Use of mesenchymal stem cells (MSCs) as cell therapy for cartilage tissue repair and regeneration. The two potential approaches of MSC-based cartilage repair and regeneration are illustrated. The first is ex vivo cartilage tissue engineering, in which a replacement tissue is constructed in vitro using MSCs combined with scaffold under appropriate environmental stimuli. The second is in vivo cartilage regeneration via MSC cell therapy using its anti-inflammatory and immunosuppressive effects. As shown in this figure, MSCs are expanded and injected locally into the affected joint. MSCs can be applied systematically as well. MSCs, due to their potential regenerative functions as indicated, will help to influence the microenvironment to aid in the regeneration of the cartilage.