Recombinant Hepatocyte Growth Factor Accelerates Cutaneous Wound Healing in a Diabetic Mouse Model

We examined effects of recombinant hepatocyte growth factor (HGF) on cutaneous wound healing, using a full-thickness cutaneous excision model in diabetic mice. Topical administration of HGF, as well as basic fibroblast growth factor (bFGF), promoted the rate of wound closure and re-epithelialization. Both HGF and bFGF enhanced expansion of the granulation tissue and stimulated neovascularization on day 7 postwounding, wherein the increase in microvessel density in HGF-treated wounds was higher than that in bFGF-treated wounds. Matrix metalloproteinases (MMP-2 and MMP-9) activities involved in cell migration, angiogenesis, and extracellular matrix (ECM) remodeling, were enhanced by HGF-treatment on day 7. On day 28 postwounding (later stages of wound healing), granulation tissue in bFGF-treated wounds remained to a greater extent than that seen in saline- and HGF-treated wounds. Likewise, bFGF- but not HGF-treatment stimulated DNA synthesis of fibroblasts in granulation tissue, suggesting that HGF stimulates wound healing with lesser degree of susceptibility to cutaneous scarring. We propose that supplement of HGF may be a potential therapeutic approach for treatment of cutaneous ulcer.     

A comparative study of fibroblasts in healing freeze and burn injuries in rats.

In rats, the healing process of a full-thickness dermal freeze injury differs from that of a burn wound. Whereas burn wounds heal by wound contraction, the movement of surrounding normal skin over the defect, freeze wounds heal without wound contraction. That absence of contraction may be due to the freeze wound's lack of myofibroblasts, the cells reportedly associated with wound contraction. Myofibroblasts can be demonstrated histologically by staining the F-actin filaments of the stress fibers with NBD-phallacidin, a fluorescent reagent specific to F-actin filaments. Fibroblasts in normal dermis have no staining stress fibers. However, staining myofibroblasts are uniformly distributed in the granulation tissue of the healing burn and in the islands of granulation tissue between residual connective tissue fibers in the healing freeze wound. These residual dermal fibers were identified by their patterns of birefringence. Residual connective tissue matrix persists following cold trauma and acts like an internal splint. Burn trauma destroys cells and the connective tissue matrix, which is completely replaced with granulation tissue which undergoes wound contraction. Freeze trauma kills the cellular components of dermis, while some residual connective tissue fibers endure. This study shows that the connective tissue matrix can play an important role in the control of wound contraction.     

Combined effects of artificial dermis and vascular endothelial growth factor concentration gradient on wound healing in diabetic porcine model

Wounds in patients with diabetes mellitus are one of the most prevalent impaired wounds in the world. Vascular endothelial growth factor (VEGF) is one of the most important proangiogenic mediators. Artificial dermal (AD) such as Pelnac^® has been shown, in humans and animal models, a great therapeutic potential in full-thickness skin wounds. We attempt to promote the wound healing in diabetic porcine models through combined use of AD and constant concentration of VEGF or VEGF concentration gradient. We created full-thickness excisional wounds in diabetic animal models. Analyzed the healing process through images, histology and immunohistochemistry. Results show that the combination of AD and concentration gradient of VEGF could provide an appropriate angiogenesis, improve granulation formation, increase epithelization and maintain the VEGF levels of the wound bed. Eventually accelerate the direct healing of diabetic wounds or make good preparation for secondary skin graft.     

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.     

