Gene expression in normal and doxorubicin-impaired wounds: importance of transforming growth factor-beta

The function of transforming growth factor-beta (TGF-beta) in vivo remains unknown despite the fact that it has been identified in numerous biologic processes involving the regulation of cell growth including tissue repair. Doxorubicin is a potent antitumor drug that has been shown to have detrimental effects on wound healing. With specific complementary DNA probes for TFG-beta and type 1 collagen, RNA from wounds of rats treated with saline solution and doxorubicin was analyzed for the expression of each gene at different times after wounding. In a second study, either 2 micrograms exogenous TGF-beta or vehicle was added to wounds of rats treated with doxorubicin, and wound RNA was analyzed in a similar manner. In wounds from rats treated with saline solution, messenger RNA (mRNA) for TGF-beta peaks on day 7 after wounding and is also elevated on days 3 and 10; mRNA for collagen is elevated on days 7 and 10. Doxorubicin decreases mRNA for TGF-beta and collagen on each day. Topical application of TGF-beta to wounds of rats treated with doxorubicin increases collagen mRNA levels to normal or supranormal levels. This study suggests that the impaired healing induced by doxorubicin may be a result of decreased gene expression for TGF-beta and that topical replacement of this growth factor may correct the defect.     

The analgesic hybrid of dermorphin/substance P and analog of enkephalin improve wound healing in streptozotocin‐induced diabetic rats

The purpose of this study was to investigate the effect of the peptide analgesic hybrid compounds: AWL3106 analog of dermorphin and substance P (7‐11), and biphalin enkephalin analog on wound healing in streptozotocin‐induced diabetic rats. The diabetes was induced in 6–7 week‐old male Wistar rats by intraperitoneal injection of streptozotocin. After 70 days, the wounds were created on the back of the rats and then, once a day for 21 days, the dressing containing lanolin ointment, 10% of keratin scaffolds, and 1 mM of AWL3106 or biphalin was applied. The wounds histology were analyzed by hematoxylin and eosin staining. The orientation and organization of collagen was analyzed by Masson's trichome staining. The number of macrophages, blood vessels, and fibroblasts were visualized by CD68, CD34, and vimentin immunoreactivity, respectively. Our results demonstrated that the wound area of AWL3106‐ and biphalin‐treated groups was greatly reduced (up to 47% on the 7 day) in comparison with untreated diabetic groups. The immunohistochemical staining of macrophages demonstrated that AWL3106 and biphalin accelerated inflammatory progression and subsequently decreased persistent inflammation. The histological analysis showed that the structure of tissue in the groups under the study was very similar to the one of wound tissue in N‐DM group. The H&E and Masson's trichome staining demonstrated that the orientation and organization of collagen as well as the number and shape of blood vessels were better in 3106‐ and BIF‐treated group than in DM group. In conclusion, the obtained data suggested that our hybrid peptides enhanced wound healing, particularly by accelerating the inflammatory phase and promoted the wound closure.     

Avocado/soybean unsaponifiables: a novel regulator of cutaneous wound healing,modelling and remodelling

We investigated the effects of avocado/soybean unsaponifiables (ASU) on the healing response of cutaneous wound defect in rats. Sixty male rats were randomly divided into three groups including control, vehicle and treatment (n = 20 in each group). A 2 × 2 cm² wound defect was made on the dorsum. The control, vehicle and treatment groups were treated daily with topical application of saline, cream and cream/ASU for 10 days, respectively. The wounds were monitored daily. The animals were euthanised at 10, 20 and 30 days post injury (D). The dry matter, hydroxyproline, collagen, n‐acetyl glucosamine (NAGLA) and n‐acetyl galactosamine (NAGAA) contents of the skin samples were measured and the histopathological and biomechanical characteristics of the samples were investigated. Statistics of P < 0·05 was considered significant. Treatment significantly increased tissue glycosaminoglycans and collagen contents at various stages of wound healing compared to controls. Treatment modulated inflammation, improved fibroplasia and produced high amounts of scar tissue at short term. At long term, treatment reduced the scar tissue size and increased the quality and rate of wound contraction and reepithelisation compared to controls. The treated lesions were more cosmetically pleasing and had significantly higher biomechanical characteristics than controls. ASU was effective in rat wound healing.     

