Effects of procoagulants on wound healing

As blood coagulation is a prelude for wound healing, a systemic haemocoagulant (Botropase) and local procoagulants (thrombin and fibrin) were evaluated on physical (wound breaking strength, wound half-closure time and period of epithelization), biochemical (granuloma-hydroxyproline and hexosamine) and histological attributes of healing wounds in albino rats. Botropase prompted all phases of tissue repair. Thrombin delayed wound contraction whereas fibrin had no discernable action. The findings that procoagulants modify healing process has bearing on their surgical use.     

Enhanced wound contraction and epithelization period in steroid treated rats: role of pyramid environment

Contribution and role of a pyramid/square box on the wound healing suppressant effect of dexamethasone was studied in rats of either sex using excision wound model to record the wound contraction rate and epithelization period. The results showed enhanced wound contraction rate and decreased epithelization period in the pyramid-exposed rats as compared to controls. Thus, it appears that pyramid environment facilitates the process of wound healing. Also, the wound healing suppressant effects of dexamethasone were significantly reduced.     

Glucocorticoid-induced contractility and F-actin content of human lung fibroblasts in three-dimensional culture

Fibroblast contractility plays a useful role in the wound healing process but contributes to architectural distortion in the lungs. Glucocorticoids (GCs) have been reported to reduce dermal fibroblast contractility, which may result in delaying wound healing, but the effects on lung fibroblasts are unknown. In this study, we examined how human lung fibroblast contractility is altered in the presence of GCs. Lung fibroblast cell lines (n = 5) were established from normal parts of surgically resected lung tissue. The effects of GCs on contractility were investigated with a type I collagen gel contraction assay. Filamentous actin (F-actin) content was detected by confocal microscopy and measured with a fluorescent phalloidin binding assay. GCs augmented fibroblast contraction in a concentration-dependent manner, with an approximate EC(50) of 1.8 x 10(-8) M, whereas other steroid derivatives had no effects. GC contractility needed de novo protein synthesis. The GC-induced increase in contractility was found to be consistent with an increase in F-actin content. In conclusion, lung fibroblast contractility was enhanced with GCs through an upregulation of lung fibroblast F-actin.     

A finite-element model for healing of cutaneous wounds combining contraction, angiogenesis and closure

A simplified finite-element model for wound healing is proposed. The model takes into account the sequential steps of dermal regeneration, wound contraction, angiogenesis and wound closure. An innovation in the present study is the combination of the aforementioned partially overlapping processes, which can be used to deliver novel insights into the process of wound healing, such as geometry related influences, as well as the influence of coupling between the various existing subprocesses on the actual healing behavior. The model confirms the clinical observation that epidermal closure proceeds by a crawling and climbing mechanism at the early stages, and by a stratification process in layers parallel to the skin surface at the later stages. The local epidermal oxygen content may play an important role here. The model can also be used to investigate the influence of local injection of hormones that stimulate partial processes occurring during wound healing. These insights can be used to improve wound healing treatments.     

miR-155 promotes cutaneous wound healing through enhanced keratinocytes migration by MMP-2

Inflammation, re-epithelization and tissue remodeling are three essential steps during wound healing. The re-epithelization process plays the most important role which mainly involves keratinocyte proliferation and migration. miR-155 has been reported to participate in cell migration and transformation, however, its function in skin wound healing is largely unknown. Here we hypothesize that overexpression of miR-155 at wound edges could accelerate wound healing mediated by enhanced keratinocyte migration. To test this hypothesis, direct local injection of miR-155 expression plasmid to wound edges was conducted to overexpress miR-155 in vivo. Results shown that miR-155 significantly promoted wound healing and re-epithelization compared to control, while did not affect wound contraction. Also, miR-155 overexpression accelerated primarily cultured keratinocyte migration in vitro, but had no effect on cell proliferation. Importantly, western blot analysis shown that MMP-2 was significantly upregulated whiles its inhibitor TIMP-1 downregulated after miR-155 treatment. Moreover, the use of ARP-101, an MMP-2 inhibitor, effectively attenuated the accelerative effects on cell migration induced by miR-155. Taken together, our results suggest that miR-155 has the promote effect on wound healing that is probably mediated by accelerating keratinocyte migration via upregulated MMP-2 level. This study provides a rationale for the therapeutic effect of miR-155 on wound healing.     