Placenta growth factor in diabetic wound healing: altered expression and therapeutic potential

Reduced microcirculation and diminished expression of growth factors contribute to wound healing impairment in diabetes. Placenta growth factor (PlGF), an angiogenic mediator promoting pathophysiological neovascularization, is expressed during cutaneous wound healing and improves wound closure by enhancing angiogenesis. By using streptozotocin-induced diabetic mice, we here demonstrate that PlGF induction is strongly reduced in diabetic wounds. Diabetic transgenic mice overexpressing PlGF in the skin displayed accelerated wound closure compared with diabetic wild-type littermates. Moreover, diabetic wound treatment with an adenovirus vector expressing the human PlGF gene (AdCMV.PlGF) significantly accelerated the healing process compared with wounds treated with a control vector. The analysis of treated wounds showed that PlGF gene transfer improved granulation tissue formation, maturation, and vascularization, as well as monocytes/macrophages local recruitment. Platelet-derived growth factor, fibroblast growth factor-2, and vascular endothelial growth factor mRNA levels were increased in AdCMV.PlGF-treated wounds, possibly enhancing PlGF-mediated effects. Finally, PlGF treatment stimulated cultured dermal fibroblast migration, pointing to a direct role of PlGF in accelerating granulation tissue maturation. In conclusion, our data indicate that reduced PlGF expression contributes to impaired wound healing in diabetes and that PlGF gene transfer to diabetic wounds exerts therapeutic activity by promoting different aspects of the repair process.     

Recombinant hepatocyte growth factor accelerates cutaneous wound healing in a diabetic mouse model

We examined effects of recombinant hepatocyte growth factor (HGF) on cutaneous wound healing, using a full-thickness cutaneous excision model in diabetic mice. Topical administration of HGF, as well as basic fibroblast growth factor (bFGF), promoted the rate of wound closure and re-epithelialization. Both HGF and bFGF enhanced expansion of the granulation tissue and stimulated neovascularization on day 7 postwounding, wherein the increase in microvessel density in HGF-treated wounds was higher than that in bFGF-treated wounds. Matrix metalloproteinases (MMP-2 and MMP-9) activities involved in cell migration, angiogenesis, and extracellular matrix (ECM) remodeling, were enhanced by HGF-treatment on day 7. On day 28 postwounding (later stages of wound healing), granulation tissue in bFGF-treated wounds remained to a greater extent than that seen in saline- and HGF-treated wounds. Likewise, bFGF- but not HGF-treatment stimulated DNA synthesis of fibroblasts in granulation tissue, suggesting that HGF stimulates wound healing with lesser degree of susceptibility to cutaneous scarring. We propose that supplement of HGF may be a potential therapeutic approach for treatment of cutaneous ulcer.     

Location of injury influences the mechanisms of both regeneration and repair within the MRL/MpJ mouse

The adult MRL/MpJ mouse regenerates all differentiated structures after through-and-through ear punch wounding in a scar-free process. We investigated whether this regenerative capacity was also shown by skin wounds. Dorsal skin wounds were created, harvested and archived from the same animals (MRL/MpJ and C57BL/6 mice) that received through-and-through ear punch wounds. Re-epithelialization was complete in dorsal wounds in both strains by day 5 and extensive granulation tissue was present by day 14 post-wounding. By day 21, wounds from both strains contained dense amounts of collagen that healed with a scar. The average wound area, as well as alpha-smooth muscle actin expression and macrophage influx were investigated during dorsal skin wound healing and did not significantly differ between strains. Thus, MRL/MpJ mice regenerate ear wounds in a scar-free manner, but heal dorsal skin wounds by simple repair with scar formation. A significant conclusion can be drawn from these data; mechanisms of regeneration and repair can occur within the same animal, potentially utilizing similar molecules and signalling pathways that subtly diverge dependent upon the microenvironment of the injury.     