The concurrent use of probiotic microorganism and collagen hydrogel/scaffold enhances burn wound healing: An in vivo evaluation

Treatment of burn wounds is technically demanding and several attempts have been taken to improve wound healing. Silver sulfadiazine antibiotic has been shown to have some beneficial effects on wound healing via reduction in infection. This study was designed to investigate the impact of collagen hydrogel-scaffold dressing with or without topical use of Saccharomyces cerevisiae on cutaneous burn wound healing in rat. Four circular 1 cm cutaneous wounds were created in the dorsum back of rats, 48 h post-burning. Thirty male rats were divided into the three major groups (1–3, n = 10), then the wounds in each group were equally divided into two subgroup treatments (6 treatments), (1) including (a) silver sulfadiazine (SSD) as positive control (PC) and (b) untreated wounds as negative control (NC) (2) including (c) S. cerevisiae and (S.C.) and (d) collagen scaffold (CS), (3) including (e) collagen hydrogel-scaffold (CH-S) and (f) S. cerevisiae with collagen hydrogel-scaffold (CH-S-S). In each group, the animals were euthanized at 12 and 22 days post-injury (DPI) and the skin samples were used for histopathological and biomechanical investigations. Collagen scaffold and hydrogel modulated the inflammation, especially when combined together. Moreover, they increased wound healing, epithelialization and biomechanical performance of wound area and also reduced the scar size. The best results gained when the combination of collagen scaffold and hydrogel were mixed with probiotic. The CH-S biological dressing along with probiotic microorganism (S.C.) significantly increased collagen content compared to the negative controls. Moreover, the CH-S-S treated lesions demonstrated greater ultimate load and stiffness compared to the untreated wounds. In conclusion, application of S. cerevisiae with a bi-phase biological dressing (CH-S) improved the morphological and biomechanical characteristics of the healing burned wounds in rats and the results were comparable to the positive control.     

Altered collagen metabolism and delayed healing in a novel model of ischemic wounds

Cellular mechanisms occurring in the healing wound have been well described in various animal models. However, the events associated with wound healing seen in ischemic skin have not been as thoroughly defined. In this series of experiments, we created a novel model of excisional skin wounds under gradient ischemia to study the cellular and extracellular events leading to delayed healing. We hypothesized that altered collagen metabolism accounts for delayed wound healing in ischemic skin. Three pairs of 4 mm punch wounds were made 4 days after bipedicle skin flaps were created on the dorsum of rats. Sham-operated control animals had the same punch wounds without flap creation. The kinetics of excisional wound healing were measured by means of computerized planimetry. In addition, wounds were excised with a 6 mm trephine, radiolabelled with ((3)H)-proline and in vitro collagen synthesis determined as collagenase digestible protein along with quantitation of DNA content. Total collagen deposition was determined as 4-hydroxy-L-proline by high-performance liquid chromatography, and wounds were histologically evaluated. Data was analyzed by means of two-way analysis of variance. Although control wounds healed by day 10, flap wounds consistently had greater surface area on days 2, 4, 6, 8, and 12 (p < 0.001). Relative collagen synthesis (% collagen/noncollagen protein), as measured by an in vitro synthesis method, showed no statistically significant differences between flap and controls wounds. However, the total collagen content (deposition) as measured by 4-hydroxy-l-proline was significantly lower in flap wounds compared with controls on days 7 (p < 0.05) and 9 (p < 0.001). In addition, a significant increase occurred in DNA content in the flap wounds on days 7 (p < 0.05) and 9 (p < 0.001) versus control wounds. These data indicate that, in ischemic wounds, significantly less collagen is deposited despite the inherent ability of the tissue to synthesize appropriate levels of collagen. Because the in vitro collagen synthesis technique only assesses the ability of the tissue to synthesize collagen in a well oxygenated environment, one cannot be assured that the tissue expresses this potential in vivo. However, these data are consistent with the hypothesis that the delay in wound closure is due to an alteration in collagen metabolism which results in a net decrease in collagen accumulation. Because of the observed increase in DNA within the ischemic wounds, we suggest that there is prolonged inflammation in these wounds which may enhance collagen degradation through the release of proteases. In addition, there may be an inability of the tissue to maintain appropriate levels of collagen in this inflammatory wound environment.     