Effects of Foeniculum vulgare essential oil compounds,fenchone and limonene,on experimental wound healing

We investigated the wound healing efficacy of the Foeniculum vulgare compounds, fenchone and limonene, using an excisional cutaneous wound model in rats. An excision wound was made on the back of the rat and fenchone and limonene were applied topically to the wounds once daily, separately or together, for 10 days. Tissue sections from the wounds were evaluated for histopathology. The healing potential was assessed by comparison to an untreated control group and an olive oil treated sham group. We scored wound healing based on epidermal regeneration, granulation tissue thickness and angiogenesis. After day 6, wound contraction with limonene was significantly better than for the control group. Ten days after treatment, a significant increase was observed in wound contraction and re-epithelialization in both fenchone and limonene oil treated groups compared to the sham group. Groups treated with fenchone and with fenchone + limonene scored significantly higher than the control group, but the difference was not statistically significant compared to the olive oil treated group. Our findings support the beneficial effects of fenchone and limonene for augmenting wound healing. The anti-inflammatory and antimicrobial activities of fenchone and limonene oil increased collagen synthesis and decreased the number of inflammatory cells during wound healing and may be useful for treating skin wounds.     

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.     

In vivo effect of whole grain flour of finger millet (Eleusine coracana) and kodo millet (Paspalum scrobiculatum) on rat dermal wound healing

Influence of finger millet and kodo millet on rat dermal wound healing was assessed by making a 4 cm2 (2 x 2 cm) excision wound on the shaven back of rats under ether anesthesia. Finger millet or kodo millet flour (300 mg) as aqueous paste was applied topically once daily for 16 days. The granulation tissue formed on day 4, 8 and 12 was used to estimate some biochemical parameters like protein, DNA, collagen and lipid peroxides. There was significant increase in protein and collagen contents and decrease in lipid peroxides. Biophysical parameters like rate of contraction and number of days for epithelialization were also studied. Rate of contraction was 88-90% in kodo millet and finger millet treated rats in comparison to 75% in untreated rats. The number of days for complete closure of wounds was lower for finger millet (13 days) and kodo millet (14 days) treated rats in comparison to untreated (16 days) rats. The results implicate a possible therapeutical role for finger millet and kodo millet in accelerating the process of wound healing.     

Myostatin-null mice exhibit delayed skin wound healing through the blockade of transforming growth factor-β signaling by decorin

Myostatin (Mstn) is a secreted growth and differentiation factor that belongs to the transforming growth factor-β (TGF-β) superfamily. Mstn has been well characterized as a regulator of myogenesis and has been shown to play a critical role in postnatal muscle regeneration. Herein, we report for the first time that Mstn is expressed in both epidermis and dermis of murine and human skin and that Mstn-null mice exhibited delayed skin wound healing attributable to a combination of effects resulting from delayed epidermal reepithelialization and dermal contraction. In epidermis, reduced keratinocyte migration and protracted keratinocyte proliferation were observed, which subsequently led to delayed recovery of epidermal thickness and slower reepithelialization. Furthermore, primary keratinocytes derived from Mstn-null mice displayed reduced migration capacity and increased proliferation rate as assessed through in vitro migration and adhesion assays, as well as bromodeoxyuridine incorporation and Western blot analysis. Moreover, in dermis, both fibroblast-to-myofibroblast transformation and collagen deposition were concomitantly reduced, resulting in a delayed dermal wound contraction. These decreases are due to the inhibition of TGF-β signaling. In agreement, the expression of decorin, a naturally occurring TGF-β suppressor, was elevated in Mstn-null mice; moreover, topical treatment with TGF-β1 protein rescued the impaired skin wound healing observed in Mstn-null mice. These observations highlight the interplay between TGF-β and Mstn signaling pathways, specifically through Mstn regulation of decorin levels during the skin wound healing process. Thus we propose that Mstn agonists might be beneficial for skin wound repair.     

