Effects of basic FGF and TGF(β1) on F-actin and ZO-1 organization during cat endothelial wound healing

Previous studies suggest the existence of two separate and distinct mechanisms of endothelial wound healing (i.e., cell migration and cell spreading), which may be controlled by unique, injury-dependent, wound- related factors. The purpose of our study was to evaluate potential biologic mediators regulating healing of the growth arrested cat endothelium by using an ex vivo, organ-culture model. Three buttons were punched from each cornea of 11 cats with a 6-mm trephine. A 1- to 2-mm diameter endothelial scrape injury (SI) was made, and buttons were cultured in (a) serum-free media (SFM), (b) serum plus media (20% fetal calf serum), (c) SFM plus basic fibroblast growth factor (bFGF), (d) SFM plus bFGF and heparin, (e) SFM plus transforming growth factor-β1 (TGF(β1)), or (f) SFM plus TGF(β1) and anti-TGF(β1). At various times from 8-48 h after injury, buttons were stained with phalloidin and anti-ZO-1, and imaged by using laser scanning confocal microscopy. Evaluation of SI in cat corneal buttons under serum- free conditions showed maintenance of normal endothelial differentiation, indicating that the organ-culture SI model mimics in vivo SI. Addition of TGF(β1) produced a dramatic reorganization of apical F-actin and development of stress fibers, as well as the loss of normal cell border- associated ZO-1 distribution. The effects of TGF(β1) were blocked by the neutralizing antibodies to TGF(β1). Addition of serum or bFGF produced much less pronounced changes in F-actin and ZO-1 distribution. These results suggest that TGF(β1) may play a critical role in modulating the wound- healing response of the corneal endothelium.