Expression of nitric oxide synthase isoforms and arginase in normal human skin and chronic venous leg ulcers

Chronic venous ulcers, an example of abnormal wound healing, show chronic inflammation with defective matrix deposition which together with the underlying vascular pathology, result in delayed healing. L-arginine is known to be metabolized by one of two pathways: nitric oxide synthase (NOS), producing nitric oxide (NO), or arginase, producing ornithine. NO is involved in many pathological conditions including vascular and inflammatory disorders. This study therefore investigated the distribution, level and activity of NOS and arginase in chronic venous ulcers in comparison with normal skin, using immunocytochemistry, western blotting, and enzyme assays. The results demonstrated an increased distribution of both NOS and arginase in chronic venous ulcer tissue compared with normal skin, with inflammatory cells and vascular endothelial cells as the main sources. These data were confirmed by western blot analysis, which showed increased levels of both enzymes in chronic venous ulcers. Moreover, there was significantly increased activity of both total NOS (p<0.04) and inducible NOS (p<0.05) in chronic venous ulcer tissue compared with normal skin, and significantly increased activity of arginase (p<0.01) in chronic venous ulcer tissue in comparison with normal skin. NO is known to combine with hydroxyl free radicals forming peroxynitrite, a potent free radical which causes tissue destruction. NO overexpression in chronic venous ulcers may be involved directly or indirectly (through production of peroxynitrite) in the pathogenesis and delayed healing of chronic venous ulcers, through its effects on vasculature, inflammation, and collagen deposition. Arginase is known to enhance matrix deposition. Thus, increased levels of arginase in chronic venous ulcers could contribute to the pathogenesis of lipodermatosclerosis associated with chronic venous insufficiency, predisposing to the formation of chronic venous ulcers and also to matrix cuff formation around blood vessels.     

Biotinylated GHK peptide incorporated collagenous matrix: A novel biomaterial for dermal wound healing in rats

Matrikines are small peptide fragments of extracellular matrix proteins that display potent tissue repair activities. Difficulties in achieving sustained delivery of bioactive concentration of matrikines in the affected area limits their therapeutic use. The present study evaluates the effects biotinylated matrikine peptide (bio-glycyl-histidyl-lysine) incorporated collagen membrane for dermal wound healing processes in rats. Biotinylated peptide incorporated collagen matrix (PIC) showed better healing when compared to wounds treated with collagen matrix [CF (collagen film)] and without collagen [CR (control)]. Binding studies indicate that biotinylated GHK (Bio-GHK) binds effectively to the collagen matrix and red blood cell (RBC) membrane when compared with t-butyloxycarbonyl substituted GHK (Boc-GHK). Wound contraction, increased cell proliferation, and high expression of antioxidant enzymes in PIC treated group indicate enhanced wound healing activity when compared to CF and CR groups. Interestingly Bio-GHK incorporated collagen increases the copper concentration by ninefold at the wound site indicating the wound healing property of Bio-GHK can also be linked with both copper localization and matrikine activities. These results demonstrate the possibility of using Bio-GHK incorporated collagen film as a therapeutic agent in the wound healing process.     

Ectopic localization of matrix metalloproteinase-9 in chronic cutaneous wounds

It has been hypothesized that excessive activity of matrix metalloproteinases (MMPs), in particular the gelatinases MMP-9 and MMP-2, contributes to poor healing of chronic skin ulcers. We compared MMP-9 and MMP-2 in wound margin biopsies of standardized acute partial-thickness wounds in healthy volunteers (n = 6) and in venous leg ulcer patients (n = 12) with those of chronic wounds of different etiologies (n = 34) by a combination of specific analyses of activity and protein localization. We also studied MMP-14 by immunohistochemistry and in situ hybridization in parallel. Neither MMP-9 (P =.814) nor MMP-2 (P =.742) endogenous activities differed significantly between acute and chronic wound tissues. Acute wound healing was characterized by induction of MMP-9 in the advancing epithelium. In chronic wounds, prominent MMP-9 immunostaining was seen in neutrophils and macrophages in the ulcer bed, but virtually no MMP-9 was detected in wound edge keratinocytes. MMP-2 was increased and activated with acute wound age. MMP-2 was found abundantly in dermal fibroblasts and endothelial cells beneath, but not in new epithelium of acute and chronic wounds. MMP-14 mRNA or protein was detected solely in the stroma of both acute and chronic wounds. In conclusion, the overall activity of gelatinases MMP-9 and MMP-2 was not increased in chronic wounds compared to normally healing wound tissues. Chronic nonhealing wounds may not be caused by excessive gelatinase activity, but are distinguished from healing wounds by an unfavorable distribution and persistance of MMP-9.     

