Thrombospondin-1 accelerates wound healing of corneal epithelia

To investigate a role of thrombospondin-1 (TSP-1), a multifunctional extracellular matrix protein, in corneal epithelial wound healing, we analyzed the expression of TSP-1 in the normal and wounded mouse corneal epithelia and the effect of exogenous TSP-1 on the wound healing. In immunohistochemical analyses of unwounded corneas, TSP-1 was only detectable in endothelial cells. In contrast, TSP-1 appeared on the wounded corneal surface and on the corneal stroma, at 30 min and 8-16 h, respectively, after making an abrasion on the corneal epithelium. This expression of TSP-1 disappeared after 36-48 h, when re-epithelialization was completed. The TSP-1 mRNA level in the wounded corneas increased as much as three fold compared with that in the unwounded corneas. In organ culture, exogenous TSP-1 stimulated the re-epithelialization of corneal epithelial wounds whereas anti-TSP-1 antibody significantly inhibited the re-epithelialization. These findings suggest the possibility that epithelial defects in the corneas stimulate the expression of TSP-1 in the wound area, resulting in the accelerated re-epithelialization of the cornea.