Contrary to the results in immunodeficient mice (Supplementary Fig. 4a), the transplanted cells elicited the gathering of host Iba1+ microglia around the graft core and induced glial scar formation, showing that immune rejection may still occur after transplantation of DOPA-MSCs into PD rat brains without immunosuppression (Supplementary Fig. 5a), although it is unclear whether the possible immune response is caused by xenogeneic cell transplantation. The gene discussed is AIF1; the disease is Parkinson disease.