Transplantation of endothelial progenitor cells accelerates dermal wound healing with increased recruitment of monocytes/macrophages and neovascularization

Endothelial progenitor cells (EPCs) act as endothelial precursors that promote new blood vessel formation and increase angiogenesis by secreting growth factors and cytokines in ischemic tissues. These facts prompt the hypothesis that EPC transplantation should accelerate the wound-repair process by facilitating neovascularization and the production of various molecules related to wound healing. In a murine dermal excisional wound model, EPC transplantation accelerated wound re-epithelialization compared with the transplantation of mature endothelial cells (ECs) in control mice. When the wounds were analyzed immunohistochemically, the EPC-transplanted group exhibited significantly more monocytes/macrophages in the wound at day 5 after injury than did the EC-transplanted group. This observation is consistent with enzyme-linked immunosorbent assay results showing that EPCs produced in abundance several chemoattractants of monocytes and macrophages that are known to play a pivotal role in the early phase of wound healing. At day 14 after injury, the EPC-transplanted group showed a statistically significant increase in vascular density in the granulation tissue relative to that of the EC-transplanted group. Fluorescence microscopy revealed that EPCs preferentially moved into the wound and were directly incorporated into newly formed capillaries in the granulation tissue. These results suggest that EPC transplantation will be useful in dermal wound repair and skin regeneration, because EPCs both promote the recruitment of monocytes/macrophages into the wound and increase neovascularization.     

In vivo model of wound healing based on transplanted tissue-engineered skin

Advances in understanding the complex process of wound healing and development of novel growth factor and gene therapies would benefit from models that mimic closely the physiology of human wounds. To this end, we developed a hybrid wound-healing model based on human tissue-engineered skin transplanted onto athymic mice. Grafted tissues were infiltrated with mouse mesenchymal cells as native and foreign dermal regions fused together. Immunohistochemical staining for human involucrin revealed that the transplanted epithelium maintained its human origin, whereas the dermis was infiltrated by numerous mouse fibroblasts and blood vessels. Grafted tissues were wounded with a 4-mm punch to create full-thickness excisional wounds. At 1 and 2 weeks, the tissues were excised and assessed for reepithelialization, differentiation, and neovascularization. Interestingly, the average rate of keratinocyte migration (120 microm/day) was similar to migration rates observed in human subjects and significantly lower than migration in mouse epidermis. Immunohistochemical staining for keratin 10, laminin, and involucrin revealed a normal pattern of differentiation in the neoepidermis. Neovascularization was significantly elevated in the granulation tissue at 1 week and subsided to the level of unwounded tissue at 2 weeks postwounding. Our data suggest that skin equivalents grafted to a mouse model may serve as a realistic model of human wound regeneration. Because skin equivalents can be prepared with patient cells and genetically modified to stimulate or suppress gene expression, this model may be ideal for addressing mechanistic questions and evaluating the efficacy of biomaterials and gene therapeutics for promoting wound healing.     

Low molecular weight hyaluronic acid prevents oxygen free radical damage to granulation tissue during wound healing

Hyaluronic acid protects granulation tissue from oxygen free radical damage and stimulates wound healing, but its molecular weight prevents it from permeating the epidermal barrier A low molecular weight hyaluronic acid preparation is able to permeate the skin, but it is unknown whether or not it retains the scavenging effects of oxygen free radicals in granulation tissue. Our experiments were conducted in rats with excisional or incisional wounds. Wound contraction over 11 days and breaking strength on the fifth day were measured. Oxygen free radical production was induced by intraperitoneal administration of two different xenobiotics: phenazine methosulfate and zymosan. The wounds were treated topically with low molecular weight hyaluronic acid (0.2%) cream or placebo. In the incisional wound group, the effects of superoxide dismutase were also determined. Absolute controls received wounds and placebo but no xenobiotics. Wound healing was significantly slower in the xenobiotic group than in the control groups. These effects were strongly reduced by topical administration of low molecular weight hyaluronic acid (0.2%) cream and in incisional wounds by topically injected superoxide dismutase. Low molecular weight hyaluronic acid is effective as the native compound against oxygen free radicals. Its pharmacological effects through transdermal administration should be tested in appropriate models.     

