Preliminary observations on expression of transforming growth factors beta1 and beta3 in equine full-thickness skin wounds healing normally or with exuberant granulation tissue.

This research article investigates if the expression of transforming growth factor beta1 and beta3 varies in normal healing horse wounds and those healing with experimentally induced excessive tissue. The study suggests that an increased expression of fibrogenic beta1 and decreased expression of antifibrotic beta3 may be associated with excessive tissue development in bandaged wounds.

Research Purpose and Methodology

• The study aimed to find out if there is a difference in the expression of two types of transforming growth factor (TGF)- beta1 and beta3 across two types of wounds in horses – one healing normally and another healing with experimentally induced exuberant granulation tissue (EGT), which is an excessive tissue.
• For the experiment, six wounds were created on each horse’s lateral metacarpi aspect. One forelimb was left untreated, while the other was bandaged to stimulate EGT development. The research involved four horses that were 2 to 4 years old and weighed between 350 to 420 kg.
• The experiment used wound biopsies, allowing a comparison of the growth factor expression between the two types of wounds.
• Wound evaluations were done visually, histologically, and using an enzyme-linked immunosorbent assay (ELISA) to assess TGF-beta1 and beta3 expression at several time intervals post-surgery- 12 and 24 hours and 2, 5, 10, and 14 days.

Research Findings

• It was observed that the bandaged wounds developed EGT. Also, TGF-beta1 peaked early and stayed elevated by the 14th day. Though the peak concentration of TGF-beta1 was higher in wounds with EGT, it was not significantly so.
• The expression pattern of TGF-beta3 was different from TGF-beta1 as TGF-beta3’s peak concentrations were delayed. While TGF-beta3 concentrations were higher in normally healing wounds, the difference was not significant.
• Thus, during both regular and exuberant wound repair, the expression of TGF-beta1 happened earlier than TGF-beta3 expression.
• EGT-healing wounds also tended to have higher concentrations of fibrogenic TGF-beta1 which helps in tissue formation and lower concentrations of antifibrotic TGF-beta3 which reduces tissue overgrowth compared to normally healing wounds, although these differences were not statistically significant.

Conclusions and Future Directions

• The study proposes that the development of EGT in bandaged wounds might be connected to an increase in the expression of fibrogenic TGF-beta1 and a decrease in antifibrotic TGF-beta3.
• This finding indicates a need for further research on the role of TGF-beta1 and TGF-beta3 to gain a better understanding of how EGT is controlled at a molecular level in horses.