Delayed healing and induction of secretory leukocyte protease inhibitor in polycystic ovary syndrome rat skin wounds

Secretory leukocyte protease inhibitor (SLPI) and estrogen promote wound healing through a decrease in the excessive inflammatory response, accelerating re-epithelialization and increasing the amount of collagen deposition. The excessive administration of estradiol valerate (EV) using hormonal therapy decreases the concentration of estrogen abruptly and induces the polycystic ovary syndrome (PCOS). In this study, the PCOS rat skin wound area was wider than that of the normal groups and the rate of keratinocyte migration in PCOS was lower than the normal group. The numbers of inflammatory cells and macrophages recruited in the PCOS group were larger than that of the normal group. More collagen was deposited in the healing area of the normal group than in the PCOS group. The level of SLPI expression was higher in the PCOS group than the normal group after wounding, with the exception of the epithelium. On the other hand, mRNA and protein expression levels of transforming growth factor-β1 (TGF-β1) were lower in the PCOS group than in the normal group. Matrix metalloproteinase-2 (MMP-2) and MMP-9 levels in the PCOS group were significantly lower than that of the normal group. Therefore, increased SLPI in PCOS skin wounds may help prevent an excessive inflammatory response and aberrant collagen deposition but not are sufficient to accelerate PCOS skin wound healing, suggesting that SLPI may act as a local rather than a systemic modulating molecule in PCOS rat skin wounds.     

Effects of subcutaneous injection of ozone during wound healing in rats

Fibroblast growth factor 2 (FGF2) regulates the wound repair process and it is secreted by inflammatory and endothelial cells, and by myofibroblasts. This study aimed to establish the expression patterns of FGF2 and myofibroblastic differentiation during wound healing in rats treated with subcutaneous ozone injection. We created full-thickness excisional wounds in rats, and the healing process was analyzed through morphometric analyses and digital quantification of immunoreactivity of smooth muscle actin and FGF2. Ozone therapy-treated wounds presented granulation tissue with a reduced number of inflammatory cells and greater dermal cellularity, and intense collagen deposition. FGF2 immunoreactivity, microvessel density, and amount of myofibroblasts were significantly higher in treated wounds compared to controls. In conclusion, it was demonstrated that subcutaneous injections of ozone accelerate and ameliorate wound repairing process. Moreover, injectable ozone therapy’s action mechanism may be associated with FGF2 overexpression.     

Platelet-derived growth factor-BB and transforming growth factor beta 1 selectively modulate glycosaminoglycans, collagen, and myofibroblasts in excisional wounds.

