Intra-articular Injection of platelet-rich fibrin releasates in combination with bone marrow-derived mesenchymal stem cells in the treatment of articular cartilage defects: An in vivo study in rabbits

The use of mesenchymal stem cells (MSCs), which can be differentiated into chondrocytes under specific conditions, has been proposed for the treatment of cartilage defects. Blood-derived platelet-rich fibrin releasate (PRFr), which is rich in growth factors and cytokines, may improve cartilage regeneration. In this study, the therapeutic effects of PRFr in combination with bone marrow-derived MSCs for articular cartilage regeneration were evaluated in a rabbit model. Critical osteochondral defects were surgically created in the femoral condyle of the rabbits, and 3 × 10⁶ of MSCs, 0.8 mL of PRFr, or a combination of MSCs and PRFr were injected intra-articularly and one week after first administration. The animals were sacrificed 12 weeks postoperatively, and the regenerated cartilages were assessed by gross inspection and histological examination. No treatment-related adverse events were noted in any of the rabbits. The size of the defect decreased and the volume of regenerated cartilage increased in the medial femoral condyles of the MSCs+PRFr group. Relative to the MSCs or PRFr group, histological examination demonstrated that the MSCs+PRFr group had thicker hyaline-like cartilaginous tissue with normal glycosaminoglycan production. Grading scores revealed that MSCs+PRFr injection had better matrix, cell distribution, and surface indices than other groups. The results showed that intra-articular injections of MSCs+PRFr into the knee can reduce cartilage defects by regenerating hyaline-like cartilage without adverse events. This approach may provide an alternative method of autologous chondrocyte implantation to repair cartilage defects with an unlimited source of cells and releasate.