Lentiviral gene therapy with platelet-derived growth factor B sustains accelerated healing of diabetic wounds over time

The treatment of diabetic wounds is a formidable clinical challenge. In this study, lentiviral vectors carrying the human platelet-derived growth factor B (PDGF-B) gene were used to treated diabetic mouse wounds. Full-thickness 2.0-cm x 2.0-cm excisional wounds were created on the dorsa of genetically diabetic C57BL/KsJ-m+/+Lepr(db) mice. Lentiviral vectors containing the PDGF-B gene were injected into the wound margins and base. Mice were killed at 14-, 21-, and 35-day intervals. Measurement of the residual epithelial gap showed a trend towards increased healing in lentiviral PDGF-treated wounds compared with untreated and saline-treated wounds at all time points. At 21 days, there was significantly increased healing in lentiviral PDGF-treated wounds (0.98+/-0.17 cm) compared with saline-treated wounds (1.22+/-0.30 cm; P<0.05). Immunohistochemistry for CD31 revealed significantly increased neovascularization in lentiviral PDGF-treated wounds compared with untreated and saline-treated wounds at 14 and 21 days (P<0.01). Picrosirius red staining demonstrated thicker and more highly organized collagen fibers in treated wounds compared with untreated and saline-treated wounds. Quantitative analysis of collagen content showed a 3.5-fold and 2.3-fold increase in lentiviral PDGF-treated wounds versus untreated and saline-treated wounds, respectively (P<0.01). Lentiviral gene therapy with PDGF-B can sustain diabetic wound healing over time and may possess promising potential in the clinical setting.     

Exogenous transforming growth factor-beta 2 enhances connective tissue formation and wound strength in guinea pig dermal wounds healing by secondary intent.

The presence of transforming growth factor-beta (TGF-beta) at the site of acute injury, its ability to attract inflammatory and connective tissue cells, and its stimulatory effect on the deposition of connective tissue matrix combine to suggest that it may play a key role in the response to injury. The effect of exogenous TGF-beta form 2 on dermal wounds healing by secondary intent was investigated using a sponge composed of collagen and heparin as a delivery vehicle. Longitudinal lenticular-shaped wounds on the dorsum of adult guinea pigs were treated at the time of wounding with delivery vehicle containing 0.5, 1, or 5 micrograms of purified, bovine bone-derived TGF-beta 2, and were compared with wounds that received vehicle only or were untreated. At days 8 and 14 the amount of connective tissue in the wounds and the extent of epithelialization were determined by histomorphometric methods, and wound breaking strength was determined. At day 8, but not at day 14, wounds treated with 1 or 5 micrograms of TGF-beta 2 contained a significantly higher proportion of connective tissue than did wounds treated with vehicle only, and they also exhibited higher wound strength. No effect on wound size or re-epithelialization was detected. The observations provide evidence that a single treatment with exogenous TGF-beta 2 delivered in collagen/heparin sponge vehicle can accelerate repair in guinea pig dermal wounds allowed to heal by secondary intent.     

Healing of incisional wounds in stomach and duodenum: The influence of experimental diabetes

The present study was performed to evaluate the effect of experimental diabetes mellitus on the mechanical properties and collagen content of healing wounds in rat stomach and duodenum. Furthermore, the effect of insulin treatment was investigated. Diabetes was induced by streptozotocin, and protamine zinc insulin was used in the treated diabetes group. Wounds were made in the nonglandular part (rumen) and the glandular oxyntic part (corpus) of the stomach and in the duodenum. The wounds were tested 7 and 20 days after operation. Experimental diabetes impaired the mechanical strength of healing wounds in stomach and duodenum. The reduction was most pronounced for breaking energy (energy absorption), while only duodenum showed a decrease for breaking strength (maximal force) of the tissues. The impairment became more pronounced by increasing healing time. A relation between mechanical strength and total collagen content was shown. Insulin treatment prevented these retardations and normalized the mechanical strength. These findings indicate that the increase of mechanical strength and collagen content in wounds in stomach and duodenum is impaired by experimental diabetes. The effects are probably a real impairment of the healing process. Insulin treatment prevented these changes.     

The local effects of cachectin/tumor necrosis factor on wound healing.

