Osteoarthritis (OA) is one of the most common diseases and represents one of the main causes of disability worldwide. While classic pharmacological or surgical approaches fail to restore the physiological joint homeostasis to address OA, which in the end stage often leads to the need for prosthetic replacement, in the last decade, huge steps forward have been made in the field of tissue regeneration, with new frontiers offering promising innovative solutions.

Two different trends can be currently identified for treating articular lesions. Biomaterials that could lead to "in situ" regeneration of cartilage, subchondral bone, meniscus, and ligament/tendons have been proposed with or without the aid of cells, with the opportunity, in the second case, of bypassing the strict limits imposed by cell manipulation regulations. On the other hand, the fascinating potential of stem cells has recently opened new paths of research to discover how and whether these powerful entities can really contribute to tissue regeneration or to joint homeostasis restoration through intra-articular injection.

This special issue aims at documenting new evidences. We invite investigators to contribute high quality original articles as well as review articles, on the new frontiers in joint regeneration with biomaterials and/or stem cells.

Potential topics include but are not limited to the following:

• Molecular mechanisms and biological effects of stem cells in joint tissues
• Potential of stem cells expansion versus cell concentrates
• Autologous versus allogenic use of stem cells
• Interaction of biomaterials with joint tissue for regeneration
• Interaction of biomaterials with stem cell strategies
• Characterization of stem cell potential in different patients and profiling of patients responsive to biomaterial or stem cell based treatments
• Biomarkers predictive of disease evolution with biomaterial or stem cell based treatments
• Applications of stem cells and biomaterials in joint tissues: cartilage, bone, meniscus, and ligaments/tendons in the clinical setting
• Genetic modification of mesenchymal stem cells for improved regenerative capabilities