy and X-ray diffraction confirmed that the isolated collagen is a triple-helical structure. The biofilm formation of Pseudomonas aeruginosa was significantly reduced by collagen incorporated with isolated 3,5,7-trihydroxyflavone (collagen-TF) sheet up to 70%. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide assay executed on fibroblast cell lines (L929) shows that the collagen-TF sheet was 100% compatible to enrich the cell adhesion and proliferation. The current study was the first report to extract, purify, and characterize ASC from S. lineolatus fish skin and characterize as type I collagen. Based on the result, we design the natural biodegradable collagen loaded with TF compound (collagen-TF) for antibiofilm properties. Compared with different sources of polymer, fish skin collagen is more effective and can be used as a biopolymer sheet for wound healing, food, drug delivery, tissue engineering, and pharmaceutical application.     

A therapeutic approach for diabetic wound healing using biotinylated GHK incorporated collagen matrices

Chronically elevated blood glucose levels result in reduced leukocyte function and cell malnutrition, which contribute to a high rate of wound infection and associated healing problems in diabetic patients. In the present study, the role of biotinylated GHK peptide (BioGHK) incorporated collagen biomaterial was tested for wound healing in diabetic rats. The rate of wound contraction and the levels of collagen, uronic acid, protein and DNA in the granulation tissue were determined. Further, the concentration of nitric oxide and other skin antioxidants was also monitored during the study. In diabetic rats treated with BioGHK incorporated collagen (Peptide Incorporated Collagen--PIC), the healing process was hastened with an increased rate of wound contraction. Glutathione (GSH) and ascorbic acid levels in the skin of streptozotocin-induced diabetic rats were higher in the PIC group as compared to control (Untreated) and collagen (Collagen Film--CF) treated groups. Superoxide dismutase (SOD) and catalase (CAT) activity was altered in all the groups. In vitro fibroblast cell culture studies suggest that PIC promotes fibroblast growth. Histological evaluation by haematoxylin-eosin and Masson's trichrome method revealed epithelialization, increased synthesis of collagen and activation of fibroblasts and mast cells in the PIC group. This study provides a rationale for the topical application of BioGHK incorporated collagen as a feasible and productive approach to support diabetic wound healing.     

Plasma treatments of dressings for wound healing: a review

This review covers the use of plasma technology relevant to the preparation of dressings for wound healing. The current state of knowledge of plasma treatments that have potential to provide enhanced functional surfaces for rapid and effective healing is summarized. Dressings that are specialized to the needs of individual cases of chronic wounds such as diabetic ulcers are a special focus. A summary of the biology of wound healing and a discussion of the various types of plasmas that are suitable for the customizing of wound dressings are given. Plasma treatment allows the surface energy and air permeability of the dressing to be controlled, to ensure optimum interaction with the wound. Plasmas also provide control over the surface chemistry and in cases where the plasma creates energetic ion bombardment, activation with long-lived radicals that can bind therapeutic molecules covalently to the surface of the dressing. Therapeutic innovations enabled by plasma treatment include the attachment of microRNA or antimicrobial peptides. Bioactive molecules that promote subsequent cell adhesion and proliferation can also be bound, leading to the recruitment of cells to the dressing that may be stem cells or patient-derived cells. The presence of a communicating cell population expressing factors promotes healing.     

Systemic administration of high-molecular weight hyaluronan stimulates wound healing in genetically diabetic mice

Hyaluronic acid (HA), an essential component of the extracellular matrix, is an efficient space filler that maintains hydration, serves as a substrate for assembly of proteoglycans and is involved in wound healing. Although numerous pieces of evidence demonstrate beneficial effects in promoting wound healing in diabetes, a systemic approach has never been tested. We used an incisional wound healing model in genetically diabetic mice to test the effects of systemic injection of HA. Diabetic (n = 56) and normoglycemic (n = 56) mice were subjected to incision and randomized (8 groups of 7 animals each) to receive HA at different doses, 7.5, 15 and 30 mg/kg/i.p., or vehicle (0.9% NaCl solution) for 12 days. At the end of the experiment animals were sacrificed and skin wounds were excised for histological, biochemical and molecular analysis. Histology revealed that the most effective dose to improve wound repair and angiogenesis in diabetic mice was 30 mg/kg. Furthermore HA injection (30 mg/kg) improved the altered healing pattern in diabetic animals, increased skin remodeling proteins TGF-β and transglutaminase-II and restored the altered expression of cyclin B1/Cdc2 complex. Evaluation of skin from diabetic animals injected with HA revealed also an increase in HA content, suggesting that systemic injection may be able to restore the reduced intracellular HA pool of diabetic mice. Finally HA markedly improved skin mechanical properties. These promising results, if confirmed in a clinical setting, may improve the care and management of diabetic patients.     

