With increasing aging populations, bone and joint degenerative pathologies have become a significant clinical burden worldwide. In the absence of effective pharmacological treatments, tissue engineering approaches explore innovative biological and biomechanical interventions. They range from injections of biologically-active cells into the joint to the implantation of specifically-designed biocompatible scaffolds. Regenerative cells are normally obtained from platelet-rich-plasma (PRP) or multipotential stromal cell (MSC)-rich tissues such as adipose tissue, bone marrow aspirate or umbilical cord/cord blood. Regenerative cells can be further processed in order to obtain acellular, biologically-active particles termed extra-cellular vesicles (EVs). These cells or cell-derived particles can be injected directly into the damaged area, or they can be embedded into biomechanically-competent scaffolds - this ensures their longer-term retention in the repair area and optimises their bioactivity. Despite significant recent achievements in this field, many critical issues remain unresolved, particularly in terms of the clinical effectiveness, as well as cost-effectiveness, of these interventions long-term. This Special issue invites original pre-clinical and clinical research in this area that includes, but not limited to, the application of PRP (and other platelet-derived products), MSCs (autologous and allogeneic) and scaffolds (natural and synthetic) in the treatment of OA and other degenerative pathologies of the bone and joint. Clinical and surgical studies exploring novel delivery methods and tools are additionally welcome, as well as systematic reviews and meta-analyses.

Keywords: Osteoarthritis (OA), platelet-rich-plasma (PRP), multipotential stromal cells (MSC), extracellular vesicles (EV), scaffold, cartilage regeneration