Recombinant platelet-derived growth factor (PDGF) and transforming growth factor beta 1 (TGF-beta 1) influence the rate of extracellular matrix formed in treated incisional wounds. Because incisional healing processes are difficult to quantify, a full-thickness excisional wound model in the rabbit ear was developed to permit detailed analyses of growth-factor-mediated tissue repair. In the present studies, quantitative and qualitative differences in acute inflammatory cell influx, glycosaminoglycan (GAG) deposition, collagen formation, and myofibroblast generation in PDGF-BB (BB homodimer)- and TGF-beta 1-treated wounds were detected when analyzed histochemically and ultrastructurally. Although both growth factors significantly augmented extracellular matrix formation and healing in 10-day wounds compared with controls (P less than 0.002). PDGF-BB markedly increased macrophage influx and GAG deposition, whereas TGF-beta 1 selectively induced significantly more mature collagen bundles at the leading edge of new granulation tissue (P = 0.007). Transforming growth factor-beta 1-treated wound fibroblasts demonstrated active collagen fibrillogenesis and accretion of subfibrils at the ultrastructural level. Myofibroblasts, phenotypically modified fibroblasts considered responsible for wound contraction, were observed in control, but were absent in early growth-factor-treated granulating wounds. These results provide important insights into the mechanisms of soft tissue repair and indicate that 1) PDGF-BB induces an inflammatory response and provisional matrix synthesis within wounds that is qualitatively similar but quantitatively increased compared with normal wounds; 2) TGF-beta 1 preferentially triggers synthesis and more rapid maturation of collagen within early wounds; and 3) both growth factors inhibit the differentiation of fibroblasts into myofibroblasts, perhaps because wound contraction is not required, due to increased extracellular matrix synthesis.     

Effects of fibroblasts and basic fibroblast growth factor on facilitation of dermal wound healing by type I collagen matrices

Healing of large open dermal wounds is associated with decreased values of the tensile strength even up to 6 months post-wounding. Results of previous studies have shown that healing is facilitated in the presence of a type I collagen sponge by promoting deposition of newly synthesized large-diameter collagen fibers parallel to the fibers of the sponge. In this study healing is evaluated in dermal wounds treated with a collagen sponge seeded with fibroblasts or coated with basic fibroblast growth factor (bFGF). Experimental results indicate that the presence of a collagen sponge results in increased wound tensile strength and increased collagen fiber diameters in the upper dermis 15 days post-wounding in an excisional guinea pig dermal wound model. In comparison, dermal wounds treated with collagen sponges seeded with fibroblasts or coated with bFGF showed increased tensile strengths 15 days postimplantation and increased degree of reepithelialization. These results indicate that fibroblast seeding and bFGF coating in conjunction with a type I collagen sponge matrix facilitate early dermal and epidermal wound healing.     

Platelet-derived growth factor (BB homodimer), transforming growth factor-beta 1, and basic fibroblast growth factor in dermal wound healing. Neovessel and matrix formation and cessation of repair.

Recombinant platelet-derived growth factor (BB homodimer, rPDGF-BB), transforming growth factor beta 1 (rTGF-beta 1), and basic fibroblast growth factor (rbFGF) can accelerate healing of soft tissues. However, little information is available characterizing the components of wound matrix induced by these growth factors and the molecular mechanisms underlying accelerated repair and wound maturation. In this study, the composition, quantity, and rate of extracellular matrix deposition within growth factor-treated lapine ear excisional wounds were analyzed at different stages of healing using specific histochemical and immunohistochemical stains, coupled with image analysis techniques. Single application of optimal concentrations of each growth factor accelerated normal healing by 30% (P less than 0.0003); rPDGF-BB markedly augmented early glycosaminoglycan (GAG) and fibronectin deposition, but induced significantly greater levels of collagen later in the repair process, compared with untreated wounds rTGF-beta 1 treatment led to rapidly enhanced collagen synthesis and maturation, without increased GAG deposition. In contrast, rbFGF treatment induced a predominantly angiogenic response in wounds, with a marked increase in endothelia and neovessels (P less than 0.0001), and increased wound collagenolytic activity (P less than 0.03). rbFGF-treated wounds did not evolve into collagen-containing scars and continued to accumulate only provisional matrix well past wound closure. These results provide new evidence that growth factors influence wound repair via different mechanisms: 1) rPDGF-BB accelerates deposition of provisional wound matrix; 2) rTGF-beta 1 accelerates deposition and maturation of collagen; and 3) rbFGF induces a profound monocellular angiogenic response which may lead to a marked delay in wound maturation, and the possible loss of the normal signal(s) required to stop repair. These results suggest that specific growth factors may selectively regulate components of the repair response by differing mechanisms, offering the potential for targeted therapeutic intervention.     

Differential expression of tissue inhibitors of metalloproteinases (TIMP-1, -2, -3, and -4) in normal and aberrant wound healing.

