Use of allogeneic scaffold-free chondrocyte pellet in repair of osteochondral defect in a rabbit model.

Cell-based therapies are currently being used in treating osteochondral defect (OCD), but technical advances are needed to tackle the problems of scaffold and grafting technique. This study aimed to test the potential of allogeneic scaffold-free bioengineered chondrocyte pellet (BCP) in treating OCD. BCP was fabricated from rabbit costal cartilage and implanted into 3 mm × 3 mm OCD in medial femoral condyle of 20 rabbits. Samples were harvested at 2, 4, 8, and 16 weeks for histology, histological scoring and histomorphometric analysis. At treated side, cartilage score was significantly better at week 4 (p = 0.027), and cartilage thickness measured in histomorphometric analysis was significantly thicker at week 4 (p = 0.028) and week 16 (p = 0.028) compared to the empty controls. At treated side, bone score remained significantly lower from week 8 onwards (p = 0.024 at week 8, p = 0.02 at week 16) whereas bone area was significantly smaller from week 4 onwards compared to the empty controls (p = 0.028 at week 4, 8, 16). No immunorejection was observed throughout the experiment. The results demonstrated that the BCP enhanced cartilage repair at early stage. Press-fitting of allogeneic BCP was a simple method for OCD repair without immunorejection. Further optimization of the treatment is required before clinical application.