Safety study to evaluate the tumorigenic potential of MSC in beige SCID and athymic mice. MSC from three different healthy donors (MSC lot numbers as indicated) were cultured deliberately to more than 25 passages. Mice received 4×107 MSC/500 μl saline intraperitoneally (n = 6 mice per cohort MSC) or subcutaneously (2×107 MSC/100 μl saline, n = 3 mice/cohort of MSC). Body weights of mice that received (A) intraperitoneal or (B) subcutaneous MSC were recorded at regular intervals. (C) In the subcutaneous model, size of the ‘lump’ formed from the MSC deposit was recorded in two dimensions and volume calculated. (D) Body weights of the control mice that received SKOV3 tumor cells (2×106 cells/100 μl). (E) Growth of SKOV3 subcutaneous tumor in control mice. (F) Survival curve of athymic mice given 106 SKOV3ip.1 (n = 15 mice) or a cocktail of 106 SKOV3ip.1 and 106 MSC (n = 13 mice) intraperitoneally.