Wound healing is characterized by hemostasis, re-epithelialization, granulation tissue formation, and remodeling of the extracellular matrix. Matrix metalloproteinases and their specific inhibitors, TIMPs, contribute to these events. We investigated a total of 47 samples of normally healing wounds, chronic venous ulcers, ulcerative vasculitis, and suction blisters using immunohistochemistry and in situ hybridization, to clarify the role of TIMPs in normal and aberrant wound repair. Expression of TIMP-1 and -3 mRNAs was found in proliferating keratinocytes in 3- to 5-day-old normally healing wounds, whereas no epidermal expression was detected in chronic ulcers. However, TIMP-3 protein was found in the proliferating epidermis in 20 of 24 samples representing both full-thickness acute and chronic wounds. TIMP-1 and TIMP-3 also were abundantly expressed by spindle-shaped, fibroblast-like, and plump, macrophage-like stromal cells, as well as by endothelial cells. In normally healing wounds, TIMP-2 protein localized under the migrating epithelial tip and to the stromal tissue under the eschar more frequently than in chronic ulcers. Occasional staining for TIMP-4 protein was detected in stromal cells of chronic ulcers near blood vessels. Our results indicate that TIMP-1 and TIMP-3 may be involved both in the regeneration of the epidermis by stabilizing the basement membrane zone and in the regulation of stromal remodeling and angiogenesis of the wound bed. Lack of TIMP-2 near the migrating epithelial wound edges might contribute to uncontrolled activity of MMP-2 in chronic ulcers. We conclude also that TIMPs are temporally and spatially tightly regulated and that the imbalance between metalloproteinases and TIMPs-1, -2, and -3 may lead to delayed wound healing.     

Expression of Thrombomodulin and Consequences of Thrombomodulin Deficiency during Healing of Cutaneous Wounds

Thrombomodulin is a cell surface anticoagulant that is expressed by endothelial cells and epidermal keratinocytes. Using immunohistochemistry, we examined thrombomodulin expression during healing of partial-thickness wounds in human skin and full-thickness wounds in mouse skin. We also examined thrombomodulin expression and wound healing in heterozygous thrombomodulin-deficient mice, compound heterozygous mice that have <1% of normal thrombomodulin anticoagulant activity, and chimeric mice derived from homozygous thrombomodulin-deficient embryonic stem cells. In both human and murine wounds, thrombomodulin was absent in keratinocytes at the leading edge of the neoepidermis, but it was expressed strongly by stratifying keratinocytes within the neoepidermis. No differences in rate or extent of reepithelialization were observed between wild-type and thrombomodulin-deficient mice. In chimeric mice, both thrombomodulin-positive and thrombomodulin-negative keratinocytes were detected within the neoepidermis. Compared with wild-type mice, heterozygous and compound heterozygous thrombomodulin-deficient mice exhibited foci of increased collagen deposition in the wound matrix. These findings demonstrate that expression of thrombomodulin in keratinocytes is regulated during cutaneous wound healing. Severe deficiency of thrombomodulin anticoagulant activity does not appear to alter reepithelialization but may influence collagen production by fibroblasts in the wound matrix.     

Morphologic examination of mesenchymal cells in healing wounds of normal and tight skin mice.

The healing process of an open wound as effected by wound contraction is complete by 3 weeks in the normal mouse. In contrast, its onset is delayed by 3 weeks and complete healing requires 6 weeks in the tight skin mouse (TSM), a mutant mouse strain with the autosomal dominant gene for tight skin. Possible mechanisms for this delay were evaluated. The frequency and distribution of myofibroblasts were studied during the 3-week delay in wound contraction by actin staining and electron microscopy. It was determined, by electron microscopy and phalloidin staining, that myofibroblasts were found in high density in noncontracting TSM wounds. Electron microscopy showed, however, that these myofibroblasts were surrounded by a pericellular matrix that separated their surface from adjacent collagen fibers. No pericellular matrix was found around cells in granulation tissue of normal mice. At 3 weeks, as TSM wounds began to contract, the number and intensity of cells stained by phalloidin in this tissue was less than that seen earlier. The pericellular matrix was fragmented at this time, and cell surface and collagen fiber associations were apparent. Finally, at 5 weeks, when wound contraction was well developed in the TSM, only a small area in the center of the healing wound beneath the epidermis contained phalloidin-positive myofibroblasts. Electron-microscopic examination of the residual granulation tissue at this time revealed the complete absence of the pericellular matrix. It is postulated that during the 3-week delay in wound closure, the presence of a localized pericellular matrix prevents the interaction between cells and collagen fibers necessary for the reorganization of collagen. It is also thought that the tightly adherent uninjured skin surrounding the healing wound may cause delayed wound closure. There was no evidence that the absence of myofibroblasts is responsible for delayed wound contraction.     