Relationship between the distribution of myofibroblasts,and stellar and circular scar formation due to the contraction of square and circular wound healing

Square skin wounds can heal to form a stellar scar with four protrusions at the four angles, whereas circular wounds can heal to form an ellipsoid scar. It is not clear why these differences occur and the aim of the present study was to clarify this phenomenon. Two square or circular full-thickness skin wounds were made on the dorsum of mice, and covered with hydrocolloid dressing. They were observed from day 0 to 15 after wounding, and used to prepare paraffin sections stained with anti-alpha-smooth muscle actin antibody to detect myofibroblasts. The square wound was transiently enlarged by edema and skin tension on day 3, at which time the angles became round, and thus the square form became more circular. Thereafter, the wound contracted rapidly and the circular form was maintained until day 11. On day 11 distinct angles appeared where the scar formation had progressed further, and there were fewer myofibroblasts than in any other section. A stellar scar with protrusions from the four angles was formed on day 15, when myofibroblasts almost disappeared in the protrusions. This indicates that due to the earlier disappearance of myofibroblasts and earlier scarring in the angles of the square wound, the scar angle cannot be pulled into the center of the wound but residual myofibroblasts on the side can pull the side into the center due to myofibroblastic contraction and consequently a stellar scar is formed. Thus, the earlier disappearance of myofibroblasts in the angles is very important for the formation of stellar scars.     

Influence of electrospun collagen on wound contraction of engineered skin substitutes

The treatment of massive full-thickness burns with engineered skin substitutes has shown promise in clinical trials. The majority of skin substitutes are comprised of fibroblasts and/or keratinocytes on collagen scaffolds, commonly generated by freeze drying which can generate significant structural heterogeneity. Electrospinning may generate collagen scaffolds with greater homogeneity. Skin substitutes were fabricated using either freeze-dried (FD) or electrospun (ES) collagen scaffolds. Cell distribution, proliferation, organization, and maturation were assessed on each scaffold type in vitro, and engraftment and healing of full thickness wounds in athymic mice were tested. In vitro evaluation of freeze-dried collagen skin substitutes (FCSS) and electrospun collagen skin substitutes (ECSS) revealed no significant differences in cell proliferation, surface hydration, or cellular organization between the ECSS and FCSS groups. Both groups exhibited excellent stratification with a continuous layer of basal keratinocytes present at the dermal-epidermal junction. After grafting to full thickness wounds in athymic mice, both skin substitutes had high rates of engraftment: 87.5% in the FCSS group and 100% in the ECSS group. Histological evaluation of wounds revealed that bovine collagen persisted in the wound at week 8 in the FCSS group while no bovine collagen was seen in the ECSS group. At 8 weeks post-grafting, the ECSS grafts were 61.3+/-7.9% original graft area whereas the FCSS grafts were 39.2+/-8.8% original area (p<0.01). These results indicate that ES scaffolds can be used to fabricate skin substitutes with optimal cellular organization and can potentially reduce wound contraction compared to FD scaffolds. These advantages may lead to reduced morbidity in patients treated with skin substitutes fabricated from ES collagen.     

Biodegradable lysine-derived polyurethane scaffolds promote healing in a porcine full-thickness excisional wound model

Lysine-derived polyurethane scaffolds (LTI-PUR) support cutaneous wound healing in loose-skinned small animal models. Due to the physiological and anatomical similarities of human and pig skin, we investigated the capacity of LTI-PUR scaffolds to support wound healing in a porcine excisional wound model. Modifications to scaffold design included the addition of carboxymethylcellulose (CMC) as a porogen to increase interconnectivity and an additional plasma treatment (Plasma) to decrease surface hydrophobicity. All LTI-PUR scaffold and formulations supported cellular infiltration and were biodegradable. At 15 days, CMC and plasma scaffolds simulated increased macrophages more so than LTI PUR or no treatment. This response was consistent with macrophage-mediated oxidative degradation of the lysine component of the scaffolds. Cell proliferation was similar in control and scaffold-treated wounds at 8 and 15 days. Neither apoptosis nor blood vessel area density showed significant differences in the presence of any of the scaffold variations compared with untreated wounds, providing further evidence that these synthetic biomaterials had no adverse effects on those pivotal wound healing processes. During the critical phase of granulation tissue formation in full thickness porcine excisional wounds, LTI-PUR scaffolds supported tissue infiltration, while undergoing biodegradation. Modifications to scaffold fabrication modify the reparative process. This study emphasizes the biocompatibility and favorable cellular responses of PUR scaffolding formulations in a clinically relevant animal model.     

