In vivo analysis of cartilage repair by synovial mesenchymal stem cell transplantation in rabbits. (a) Cell transplantation on a cartilage defect in a rabbit by the local adherent technique. The osteochondral defect was faced upward (upper panel), and the defect was filled with synovial mesenchymal stem cell (MSC) suspension (lower panel) and held stationary for 10 minutes for the cells to adhere. (b) Macroscopic observation of cartilage defects after cell transplantation. For the control group, the cartilage defect was left empty. For the intra-articular group, synovial MSCs were injected into the knee joint after the capsule was closed. For the local adherent group, the defect was filled with the synovial MSC suspension and held still for 10 minutes. Femoral condyles 4, 12 and 24 weeks post surgery are shown. The corners of the margin between repaired tissue and native cartilage are indicated as arrowheads in the local adherent group at 24 weeks.