A Comprehensive Review of Stem Cells for Cartilage Regeneration in Osteoarthritis.

Osteoarthritis (OA) is an age related joint disease associated with degeneration and loss of articular cartilage. Consequently, OA patients suffer from chronic joint pain and disability. Weight bearing joints and joints that undergo repetitive stress and excessive 'wear and tear' are particularly prone to developing OA. Cartilage has a poor regenerative capacity and current pharmacological agents only provide symptomatic pain relief. OA patients that respond poorly to conventional therapies are ultimately treated with surgical procedures to promote cartilage repair by implantation of artificial joint structures (arthroplasty) or total joint replacement (TJR). In the last two decades, stem cells derived from various tissues with varying differentiation and tissue regeneration potential have been used for the treatment of OA either alone or in combination with natural or synthetic scaffolds to aid cartilage repair. Although stem cells can be differentiated into chondrocytes in vitro or aid cartilage regeneration in vivo, their potential for OA management remains limited as cartilage regenerated by stem cells fails to fully recapitulate the structural and biomechanical properties of the native tissue. Efficient tissue regeneration remains elusive despite the simple design of cartilage, which unlike most other tissues is avascular and aneural, consisting of a single cell type. In this article, we have comprehensively reviewed the types of stem cells that have been proposed or tested for the management of OA, their potential efficacy as well as their limitations. We also touch on the role of biomaterials in cartilage tissue engineering and examine the prospects for their use in cell-based therapies.