Platelet-rich plasma (PRP) is an autologous blood product used to treat acute and chronic tendon, ligament and muscle injuries in over 86,000 US athletes annually. The World Anti-Doping Agency (WADA) banned intramuscular PRP injection in competitive athletes in 2010 due to concerns that it may increase performance-enhancing growth factors. The ban on PRP was removed in 2011 due to limited evidence for a systemic ergogenic effect of PRP, but the growth factors within PRP remain prohibited.
This study aimed to quantify the impact of PRP injection on systemic growth factors with performance-enhancing effects, and to identify molecular markers to detect treated athletes.
Six ergogenic growth factors monitored by WADA, namely: human growth hormone (hGH), insulin growth factor-1 (IGF-1), insulin growth factor binding protein-3 (IGFBP-3), basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), and platelet derived growth factor-BB (PDGF-BB) were measured in 25 patients before (baseline), and 0.25, 3, 24, 48, 72 and 96 hours after intratendinous leukocyte-rich PRP injection. Eating and exercise were prohibited for 3h before testing. Growth factors were quantified by ELISA and the change relative to each individual’s baseline was calculated.
Relative to serum, PRP contained significantly more bFGF (226 vs 5 pg/mL), VEGF (1,426 vs 236 pg/mL) and PDGF-BB (26,285 vs 392 pg/mL), but IGF-1 and hGH were not elevated. Serum levels increased significantly for IGF-1 at 24h and 48h, for bFGF at 72h and 96h, and for VEGF at 3h, 24h, 48h, 72h, at 96h. VEGF was increased in all 25 patients after PRP treatment.
Serum IGF-1, VEGF and bFGF levels are significantly elevated following PRP injection, supporting a possible ergogenic effect of PRP. An indirect marker for hGH doping, the product of IGFBP-3 x IGF-1, also increased significantly after PRP. Importantly, IGF-1 concentration was lower in PRP relative to serum at baseline, so the observed increase in serum IGF-1 after PRP treatment is likely due to activation of the hGH-IGF-1 axis. VEGF is elevated in all patients after PRP, and >88% of patients had elevated VEGF at each time point from 3 to 96h after PRP, suggesting that VEGF may be a sensitive molecular marker to detect athletes recently treated with PRP.