Showing papers in "Wound Repair and Regeneration in 1994"
TL;DR: The report that follows defines wound, acute wound, chronic wound, healing and forms of healing, wound assessment, wound extent, wound burden, and wound severity, broadly applicable to all wounds.
Abstract: Chronic wounds represent a worldwide problem. For laboratory and clinical research to adequately address this problem, a common language needs to exist. This language should include a system of wound classification, a lexicon of wound descriptors, and a description of the processes that are likely to affect wound healing and would healing end points. The report that follows defines wound, acute wound, chronic wound, healing and forms of healing, wound assessment, wound extent, wound burden, and wound severity. The utility of these definitions is demonstrated as they relate to the healing of a skin wound, but these definitions are broadly applicable to all wounds.
574 citations
TL;DR: In a porcine wound model, full‐thickness wounds were substituted by reconstituted and native collagen sponges in combination with autologous split‐skin mesh grafts and covered with a semipermeable wound membrane, and the native collagen/elastin matrix resulted in optimal dermal regeneration and little wound contraction.
Abstract: Collagenous dermal templates can prevent scarring and wound contraction in the healing of full-thickness defects. In a porcine wound model, full-thickness wounds were substituted by reconstituted and native collagen sponges in combination with autologous split-skin mesh grafts and covered with a semipermeable wound membrane. Native collagen sponges were also linked with either hyaluronic acid, elastin, or fibronectin. Reconstituted collagen matrixes, composed of cross-linked small collagen fibrils, disintegrated within a week and did not contribute to dermal regeneration, whereas native collagen matrixes, composed of intact collagen fibers, disintegrated within 2 weeks and did contribute to dermal regeneration. Addition of extracellular matrix proteins retarded the disintegration to 4 weeks. However, fibronectin-treated matrixes caused aberrant epithelization. When hyaluronic acid was added, matrixes were invaded by more fibroblasts and myofibroblasts. This process correlated with fibrosis and wound contraction. In contrast, the native collagen/elastin matrix reduced the amount of fibroblasts and myofibroblasts. This latter matrix resulted in optimal dermal regeneration and little wound contraction.
89 citations
TL;DR: Mild hypothermia during halothane‐induced anesthesia slightly impairs resistance to dermal infection in guinea pigs and no difference was found between the hypothermic and normothermic animals.
Abstract: Because various immune functions are impaired at temperatures only 1 degrees to 3 degrees C less than normal, we tested the hypothesis that mild hypothermia during anesthesia impairs resistance to dermal infections. Guinea pigs were anesthetized for 6 hours with 1% inspired halothane. Their core temperatures were maintained at either 39 degrees C (normal for guinea pigs, n = 12) or 36 degrees C (n = 12). Two hours after induction of anesthesia, three doses each of Staphylococcus aureus (10(8), 10(7), and 10(6) organisms) were injected intradermally at nine sites on each animal's back. Core temperatures were not controlled after recovery from the anesthetic, and animals in each group were maintained in the same environment. Four days after anesthesia, each injection site was excised to obtain a count of viable bacteria. Subcutaneous oxygen partial pressure values, averaged over time, were 53 +/- 3 mm Hg (mean +/- SEM) in the hypothermic group and 62 +/- 4 mm Hg in the normothermic group (p = 0.06). Capillary perfusion, as assessed by laser Doppler flowmetry, was comparable in the two groups. One day after injection of 10(8) bacteria, the area of induration was 89 +/- 11 mm(2) in the hypothermic group but only 61 +/- 6 mm(2) in the normothermic group (p 0.05). After inoculation with 10(8) bacteria, the fraction recovered was 1.0 +/- 0.2 in the hypothermic groups and 0.6 +/- 0.2 in the normothermic group (p < 0.05). After inoculation with 10(7) and 10(6) bacteria, the fraction recovered was less than 0.2, and no difference was found between the hypothermic and normothermic animals. Thus mild hypothermia during halothane-induced anesthesia slightly impairs resistance to dermal infection.