Influence of sea buckthorn (Hippophae rhamnoides L.) flavone on dermal wound healing in rats

The present investigation was undertaken to determine the efficacy of topical administration of flavone of sea buckthorn (Hippophae rhamnoides L.) on cutaneous wound healing in rats. Four full-thickness excision wounds were created on the back of rat and 1.0% w/v flavone prepared in propylene glycol was applied topically. Control animals received the vehicle alone in an identical manner. The healing of the wound was assessed by the rate of wound contraction, period of epithelialization, hydroxyproline, hexosamine, antioxidants estimation and histopathology of the granulation tissue. The sea buckthorn flavone promoted the wound healing activity as indicated by improved rate of wound contraction, decreased time taken for epithelialization (16.3 days versus 24.8 days in controls) and significant increase in hydroxyproline (26.0%) and hexosamine (30.0%) content. These findings were also confirmed by histopathological examinations. In addition, it was observed that sea buckthorn flavone possesses potent antioxidant properties as evidenced by significant increase in reduced glutathione (55.0%), vitamin C (70.0%) and catalase (20.0%) activities in wound granulation tissue. The flavone treatment also resulted in significant decrease in lipid peroxide levels (39.0%). The results suggest that the sea buckthorn flavone promotes wound healing activity.     

Anti‐aging pharmacology in cutaneous wound healing: effects of metformin,resveratrol, and rapamycin by local application

Cutaneous wounds are among the most common soft tissue injuries and are particularly hard to heal in aging. Caloric restriction (CR) is well documented to extend longevity; pharmacologically, profound rejuvenative effects of CR mimetics have been uncovered, especially metformin (MET), resveratrol (RSV), and rapamycin (RAPA). However, locally applied impacts and functional differences of these agents on wound healing remain to be established. Here, we discovered that chronic topical administration of MET and RSV, but not RAPA, accelerated wound healing with improved epidermis, hair follicles, and collagen deposition in young rodents, and MET exerted more profound effects. Furthermore, locally applied MET and RSV improved vascularization of the wound beds, which were attributed to stimulation of adenosine monophosphate‐activated protein kinase (AMPK) pathway, the key mediator of wound healing. Notably, in aged skin, AMPK pathway was inhibited, correlated with impaired vasculature and reduced healing ability. As therapeutic approaches, local treatments of MET and RSV prevented age‐related AMPK suppression and angiogenic inhibition in wound beds. Moreover, in aged rats, rejuvenative effects of topically applied MET and RSV on cell viability of wound beds were confirmed, of which MET showed more prominent anti‐aging effects. We further verified that only MET promoted wound healing and cutaneous integrity in aged skin. These findings clarified differential effects of CR‐based anti‐aging pharmacology in wound healing, identified critical angiogenic and rejuvenative mechanisms through AMPK pathway in both young and aged skin, and unraveled chronic local application of MET as the optimal and promising regenerative agent in treating cutaneous wound defects.     

JNK signaling pathway required for wound healing in regenerating Drosophila wing imaginal discs

We have examined wound healing during regeneration of Drosophila wing imaginal discs fragments by confocal microscopy and assessed the role of components of the JNK pathway in this process. After cutting, columnar and peripodial epithelia cells at the wound edge start to close the wound through formation and contraction of an actin cable. This is followed by a zipping process through filopodial protrusions from both epithelia knitting the wound edges from proximal to distal areas of the disc. Activation of the JNK pathway is involved in such process. puckered (puc) expression is induced in several rows of cells at the edge of the wound, whereas absence of JNK pathway activity brought about by hemipterous, basket, and Dfos mutants impair wound healing. These defects are accompanied by lowered or loss of expression of puc. In support of a role of puc in wound healing, hep mutant phenotypes are rescued by reducing puc function, whereas overexpression of puc inhibits wound healing. Altogether, these results demonstrate a role for the JNK pathway in imaginal disc wound healing, similar to that reported for other healing processes such as embryonic dorsal closure, thoracic closure, and adult epithelial wound healing in Drosophila. Differences with such processes are also highlighted.     

