Treatment of inflammatory diseases with mesenchymal stem cells.

Human mesenchymal stem cells (hMSCs) are rare progenitor cells present in adult bone marrow that have the capacity to differentiate into a variety of tissue types, including bone, cartilage, tendon, fat, and muscle. In addition to multilineage differentiation capacity, MSCs regulate immune and inflammatory responses, providing therapeutic potential for treating diseases characterized by the presence of an inflammatory component. The availability of bone marrow and the ability to isolate and expand hMSCs ex vivo make these cells an attractive candidate for drug development. The low immunogenicity of these cells suggests that hMSCs can be transplanted universally without matching between donors and recipients. MSCs universality, along with the ability to manufacture and store these cells long-term, present a unique opportunity to produce an "off-the-shelf" cellular drug ready for treatment of diseases in acute settings. Accumulated animal and human data support MSC therapeutic potential for inflammatory diseases. Several phase III clinical trials for treatment of acute Graft Versus Host Disease (GVHD) and Crohn's disease are currently in progress. The current understanding of cellular and molecular targets underlying the mechanisms of MSCs action in inflammatory settings as well as clinical experience with hMSCs is summarized in this review.