Scheme 1.

Cartilage repair modalities. (a) Full-thickness cartilage injury. (b) Microfracture. Channels were produced 3−4 mm deep to penetrate the subchondral bone to allow BM-MSCs to migrate from the bone marrow to the defect area. (c) Mosaicplasty. Healthy osteochondral plugs were implanted from the little weight-bearing area into the defect area. (d) Autologous chondrocyte implantation. The defect area was filled with autologous chondrocytes and covered with a periosteal slice. (e) MSC implantation. The defect area was filled with MSCs. (f) The combination of MSCs and inducing factors was loaded into the defect. (g) The biocompatible scaffold contained MSCs and inducing factors were implanted into the defect area to repair the lesion.