62 citations
TL;DR: The fibrinolytic system seems to be intimately involved in the early formation of intraabdominal adhesions, as shown in rabbits tested in a controlled prospective study in rabbits.
Abstract: It has been hypothesized that peritoneal hypofibrinolysis is of importance in the formation of postoperative adhesions, but results from experiments with fibrinolytic modulators are conflicting. We tested this hypothesis in a controlled prospective study in rabbits, comparing the effects of fibrinolytic inhibition (tranexamic acid) to fibrinolysis enhancement by local instillation of gel containing tissue-type plasminogen activator. Adhesion formation was measured after 1 week in a strictly standardized way and is presented as a percentage of an induced lesion that was covered by adhesions. Fibrinolytic inhibition significantly increased adhesion formation, both to the parietal peritoneum (34.2%+/- 3.2%) compared with untreated control (19.7%+/- 3.3%, p < 0.01) and to the bowel (76.3%+/- 5.8%) compared with untreated control (51.2%+/- 8.7%, p < 0.05). Control gel significantly increased adhesions to the parietal peritoneum (35.6%+/- 4.6%) versus untreated control (19.7%+/- 3.3%, p < 0.05), whereas gel containing tissue-type plasminogen activator significantly reduced the amount of adhesions to the parietal peritoneum (4.9%+/- 1.7%) compared with untreated control (19.7%+/- 3.3%, p < 0.01) and abolished adhesion formation to the injured bowel. The fibrinolytic system thus seems to be intimately involved in the early formation of intraabdominal adhesions.
57 citations
TL;DR: Data suggest that concentrations of transforming growth factor‐β isoforms rather than total transforming growthfactor‐β concentration may be important in the regulation of fibrosis in prenatal and postnatal wound healing.
Abstract: Macrophages are believed to play a crucial role in wound healing by synthesizing and secreting numerous cytokines. Some of these cytokines, such as transforming growth factor-beta and tumor necrosis factor-alpha, promote fibrosis and repair. We have shown that macrophages are recruited to sterile fetal wounds and have the potential to regulate repair by synthesizing transforming growth factor-beta(1), transforming growth factor-beta(2), and tumor necrosis factor-alpha. Transforming growth factor-beta was present in fetal lamb wounds in higher amounts than in adult sheep wounds. Furthermore, the concentrations and ratios of the transforming growth factor-beta isoforms in wounds that healed without scarring were different from those in wounds that scarred; transforming growth factor-beta(2) was highest in fetal wounds that did not scar and lowest in adult wounds. These data suggest that concentrations of transforming growth factor-beta isoforms rather than total transforming growth factor-beta concentration may be important in the regulation of fibrosis in prenatal and postnatal wound healing.
47 citations
TL;DR: Treatment with lamin Gel significantly increased the percentage of closure of plantar ulcers and the proportion of patients healing 98% or better and the rate of closure was three times faster with lamination Gel treatment compared with standard care and vehicle.
Abstract: A multicenter, randomized, evaluator-blinded, placebo-controlled clinical study was conducted to evaluate the safety and effectiveness of glycyl-l-histidyl-l-lysine: copper complex (lamin Gel) in the treatment of diabetic neuropathic ulcers. All patients were enrolled in an aggressive standardized wound care protocol consisting of sharp debridement at study entry, daily application of a metered dose of drug, standardized pressure-relieving footwear, and patient education relating to diabetes control and activity modifications. Treatment with lamin Gel significantly increased the percentage of closure of plantar ulcers (98.5% median area percentage closure compared with 60.8% for vehicle; p < 0.05) and the proportion of patients healing 98% or better. The rate of closure was three times faster with lamin Gel treatment compared with standard care and vehicle. The enhancement of wound closure was more pronounced (median of 89.2% compared with -10.3% for vehicle; p < 0.01) in larger (greater than 100 mm(2) initial area at study entry) plantar ulcers caused by the failure of this size of ulcer to respond adequately to standardized wound care treatments in the absence of lamin Gel. Treatment must commence immediately after the initial wound debridement to obtain optimal enhancement of the ulcer closure. The incidence of ulcer infections was significantly lower (7% incidence compared with 34% for vehicle, p < 0.05) in the plantar ulcers treated immediately after debridement with the lamin Gel.