Fibrosin: a novel lymphokine in wound healing.

Several growth factors are actively synthesized during wound repair and function to stimulate different cell types involved in the process of healing. Fibrosin is a novel fibrogenic lymphokine that stimulates several biological activities that relate to in vivo scarring. To investigate the role of fibrosin, we used "punch biopsy" and linear wounding procedures in a murine model of wound healing. Histological examination showed that recombinant fibrosin stimulated epithelialization of wounds and accelerated healing of both punch biopsy and linear wounds. Fibrosin enhanced healing of linear wounds by reducing the time for healing by approximately 30-40%. From our data we estimated the healing time of control wounds to be 22-24 days; wounds treated with fibrosin appeared to heal in 14-16 days. Our observations suggest that fibrosin enhances wound healing and may be involved in accelerating epithelialization, collagen matrix formation, and also remodeling of the extracellular matrix in vivo. Thus fibrosin may function during different phases of wound healing and act as a potent inducer of scar formation and wound healing. This finding may have direct clinical applications.     

α7nAChR的激活通过抑制TNF-α表达促进糖尿病小鼠伤口愈合

 目的：观察糖尿病小鼠伤口愈合期间巨噬细胞浸润及肿瘤坏死因子 α（TNF-α）表达特征,探讨α7烟碱型乙酰胆碱受体（α7nAChR）特异性激动剂PNU-282987是否可通过抑制TNF-α表达促进糖尿病小鼠伤口的愈合。方法：(1) 制作糖尿病小鼠切创模型（糖尿病组）,正常小鼠在相同部位制作相同大小创口作为对照（对照组）,分别于切创后1 d、3 d、5 d、10 d、14 d和21 d（每个时间段5只）提取创口样本。免疫组化观察创口中巨噬细胞和成纤维细胞数量,Western blotting检测TNF-α表达水平,Masson染色观察胶原沉积情况。 (2) 在糖尿病小鼠切创后,选择合适的干预时间窗进行PNU-282987干预,然后观察上述指标变化。结果：(1) 与对照组相比,糖尿病组创口愈合明显延迟,在切创初期的伤口中巨噬细胞数量和TNF-α表达水平较低（P<0.05）,而切创5 d后的伤口巨噬细胞数量和TNF-α表达水平显著增加（P<0.05）,成纤维细胞数量和胶原含量减少（P<0.05）。 (2) 在切创5 d后对糖尿病小鼠腹腔注射PNU-282987,可显著减少伤口中TNF-α表达,提高成纤维细胞数量和胶原含量,促进伤口愈合。结论：糖尿病伤口愈合具有炎症反应发生迟但不易消退的特征。在炎症反应明显期激活α7nAChR可抑制TNF-α表达,促进糖尿病小鼠的伤口愈合。     

Promoted activation of matrix metalloproteinase (MMP)-2 in keloid fibroblasts and increased expression of MMP-2 in collagen bundle regions: implications for mechanisms of keloid progression

