Preliminary observations on expression of transforming growth factors β1 and β3 in equine full-thickness skin wounds healing normally or with exuberant granulation tissue

Abstract

Objective - To determine whether transforming growth factor (TGF)-β1 and β3 expression differs between equine limb wounds healing normally and those healing with experimentally induced exuberant granulation tissue (EGT). Study Design - Six wounds were created on the lateral aspect of both metacarpi of each horse; one forelimb was untreated, and the other was bandaged to stimulate the development of EGT. Sequential wound biopsies allowed comparison of growth factor expression between the two types of wound. Animals - Four horses (2 to 4 years of age; 350 to 420 kg). Methods - Wounds were assessed grossly, histologically, and by enzyme-linked immunosorbent assay (ELISA) for TGF-β1 and -β3 expression at 12 and 24 hours and 2, 5, 10, and 14 days postoperatively. Results - Bandaged wounds developed EGT. In all wounds, TGF-β1 peaked early and remained elevated at 14 days. Peak TGF-β1 concentration was higher in wounds with EGT, but not significantly so. Expression of TGF-β3 differed from TGF-β1, with peak TGF-β3 concentrations being delayed. Concentrations of TGF-β3 were higher in wounds healing normally, but this difference was not significant. Conclusions - During both normal and exuberant wound repair, the expression of TGF-β1 occurred earlier than TGF-β3 expression. Wounds healing with EGT tended to have higher concentrations of fibrogenic TGF-β1 and lower concentrations of antifibrotic TGF-β3 than wounds healing normally, although these differences were not statistically significant. Clinical Relevance - This study suggests that the production of EGT in bandaged wounds may be related to increased expression of fibrogenic TGF-β1 and decreased expression of antifibrotic TGF-β3. Further investigation of the roles of TGF-β1 and -β3 may be important in understanding the molecular control of EGT in horses. © Copyright 2002 by The American College of Veterinary Surgeons.