Platelet factors and the human vascular wall. Part 2. Such factors are not required for endothelial cell proliferation and migration.

The effects of platelet factors on human umbilical venous endothelial cell DNA-synthesis at various serum concentrations were studied. While [3H]thymidine uptake of these cells was almost linearly related to the concentration of serum in the culture medium, no significant differences were found at any serum level between cultures treated with sera derived from either platelet-rich or platelet-poor plasma. The role of platelet factors in cellular migration into standardized mechanical "wounds" was also investigated following inhibition of the proliferative response by irradiation of endothelial monolayers. Repopulation of such "wounds" was not affected by platelet factors. We conclude that endothelial cells proliferate and migrate in vitro independently of platelet factors.