Expression of transforming growth factor beta(1), beta(3), and basic fibroblast growth factor in full-thickness skin wounds of equine limbs and thorax

Objective-To map the expression of transforming growth factor (TGF)-beta (1 ), TGF-beta (3), and basic fibroblast growth factor (bFGF) in full-thicknes s skin wounds of the horse. To determine whether their expression differs b etween limbs and thorax, to understand the pathogenesis of exuberant granul ation tissue. Study Design-Six wounds were created on one lateral metacarpal area and one midthoracic area of each horse. Sequential wound biopsies allowed comparis on of the temporal expression of growth factors between limb and thoracic w ounds. Animals-Four 2- to 4-year-old horses. Methods-Wounds were assessed grossly and histologically at 12 and 24 hours, and 2, 5, 10, and 14 days postoperatively. ELISAs were used to measure the growth factor concentrations of homogenates of wound biopsies taken at the same timepoints. Results-TGF-beta (1) peaked at 24 hours in both locations and returned to b aseline in thoracic wounds by 14 days but remained elevated in limb wounds for the duration of the study. Expression kinetics of TGF-beta (3) differed from those of TGF-beta (1). TGF-beta (3) concentrations gradually increase d over time, showing a trend toward an earlier and higher peak in thoracic compared with limb wounds. bFGF expression kinetics resembled those of TGF- beta (1), but no statistically significant differences existed between limb and thoracic wounds. Conclusions-Growth factor expression is up-regulated during normal equine w ound repair. TGF-beta (1) and TGF-beta (3) show a reciprocal temporal regul ation. Statistically significant differences exist between limb and thoraci c wounds with respect to TGF-beta (1) expression. Clinical Relevance-The persistence of TGF-beta (1) expression in leg wounds may be related to the development of exuberant granulation tissue in this location, because TGF-beta (1) is profibrotic. (C) Copyright 2001 by The Am erican College of Veterinary Surgeons.