Expression of Thrombospondin 1 and 2 in Scarred and Vascularized Corneas

Abstract

Abstract: : Purpose: Thrombospondin (TSP) 1 and 2 are multifunctional matricellular glycoproteins. They are involved in wound healing and are potent anti–angiogenic agents. TSP 1 is present during the early (inflammatory) phase of skin repair whereas TSP 2 is found in the late (remodelling) phase. The purpose of this study was to evaluate TSP 1 and 2 expression in scarred and vascularized corneas. Methods: Archived frozen normal, fibrotic and vascularized human corneal specimens were used for immunohistochemical staining with polyclonal antibodies to TSP 1 and 2. In addition specimens were stained with IgG fragments, which served as a control. Results: TSP 1 and 2 were expressed in the basal epithelium and endothelium of normal corneas but the stroma and stromal cells (keratocytes) were devoid of the proteins. However, TSP 1 and 2 were expressed in the stroma and stromal cells of established (late) corneal scars. They were also found in the endothelium of blood vessels in addition to the corneal epithelium and endothelium. No staining was observed in sections stained with IgG fragments. Conclusions: These results demonstrate that TSP 1 and 2 are expressed in the stroma of vascularized and scarred human corneas but are absent in normal corneas. The persistence of TSP 1 into the late (remodelling) phase of corneal repair suggests that the mechanisms of stromal repair differ between cornea and skin.

Keywords: cornea: stroma and keratocytes • neovascularization • wound healing