ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10301.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10302.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

Connective tissue formation is markedly reduced in full‐thickness mouse dermal wounds that are covered with synthetic, adherent, moisture vapor—permeable membrane when compared with formation in similar but nonoccluded wounds. The transforming growth factors‐β (TGF‐β) are a family of multifunctional peptides thought to have a critical role in the regulation of development and tissue repair. Treatment with exogenous TGF‐β1stimulated connective tissue formation in wounds covered with synthetic, adherent, moisture vapor—permeable membrane but had no effect on air‐exposed wounds, suggesting that the quantity of endogenous TGF‐β1in wounds covered with synthetic, adherent, moisture vapor—permeable membrane was less than that in air‐exposed wounds. Immunolocalization studies with an anti‐TGF‐β1antibody confirmed that wounds covered with synthetic, adherent, moisture vapor—permeable membrane demonstrated markedly reduced levels of endogenous extracellular, matrix‐associated TGF‐β1as early as 24 hours after wounding. Immunoreactive TGF‐β2was not detected. These findings suggest that endogenous TGF‐β1, but not TGF‐β2, is required for normal connective tissue formation in this model and that impaired healing is associated with low levels of TGF‐β1. Histologic analysis confirmed previous demonstrations that exogenous TGF‐β2stimulates enhanced cellularity and connective tissue formation. Immunolocalization showed that exogenous TGF‐β2stimulates increased expression of endogenous TGF‐β1. Northern blot analysis revealed that TGF‐β2increased the expression of genes encoding the α1‐chain of types I and III collagens and tissue inhibitor of metalloproteinase‐1. These observations show that TGF‐β2acts through a variety of mechanisms to stimulate repair in healing‐impaired wounds that are also deficient in endogenous TGF‐β1, but they do not distinguis

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10303.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

The perforated rat mesentery model was used to study the effect of transforming growth factor‐β (TGF‐β) on connective tissue repair and influx of macrophages into the peritoneal cavity during such repair. Sprague‐Dawley rats were laparotomized, and mesenteric wounds were made with a scalpel. A daily intraperitoneal injection of 0.5 µg TGF‐β was given for either 2 or 4 days. After 1 to 10 days, the animals received an intravenous injection of tritium‐labeled thymidine before decapitation. Macrophages were collected by peritoneal washing, and the number of closed perforations was counted. Peritoneal cells were quantitated and a labeling index was determined by autoradiography. TGF‐β given for either 2 (p<0.001) or 4 (p<0.004) days accelerated closure of perforations on days 3 to 7 after injury. Laparotomy as such significantly increased leukocyte influx (p<0.004), as well as macrophage‐labeling index (p<0.02). However, TGF‐β did not significantly influence either leukocyte influx or macrophage‐labeling index. We concluded that TGF‐β significantly enhances connective tissue repair in this perforated rat mesentery model and that TGF‐β—induced stimulation of repair is not caused by an increased influx of macroph

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10304.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

Hypertrophic scars, which commonly occur after thermal and traumatic injury of the skin, are a fibroproliferative disorder of the dermal matrix wherein components of the inflammatory process, including the fibrotic growth factor, transforming growth factor‐β, appear to activate dormant fibroblasts leading to cellular proliferation and excessive matrix synthesis. To investigate the potential beneficial role and mechanism of interferon alfa‐2b in controlling excessive collagen production in hypertrophic scar, we measured dose response, time of onset, and duration of action in hypertrophic scar fibroblasts in vitro and compared them with those of site‐matched normal fibroblasts obtained from four patients after thermal injury. Interferon alfa‐2b reduced collagen protein synthesis and type I messenger RNA levels in both hypertrophic scar and normal fibroblasts after treatment, but these changes were apparent only after approximately 72 hours. Significant reductions in collagen synthesis occurred in four pairs of normal and hypertrophic scar fibroblasts (p<0.05), accompanied by significant reductions in type I (p<0.05) but not type III procollagen messenger RNA. Hypertrophic scar fibroblasts recovered completely from the effects of interferon alfa‐2b on procollagen type I messenger RNA within 48 hours of cessation of treatment in contrast to normal skin fibroblasts, in which the reduction in type I procollagen messenger RNA by interferon alfa‐2b persisted beyond 72 hours after treatment. These data suggest that interferon alfa‐2b reduces collagen synthesis in both normal and hypertrophic fibroblasts but the hypertrophic fibroblast may remain less sensitive

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10305.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

