Bone Marrow Stromal Cell Infusions for Stem Cell Transplant Complications

Background: * Bone marrow stromal cells (BMSC) from bone marrow biopsies can be used to treat disorders that cause inflammation and immune system diseases. BMSC have been used to treat graft versus host disease (GVHD), a complication that can develop after stem cell transplants. BMSC have also been used to treat other post-transplant complications, like marrow failure or tissue injury. * The National Institutes of Health (NIH) has developed a procedure for collecting and preserving BMSC from volunteer donors. These donors have passed tests to ensure that their cells are healthy enough to be used for treatment. Researchers want to use the collected cells to treat people with GVHD, marrow failure, or tissue injury following stem cell transplants. Objectives: \- To test the safety and effectiveness of NIH-collected BMSC to treat complications from stem cell transplants. Eligibility: * Individuals between 18 and 75 years of age who have complications from stem cell transplants. * Complications are acute GVHD, poor bone marrow function, or tissue or organ damage. Design: * Participants will be screened with a physical exam and medical history. They will also have imaging studies and blood tests. * Participants will provide blood, skin, and bone marrow samples before the BMSC treatment. Additional samples, including tissue samples, will be collected after the start of treatment. * Participants will have up to three BMSC infusions. There will be a week between each infusion. Participants will be monitored closely during each infusion. Any side effects will be treated. * Treatment will be monitored with frequent blood tests and physical exams. * After the end of the infusions, participants will have regular followup visits for up to 2 years.