Arthritic diseases such as osteoarthritis (OA) and rheumatoid arthritis (RA) cause considerable pain, reduced mobility and significant disability among affected patients and present a major challenge to clinicians and basic scientists due to the limited inherent repair capacity of articular cartilage. The poor capacity of articular cartilage for self-repair is largely due to its avascular nature and has resulted in the development of a variety of surgical treatments including Autologous Chondrocyte Implantation (ACI) or Autologous Chondrocyte Transplantation (ACT), microfracture and mosaicplasty. Mesenchymal stem cells (MSCs) are multipotent progenitor cells with significant potential for chondrogenesis and new cartilage formation. Novel approaches using MSCs derived from bone marrow and adipose tissue have been proposed as alternatives to patient derived chondrocytes. In this paper we provide a scientific background to the biology of articular cartilage biology and its degeneration in arthritis. We also summarize some of the recent patents on applications of MSCs in articular cartilage tissue engineering and regenerative medicine for OA, RA and other joint diseases that involve cartilage degradation.