Previous experimental studies have suggested that tumor necrosis factor (TNF) may have either a beneficial or a detrimental role in wound healing. Control and doxorubicin-treated (6 mg/kg, intravenously) rats underwent paired dorsal 5-cm linear wounds and had either vehicle or recombinant (r)TNF (0.5, 5, or 50 micrograms) applied locally to the wound. Paired wounds were harvested at 7 and 14 days after wounding and analyzed for wound-bursting strength (WBS) and activity of the gene for type 1 collagen and TNF. Doxorubicin treatment decreased WBS at 14 days but not at 7 days after wounding. Local application of 50 micrograms of rTNF decreased WBS in saline-treated rats and concentrations of 5 and 50 micrograms decreased WBS in doxorubicin-treated rats when measured 7 days after wounding. These effects dissipated when WBS was measured 14 days after wounding. Doxorubicin decreased wound collagen gene expression and local TNF treatment decreased wound collagen gene expression in saline-treated rats and further decreased it in doxorubicin-treated rats. The decrement in collagen gene expression induced by rTNF increased as the local dose of rTNF increased. The gene for TNF was not detectable in wounds from normal or doxorubicin-treated rats at 3, 7, 10, or 14 days after wounding. These data suggest that the gene for TNF is not expressed in wounds and that the local application of TNF is detrimental to wound healing as it decreases WBS and activity of the gene for collagen.     

A modified collagen gel enhances healing outcome in a preclinical swine model of excisional wounds

Collagen‐based dressings are of great interest in wound care. However, evidence supporting their mechanism of action is scanty. This work provides first results from a preclinical swine model of excisional wounds, elucidating the mechanism of action of a modified collagen gel (MCG) dressing. Following wounding, wound‐edge tissue was collected at specific time intervals (3, 7, 14, and 21 days postwounding). On day 7, histological analysis showed significant increase in the length of rete ridges, suggesting improved biomechanical properties of the healing wound tissue. Rapid and transient mounting of inflammation is necessary for efficient healing. MCG significantly accelerated neutrophil and macrophage recruitment to the wound site on day 3 and day 7 with successful resolution of inflammation on day 21. MCG induced monocyte chemotactic protein‐1 expression in neutrophil‐like human promyelocytic leukemia‐60 cells in vitro. In vivo, MCG‐treated wound tissue displayed elevated vascular endothelial growth factor expression. Consistently, MCG‐treated wounds displayed significantly higher abundance of endothelial cells with increased blood flow to the wound area indicating improved vascularization. This observation was explained by the finding that MCG enhanced proliferation of wound‐site endothelial cells. In MCG‐treated wound tissue, Masson's trichrome and picrosirius red staining showed higher abundance of collagen and increased collagen type I:III ratio. This work presents first evidence from a preclinical setting explaining how a collagen‐based dressing may improve wound closure by targeting multiple key mechanisms. The current findings warrant additional studies to determine whether the responses to the MCG are different from other collagen‐based products used in clinical setting.     

Topical steroids for chronic wounds displaying abnormal inflammation

Introduction

Chronic, non-healing wounds are often characterised by an excessive, and detrimental, inflammatory response. We review our experience of using a combined topical steroid, antibiotic and antifungal preparation in the treatment of chronic wounds displaying abnormal and excessive inflammation.

Methods

A retrospective review was undertaken of all patients being treated with a topical preparation containing a steroid (clobetasone butyrate 0.05%), antibiotic and antifungal at a tertiary wound healing centre over a ten-year period. Patients were selected as the primary treating physician felt the wounds were displaying excessive inflammation. Healing rates were calculated for before and during this treatment period for each patient. Changes in symptom burden (pain, odour and exudate levels) following topical application were also calculated.

Results

Overall, 34 ulcers were identified from 25 individual patients (mean age: 65 years, range: 37–97 years) and 331 clinic visits were analysed, spanning a total time of 14,670 days (7,721 days ‘before treatment’ time, 6,949 days ‘during treatment’ time). Following treatment, 24 ulcers demonstrated faster rates of healing, 3 ulcers showed no significant change in healing rates and 7 were healing more slowly (p=0.0006). Treatment generally reduced the burden of pain and exudate, without affecting odour.

Conclusions

In normal wound healing, inflammation represents a transient but essential phase of tissue repair. In selected cases, direct application of a steroid containing agent has been shown to improve healing rates, presumably by curtailing this phase. Further evaluation is required to establish the role of preparations containing topical steroids without antimicrobials in the management of chronic wounds.     

