TYPE-IV COLLAGENASE(S) AND TIMPS MODULATE ENDOTHELIAL-CELL MORPHOGENESIS IN-VITRO

It has been proposed that proteases are important in endothelial cell behavior. We examined the contribution of the gelatinase/type IV colla genase system in an in vitro model of endothelial differentiation. Hum an umbilical vein endothelial cells rapidly align and form networks of tubes when cultured on a basement membrane preparation, Matrigel. Zym ograms of culture supernates demonstrate a 72-kD and a 92-kD gelatinas e activity; the cells produce most of the 72-kD gelatinase, whereas th e 92-kD activity is derived entirely from the Matrigel. Addition of an tibodies against type IV gelatinase/collagenase decreases the area of the tube network. Both tissue inhibitors of metalloproteinases, TIMP-1 and TIMP-2, similarly decrease tube formation when added to cultures. Conversely, exogenous recombinant 72-kD gelatinase increases tube-for ming activity. The effects of the anti-gelatinase antibodies and the T IMPs are not additive. Inhibition by either antibodies or TIMPs is gre atest when they are added at culture initiation, suggesting that the p rotease activity is important in the early steps of morphogenesis. How ever, culture of the cells on Matrigel does not increase early express ion of mRNA for the 72-kD gelatinase. Expression of message for the en zyme actually decreases during the course of the assay, while transcri ption of mRNAs for TIMPs increases, further supporting the concept tha t collagenases facilitate an early event in tube formation. These data demonstrate that gelatinase/type IV collagenase activity is important in endothelial cell morphogenesis on Matrigel, and suggest a role for collagenases in formation of new capillaries in vivo. (C) 1993 Wiley- Liss, Inc.