47 citations
TL;DR: Use of recombinant human interleukin‐1β in this study was safe but, at the dose levels tested, did not result in improvement in the healing ratio.
Abstract: Interleukin-1beta is produced by numerous cell types including monocytes and fibroblasts. It has been shown to stimulate multiple cell types including fibroblasts, keratinocytes, endothelial cells, neutrophils, macrophages, and lymphocytes. Previously, interleukin-1beta was shown to accelerate healing in partial-thickness and full-thickness wounds in animals and was also shown to be safe when applied topically in Phase I human trials. Therefore a prospectively randomized, blind, placebo-controlled trial was performed with patients with chronic pressure ulcers. Doses of interleukin-1beta of .01 microg, .10 microg, and 1.0 microg per square centimeter did not show acceleration of healing of the pressure ulcers. Therefore use of recombinant human interleukin-1beta in this study was safe but, at the dose levels tested, did not result in improvement in the healing ratio.
37 citations
TL;DR: This work has developed a biosynthetic wound dressing with a drug delivery capability that is capable of suppressing bacterial growth and minimizing cellular damage in the treatment of wounds inflicted on rats and rabbits and was evaluated in a nonrandomized open‐label study of 31 clinical cases.
Abstract: A bilaminar wound dressing composed of an outer membrane and an inner three-dimensional matrix of a fabric or a sponge may be considered to constitute an ideal structure that promotes wound healing: the outer membrane prevents body fluid loss, controls water evaporation, and protects the wound surface from bacterial invasion, and the inner matrix encourages adherence by tissue growth into the matrix. Using this concept, we developed a biosynthetic wound dressing with a drug delivery capability. This medicated wound dressing is composed of a spongy sheet of a chitosane derivative and collagen mixture that is laminated to an antimicrobial-impregnated polyurethane membrane. In this study, a gentamycin sulfate-impregnated wound dressing was prepared and evaluated. The antimicrobial efficacy of this wound dressing was examined on an agar plate seeded with Pseudomonas aeruginosa. Also, the cytotoxicity of an antimicrobial released from this wound dressing was examined in an in vitro system with cultured skin substitutes. Both in vitro tests have shown that this wound dressing is capable of suppressing bacterial growth and minimizing cellular damage. In addition, in the treatment of wounds inflicted on rats and rabbits, this wound dressing was shown to be efficacious in covering full-thickness and split-thickness skin defects. Finally, the efficacy of this wound dressing was evaluated in a nonrandomized open-label study of 31 clinical cases. In 31 cases treated with this wound dressing, good or excellent wound healing was achieved.
37 citations
TL;DR: The results suggest that the combination of platelet‐derived growth factor‐BB and insulin‐like growth factor-I stimulates bone formation in wounds in long bones of adult animals and that these growth factors act via different pathways during the repair process.
Abstract: The combination of insulin-like growth factor-I and platelet-derived growth factor-BB has previously been shown to stimulate healing of soft tissue wounds and the formation of bone and ligament around teeth. The purpose of the present study was to evaluate the effects of platelet-derived growth factor-BB and insulin-like growth factor-I individually and in combination on the healing of osseous wounds. Four standardized cortical wounds were created in each tibia of 11 adult Yucatan miniature pigs. The wounds in one tibia per animal were treated with either purified recombinant human insulin-like growth factor-I, platelet-derived growth factor-BB, or both in a methylcellulose gel. The wounds in each contralateral tibia received placebo gel alone. Coded serial sections of each wound were evaluated by computer-aided histomorphometry 21 days after surgery. The area and perimeter of the newly formed mineralized callus, the thickness of the total callus, and the percentage of mineralized tissue within the callus were significantly increased compared with the values of matched controls only in wounds treated with a combination of insulin-like growth factor-I and platelet-derived growth factor-BB. No significant differences in the measured parameters of callus formation were found in wounds treated with either insulin-like growth factor-I or platelet-derived growth factor-BB alone. Cartilage was present only in sites treated with insulin-like growth factor-I alone. These results suggest that the combination of platelet-derived growth factor-BB and insulin-like growth factor-I stimulates bone formation in wounds in long bones of adult animals and that these growth factors act via different pathways during the repair process.