A recombinant human collagen hydrogel for the treatment of partial-thickness burns: A prospective,self-controlled clinical study

IntroductionAllogeneic and xenogeneic skin are recognized as the best coverings for skin burn wounds, but currently face a supply shortage. To solve this problem, our research group developed a standardized manufactured hydrogel dressing based on a new type of highly bioactive recombinant human collagen.Study designProspective self-controlled trial.ObjectiveTo evaluate the efficacy and safety of recombinant human collagen hydrogel in the treatment of partial burn wounds to the skin compared to those of xenogeneic skin.MethodsThis study included twenty-one patients admitted to Shanghai Changhai Hospital within 48 h after receiving partial-thickness skin burns. The wounds were symmetrically separated along the axis and treated with recombinant human collagen hydrogel (RHCH) or a human-CTLA4-Ig gene-transferred pig skin xenotransplant. The condition of the wound surfaces was recorded on days 0 (of enrollment), 5, 10, 15, and 20, and bacterial drug sensitivity testing, hematuria examination, and electrocardiographic tests were conducted on days 0, 10, 20, or on the day of wound healing.ResultsThere were no statistically significant differences in wound healing time between the two groups. The median number of days to healing was 11.00 ± 0.56 for xenogeneic skin vs. 11.00 ± 1.72 for RHCH.ConclusionDuring the observation period, the therapeutic effect of the RHCH developed by our group on partial-thickness burn wounds was not significantly different from that of gene-transferred xenogeneic skin. Thus, our designed RHCH shows potential for clinical use to treat burn wounds on the skin.     

Laser photostimulation accelerates wound healing in diabetic rats

In this study, we examined the hypothesis that laser photostimulation can facilitate healing of impaired wounds in experimental diabetes using a rat model. Diabetes was induced in male rats by streptozotocin injection and two 6 mm diameter circular wounds were created on either side of the spine. The left wound of each animal was treated with a 632.8 nm He:Ne laser at a dose of 1.0 J/cm2 for five days a week until the wounds closed (three weeks). Measurements of the biomechanical properties of the laser-treated wounds indicated there was a marginal increase in maximum load (16%), stress (16%), strain (27%), energy absorption (47%) and toughness (84%) compared to control wounds of diabetic rats. Biochemical assays revealed that the amount of total collagen was significantly increased in laser treated wounds (274 +/- 8.7 microg) over the control wounds (230 +/- 8.4 microg). Sequential extractions of collagen from healing wounds showed that laser treated wounds had significantly greater concentrations of neutral salt soluble (15%) and insoluble collagen (16%) than control wounds, suggesting accelerated collagen production in laser treated wounds. There was an appreciable decrease in pepsin soluble collagen (19%) in laser treated wounds over control wounds, indicating higher resistance to proteolytic digestion. In conclusion, the biomechanical and biochemical results collectively suggest that laser photostimulation promotes the tissue repair process by accelerating collagen production and promoting overall connective tissue stability in healing wounds of diabetic rats.     

Topical platelet-derived growth factor enhances wound closure in the absence of wound contraction: an experimental and clinical study

The effects of platelet-derived growth factor (PDGF) on wound healing in animal and human models were investigated. Four 1-cm2 wounds were made on the dorsum of 3 rats. A 0.5-cm punch wound was made behind each ear of 4 patients. Half the wounds were treated daily with vehicle, controls, and the rest were treated with PDGF. Treated wounds closed faster than the controls (animals: 16 +/- 3.2 days vs. 17.8 +/- 2.17 days; p < 0.05) and (patients: 16 +/- 0.67 days vs. 19.5 +/- 0.33 days; p < 0.05). Biopsies were taken at day 20 for polarized light-Sirius red histological analysis. The granulation tissue of PDGF-treated wounds showed fine collagen fibers with weak birefringence, characteristic of immature granulation tissue, deposited throughout the healed wound site. Such a pattern indicates wound closure by reepithelialization and filling in with scar. Control wound biopsies showed a small area of immature granulation tissue surrounded by intact dermal thick collagen fibers with strong birefringence. Such a pattern indicates wound closure by wound contraction. This shows that PDGF enhances wound closure by reepithelialization and the prevention of wound contraction.     