Endothelial selectins regulate skin wound healing in cooperation with L-selectin and ICAM-1

Skin wound healing is mediated by inflammatory cell infiltration that is highly regulated by various adhesion molecules. Mice lacking intercellular adhesion molecule-1 (ICAM-1) delayed skin wound healing and mice lacking both L-selectin and ICAM-1 (L-selectin/ICAM-1(-/-)) show more delayed wound healing. Deficiency of both endothelial selectins (E-selectin or P-selectin) also delays wound healing. However, the relative contribution and interaction of selectins and ICAM-1 to the wound healing remain unknown. To clarify them, repair of excisional wounds was examined in L-selectin/ICAM-1(-/-) mice, wild-type mice with both E- and P-selectin blockade, and L-selectin/ICAM-1(-/-) mice with both E- and P-selectin blockade. Wild-type mice with both E- and P-selectin blockade showed delayed wound healing that was comparable with that in L-selectin/ICAM-1(-/-) mice. Combined E- and P-selectin blockade in L-selectin/ICAM-1(-/-) mice resulted in more significant delay. Mice lacking or blocked for adhesion molecules also showed suppressed keratinocyte migration, angiogenesis, granulation tissue formation, leukocyte infiltration, and cytokine expression, including transforming growth factor-beta and interleukin-6. Application of basic fibroblast growth factor (bFGF) but not platelet-derived growth factor to the wounds significantly improved wound healing in L-selectin/ICAM-1(-/-) mice with both E- and P-selectin blockade. bFGF significantly increased the leukocyte infiltration and subsequent fibrogenic cytokine production, as well as keratinocyte migration, angiogenesis, and collagen synthesis despite the loss of four kinds of adhesion molecules. These results indicate that skin wound healing is regulated cooperatively by all selectins and ICAM-1 and may provide critical information for the therapy of skin wounds.     

CARP, a cardiac ankyrin repeat protein, is up-regulated during wound healing and induces angiogenesis in experimental granulation tissue

Cardiac ankyrin repeat protein (CARP) was identified by subtractive hybridization as one of a group of genes that are rapidly modulated by acute wounding of mouse skin. Quantitative RT-PCR showed that CARP was strongly induced during the first day after wounding (157.1-fold), and the high level persisted for up to 14 days. Immunohistochemistry and in situ hybridization revealed that CARP was expressed in skeletal muscle, vessel wall, hair follicle, inflammatory cells, and epidermis in the wound area. To examine the effects of CARP on wound healing, we developed an adenoviral CARP vector to treat subcutaneously implanted sponges in either rats or Flk-1(LacZ) knock-in mice. Four days after infection, CARP-infected sponges in rats showed a remarkable increase in the vascular component in granulation tissue as compared to Ad-LacZ controls. This result was confirmed by CD34 immunostaining. By 7 days post-infection of sponge implants in Flk-1(LacZ) knock-in mice, granulation tissue showed many more LacZ-positive cells in Ad-CARP-infected sponges than in virus controls. Ad-CARP treatment also induced neovascularization and increased blood perfusion in rabbit excisional wounds in and ischemic rat wounds. These findings indicate that CARP could play a unique role in therapeutic angiogenesis during wound healing.     