After severe thermal injury, hypertrophic scarring which is associated with accumulation of extracellular matrix proteins including fibronectin, frequently develops. We have recently demonstrated that interferon alfa‐2b significantly reduces the level of type 1 procollagen messenger RNA expressed by both hypertrophic and normal dermal fibroblasts. In this report, we provide evidence that this cytokine also significantly decreases the expression of fibronectin messenger RNA in human hypertrophic scar and normal dermal fibroblasts. Four dermal fibroblast cell strains were established in cell culture from four human postburn hypertrophic scar tissues with the use of normal dermal fibroblasts from the same patients as controls. These cells were then treated with 2000 U/ml interferon alfa‐2b in culture medium at various times. The results of Northern analysis of interferon‐treated dermal fibroblasts indicate that this cytokine reduced the expression of fibronectin messenger RNA as early as 12 hours after treatment and reached its lowest level (24% relative to untreated fibroblasts) after 96 hours. When the expression of fibronectin messenger RNA was quantified by densitometry for each individual paired cell strain, a differential response to interferon treatment was found among cell strains. The level of fibronectin messenger RNA expression decreased from 17.2% to 69% in hypertrophic scar fibroblasts and 47% to 83.7% in normal fibroblasts relative to that of untreated control values. Although this decrease was less pronounced in normal fibroblasts than in hypertrophic scar fibroblasts, this reduction was significant in both interferon alfa‐2b treated hypertrophic scar fibroblasts (6.39 ± 0.71 versus 2.88 ± 0.9,n= 4,p<0.05) and normal cells compared with untreated controls (5.47 ± 0.89 versus 3.64 ± 0.99,n= 4,p<0.05) as assessed with Student's pairedttest. Rehybridization of the RNA blot prepared from interferon alfa‐2b treated and untreated hypertrophic scar fibroblasts with a complementary DNA for the tissue inhibitor of metalloproteinase type 2 gelatinase inhibitor showed no significant changes in abundance of this transcript. This result suggests that this cytokine selectively suppresses the expression of fibronectin messenger RNA and that this reduction is not due to RNA loading. A dot blot analysis of total RNA extracted from these tissues was carried out to compare the expression of fibronectin messenger RNA between human hypertrophic scar tissues and normal dermis obtained from the same patients. The blot was initially hybridized with fibronectin complementary DNA and subsequently with a complementary DNA for the tissue inhibitor of metalloproteinase type 2 to correct for RNA loading. When the ratio of fibronectin to tissue inhibitor or metalloproteinase type 2 messenger RNA expression for each hypertrophic scar tissue was compared with its normal control, this ratio was fourfold higher in human hypertrophic scar tissues relative to normal controls. In contrast, the expression of this message in cultured hypertrophic scar fibroblasts was not significantly different from that in normal fibroblasts. The results of this study suggest that hypertrophic scarring developing after thermal injury is associated with an overexpression of fibronectin messenger RNA, and interferon alfa‐2b may be of therapeutic value to down‐regulate the expression o

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10306.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

Reepithelialization of the airway mucosa is an essential step toward restoring a normal functional protective barrier during the repair of airway epithelial wounds. We investigated the role of epidermal growth factor in the wound healing of human surface epithelial cells cultured from nasal polyp explants on a type I collagen gel in serum‐free defined medium. By using image analysis techniques, we measured the outgrowth area, the ciliated surface, the ciliary beating frequency, and the in vitro wound repair rate in the presence of different epidermal growth factor concentrations. We observed a significant dose‐dependent increase in the outgrowth area (10‐fold increase with epidermal growth factor doses of 0 to 20 ng/ml), in the percentage of the outgrowth surface covered by ciliated cells (30% without epidermal growth factor and 43% with epidermal growth factor 20 ng/ml) and in the ciliary beating frequency (12.6 to 14.5 Hz). The wound repair rate was improved by 29% in the presence of epidermal growth factor 10 ng/ml. These results suggest that epidermal growth factor could be involved in the wound repair process of the airway epith

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10307.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

It has been proposed that occlusive wound dressings may enhance chronic wound repair by the stimulatory action of the fluid accumulating beneath the dressings. In this report, we investigated the in vitro proliferative effects of chronic wound fluid obtained from under a polyurethane membrane applied for 24 hours to venous ulcers in the ambulatory setting. By measuring cell counts and DNA synthesis, we found that chronic wound fluid inhibited the proliferation of human dermal fibroblasts (p= 0.008) and failed to stimulate the proliferation of microvascular endothelial cells (p= 0.03) and keratinocytes (p= 0.03). The inhibitory activity of chronic wound fluid on fibroblast proliferation was blocked after the fluid was heated to 100° C, but not 56° C, and was mainly restricted to a fraction of chronic wound fluid enriched in components less than 30 kd in molecular weight (p= 0.028). At concentrations ranging from 1% to 4% and in the presence of serum, chronic wound fluid decreased the viability of fibroblasts, as shown by a decreased ability of the cells to exclude trypan blue (p= 0.02), and the viability of endothelial cells, as shown by an increased release of tritiated adenine (p= 0.03). We conclude that the wound fluid obtained from beneath occlusive dressings applied to chronic wounds inhibits cell proliferatio

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10308.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

摘要:

Inhibition of wound healing by bacteria may result in part from the conversion of plasminogen to plasmin. This conversion results in dissolution of the fibrin seal in a wound or between skin graft and bed. Aprotinin blocks conversion to plasmin, preserving the fibrin clot. The current study was undertaken to determine the effects of high concentrations of bacteria on wound healing and how these effects are mitigated by aprotinin. Dorsal full‐thickness skin incisions were made in 40 anesthetized guinea pigs and closed with nylon sutures. Animals were divided into four groups: (1) control wounds, (2) infected wounds, (3) wounds treated with aprotinin, and (4) infected wounds plus aprotinin (single dose). Animals were killed 3 and 4 weeks after the operation. Skin strips containing segments of the healing wounds were pulled apart by a tensiometer until rupture. Stress‐strain curves were generated, and wound strength and toughness were determined. All wounds, including those inoculated with bacteria, appeared healed. The 3‐week infected group healed with the least strength and toughness (p<0.001). A single dose of aprotinin administered with the bacterial inoculum reversed this inhibition. In the 4‐week groups, the strongest and toughest wounds resulted from bacterial inoculation alone. Aprotinin alone augmented wound healing when compared with controls. These data suggest that wound healing in both clean and infected wounds is augmented when the plasminogen‐plasmin pathway is

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10309.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY

ISSN:1067-1927    

DOI:10.1046/j.1524-475X.1993.10310.x

出版商:Blackwell Science    

年代:1993

数据来源: WILEY