In recent decades, the biomedical applications of mesenchymal stem cells (MSCs) have attracted increasing attention. MSCs are easily extracted from the bone marrow, fat, and synovium, and differentiate into various cell lineages according to the requirements of specific biomedical applications. As MSCs do not express significant histocompatibility complexes and immune stimulating molecules, they are not detected by immune surveillance and do not lead to graft rejection after transplantation. These properties make them competent biomedical candidates, especially in tissue engineering. We present a brief overview of MSC extraction methods and subsequent potential for differentiation, and a comprehensive overview of their preclinical and clinical applications in regenerative medicine, and discuss future challenges.

Recently, cartilage tissue engineering (CTE) attracts increasing attention in cartilage defect repair. In this work, kartogenin (KGN), an emerging chondroinductive nonprotein small molecule, was incorporated into a thermogel of poly(L-lactide-co-glycolide)-poly(ethylene glycol)-poly(L-lactide-co-glycolide) (PLGA-PEG-PLGA) to fabricate an appropriate microenvironment of bone marrow mesenchymal stem cells (BMSCs) for effective cartilage regeneration. More integrative and smoother repaired articular surface, more abundant characteristic glycosaminoglycans (GAGs) and collagen II (COL II), and less degeneration of normal cartilage were obtained in the KGN and BMSCs coloaded thermogel group in vivo. In conclusion, the KGN-loaded PLGA-PEG-PLGA thermogel can be utilized as an alternative support for BMSCs to regenerate damaged cartilage in vivo.

The osteochondral defects caused by vigorous trauma or physical disease are difficult to be managed. Tissue engineering provides a possible option to regenerate the damaged osteochondral tissues. For osteochondral reconstruction, one intact scaffold should be considered to support the regeneration of both cartilage and subchondral bone. Therefore, the biphasic scaffolds with the mimic structures of osteochondral tissues have been developed to close this chasm. A variety of biomimetic bilayer scaffolds fabricated from natural or synthetic polymers, or the ones loading with growth factors, cells, or both of them make great progresses in osteochondral defect repair. In this review, the preparation and in vitro and/or in vivo verification of bioinspired biphasic scaffolds are summarized and discussed, as well as the prospect is predicted.