Mesenchymal stem cells in autoimmune disease.

Autoimmune diseases afflict more than 3% of the U.S. population. Current therapy for mild to moderate cases is symptomatic, however advanced cases suffer high morbidity and mortality. Advanced patients have benefited from stem cell therapy in the form of bone marrow transplantation in conjunction with high-dose cytotoxic therapy. Broader application of stem cell therapy requires better understanding of how adult stem cells affect development and foster treatment of autoimmune pathologies, and of better ways to manipulate the host immune responses. While extensive research documents the role of hematopoietic stem cells (HSCs) in autoimmune disease, few studies have addressed if and how mesenchymal stem cells (MSCs) contribute to their etiopathology. Recent characterization of MSCs and their role in hematopoiesis and immune modulation suggest that their potential for cell therapy extends beyond their traditional accessory function in HSC engraftment. MSCs contribute significantly to tissue restructuring and immune functioning, in addition to facilitating durable, long-lasting stem cell engraftment. MSCs are relatively easy to obtain and expand in in vitro cultures, rendering them a prime candidate for genetic manipulations for stem cell therapy. They have the potential to differentiate into multiple lineages such as osteoblasts, adipose tissue, cartilage, tendon, and stromal cells. The role of MSCs for autoimmune disease therapy could thus be based both on immune function modulation and contribution to hematopoiesis. In this review, we examine the biology of MSCs, and their potential for cell therapy of autoimmune disease.