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.     

Gamma radiation inhibits fibroblast-mediated collagen gel retraction

Radiation exposure is known to impair healing in irradiated areas. Fibroblasts play a major role in the production and modification of extracellular matrix in wound repair. Since one important aspect of wound repair is the contraction of the wound, this study investigated the effects of radiation on the ability of fibroblasts to mediate collagen gel contraction in an in vitro model of wound retraction. After irradiation, the cells were detached and suspended in a solution of rat tail tendon collagen. Radiation exposure decreased retraction, and this effect was dose dependent. In order to define the mechanism of reduced gel retraction, we investigated alpha2beta1 cell surface integrin and fibronectin, which are thought to mediate contraction, and prostaglandin E2 (PGE2), which is known to inhibit this process. PGE2 release increased dose responsively following radiation. The cyclooxygenase inhibitor indomethacin could partially restore the contractile activity of irradiated fibroblasts. Fibronectin production in gel culture showed a significant decrease. In contrast, there was no decrease in alpha2beta1 integrin expression in radiated cells. In conclusion, radiation decreases fibroblast-mediated gel contraction. Increased PGE2 production and decreased fibronectin production by irradiated fibroblasts may contribute to this effect and may be in part responsible for poor healing of radiated tissue.     

Histatin 1 enhanced the speed and quality of wound healing through regulating the behaviour of fibroblast

ObjectivesHistatin 1(Hst 1) has been proved to promote wound healing. However, there was no specific study on the regulation made by Hst 1 of fibroblasts in the process of wound healing. This research comprehensively studied the regulation of Hst 1 on the function of fibroblasts in the process of wound healing and preliminary mechanism about it.Materials and methodsThe full‐thickness skin wound model was made on the back of C57/BL6 mice. The wound healing, collagen deposition and fibroblast distribution were detected on days 3, 5 and 7 after injury. Fibroblast was cultured in vitro and stimulated with Hst 1, and then, their biological characteristics and functions were detected.ResultsHistatin 1 can effectively promote wound healing, improve collagen deposition during and after healing and increase the number and function of fibroblasts. After healing, the mechanical properties of the skin also improved. In vitro, the migration ability of fibroblasts stimulated by Hst 1 was significantly improved, and the fibroblasts transformed more into myofibroblasts, which improved the function of contraction and collagen secretion. In fibroblasts, mTOR signalling pathway can be activated by Hst 1.ConclusionsHistatin 1 can accelerate wound healing and improve the mechanical properties of healed skin by promoting the function of fibroblasts. The intermolecular mechanisms need to be further studied, and this study provides a direction about mTOR signalling pathway.     

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-     

Efficacy of Butea monosperma on dermal wound healing in rats

Wound healing occurs as a fundamental response to tissue injury. Several natural products have been shown to accelerate the healing process. The present investigation was undertaken to determine the efficacy of topical administration of an alcoholic bark extract of Butea monosperma (B. monosperma) on cutaneous wound healing in rats. Full-thickness excision wounds were made on the back of rat and B. monosperma extract was administered topically. The granulation tissue formed on days 4, 8, 12 and 16 (post-wound) was used to estimate total collagen, hexosamine, protein, DNA and uronic acid. The extract increased cellular proliferation and collagen synthesis at the wound site, as evidenced by increase in DNA, total protein and total collagen content of granulation tissues. The extract treated wounds were found to heal much faster as indicated by improved rates of epithelialization and wound contraction, also confirmed by histopathological examinations. Also, the tensile strength of drug-treated wounds was increased significantly. In addition, we show that B. monosperma possesses antioxidant properties, by its ability to reduce lipid peroxidation. The results clearly substantiate the beneficial effects of the topical application of B. monosperma in the acceleration of wound healing.     