Aims:  Keloid is characterized by excessive deposition of collagen, resulting from aberrant extracellular matrix (ECM) production and degradation. The aim was to investigate the role of matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) in pathological wound healing in keloids.
Methods and results:  Semiquantitative analysis of 60 keloid tissue samples and 25 mature scar tissue samples demonstrated significantly increased expression of MMP-2, TIMP-2 and TIMP-3 in keloids compared with mature scars. Within keloid regions, MMP-2 expression was significantly higher in collagen bundle regions than in non-collagen bundle regions. Double immunofluorescence revealed that keloid fibroblasts between collagen bundles exhibited MMP-2, TIMP-2 and membrane-type 1 MMP (MT1-MMP) co-expression, whereas only MMP-2 expression was evident on the edge of collagen bundles. Western blot analysis and gelatin zymography of 13 keloid-derived fibroblasts (KFbs) and six normal skin dermal-derived fibroblasts (NFbs) demonstrated that unstimulated KFbs exhibited significantly increased MMP-2 activity and expression compared with NFbs under the same conditions.
Conclusions:  These results together indicate that MMP-2 activity can be promoted in keloid fibroblasts between collagen bundles in cooperation with TIMP-2 and MT1-MMP. This could contribute to remodelling of collagen bundle regions and invasion of fibroblasts into peripheral normal regions through promoted degradation of ECM.     

Expression and activity of matrix metalloproteinase-2 and -9 in experimental granulation tissue

The restoration of functional connective tissue is a major goal of the wound healing process which is probably affected by matrix-modifying enzymes. To evaluate the spatial and temporal expression of matrix metalloproteinases (MMP) MMP-2 and MMP-9 and to study the regulation of MMP-2 in wound healing, subcutaneously implanted viscose cellulose sponges in rats were used to induce granulation tissue formation for up to 3 months. MMP-2 mRNA expression was seen throughout the experiment and it was highest after 2 months. MMP-9 gene expression was low between days 8-21 and increased after 4 weeks of granulation tissue formation. Membrane-type 1 MMP (MT1-MMP) mRNA was upregulated early and tissue inhibitor 2 of MMP (TIMP-2) mRNA later during wound healing. In in situ hybridization the expression of MMP-2 mRNA was seen mostly in fibroblast-like cells and MMP-9 mRNA in macrophage-like cells. MMP-9 immunoreactivity was detected in the polymorphonuclear leukocytes and macrophage-like cells on days 3-8. MMP-9 proteolytic activity was observed only on days 3-8. The active form of the MMP-2 increased up to day 14, whereafter it remained at a constant level, whereas latent MMP-2 did not show any apparent changes during the experimental period. We conclude that MMP-2 is important during the prolonged remodelling phase, whereas the gelatinolytic activity of MMP-9 was demonstrated only in early wound healing, and the MMP-9 gene is upregulated when the granulation tissue matures.     

TGF-β1-treated ADSCs-CM promotes expression of type I collagen and MMP-1, migration of human skin fibroblasts, and wound healing in vitro and in vivo

Conditioned medium from adipose-derived stem cells (ADSCs) stimulates both collagen synthesis and migration of dermal fibroblasts. However, it is still unknown whether conditioned media from tumor growth factor (TGF)-β1-treated ADSCs (TGF-β1-treated ADSCs-CM) induces increased expression of type I collagen, matrix metalloproteinase-1 (MMP-1), and migration as well as cell cycle regulatory proteins in fibroblasts, compared to non-treated ADSCs-CM. Our data showed that TGF-β1-treated ADSCs-CM promoted effectively the proliferation and migration of human skin fibroblasts, compared to non-treated ADSCs-CM. In addition the expression of MMP-1 were markedly increased by treatment of TGF-β1-treated ADSCs-CM in fibroblasts, compared to non-treated ADSCs-CM. Expression of type I collagen protein were slightly increased by treatment of TGF-β1-treated ADSCs-CM in fibroblasts. The expression of cell cycle regulators of G1/S phase transition were not markedly altered by treatment of TGF-β1-treated ADSCs-CM. Finally, artificial wounds were made using a 4-mm punch biopsy in hairless mice and TGF-β1-treated ADSCs-CM were injected into the wound area. The injection of TGF-β1-treated ADSCs-CM promoted the wound healing process in hairless mice. Taken together, our data indicated that TGF-β1-treated ADSCs-CM induced up-regulation of type I collagen and MMP-1, promoted the migration of skin fibroblasts, and thereby promoted the wound healing process in vivo. Our data indicate that TGF-β1-treated ADSCs-CM will be a component for a wound healing accelerating agent.     

