Effects of the breed, sex and age on cellular content and growth factor release from equine pure-platelet rich plasma and pure-platelet rich gel

PLT counts were 1.8 and 0.6 times higher in P-PRP than in whole blood and PPP, respectively; WBC counts were 0.5 and 0.1 times lower in P-PRP, in comparison with whole blood and PPP, respectively. TGF-β1 and PDGF-BB concentrations were 2.3 and 262 times higher, respectively, in P-PRG than in plasma, and 0.59 and 0.48 times higher, respectively, in P-PRG than in PPG. P-PRG derived from CCH females or young horses presented significantly (P <？0.001) higher PDGF-BB concentrations than P-PRG derived from ACH males or older horses.Our results indicated that P-PRP obtained by a manual method was affected by intrinsic factors such as the breed, gender and age. Equine practitioners should be aware that cellular and GF release from P-PRP/P-PRG could change according with the intrinsic variables associated with a patient in particular.The clinical use of platelet concentrates (PC) is currently a common biological therapy for musculoskeletal diseases [1-4] and wounds in horses [5]. PC intended for regenerative medicine are classified as: pure-platelet rich plasma (P-PRP), leukocyte-platelet rich plasma (L-PRP) and platelet rich fibrin (PRF). P-PRP and L-PRP are obtained in a liquid form by using anticoagulants. PRF is as a second generation PC that does not require anticoagulant for its elaboration [6].Equine P-PRP displays slightly higher platelet counts (1.3-4 fold) and leukocyte (WBC) counts (0.5-2 fold) than whole blood. Equine L-PRP has increased platelet (5 fold) and leukocyte (3 fold or more) counts when compared to whole blood. When PC are activated by adding thrombin or a calcium salt, they form a fibrin polymer and are known as platelet gels (PG). Thus, PG from P-PRP is denominated as pure-platelet rich gel (P-PRG) and PG from L-PRP is termed leukocyte-platelet rich gel (L-PRG) [7].Platelet gels release several growth factors (GF), such as transforming growth factor beta 1 (TGF-β1) [8,9] and platelet derived growth factor type BB (PDGF-BB) [10]. These proteins have a