Rho A and the Rho kinase pathway regulate fibroblast contraction: Enhanced contraction in constitutively active Rho A fibroblast cells

Fibroblast cells play a central role in the proliferation phase of wound healing processes, contributing to force development. The intracellular signaling pathways regulating this non-muscle contraction are only partially understood. To study the relations between Rho A and contractile responses, constitutively active Rho A (CA-Rho A) fibroblast cells were reconstituted into fibers and the effects of calf serum (CS) on isometric force were studied. CS-induced force in CA-Rho A fibroblast fibers was twice as large as that in wild type (NIH 3T3) fibroblast fibers. During this response, the translocation of Rho A from the cytosol to the membrane was detected by Rho A activity assays and Western blot analysis. Pre-treatment with a Rho specific inhibitor (C3-exoenzyme) suppressed translocation as well as contraction. These results indicate that Rho A activation is essential for fibroblast contraction. The Rho kinase inhibitor (Y27632) inhibited both NIH 3T3 and CA-Rho A fibroblast fiber contractions. Activation of Rho A is thus directly coupled with Rho kinase activity. We conclude that the translocation of Rho A from the cytosol to the membrane and the Rho kinase pathway can regulate wound healing processes mediated by fibroblast contraction.     

LEP and LEPR are possibly a double-edged sword for wound healing

Wound healing is a complex and error-prone process. Wound healing in adults often leads to the formation of scars, a type of fibrotic tissue that lacks skin appendages. Hypertrophic scars and keloids can also form when the wound-healing process goes wrong. Leptin (Lep) and leptin receptors (LepRs) have recently been shown to affect multiple stages of wound healing. This effect, however, is paradoxical for scarless wound healing. On the one hand, Lep exerts pro-inflammatory and profibrotic effects; on the other hand, Lep can regulate hair follicle growth. This paper summarises the role of Lep and LepRs on cells in different stages of wound healing, briefly introduces the process of wound healing and Lep and LepRs, and examines the possibility of promoting scarless wound healing through spatiotemporal, systemic, and local regulation of Lep levels and the binding of Lep and LepRs.     

Differential and combined effects of cardiotrophin-1 and TGF-beta1 on cardiac myofibroblast proliferation and contraction

Myofibroblasts respond to an array of signals from mitogens and cytokines during the course of wound healing following a myocardial infarction (MI), and these signals may coordinate ventricular myofibroblast proliferation. Furthermore, myofibroblasts are contractile and contribute to wound contraction by imparting mechanical tension on surrounding extracellular matrix. Although TGF-beta(1), CT-1, and PDGF-BB participate in various stages of post-MI wound healing, their combined net effect(s) on myofibroblast function is unknown. We investigated myofibroblast proliferation, expression of cell cycle proteins, and contractile function of cells treated with TGF-beta(1) and/or CT-1. We confirmed that TGF-beta(1) (10 ng/ml) suppresses proliferation of these cells, whereas CT-1 (10 ng/ml) and, for comparative purposes, PDGF-BB (1 ng/ml) treatments were associated with proliferation. Specific TGF-beta(1) treatment ablated CT-1-induced myofibroblast proliferation. TGF-beta(1) effects were specific, as they were suppressed by either TGF-beta-neutralizing antibody or viral Smad7 overexpression. TGF-beta(1) treatment also increased expression of p27 and decreased expression of cyclin E and Cdk2 in primary cells. CT-1 (10 ng/ml) treatment of myofibroblasts had no effect on collagen gel deformation versus controls, whereas TGF-beta(1) (10 ng/ml) and PDGF (10 ng/ml) treatments were associated with significant cell contraction; again, TGF-beta(1)-mediated contraction was unaffected by CT-1. Alone, CT-1 and TGF-beta(1) treatments exert opposing effects on myofibroblast function, whereas in combination TGF-beta(1)-mediated effects supersede those of CT-1 (and PDGF-BB). Thus TGF-beta(1) and CT-1 exert differential effects on myofibroblast proliferation and contraction in vitro, and we suggest that a balance of these effects may be important for the execution of normal cardiac wound healing.