Mesenchymal stromal cells enhance wound healing by ameliorating impaired metabolism in diabetic mice

Background aimsMesenchymal stromal cells (MSCs) have been documented to improve delayed wound healing in diabetes, but the underlying mechanism remains obscure. We aimed to investigate whether the therapeutic effects on wounds was associated with metabolic alterations by paracrine action of MSCs.MethodsMSCs from mice with high-fat diet/streptozotocin–induced diabetes or wild-type C57BL/6 mice were evaluated for their paracrine potential in vitro using enzyme-linked immunosorbent assay and immunohistochemical staining assay. MSCs were then evaluated for their therapeutic potential in vivo using an excisional cutaneous wound model in mice with diabetes. Metabolic alterations and glucose transporter four (GLUT4) as well as PI3K/Akt signaling pathway expression after wounding were also examined.ResultsMSCs from normal mice expressed even more insulin-like growth factor-1 (IGF-1) than mice with diabetes, suggesting putative paracrine action. Furthermore, compared with IGF-1 knockdown MSCs, normal MSCs markedly accelerated wound healing, as revealed by higher wound closure rate and better healing quality at 21 days post-wound. By contrast, MSCs administration increased the level of insulin as well as GLUT4 and PI3K/Akt signaling pathway expression but repressed the biochemical indexes of glucose and lipid, resulting in obvious metabolic improvement.ConclusionsThese findings suggest that IGF-1 is an important paracrine factor that mediates the therapeutic effects of MSCs on wound healing in diabetes, and the benefits of MSCs may be associated with metabolism improvements, which would provide a new target for treatment.     

糖尿病伤口愈合的分子机制

伤口愈合不良是糖尿病的一个并发症,严重时可能导致截肢,已成为糖尿病患者住院率最高的疾病,但是其确切的分子机制尚不清楚。目前研究发现糖尿病发生时有多种分子和细胞功能受损,如生长因子、一氧化氮、活性氧分子、基质金属蛋白酶、m icroRNA、内皮祖细胞等,最终导致糖尿病伤口愈合不良。本文将就其近年研究的相关分子机制予以详述。     

Syndecans in wound healing, inflammation and vascular biology

Syndecans are heparan sulphate proteoglycans consisting of a type I transmembrane core protein modified by heparan sulphate and sometimes chondroitin sulphate chains. They are major proteoglycans of many organs including the vasculature, along with glypicans and matrix proteoglycans. Heparan sulphate chains have potential to interact with a wide array of ligands, including many growth factors, cytokines, chemokines and extracellular matrix molecules relevant to growth regulation in vascular repair, hypoxia, angiogenesis and immune cell function. This is consistent with the phenotypes of syndecan knock-out mice, which while viable and fertile, show deficits in tissue repair. Furthermore, there are potentially important changes in syndecan distribution and function described in a variety of human vascular diseases. The purpose of this review is to describe syndecan structure and function, consider the role of syndecan core proteins in transmembrane signalling and also their roles as co-receptors with other major classes of cell surface molecules. Current debates include potential redundancy between syndecan family members, the significance of multiple heparan sulphate interactions, regulation of the cytoskeleton and cell behaviour and the switch between promoter and inhibitor of important cell functions, resulting from protease-mediated shedding of syndecan ectodomains.     

Blood-derived small Dot cells reduce scar in wound healing

Wounds in fetal skin heal without scar, however the mechanism is unknown. We identified a novel group of E-cadherin positive cells in the blood of fetal and adult mice and named them "Dot cells". The percentage of Dot cells in E16.5 fetal mice blood is more than twenty times higher compared to adult blood. Dot cells also express integrin beta1, CD184, CD34, CD13low and Sca1low, but not CD45, CD44, and CD117. Dot cells have a tiny dot shape between 1 and 7 microm diameters with fast proliferation in vitro. Most of the Dot cells remain positive for E-cadherin and integrin beta1 after one month in culture. Transplantation of Dot cells to adult mice heals skin wounds with less scar due to reduced smooth muscle actin and collagen expression in the repair tissue. Tracking GFP-positive Dot cells demonstrates that Dot cells migrate to wounds and differentiate into dermal cells, which also express strongly to FGF-2, and later lose their GFP expression. Our results indicate that Dot cells are a group of previously unidentified cells that have strong wound healing effect. The mechanism of scarless wound healing in fetal skin is due to the presence of a large number of Dot cells.     

Impaired intestinal wound healing in Fhl2-deficient mice is due to disturbed collagen metabolism

Four and one half LIM domain protein FHL2 participates in many cellular processes involved in tissue repair such as regulation of gene expression, cytoarchitecture, cell adhesion, migration and signal transduction. The repair process after wounding is initiated by the release of peptides and bioactive lipids. These molecules induce synthesis and deposition of a provisional extracellular matrix. We showed previously that sphingosine-1-phosphate (S1P) triggers a signal transduction cascade mediating nuclear translocation of FHL2 in response to activation of the RhoA GTPase. Our present study shows that FHL2 is an important signal transducer influencing the outcome of intestinal anastomotic healing. Early wound healing is accompanied by reconstitution and remodelling of the extracellular matrix and collagen is primarily responsible for wound strength. Our results show that impaired intestinal wound healing in Fhl2-deficient mice is due to disturbed collagen III metabolism. Impaired collagen III synthesis reduced the mechanical stability of the anastomoses and led to lower bursting pressure in Fhl2-deficient mice after surgery. Our data confirm that FHL2 is an important factor regulating collagen expression in the early phase of wound healing, and thereby is critically involved in the physiologic process of anastomosis healing after bowel surgery and thus may represent a new therapeutic target.     

