Cartilage repair in a rabbit model: Development of a novel subchondral defect and assessment of early cartilage repair using a rabbit mesenchymal stem cell seeded scaffold

Purpose: To develop a subchondral defect in a rabbit model and assess cartilage repair using a mesenchymal stem cell-seeded scaffold. Materials and Methods: To achieve this goal, a bovine explant model and two pilot rabbit studies were conducted. Initial work using chondral explant tissue harvested from stifle joints of 12-month-old cattle sourced from a local abattoir, followed by a pilot rabbit study demonstrated that a chondral defect was an unsuitable model for the scaffold being studied. Assessment of a novel reproducible technique for subchondral defect creation was conducted using a rabbit model in accordance with University guidelines and ethical approval with 4 test groups, empty 3mm x1mm defect (n=6), empty 3mm x3mm defect (n=6), press-fit scaffold in 3mm x1mm defect (n=6), press-fit cell-seeded scaffold in 3mm x1mm defect (n=6). l. In brief, skeletally mature rabbits, weighing more than 3kg were anesthetized and bilateral defects were created on the medial femoral condyle using an electrical drill with a previously sterilized 2.8mm drill bit covered with a sterile depth stop. The walls of the defect were finished with a dental curette, and the scaffold press-fit into place. Defects was assessed histologically after 28 days implantation. Results: The subchondral defects could be created with the same reproducibility as osteochondral defects and tissue repair was achieved in both cell free and cell-seeded scaffolds. Conclusion: A reproducible subchondral defect was successfully created in a rabbit model to assess cartilage repair using a cell-seeded scaffold. Early cartilage repair was achieved in both cell free and cell-seeded scaffolds, with improved repair seen in the cell free scaffold grou