Abstract-Introduction:Mesenchymal stem cells (MSCs) show great promise in regenerative medicine. Clinical applications of MSCs have recently increased significantly, especially for immune diseases. Autologous transplantation is considered a safe therapy. However, its main disadvantages are poor stability and quality of MSCs from patient to patient, and labor-intensive and time-consuming culture procedures. Therefore, allogeneic MSC transplantation has recently emerged as a potential replacement for autologous transplantation. "Off the shelf" MSC products, or socalled "stem cell drugs", have rapidly developed; these products have already been approved in various countries, including Canada, Korea and Japan. This study aims to evaluate a new stem cell product or "drug", termed Modulatist TM , derived from umbilical cord mesenchymal stem cells (UCMSCs), which have strong immunomodulatory properties, compared to bone marrow-derived MSCs (BMMSCs) or adipose tissue-derived stem cells (ADSCs). Methods: Modulatist TM was produced from MSCs derived from whole umbilical cord (UC) tissue (which includes Wharton's jelly and UC), according to GMP compliant procedures. Bone marrow-and adipose tissue-derived MSCs were isolated and proliferated in standard conditions, according to GMP compliant procedures. Immunomodulation mediated by MSCs was assessed by allogenic T cell suppression and cytokine release; role of prostaglandin E2 in the immunomodulation was also evaluated. Results: The results showed that Modulatist TM exhibited stronger immunomodulation than BMMSC and ADSC in vitro. Modulatist TM strongly suppressed allogeneic T cells proliferation and decreased cytokine production, compared to BMMSCs and ADSCs. Conclusion: Modulatist TM is a strong immunomodulator and promising MSC product. It may be useful to modulate or treat autoimmune diseases.