Evaluation of autologous bone marrow‐derived nucleated cells for healing of full‐thickness skin wounds in rabbits

The aim of the study was to evaluate the potential of autologous bone marrow‐derived nucleated cells to enhance the rate of healing of full‐thickness excisional skin wounds in rabbits. The study was conducted on 20 New Zealand white rabbits of either sex. Two, 2 × 2 cm full‐thickness skin (thoracolumabar region) excisional wounds were created; one on each side of the dorsal midline in each animal. The wounds were randomly assigned to either injection of autologous bone marrow‐derived nucleated cells into the wound margins (BI), or topical application of sterile saline solution (normal saline, NS), which served as control. The wound healing was assessed by evaluation of granulation tissue formation, wound contraction, epithelisation and histopathological and histochemical changes up to 28 days after creation of the wound. Granulation tissue appeared significantly faster in BI‐treated wounds (3.22 ± 0.22 days) than in NS‐treated wounds (4.56 ± 0.47 days). Better epithelisation was seen histologically in BI wounds than in NS‐treated wounds. Wound contraction was significantly more in BI wounds when compared with NS wounds on 21 post‐surgery. Histopathological examination of the healing tissue showed early disappearance of inflammatory reaction, significantly more neovascularisation, and more fibroplasias and early lay down and histological maturation of collagen in BI wounds than in control wounds. It was concluded that injection of autologous bone marrow‐derived nucleated cells in the wound margins induced faster and better quality healing of excisional skin wounds in rabbits when compared with normal saline. The injection of autologous bone marrow‐derived nucleated cells can be used to promote healing of large full‐thickness skin wounds in rabbits.     

Effect of oxidized regenerated cellulose/collagen matrix on dermal and epidermal healing and growth factors in an acute wound

Rapid healing of acute wounds, e.g., in burned patients, can be essential for survival. Oxidized regenerated cellulose/collagen (ORC/collagen) has been shown to improve wound healing of chronic wounds. The aim of the present study was to determine the effect of ORC/collagen on dermal and epidermal healing as well as growth factor concentration in acute wounds. Rats received a full-thickness excision wound and were treated with either ORC/collagen plus a hydrocolloid dressing or a hydrocolloid dressing alone. Planimetry, immunological assays, histological and immunohistochemical techniques were used to determine dermal and epidermal regeneration, protein concentration, and growth factor concentration. In addition, dermal vascularization and structure were determined. Wounds treated with ORC/collagen showed a significantly faster reepithelization than those treated with hydrocolloid alone, p < 0.05. This accelerated wound healing rate may be explained by significantly higher levels of platelet-derived growth factor, keratinocyte growth factor, insulin-like growth factor-I, and insulin-like growth factor binding protein-3 in the ORC/collagen group leading to antiapoptotic effects of skin cells, p < 0.05. There were no significant differences in collagen morphology or deposition, neo-angiogenesis, or vascular endothelial growth factor concentration between both treatment groups. We conclude that ORC/collagen matrix accelerates epidermal regeneration and locally increases growth factor concentrations. Increased reepithelization was associated with decreased skin cell apoptosis. Based on our data we hypothesize that the ORC/collagen matrix may also have beneficial effects on acute wounds in a clinical setting.     

Effect of topical recombinant TGF-beta on healing of partial thickness injuries

Peptide growth factors produced by platelets, macrophages, epidermal, and dermal cells may play key roles in regulating healing of partial-thickness skin wounds. We examined the effects of recombinant transforming growth factor beta (TGF-beta) on cultures of epidermal and dermal cells in vitro and on healing of partial-thickness injuries in vivo. Increasing concentrations of TGF-beta (0.1, 1, and 10 ng/ml) progressively inhibited serum-stimulated DNA synthesis by up to 95% in cultures of adult human keratinocytes during 48 hr of exposure to TGF-beta. In contrast, TGF-beta (10 and 100 ng/ml) in serum-free media stimulated DNA synthesis by up to 80% compared to serum-free control cultures of adult human dermal fibroblasts. To evaluate the effects of TGF-beta on healing of partial-thickness injuries in vivo, wounds (20 x 20 x 0.6 mm) were created on the dorsal thoracolumbar region of adult pigs by an electrokeratome and were treated daily for 5 days after injury with vehicle or vehicle containing 0.1 or 1 microgram/ml TGF-beta and covered with occlusive dressing. Computerized planimetry of wound photographs demonstrated that TGF-beta treatment stimulated statistically significantly increases in the area of regenerated epidermis compared to wounds treated with saline vehicle on Days 3, 4, 5, and 7 after injury probably due to TGF-beta increasing the rate of epidermal cell migration. In addition, morphometry of biopsy specimens showed that TGF-beta treatment stimulated statistically significant increases in the cross-sectional depths of regenerated dermis compared to wounds treated with saline or Silvadene vehicles on Days 5, 6, and 8 after injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

