Methods and compositions for treating an autoimmune disease, such as new onset type 1 diabetes (T1D) in a subject using autologous or allogeneic mesenchymal stem cells administered to the subject prior to autoimmune-induced complete depletion of insulin-producing pancreatic beta cells, e.g., within six months of new onset type 1 diabetes (T1 D) diagnosis or prior to the onset of disease in a subject determined to be at high risk for T1 D.
