1000 Section - Exercise Preconditioning Enhances the Therapeutic Efficacy of Platelet-Rich Plasma in a Rat Model of Osteoarthritis by Synergistically Targeting Subchondral Bone and Cartilage

Objectives : Despite reported benefits of exercise for osteochondral regeneration, its mechanisms remain unclear. This study aimed to determine if exercise preconditioning improves PRP's therapeutic efficacy in rat knee OA by altering plasma composition.

Design: Following MIA-induced OA in 68 rats, half underwent a 3-week exercise preconditioning regimen (Group B) while the other half remained sedentary (Group A). Blood collected at week 6 yielded nPRP from controls and ePRP from preconditioned rats. Subsequent subgroups received saline, PRP alone, or PRP with concurrent exercise weekly for 3 weeks. Pain behavior was tracked throughout the study, and joint tissues were collected for analysis at week 15.

Results:

Behavioral and histological assessments demonstrated that all PRP-treated groups exhibited pain alleviation during the treatment period (weeks 6–9), with the most significant behavioral improvement observed at week 9 in groups A3 and B3 receiving combined exercise and PRP intervention . Histological analysis at week 15 (six weeks after the final treatment) further revealed that all PRP-treated groups showed significant reductions in synovitis, fibrosis, and cartilage damage compared to their respective saline control groups ; however, no significant differences were observed between ePRP and nPRP groups under the same treatment conditions. Notably, exercise preconditioning (samples derived from Group B) demonstrated a unique protective effect on the subchondral bone. Furthermore, regardless of whether nPRP or ePRP was used, the subgroups receiving combined exercise intervention (A3, B3) exhibited superior cartilage protection compared to those receiving PRP injection alone (A2, B2).

Conclusion: In summary, exercise preconditioning and PRP therapy act synergistically in OA treatment: the former preserves subchondral bone structure and inhibits abnormal bone turnover, while the latter alleviates pain and suppresses synovitis. Their combination enhances cartilage protection, offering a potential strategy to simultaneously target synovitis, cartilage degeneration, and aberrant subchondral bone remodeling.