Swatting flies: modelling wound healing and inflammation in Drosophila

Aberrant wound healing can lead to a variety of human pathologies, from non-healing chronic wounds that can become dangerously infected, to exuberant fibrotic healing in which repair is accompanied by excessive inflammation. To guide therapeutic intervention, we need a better understanding of the fundamental mechanisms driving tissue repair; this will require complementary wound-healing studies in several model organisms. Drosophila has been used to model genetic aspects of numerous human pathologies, and is being used increasingly to gain insight into the molecular and genetic aspects of tissue repair and inflammation, which have classically been modelled in mice or cultured cells. This review discusses the advantages and disadvantages of Drosophila as a wound-healing model, as well as some exciting new research opportunities that will be enabled by its use.     

IL-5-overexpressing mice exhibit eosinophilia and altered wound healing through mechanisms involving prolonged inflammation

Leucocytes are essential in healing wounds and are predominantly involved in the inflammatory and granulation stages of wound repair. Eosinophils are granulocytic leucocytes and are specifically regulated by interleukin-5 (IL-5), a cytokine produced by T helper 2 (Th2) cells. To characterize more clearly the role of the IL-5 and eosinophils in the wound healing process, IL-5-overexpressing and IL-5-deficient mice were used as models of eosinophilia and eosinophil depletion, respectively. Our results reveal a significantly altered inflammatory response between IL-5-overexpressing and IL-5 knockout mice post-wounding. Healing was significantly delayed in IL-5-overexpressing mice with wounds gaping wider and exhibiting impaired re-epithelialization. A delay in collagen deposition was observed suggesting a direct effect on matrix synthesis. A significant increase in inflammatory cell infiltration, particularly eosinophils and CD4(+) cells, one of the main cell types which secrete IL-5, was observed in IL-5-overexpressing mice wounds suggesting that one of the main roles of IL-5 in wound repair may be to promote the infiltration of eosinophils into healing wounds. Healing is delayed in IL-5-overexpressing mice and this corresponds to significantly increased levels of eosinophils and CD4(+) cells within the wound site that may contribute to and exacerbate the inflammatory response, resulting in detrimental wound repair.     

The plasmid encoding HSP47 enhances collagen expression and promotes skin wound healing in an alloxan-induced diabetic model

The objective of this work was initially to investigate the effects on skin wound healing process by local injection of HSP47 recombinant plasmid in an alloxan-induced diabetic rat model and assess the possibility and utility of gene therapy based on HSP47 plasmid to improve the diabetic skin wound healing. Rats were injected intraperitoneally with alloxan (120 mg/kg) to induce diabetes. The fragment containing the rat 47 kDa heat shock protein (HSP47) gene lacking its own promoter was cloned into plasmids containing a promoter and green fluorescent protein (GFP). The resulting gene constructs were first tested in vitro using 3T3 fibroblast cell line and subsequently in vivo after inducing wounds with alloxan in diabetic rats. Immunohistochemistry, quantitative fluorescent RT-PCR, and Western blotting 3-5 days after plasmid injection were performed to measure the expression changes of HSP47 and collagen I. The results demonstrate an increase of HSP47 levels in vitro in 3T3 fibroblast cells and in vivo in diabetic rat after treatment with plasmids expressing HSP47. The level of collagen I around the wound during the repair process was higher in the treated group than that in the control group, indicating that the constructs may have use in human gene therapy in cases of impaired skin wound healing in diabetes.     

The effects of topical treatment with acidified nitrite on wound healing in normal and diabetic mice

The effects of the application of a nitric oxide generating acidified nitrite cream comprising sodium nitrite and citric acid, on the healing of incisional wounds in mice, has been investigated. The effects of acidified nitrite on wound healing were critically dependent on the time of application after wounding. Application of acidified nitrite starting on the day of wounding and on consecutive days thereafter significantly inhibited both half time to closure and extent of wound closure. Conversely, application starting on days 1-4 after wounding and on consecutive days thereafter significantly augmented the rate and extent of wound healing. Optimal effects on improving wound healing were observed with cream concentrations of 3.0% (w/v) sodium nitrite and 4.5% (w/v) citric acid. Starting application on day 5 after wounding had no effect on the rate or extent of wound healing. In diabetic Lepr db/db mice, starting treatment at day 2 after wounding, acidified nitrite at 3.0% (w/v) sodium nitrite and 4.5% (w/v) citric acid significantly increased the rate and extent of wound healing. This suggests that acidified nitrite is effective in improving wound healing against a diabetic background. The present data shows that acidified nitrite cream, a clinically effective means of topically delivering nitric oxide, augments the wound healing process and may be of clinical benefit.