Influence of fibrin, fibrinogen and fibrinogen degradation products on cultured endothelial cells.

Thin films of a fibrin-agar mixture induced significant morphological changes in porcine aortic endothelial cells in vitro. The cells became spindle shaped, piled up and consequently the intercellular spaces widened. These morphological changes became more significant with higher concentrations of fibrin. Films of fibrinogen-agar or thrombin-agar mixtures induced no such morphological changes thereby suggesting that fibrin itself injures the endothelial cells. Despite the lack of morphological effects of fibrinogen degradation product D or E on cultured endothelial cells, lower molecular weight fibrinogen degradation products separated by Sephadex G-25 chromatography did induce injury in the endothelial cells. As damage to the endothelium is a key event in initiation of atherosclerosis, fibrinogen and its metabolites probably play important roles.