Role of Platelets and Fibrin in the Healing Sequence

Abstract

UNLABELLED: The signals that initiate repair are poorly characterized. These studies investigate the capacity of platelets and fibrin to initiate angiogenesis, fibroplasia, collagen synthesis and monocyte migration in the rabbit cornea assay. METHODS: Autologous platelets and platelet-free fibrin were isolated from rabbit blood. Released and control platelet preparations and autologous and commercial fibrin were implanted in rabbit corneas. RESULTS: Thrombin-released platelets produced angiogenesis and opacification. Histology showed fibroplasia, corneal thickening, and neovascularization. Collagen synthesis was elevated to twice control levels in thrombin-activated platelet preparations. Various control platelet preparations produced no angiogenesis, no opacification, and no histologic change. All fibrin injections elicited a cellular exudate from the limbal vessels, followed by angiogenesis and corneal opacification. Histology showed a mononuclear infiltrate with neovascularization and fibroplasia. Control injections of rabbit skin collagen and fibroblasts produced no response.