Effects of PerClot® on the healing of full-thickness skin wounds in rats

PerClot^® is a hemostatic material made of polysaccharide from modified starch and has been shown to assist in topical hemostasis. The principal goal in treating surgical and non-surgical wounds is the need for rapid closure of the lesion. This study investigated whether topical application of PerClot^® could improve impaired wound healing in Sprague-Dawley (SD) rats. Full-thickness skin wounds were created on the back of the rats. Immediately, PerClot^® was introduced into the wound bed, while wounds receiving starch or nothing served as controls. Wound closure was monitored using well-recognized wound-healing parameters: histological examination for inflammatory cells and fibroblast infiltration, newly formed capillaries, and collagen deposition. Meanwhile, transforming growth factor (TGF-β1) was measured by immunochemistry. Wound closure was significantly accelerated by local application of PerClot^®. Furthermore, PerClot^®-treated wounds showed significantly increased fibroblast numbers at 5 days post-wounding, and newly formed capillaries at 7 days post-wounding, and collagen regeneration at 7 and 14 days post-wounding. The number of infiltrating fibroblasts expressing TGF-β1 was significantly higher than that in the controls at 7 and 14 days post-wounding. PerClot^® can improve the wound healing and this effect might involve an increase in the activity of fibroblasts and increased release of TGF-β1.     

TGF-beta 1 accelerates wound healing: reversal of steroid-impaired healing in rats and rabbits.

TGF-beta modulates events of normal wound healing through multiple pathways that influence cell infiltration, proliferation, angiogenesis, extracellular matrix synthesis and remodeling. The effects of topically applied TGF-beta 1 on wound healing in two models of healing were evaluated when the healing response was impaired by the administration of methylprednisolone to rats or rabbits. TGF-beta 1 increased the healing of linear incision wounds on rats, as measured by breaking strength, to that of normal rats. Full thickness open wounds were also created on the inner ears of rabbits to simulate a non-contracting wound with limited blood supply. Healing was further impaired by the administration of methylprednisolone. The single application of TGF-beta 1 improved the healing of open wounds. TGF-beta 1 stimulated increased granulation tissue formation, as well as reepithelialization. The amount of granulation tissue and epithelialization were similar to wounds from normal-healing control rabbits. The delayed healing caused by methylprednisolone permitted the evaluation of multiple applications of TGF-beta 1 to wounds. Two applications of TGF-beta 1 spaced 7 days apart further improved the healing response when compared to a single application. Thus, single or multiple topical applications of TGF-beta 1 reversed impaired healing conditions secondary to methylprednisolone when used on incisional or open wounds. These observations support the hypothesis that growth factors, such as TGF-beta 1, may be useful as accelerators of wound repair in patients with impaired healing conditions.     

Interleukin-6 treatment augments cutaneous wound healing in immunosuppressed mice.

It has been postulated that the inflammatory response that occurs after cutaneous wounding is a prerequisite for healing and that inflammatory cytokines, such as interleukin-6 (IL-6) are involved in this process. We showed previously that IL-6-deficient mice display delayed wound healing, which could be reversed by administration of a murine IL-6 expression plasmid or recombinant murine IL-6 (rMuIL-6). In the present study, we observed that delayed cutaneous wound healing, which occurs as a result of glucocorticoid-induced immunosuppression, can also be reversed by rMuIL-6, as evidenced by epithelialization, granulation tissue formation, and wound closure. In vehicle control mice, rMuIL-6 did not augment healing but rather delayed the process. Immunochemical studies indicated that the expression of matrix metalloproteinase-10 (MMP-10) was increased in dexamethasone-treated mice and that rMuIL-6 treatment reduced its expression, indicating that IL-6 may influence dermal matrix formation and, specifically, collagen synthesis. These results demonstrate that IL-6 can restore abnormal wound repair that occurs in immunodeficiency and suggest its use as a potential therapy.