Platelet concentrates: effects of calcium and thrombin on endothelial cell proliferation and growth factor release

Clinical evidence suggests that platelet concentrate (PC) could have beneficial therapeutic effects on hard and soft tissue healing, due to the contents of growth factors (GFs) stored in the platelets. The objectives of this study were: 1) to determine the concentrations of platelet-derived growth factor-BB (PDGF-BB), transforming growth factor-beta1 (TGF-beta1), vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) released from PCs and whole blood (WB), before and after the addition of various concentrations of calcium and thrombin, and 2) to assess the physiological importance of the released GFs on angiogenesis.

WB and PCs were harvested and prepared from three healthy volunteers. Enzyme-linked immunosorbent assay tests, specific for PDGF-BB, TGF-beta1, VEGF, and bFGF, were performed on WB and PC supernatants, collected before and 30 minutes after the addition of various concentrations of calcium and thrombin. The supernatants were also added to human umbilical vein endothelial cell (HUVEC) cultures in order to measure their effects on endothelial cell proliferation.

Growth factor concentrations detected in PC supernatants were significantly greater (280% to 800% increase) than concentrations present in WB supernatants. Calcium and thrombin induced immediate GF release from PCs in a dose-dependent fashion. Furthermore, PC supernatants led to greater HUVEC proliferation rates than WB supernatants. However, there was no correlation between the concentrations of specific GFs and HUVEC proliferation rates.

These results suggest that PCs could stimulate blood vessel formation. They also reinforce the relevance for using PCs in regenerative therapies.