Abstract
In order to investigate the mechanism by which platelets support the integrity of vascular endo-thelium, the effects of platelet-derived factors on the growth of cultured porcine aortic endothelial cells were studied. The human platelet lysate stimulated the incorporation of [3H]thymidine into DNA in a dose-dependent manner. Gel exclusion chromatography revealed at least two peaks of activity on endothelial cells, the major peak being at an apparent molecular weight of 20, 000. The major part of the activity was heat-labile and trypsin-sensitive, and did not stimulate the growth of fibroblasts. These observations suggest that this platelet-derived factor is a new peptide growth factor that preferentially stimulates the proliferation of vascular endothelial cells.
