Extracorporeal Photopheresis and Mesenchymal Stem Cell Infusion for GVHD

This is a Phase II study of human MSCs for the treatment of High-Risk aGVHD (HRaGVHD) and steroid-refractory acute GVHD (SRaGVHD). MSCs are cells that can help the body heal from injury and maintain a healthy immune system. MSCs have been used to prevent and treat a GvHD. In previous human studies, MSC infusion has been generally well-tolerated and safe, and in some cases, benefit was reported. The donor of the MSCs could be a relative or a stranger, and does not need to be the same individual who donated the stem cells for the stem cell transplant. All donors are screened for infectious diseases, similar to a blood donor. All donors have a physical exam. Corticosteroids may be administered with MSCs/ECP. Continued use of anti-infective medications, GVHD prophylaxis medications (including calcineurin inhibitors), transfusion support, and topical steroid therapy is permitted. Participants will be assessed for safety and tolerability using a continuous monitoring approach. In order to be included in the tolerability review, participants must have received at least 1 treatment with MSCs.