36 citations
TL;DR: The results indicate that differential responsiveness to growth factors is related to local tissue hypoxia, angiogenesis alone is an insufficient stimulus for repair, and suggest new therapeutic approaches for the treatment of chronic wounds.
Abstract: Both recombinant basic fibroblast growth factor and platelet-derived growth factor-BB homodimer are potent inducers of new tissue generation in models of normal dermal repair. However, their therapeutic targets include chronic wounds, which are frequently characterized by local tissue hypoxia. To explore the potential of recombinant basic fibroblast growth factor and platelet-derived growth factor-BB homodimer to stimulate more clinically relevant repair, we created an ischemic dermal wound on the rabbit ear by ligating two of the arteries which feed the ear. Both recombinant basic fibroblast growth factor and platelet-derived growth factor-BB homodimer stimulated marked neovascularization of the wound (p < 0.0001), but only recombinant platelet-derived growth factor-BB homodimer accelerated and augmented granulation tissue formation (p = 0.01) and reepithelialization. This study is the first demonstration of a direct angiogenic effect of recombinant platelet-derived growth factor-BB homodimer in vivo. India ink perfusion coupled with endothelial cell-specific histochemistry showed that nearly all the neovessels in all wounds were functional, indicating rapid capillary morphogenesis. In the nonischemic (normal) rabbit ear, recombinant basic fibroblast growth factor and platelet-derived growth factor-BB homodimer accelerated healing comparably, as expected. Higher doses of recombinant basic fibroblast growth factor also failed to elicit stimulatory effects in ischemic wounds. These results indicate that differential responsiveness to growth factors is related to local tissue hypoxia, angiogenesis alone is an insufficient stimulus for repair. These data also suggest new therapeutic approaches for the treatment of chronic wounds.
34 citations
TL;DR: Oxygen treatment seemed to enhance the healing response significantly and oxygen‐impermeable dressings may be useful only in the early stages of healing, before granulation tissue formation.
Abstract: Although it has been shown that both the level of tissue oxygen and its gradient are critical factors in the healing process, optimal conditions for oxygen therapy have not been determined. In this study, both the oxygen level and oxygen gradient for a full-thickness defect were modified on the basis of preceding in vitro studies to determine the effect on the healing process. The goal of this study was to help determine the optimal clinical oxygen treatment protocol. Specifically, the healing of full-thickness defects in a rabbit model as determined by histomorphometric analyses (cell and tissue volume fraction, epithelialization, and contraction) under two types of dressings with or without oxygen treatment (70% O(2)) was investigated. One of the dressings was more oxygen permeable than the other. No significant differences were found in the histomorphometric response between the wounds covered with the oxygen-permeable and oxygen-impermeable dressings in the group without supplemental oxygen. Oxygen treatment, however, seemed to enhance the healing response significantly. According to the histomorphometric response, the wounds covered with the oxygen-impermeable dressings were significantly better than those with the oxygen-permeable dressing in the oxygen-treated group after 1 week, but the wounds covered by the oxygen-permeable dressings were better healed at 3 weeks. Therefore, oxygen-impermeable dressings may be useful only in the early stages of healing, before granulation tissue formation.
TL;DR: The use of endogenous growth regulatory peptides in topical ophthalmic and chronic cutaneous wound healing and regulatory expectations with respect to product quality, safety, and efficacy that may be particularly germane to these products will be discussed.