Higher numbers of autologous fibroblasts in an artificial dermal substitute improve tissue regeneration and modulate scar tissue formation

Cultured skin substitutes are increasingly important for the treatment of burns and chronic wounds. The role of fibroblast numbers present in a living-skin equivalent is at present unknown. The quality of dermal tissue regeneration was therefore investigated in relation to the number of autologous fibroblasts seeded in dermal substitutes, transplanted instantaneously or precultured for 10 days in the substitute. A full-thickness porcine wound model was used to compare acellular dermal substitutes (ADS) with dermal substitutes seeded with fibroblasts at two densities, 1x10(5) (0-DS10) and 5x10(5) cells/cm(2) (0-DS50), and with dermal substitutes seeded 10 days before operation at the same densities (10-DS10 and 10-DS50) (n=7 for each group, five pigs). After transplantation of the dermal substitutes, split-skin mesh grafts were applied on top. Wound healing was evaluated blind for 6 weeks. Cosmetic appearance was evaluated and wound contraction was measured by planimetry. The wound biopsies taken after 3 weeks were stained for myofibroblasts (alpha-smooth muscle actin), and after 6 weeks for scar tissue formation (collagen bundles organized in parallel and the absence of elastin staining). Collagen maturation was investigated with polarized light. For wound cosmetic parameters, the 10-DS50 and 0-DS50 treatments scored significantly better than the ADS treatment, as did the 10-DS50 treatment for wound contraction (p<0.05, paired t-test). Three weeks after wounding, the area with myofibroblasts in the granulation tissue, determined by image analysis, was significantly smaller for 0-DS50, 10-DS10, and 10-DS50 than for the ADS treatment (p<0.04, paired t-test). After 6 weeks, the wounds treated with 0-DS50, 0-DS10, and 10-DS50 had significantly less scar tissue and significantly more mature collagen bundles in the regenerated dermis. This improvement of wound healing was correlated with the higher numbers of fibroblasts present in the dermal substitute at the moment of transplantation. In conclusion, dermal regeneration of experimental full-skin defects was significantly improved by treatment with dermal substitutes containing high numbers of (precultured) autologous fibroblasts.     

Diminished type III collagen promotes myofibroblast differentiation and increases scar deposition in cutaneous wound healing

The repair of cutaneous wounds in the postnatal animal is associated with the development of scar tissue. Directing cell activities to efficiently heal wounds while minimizing the development of scar tissue is a major goal of wound management and the focus of intensive research efforts. Type III collagen (Col3), expressed in early granulation tissue, has been proposed to play a prominent role in cutaneous wound repair, although little is known about its role in this process. To establish the role of Col3 in cutaneous wound repair, we examined the healing of excisional wounds in a previously described murine model of Col3 deficiency. Col3 deficiency (Col3+/-) in aged mice resulted in accelerated wound closure with increased wound contraction. In addition, Col3-deficient mice had increased myofibroblast density in the wound granulation tissue as evidenced by an increased expression of the myofibroblast marker, α-smooth muscle actin. In vitro, dermal fibroblasts obtained from Col3-deficient embryos (Col3+/- and -/-) were more efficient at collagen gel contraction and also displayed increased myofibroblast differentiation compared to those harvested from wild-type (Col3+/+) embryos. Finally, wounds from Col3-deficient mice also had significantly more scar tissue area on day 21 post-wounding compared to wild-type mice. The effect of Col3 expression on myofibroblast differentiation and scar formation in this model suggests a previously undefined role for this ECM protein in tissue regeneration and repair.     

