Stem cell transplantation using umbilical cord blood is a standard treatment option for blood disorders in children, but not for adults, due to the difficulty of obtaining a sufficiently large dose of cells.
To solve this problem, researchers from the University of Minnesota examined a new technique that combines two cord blood units from different donors for transplantation into adult or adolescent leukemia patients. Their study is to be published in the February 1, 2005, issue of Blood, the official journal of the American Society of Hematology.
Twenty-three patients with high-risk acute and chronic leukemias were studied for up to two and a half years. As is often the case, a suitably matched volunteer donor could not be found for these patients, and without an exact match, a transplant would likely be unsuccessful.
Cord blood is more tolerant of differences between patient and donor, making it possible to perform cord blood transplants without an exact match. Though a single cord blood unit with a satisfactory dose could not be found for these patients, senior study author John Wagner, M.D., Scientific Director of Clinical Research of the University of Minnesota's Blood and Marrow Transplantation Program and Stem Cell Institute, theorized that they could still have successful transplants if two partially-matched units were used for each patient.
"Currently, many adult leukemia patients are not eligible for an umbilical cord blood transplant due to the inability to find a single unit of blood with enough cells for transplantation. With this new technique of increasing the dose by combining two units, this procedure could be made available to thousands more patients and has the potential to save many lives," said Juliet N. Barker, M.B., B.S., Assistant Professor of Medicine at the University of Minnesota and co-author of the study.
While two patients with acute leukemia in relapse died from infection shortly after the transplant, in the remaining 21 patients, the transplanted stem cells completely incorporated themselves in the patient's body and began to produce normal, healthy cells. Disease-free survival was 57 percent at one year and, for those who received the transplant while their cancer was in remission, the success rate was even higher at 72 percent.
"The results of this study are heartening, but further investigation of this approach in larger clinical trials is needed to determine the full impact of this transplant procedure for adults and larger adolescents," said George Q. Daley, M.D., Ph.D., Associate Director of the Stem Cell/Developmental Biology research program at Children's Hospital Boston.