Abstract: The use of recombinant DNA technology has enabled the development of an increasing number of endogenous growth regulatory peptides for potential use as therapeutic biologics. Numerous such recombinant peptides are now licensed, and many are in various stages of pharmaceutical development. Although currently there are a number of "Points to Consider" and related guidance documents available concerning various issues of biotechnology-derived products, the purpose of this article is to focus on the use of these biologics in topical ophthalmic and chronic cutaneous wound healing. Regulatory expectations with respect to product quality, safety, and efficacy that may be particularly germane to these products will be discussed. Providing regulatory guidance on these issues may not only facilitate the introduction of safe and effective new biologic therapies into clinical trials at the investigational level but also provide appropriate information to aid in their eventual approval for licensure and widespread clinical use.
TL;DR: A model in which a wound was created on the ear of the hairless mouse—a well established model for directly viewing and measuring skin microcirculation was used to examine the effect of topical wound agents on epithelialization and neovascularization and suggests clinical implications for their use.
Abstract: Microvascular ingrowth into damaged tissue is an essential component of the normal healing process. In fact, wound therapy is often aimed at promoting neovascularization. However, little is known about the mechanisms that regulate microvascular ingrowth into a healing wound. This limited knowledge is largely due to the lack of adequate models in which microvascular ingrowth can be quantitatively analyzed throughout the healing process. To address this deficiency, we developed a model in which a wound was created on the ear of the hairless mouse-a well established model for directly viewing and measuring skin microcirculation. While the animals were under ketamine and xylazine anesthesia, 2.25 mm diameter full-thickness wounds were created on the dorsum of hairless mouse ears down to but not including the cartilage (0.125 mm depth). With the use of video microscopy and computer-assisted digitized planimetry, the precise epithelial and neovascular wound edge was viewed and measured regularly throughout healing. Therefore, this model can provide objective data on wound epithelialization and neovascularization throughout healing. This model was used to examine the effect of topical wound agents on epithelialization and neovascularization. Differential effects by these anti-microbial agents on these two processes were observed, which suggests clinical implications for their use.
TL;DR: It is concluded that the highly organized collagen deposition in scarless human fetal wound repair appears to be intrinsic to the human fetal fibroblasts and occurs in the absence of an adult‐like inflammatory response.
Abstract: The fetus heals skin wounds without scar formation. Human fetal skin that is transplanted to a subcutaneous location on an adult athymic mouse and subsequently wounded heals without scar formation, whereas the same skin heals with scar formation when transplanted to a cutaneous location. In situ hybridization with species-specific DNA probes and immunohistochemistry were performed to characterize the healing process of human fetal skin in these two locations. Species-specific human and mouse DNA probes were constructed and used to probe graft wounds under high stringency in situ hybridization conditions. Immunostaining for species-specific fibroblasts, macrophages, and neutrophils was also performed. We found that the cutaneous human fetal grafts healed with scar and showed an influx of mouse fibroblasts and macrophages. In contrast, subcutaneous human fetal grafts showed exclusively human fetal fibroblasts in the wound environment, an absence of inflammatory cells, and scar-free repair. We conclude that the highly organized collagen deposition in scarless human fetal wound repair appears to be intrinsic to the human fetal fibroblasts and occurs in the absence of an adult-like inflammatory response.
TL;DR: In vivo, the steady state content of fibronectin messenger RNA and protein was highest in abnormal wounds, less in most normal scars, and lowest in normal skin, while in vitro, fibroblasts from keloids and hypertrophic scars overexpressed fibronECTin in vivo relative to normal skin and normal scar and retain this characteristic in vitro relative tonormal skin.
