Investigation into the Short-Term Effects of Intra-Articular Allogenic PRP in the Equine LPS Model of Joint Inflammation: A Randomised Control Trial

This study aimed to investigate the effects of allogenic platelet-rich plasma (PRP) injection in lipopolysaccharide (LPS) inflamed equine radiocarpal joints. A preliminary study using a 0.0625 ng LPS dose was performed in the middle carpal joint and compared within animal to a saline control to confirm that synovitis was consistently produced using this dose. The main PRP effect study involved a bilateral 0.0625 ng LPS inflammation model with a within-animal comparison of LPS plus PRP versus a LPS plus saline control. Serial synovial fluid analysis was performed on samples obtained at post-injection hours (PIH) 0, 8, 24, 72, and 168. Synovial fluid analysis and clinical parameters were further complimented by objective gait and thermographic analyses. The 0.0625 ng dose induced a statistically significant increase in the synovial TP and WBC concentrations from baseline (p < 0.001) and control (p < 0.001, p = 0.013) values at PIH 8 in the preliminary study. No significant reduction in clinical or inflammatory markers was found in the PRP effect study, but a statistically significant increase in TP (p < 0.001) and PGE2 (p < 0.001) from baseline and control at PIH 8 in the PRP group (p < 0.001) was identified, which returned to baseline by 72 and 24 h, respectively. The protocol used in this study generated PRP with a PDGF-BB concentration of 7889.76 pg/mL, TGF-ß1 concentration of 27,369.96 pg/mL and platelet count of 954 × 109 cells/L. In conclusion, there does not appear to be any measurable anti-inflammatory effect of PRP treatment at this dose and treatment timing in this model of joint inflammation during the early inflammatory phase. Platelet-rich plasma appears to induce an increase in PGE2, although this increase was transient and self-limiting.