Effect of different bone substitutes on the concentration of growth factors in platelet-rich plasma

This study is conducted to determine the effect of different kinds of bone substitutes and collagen on the concentration of platelet-derived growth factor (PDGF) and transforming growth factor beta-1 (TGF beta-1) in platelet-rich plasma (PRP). PRP is treated with thrombin, hydroxyapatite (HA), and thrombin, HA alone, collagen-grafted HA, calcium metaphosphate (CMP), and collagen-grafted CMP. The concentrations of PDGF-AB and TGF beta-1 are measured. After PRP treated with HA and CMP, the concentrations of PDGF and TGF beta-1 are not significantly different from the concentration of them in PRP alone. The concentrations of PDGF in PRP with collagen-grafted HA and collagen-grafted CMP are significantly higher than that of PRP with HA and CMP. The concentrations of PDGF and TGF beta-1 in PRP with collagen-grafted CMP are higher than with collagen-grafted HA. The results of multiple regression analysis show that PDGF increased with the use of collagen and thrombin, and is higher in native whole blood with higher platelet counts. However, PDGF decreased with the use of HA. In conclusion, HA and CMP do not seem to be able to activate platelets by themselves. However, if they had collagen grafted onto them, they could activate platelets and release growth factors.