Abstract: Objective To study the effect of freeze-drying preservation method and activation time on platelet rich plasma (PRP) growth factor (GFs) content. Methods 20 PRPs were collected from healthy blood donors, of which platelet concentration was (1 031±150.1) × 109/L. Each PRP sample is divided into 5 groups, (1) fresh PRP (PRP), (2) frozen PRP activated by calcium gluconate (F-Ca PRP), (3) PRP activated by calcium gluconate followed by freezing (Ca-F PRP), (4) PRP freeze-dried first, then activated by calcium gluconate (FD-Ca PRP), (5) PRP activated by calcium gluconate followed by freeze drying (Ca-FD PRP). The concents of transforming growth factor-β1 (TGF-β1), vascular endothelial growth factor (VEGF), and platelet-derived growth factor-BB (PDGF-BB) were quantified by ELISA. Results TGF-β1 and PDGF-BB concentrations in FD-Ca PRP were not statistically different from PRP, while the VEGF was elevated and statistically different compared with the PRP. TGF-β1 and VEGF concentrations in the other three groups were not statistically different from PRP, while the differences in PDGF-BB were statistically significant. Conclusion The freezing and freeze-drying on PRP did not affect the concentrations of the three main growth factors from PRP, and compared with freezing on PRP, freeze-drying was less required with storage conditions. It suggested that wider possibilities of freeze-dried PRP for clinical applications.

Key words: Platelet-rich plasma, Frozen, Freeze-dried, Growth factor