Abstract: The overproduction of fibronectin and type I collagen in keloids and hypertrophic scars implicates altered regulation of extracellular matrix components as an important aspect of these wound healing pathologies. However, little is known about the similarities and differences in extracellular matrix gene expression during normal and abnormal wound healing. This study compared the content of fibronectin messenger RNA and rates of fibronectin protein biosynthesis in fibroblasts derived from normal skin, normal scar, keloid, and hypertrophic scar. Fibronectin expression was enhanced in cells from both normal and abnormal wounds relative to cells from quiescent normal skin. Matched pairs of normal and keloid fibroblasts from the same individuals were also compared, and three of the four pairs showed higher fibronectin expression by the keloid cells at the levels of messenger RNA and protein synthesis. This was consistent with previous studies showing elevated steady state content of fibronectin in keloid cells relative to normal cells from the same individual. Fibronectin messenger RNA and protein content in the tissues from which these cells were derived was examined by in situ hybridization and immunohistochemistry. These studies revealed that in vivo, the steady state content of fibronectin messenger RNA and protein was highest in abnormal wounds, less in most normal scars, and lowest in normal skin. Thus, fibroblasts from keloids and hypertrophic scars overexpressed fibronectin in vivo relative to normal skin and normal scar and retain this characteristic in vitro relative to normal skin. Although normal scars contained little fibronectin protein and messenger RNA, cultured fibroblasts derived from these scars had contents of fibronectin messenger RNA and rates of biosynthesis in vitro similar to those of keloid fibroblasts. This indicates that the fibronectin regulatory pathway in scar fibroblasts is influenced by the tissue environment. These results are discussed with respect to the relationship of fibronectin expression in keloids, hypertrophic scars, and normal wounds in human beings.
TL;DR: Results suggest that the glycosaminoglycan component of the proteoglycan, rather than the protein core, is responsible for the increment of activity of the extracellular matrix analog.
Abstract: Previous studies have shown that a simple analog of extracellular matrix delays wound contraction and, if seeded with keratinocytes, inhibits scar synthesis by inducing partial regeneration of the dermis and the epidermis in full-thickness skin wounds in the guinea pig. The active extracellular matrix analog was selected from a large number of copolymers of type I collagen and chondroitin-6-sulfate differing in average pore diameter and degradation rate. However, these previous studies did not provide information on the potential role of the glycosaminoglycan component of this collagen-glycosaminoglycan matrix. The present study focuses on the effect of substitution of chondroitin-6-sulfate by other glycosaminoglycans or with the corresponding proteoglycans. The three substituents of chondroitin-6-sulfate studied were dermatan sulfate, decorin (a proteoglycan-containing dermatan sulfate chain), and aggrecan (a proteoglycan in which 90% of the glycosaminoglycan component was chondroitin-6-sulfate). Each test matrix was grafted on full-thickness skin wounds in the guinea pig, and the wound contraction kinetics were followed. Previous studies have strongly suggested that delay in onset of contraction is necessary for regeneration. Substitution of chondroitin-6-sulfate by either dermatan sulfate or decorin increased the delay in wound contraction by the greatest increment. However, the difference between substitution either by the dermatan sulfate chains or by the corresponding proteoglycan was not significant. Substitution of chondroitin-6-sulfate by aggrecan did not affect the activity of the extracellular matrix analog. These results suggest that the glycosaminoglycan component of the proteoglycan, rather than the protein core, is responsible for the increment of activity. It is speculated that the morphogenetic activity of the extracellular matrix analog resides in its putative ability to neutralize transforming growth factor-beta, leading thereby to downregulation of the inflammatory response in the wound bed.
TL;DR: Although basic fibroblast growth factor proved safe, no enhancement of donor site healing was seen in this small study, and studies should focus on accelerating healing in patients with larger burns where donor site Healing is delayed and reharvest is required.
Abstract: A phase I/II clinical study was performed to evaluate the safety and potential efficacy of topical recombinant human basic fibroblast growth factor on the healing of partial-thickness skin graft donor sites in burned children. Each child served as his or her own control. In a blinded and random fashion, one donor site was sprayed with basic fibroblast growth factor (5 microg/cm(2)) on days 0 to 4 after harvest, whereas the other site was treated with vehicle. Twelve patients were entered in the study but one patient died of sepsis that was unrelated to growth factor treatment. Of the remaining 11 patients, no adverse events related to basic fibroblast growth factor occurred. Serum basic fibroblast growth factor levels were never detected and antibody levels remained unchanged. No differences in the rate of epithelialization or days until complete closure were noted (basic fibroblast growth factor = 12.9 +/- 3.9 days, placebo = 12.2 +/- 5.5 days; mean +/- standard error of the mean). No differences in pain, itching, wound fragility, erythema, scarring, or pigmentation were noted. All of the scars matured within 1 year with good to excellent results. Investigators, patients, or families could not distinguish between the two wounds. Although basic fibroblast growth factor proved safe, no enhancement of donor site healing was seen in this small study. Because the time for donor site healing limits subsequent autograft use in patients with sizeable burns, studies should focus on accelerating healing in patients with larger burns where donor site healing is delayed and reharvest is required.