Acticoat™ stimulates inflammation,but does not delay healing,in acute full‐thickness excisional wounds

Acticoat? has antimicrobial and anti‐inflammatory effects which aid wound healing. However, in vitro studies indicate that Acticoat? is cytotoxic and clinical and in vivo studies suggest that it may delay healing in acute wounds. Therefore, this study investigated the effects of Acticoat? on healing in acute full‐thickness excisional wounds. Using a porcine model, healing was assessed on days 3, 6, 9 and 15 post‐wounding. Five wounds dressed with Acticoat? and five wounds dressed with polyurethane film (control) were assessed per day (n = 40 wounds). The rate of healing, inflammatory response, restoration of the epithelium and blood vessel and collagen formation were evaluated. No difference was found in the rate of healing between wounds treated with Acticoat? and the control wounds. Inflammation was increased in Acticoat?‐treated wounds on day 3 post‐wounding compared to the control wounds. However, by day 15 post‐wounding, the epithelium of the Acticoat?‐treated wounds closely resembled normal epithelium. Acticoat?‐treated wounds also contained a higher proportion of mature blood vessels, and differences in collagen deposition were apparent. Despite inducing an inflammatory response, Acticoat? did not delay healing in acute wounds. Conversely, the improved quality of the epithelium and blood vessels within Acticoat?‐treated wounds indicates that Acticoat? has a beneficial effect on healing.     

Effect of ultraviolet therapy on rat skin wound healing

Ultraviolet (UV) light therapy has been suggested as a treatment for pressure sores and crural ulcerations even though controlled trials are few. Therefore, the effect of UV light therapy on wound healing was studied in rat skin. A dose-dependent, significant improvement in the diminution of wound size was found between 4 and 15 days in wounds treated with UV as compared with untreated control wounds in the opposite side of the same animals. Wound closure, however, did not occur earlier in the treated wounds. UV had a marked warming effect; warmth alone without UV had no effect on wound healing. No significant difference was found in the tensile strength of UV-treated wounds at 7 and 15 days when compared with untreated wounds. Moreover, the intensity of the inflammation was equal in both treated and control wounds when studied histologically. We did not find any effect on clinical infection rate or bacterial colonization of the wounds. Although UV therapy seems to have an effect on wound healing in rat skin the present results are rather nonsupportive of the clinical benefits that are expected from this kind of treatment.     

A modified collagen gel dressing promotes angiogenesis in a preclinical swine model of chronic ischemic wounds

We recently performed proteomic characterization of a modified collagen gel (MCG) dressing and reported promising effects of the gel in healing full‐thickness excisional wounds. In this work, we test the translational relevance of our aforesaid findings by testing the dressing in a swine model of chronic ischemic wounds recently reported by our laboratory. Full‐thickness excisional wounds were established in the center of bipedicle ischemic skin flaps on the backs of animals. Ischemia was verified by laser Doppler imaging, and MCG was applied to the test group of wounds. Seven days post wounding, macrophage recruitment to the wound was significantly higher in MCG‐treated ischemic wounds. In vitro, MCG up‐regulated expression of Mrc‐1 (a reparative M2 macrophage marker) and induced the expression of anti‐inflammatory cytokine interleukin (IL)‐10 and of fibroblast growth factor‐basic (β‐FGF). An increased expression of CCR2, an M2 macrophage marker, was noted in the macrophages from MCG treated wounds. Furthermore, analyses of wound tissues 7 days post wounding showed up‐regulation of transforming growth factor‐β, vascular endothelial growth factor, von Willebrand's factor, and collagen type I expression in MCG‐treated ischemic wounds. At 21 days post wounding, MCG‐treated ischemic wounds displayed higher abundance of proliferating endothelial cells that formed mature vascular structures and increased blood flow to the wound. Fibroblast count was markedly higher in MCG‐treated ischemic wound‐edge tissue. In addition, MCG‐treated wound‐edge tissues displayed higher abundance of mature collagen with increased collagen type I : III deposition. Taken together, MCG helped mount a more robust inflammatory response that resolved in a timely manner, followed by an enhanced proliferative phase, angiogenic outcome, and postwound tissue remodeling. Findings of the current study warrant clinical testing of MCG in a setting of ischemic chronic wounds.