Current concepts and challenges in osteochondral tissue engineering and regenerative medicine

In the past few years, great progress has been made to validate tissue engineering strategies in preclinical studies and clinical trials on the regeneration of osteochondral defects. In the preclinical studies, one of the dominant strategies comprises the development of biomimetic/bioactive scaffolds, which are used alone or incorporated with growth factors and/or stem cells. Many new trends are emerging for modulation of stem cell fate toward osteogenic and chondrogenic differentiations, but bone/cartilage interface regeneration and physical stimulus have been showing great promise. Besides the matrix-associated autologous chondrocyte implantation (MACI) procedure, the matrix-associated stem cell implantation (MASI) and layered scaffolds in acellular or cellular strategy are also applied in clinic. This review outlines the progresses at preclinical and clinical levels, and identifies the new challenges in osteochondral tissue engineering. Future perspectives are provided, e.g., the applications of extracellular matrix-like biomaterials, computer-aided design/manufacture of osteochondral implant, and reprogrammed cells for osteochondral regeneration.