TL;DR: Subcutaneous insertion of expanded polytetrafluoroethylene tubes with local anesthesia constitutes a minimally invasive model permitting quantitative and qualitative studies of the wound healing potential in human beings and increments of collagen deposition with time may be easily assessed.
Abstract: Subcutaneous insertion of expanded polytetrafluoroethylene tubes with local anesthesia constitutes a minimally invasive model permitting quantitative and qualitative studies of the wound healing potential in human beings. Light and electron microscopic examination of these implants in rats showed a normally appearing granulation tissue. The amount of hydroxyproline accumulated in the expanded polytetrafluoroethylene tubes may be assayed and converted to collagen content. In 28 surgical patients, the collagen content increased from 6.6 microg/cm (interquartile range: 5.1 to 9.9) after 5 days to 12.4 microg/cm (7.1 to 16.8) after 10 days (p 0.05). No infectious or hemorrhagic complications from the insertion occurred in any of the patients. Increments of collagen deposition with time may be easily assessed by this expanded polytetrafluoroethylene tube model, which is inexpensive and has high patient acceptance. Measurement variability was encountered, which has to be taken into account when designing clinical trials.
TL;DR: Examination of transforming growth factor‐β1 synthesis by human dermal fibroblasts derived from both normal and fibrotic cutaneous tissues found it to cause a dose‐dependent increase in glycosaminoglycan synthesis in hypertrophic scar and normal skin but not in normal scar fibro Blasts in cell‐mediated glycosamine synthesis.
Abstract: Transforming growth factor-beta(1) is a well-known and potent biological response modifier that plays an important role in tissue repair and fibrosis. Among the extracellular constituents known to accumulate in fibrotic tissues, glycosaminoglycans are prominent. In this study we examined transforming growth factor-beta(1) synthesis by human dermal fibroblasts derived from both normal and fibrotic cutaneous tissues. We studied the influence of transforming growth factor-beta(1) on glycosaminoglycan synthesis and explored the role of transforming growth factor-beta(1) as an autocrine mediator of its own expression. These investigations are directed at understanding the persistence of the fibrotic phenotype in scarred skin. Transforming growth factor-beta(1) activity was measured by means of a mink lung epithelium growth inhibitory assay. Replicate explants (n = 3) of fibroblasts each derived from normal skin, normal scar, or hypertrophic scar were studied by adding exogenous transforming growth factor-beta(1) at a concentration range of 0 to 10 ng/ml. The resulting conditioned media were removed and assayed for transforming growth factor-beta(1) activity, then the cells were pulsed for an additional 24 hours with radiolabeled glycosaminoglycan precursor, [(3)H]-glucosamine, to evaluate glycosaminoglycan production. Cell-free glycosaminoglycan synthetic profiles were also developed. Transforming growth factor-beta(1) was found to cause a dose-dependent increase in glycosaminoglycan synthesis in hypertrophic scar and normal skin but not in normal scar fibroblasts in cell-mediated glycosaminoglycan synthesis; the reverse was observed in cell-free glycosaminoglycan synthesis, where transforming growth factor-beta(1) increased glycosaminoglycan synthesis in normal scar but not in normal skin or hypertrophic scar. Most endogenous transforming growth factor-beta(1) existed in latent form for normal skin cells but in active form for normal scar and hypertrophic scar fibroblasts.
TL;DR: I am pleased and greatly honored to have received the first Lifetime Achievement Award from the Wound Healing Society.