Effect of collagen cross-linking inhibition by local application of beta-aminopropionitrile fumarate on wound contraction and healing (macroscopic study)

Wound contraction is a major component of second-intention wound healing. The mechanism of this process is not completely understood. Two theories have been described for the mechanism of the wound contraction. To evaluate the collagen cross-linking inhibition on wound contraction, the present study was carried out. Macroscopical aspects of second-intention healing of full-thickness, excisional wounds were studied in five normal male mixed-breed dogs. Under general anesthesia, two full-thickness skin wounds (20 × 20 mm) were created on the back of each dog symmetrically. Left-side wounds (test group) and right-side wounds (control group) were treated topically with beta-aminopropionitrile fumarate 5 mg/ml in methyl cellulose gel and methyl cellulose gel, respectively. Wounds were treated starting at 24 h after wounding and continued for ten successive days. The wounds were evaluated over a 4-week period. At the days 0, 3, 7, 10, 14, 17, 21, 24, and 28, digital photographs were taken of all wounds. Rulers were held vertically and horizontally close to the wound as a reference. The area of the epithelialization and granulation tissue were measured for each wound using Scion Image software. Percent of the wound contraction, epithelialization, and healing were calculated for each wounds. Wound contraction, epithelialization, and healing were significantly decreased in the wounds treated by beta-aminopropionitrile fumarate (P < 0.05). Our data demonstrated that the collagen and collagen cross-linking play a key role in the wound contraction and healing during the first 10 days of the wound healing.     

基质细胞衍生因子-1α联合Integra支架修复全层皮肤缺损创面的实验研究

观察基质细胞衍生因子-1α(SDF-1α)联合Integra支架促进全层皮肤缺损创面愈合的作用,并探讨其作用机制。 方法选取6～8周龄的雄性健康C57小鼠30只,在其脊柱两侧对称部位分别作直径1 cm的圆形全层皮肤缺损创面,采用真皮支架Integra作为创面覆盖物。将30只小鼠背部左右对称创面按随机数字表法分为2组：SDF-1α组和对照组,各30个创面。SDF-1α组经皮下往创面内注射SDF-α,对照组皮下注射磷酸盐缓冲溶液。术后第3、6、12、18和24天观察创面的愈合时间和愈合创面收缩情况,并留取创面及周围组织标本行苏木精-伊红染色和免疫组织化学染色观察浸润细胞、肉芽组织厚度及血管化情况。对数据进行t检验。 结果(1) SDF-1α组创面完全愈合时间为(15.7±1.6)d,明显短于对照组的(19.6±1.8)d,差异有统计学意义(t＝3.967,P<0.05);(2)SDF-1α组术后第3、6、12天愈合创面收缩率分别为(7.3±3.3)%、(14.7±8.4)%、(27.6±6.3)%,与对照组[(8.3±2.5)%、(17.5±6.4)%、(31.2±16.5)%]比较,差异均无统计学意义(t＝0.6427、0.262、0.208,P值均大于0.05);SDF-1α组术后第18、24天愈合创面收缩率为(36.6±6.7)%、(58.2±7.1)%,小于对照组[(67.6±10.7)%、(81.1±8.3)%],差异均有统计学意义(t＝2.463、2.094,P值均小于0.05);(3)创面肉芽组织术后第3天SDF-1α组浸润细胞数目为(181.7±28.8)个/视野,与对照组[(190.8±33.4)个/视野]比较,差异无统计学意义(t＝ 4.08, P<0.05);术后第6天SDF-1α组浸润细胞数目[(382.2±43.4)个/视野],与对照组[((478.2±38.8)个/视野]比较,差异无统计学意义(t＝ 6.20,P<0.05);(4)肉芽组织的厚度术后第6、12天SDF-1α组创面的肉芽组织厚度为(255.8±41.8)、(387.6±36.8)μm,均小于对照组(407.3±43.4)、(490.2±49.4)μm],差异均有统计学意义(t＝4.08、6.159,P值均小于0.05);(5)SDF-1α组术后第24天愈合创面与正常皮肤更为相似,对照组瘢痕明显,表皮薄;(6)SDF-1α组术后第12天创面肉芽组织中CD3、CD31阳性细胞的密度稍高于对照组,肉芽组织的血管密度明显高于对照组。 结论局部使用SDF-1α可以促进全层皮肤缺损创面肉芽组织血管化,改善创面修复的效果。