3D bioprinting for the repair of articular cartilage and osteochondral tissue

The poor intrinsic healing properties of cartilage result in the frequent development of osteoarthritis and chronic tissue degeneration following injury. Articular cartilage tissue engineering has produced several therapies, but the fabrication of functional and anatomically accurate engineered osteochondral tissue has proved elusive. 3D bioprinting's ability to fabricate complex tissue scaffolds that incorporate cells, extracellular matrix components, and growth factors enables engineered tissue that mimics the structure and function of natural tissue. Recent advances have allowed 3D bioprinting to emerge as a promising technology for the fabrication of tissue engineered osteochondral tissue suitable for the replacement of damaged cartilage. In this paper, we review pathologies, current treatments for osteochondral injuries, and recent advances in 3D bioprinting osteochondral tissue. Innovations in bioink formulation, bioprinting techniques, and results from preclinical studies are highlighted. Finally, we discuss the role that 3D bioprinting may have in the next generation of tissue engineered implants despite the substantial challenges that remain for the clinical translation of transplanted bioprinted osteochondral tissue, including the recapitulation of the complex zonal properties of cartilage, improving the mechanical properties of printed tissue scaffolds, and regulatory hurdles.