Platelet surface membranes are highly mitogenic for coronary artery smoothmuscle cells - A novel mechanism for sustained proliferation after vessel injury?

The effects of isolated platelet surface membranes on DNA synthesis and pro liferation of bovine coronary artery smooth muscle cells (SMC) were studied , Platelet membranes were very potent mitogens for SMC. The potency was abo ut 10-fold higher than the maximum effects of platelet-derived growth facto r-BB (PDGF), Platelet membrane-induced mitogenesis was inhibited by rapamyc in, wortmannin or heating for 15 min at 70 degrees C but not by the PDGF re ceptor antagonist SCH 13.929 or by neutralizing PDGF antibodies, Only a par tial (30%) inhibition was seen with PD 98059. in contrast, PDGF-induced SMC mitogenesis was heat-stable but sensitive to SCH 13.929, PDGF antibodies, and PD 98059. These findings provide evidence for a novel mechanism for pla telet-induced SMC proliferation that is independent of PDGF secretion. Plat elet membranes, attached to or incorporated into the vessel wall, could mai ntain sustained SMC proliferation following injury. (C) 1999 Academic Press .