Abstract:

BACKGROUND: Platelet is a rich source of autologous growth factors. Bovine thrombin is the most common used activator to promote growth factors release from platelet. The clinical use of thrombin has some risks.
OBJECTIVE: To observe the effect of freeze-thaw by liquid nitrogen to promote platelet-derived growth factor-AA and transforming growth factor-β1 release from platelet in comparison with bovine thrombin.
METHODS: Platelet rich plasma and platelet poor plasma were manufactured from venous blood of five healthy volunteers by secondary centrifugation. The platelet rich plasma was then washed to get rid of the plasma and to manufacture the washed platelet. Washed platelet was activated by freeze-thaw method using liquid nitrogen to promote growth factor release and platelet rich plasma was activated by 1 000, 500, 250, 125, 62.5, 31.25 U/mL bovine thrombin/calcium chloride. Mass concentrations of platelet-derived growth factor-AA and transforming growth factor-β1 in washed platelet, platelet rich plasma and platelet poor plasma were assayed using enzyme linked immunosorbent assay. 
RESULTS AND CONCLUSION: The concentrations of platelet-derived growth factor-AA and transforming growth factor-β1 in the washed platelet activated by freeze-thaw were (8.973±1.213) and (27.445±2.273) μg/L. There was no significant difference from the concentration in the bovine thrombin of 500-1 000 U/mL activated platelet rich plasma (P > 0.05). These suggested that freeze-thaw can be used as a safe and effective technique to active washed platelet instead of bovine thrombin.