The present invention concerns a method for treatment of traumatic brain injury (TBI) in a human or non-human animal subject, comprising administering stem or progenitor cells to the subject, such as mesenchymal stromal cells; and administering one or more PPARγ agonists, such as pioglitazone (PG), to the subject before, during, and/or after administration of the stem or progenitor cells. Another aspect of the invention concerns a pharmaceutical composition useful for treating TBI, the composition comprising stem cells or progenitor cells, such as mesenchymal stromal cells, and one or more PPARγ agonists, such as PG.