1. Experimental Cell Therapy, Department of Hematology and Oncology, Hannover Medical School, 30625 Hannover, Germany.
2. Division of Experimental Hematology, Cincinnati Children's Research Foundation, Cincinnati, OH 45229-3039.
3. Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 117984 Moscow, Russia.
4. Bone Marrow Transplantation, University Hospital Eppendorf, 20251 Hamburg, Germany.