BACKGROUND: Concentrated leukocytes in leukocyte- and platelet-rich plasma (L-PRP) may deliver increased levels of pro-inflammatory cytokines to activate the NF-κB signaling pathway, to counter the beneficial effects of growth factors on osteoarthritic cartilage. However, to date no relevant studies have substantiated that in vivo.

MATERIAL AND METHODS: Autologous L-PRP and pure platelet-rich plasma (P-PRP) were prepared, measured for componential composition, and injected intra-articularly after 4, 5, and 6 weeks post-anterior cruciate ligament transection. Caffeic acid phenethyl ester (CAPE) was injected intraperitoneally to inhibit NF-κB activation. All rabbits were sacrificed after 8 weeks postoperative. Enzyme-linked immunosorbent assays were performed to determine interleukin 1β (IL-1β) and prostaglandin E2 (PGE2) concentrations in the synovial fluid, Indian ink staining was performed for gross morphological assessment, and hematoxylin and eosin staining and toluidine blue staining were performed for histological assessment.

RESULTS: Compared with L-PRP, P-PRP injections achieved better outcomes regarding the prevention of cartilage destruction, preservation of cartilaginous matrix, and reduction of IL-1β and PGE2 concentrations. CAPE injections reversed the increased IL-1β and PGE2 concentrations in the synovial fluid after L-PRP injections and improved the outcome of L-PRP injections to a level similar to P-PRP injections, while they had no influence on the therapeutic efficacy of P-PRP injections.

CONCLUSIONS: Concentrated leukocytes in L-PRP may release increased levels of pro-inflammatory cytokines to activate the NF-κB signaling pathway, to counter the beneficial effects of growth factors on osteoarthritic cartilage, and finally, result in a inferior efficacy of L-PRP to P-PRP for the treatment of osteoarthritis.

Keywords: Dinoprostone - metabolism, Cytokines - metabolism, Interleukin-1beta - metabolism, Leukocyte Transfusion - methods, Osteoarthritis, Knee - therapy, Platelet Transfusion - methods, platelet-rich plasma, Random Allocation, Synovial Fluid - metabolism