Abstract: I am pleased and greatly honored to have received the first Lifetime Achievement Award from the Wound Healing Society. When Drs. Kelman Cohen and Robert Diegelmann called me in July of 1993 to tell me about the award, I was surprised, delighted, and deeply moved. After talking to them, I began to think about how and when I got interested in wound healing and wound healing research . It began when I was a college student.
TL;DR: It is concluded that growth hormone stimulated granulation tissue formation and collagen deposition dose‐dependently in the wound cylinders when injected every third day, and the results suggest that growth hormones treatment does not cause excessive collagen deposition in newly formedgranulation tissue.
Abstract: The influence of growth hormone on granulation tissue formation was investigated in wire mesh cylinders implanted subcutaneously in rats. Two groups of 10 rats (study 1) and 1 group of 12 rats (study 2) were used for the investigation. Growth hormone, 0.02 and 0.2 IU (study 1), 0.05 and 0.2 IU (study 2), or vehicle only, was injected into the cylinders every third day for 16 days. In study 2, wound fluid was aspirated before injection of growth hormone and saved for later analysis of the aminoterminal propeptide of collagen type III. In both studies, growth hormone significantly increased the formation of granulation tissue and of total collagen content dose-dependently, whereas the relative amount of collagen was unaffected by growth hormone treatment. Wound fluid aminopropeptide increased significantly after implantation of the cylinders until day 7, before declining slightly, with no difference between the groups. We conclude that growth hormone stimulated granulation tissue formation and collagen deposition dose-dependently in the wound cylinders when injected every third day. The results suggest that growth hormone treatment does not cause excessive collagen deposition in newly formed granulation tissue.
TL;DR: The data suggest that metabolism, absorption, or distribution of these corticosteroids results in their inability to inhibit collagen synthesis in vivo, and fluorination in the 9α position of the adrenal steroid nucleus is not required for the inhibition of collagen synthesis by methyl‐20‐dihydroprednisolonate.
Abstract: Inhibition of wound healing by anti-inflammatory steroids is associated with decreased collagen synthesis. Methyl-20-dihydroprednisolonate has been previously reported to be anti-inflammatory without inhibiting collagen synthesis in skin when given either subcutaneously or intraperitoneally. The data we now report show that this prednisolone derivative, as well as two 9alpha fluorinated derivatives inhibit both collagen synthesis and pro-alpha(1) (I) collagen gene promoter activity in rat skin fibroblasts. Our data suggest that metabolism, absorption, or distribution of these corticosteroids results in their inability to inhibit collagen synthesis in vivo. In addition our data indicate that fluorination in the 9alpha position of the adrenal steroid nucleus is not required for the inhibition of collagen synthesis by methyl-20-dihydroprednisolonate.
TL;DR: Wound fluids from a repair environment appear to support myoblast proliferation early but suppress myOBlast differentiation later, suggesting that the wound repair environment cannot fully support skeletal muscle regeneration.
Abstract: The ability of wound fluids to support events required for skeletal muscle regeneration was examined. Wound fluids were obtained from polyvinyl alcohol sponges 1, 3, 5, 10, and 15 days after implantation. Neonatal rat L8 myoblasts were used to test the ability of early wound fluids to promote myoblast proliferation and late wound fluids to promote myoblast differentiation-two characteristics deemed critical for effective skeletal muscle regeneration. Early wound fluids (1- and 3-day) stimulated DNA replication by myoblasts, as judged by tritiated thymidine uptake, up to ninefold (p < 0.05). Later wound fluids (5-, 10-, and 15-day) displayed decreasing ability to stimulate proliferation, with 15-day wound fluid failing to significantly stimulate proliferation. In contrast, myoblast differentiation, as judged by myotube fusion and creatine kinase activity, was progressively reduced by wound fluids of increasing age. In fact, late wound fluids (5, 10, and 15 days) reduced myotube fusion by 88% to 100% and depressed creatine kinase activity by 60% to 75% (p < 0.05). Thus, wound fluids from a repair environment appear to support myoblast proliferation early but suppress myoblast differentiation later. These characteristics suggest that the wound repair environment cannot fully support skeletal muscle regeneration.