But which is better -- using stem cells that come from bone marrow, or those from cord blood (the blood remaining in the umbilical cord after a baby's birth)?

Researchers at the Medical College of Wisconsin in Milwaukee, along with colleagues from the New York Blood Center, are finding some answers.

They have learned that there are advantages and disadvantages to both, but that transplants using cord blood stem cells have about the same survival rates as those from bone marrow cells.

The results of the study were presented Monday (Dec. 10) at the annual meeting of the American Society of Hematology held at the Orange County Convention Center in Orlando, Fl.

Stem cell transplants using bone marrow have been a standard treatment for blood cancers for many years; transplants of cells from cord blood are newer.

A study comparing them was done several years ago using cord blood from HLA-matched related donors (meaning the six human leucocyte antigens in their blood are a perfect match). The problem is that there are very few patients who benefit because there aren't many who have related donors who match.

This new study compares transplants using stem cells from unrelated donors which came from bone marrow with those whose stem cells came from cord blood. In both cases the donors and recipients were HLA matched as closely as possible, but many had some degree of mismatch.

Since cord blood transplants began, doctors have suspected that they produced less acute graft-vs-host disease (GVHD), an often-fatal complication of stem cell transplants. In GVHD the donor cells from bone marrow attack the host cells they consider foreign.

Researchers wanted to know if that was true. They also wanted to know whether using cord blood would give the same survival rates as using bone marrow if the donors were unrelated.

The researchers looked at 362 cord blood transplants and 275 bone marrow transplants, all using unrelated donors. The patients were all under age 16 and had acute or chronic leukemia, juvenile chronic myelogenous leukemia, or myelodysplastic syndrome.

By comparing rates of GVHD and survival rates, the researchers came to several conclusions to aid doctors in deciding which source of stem cells to use.

First, they were able to confirm that cord blood transplants do produce less GVHD.

"But," says Mary Horowitz, M.D., M.S., professor of neoplastic diseases and scientific director of the International Bone Marrow Transplant Registry (IBMTR) at the Medical College, "we also learned that the cord blood transplants engraft more slowly than the bone marrow transplants, meaning they may have a higher rate of graft failure."

"Second," says Dr. Horowitz, "There appears to be no difference in survival rates between cord blood and bone marrow transplants when all or all-but-one antigen match, despite the findings that cord blood has slower engraftment."

One big advantage of using cord blood for stem cell transplants, Dr. Horowitz points out, is the potential greater availability. If cord blood was salvaged from more births, the supply of stem cells would be very large. The sheer numbers would improve the odds of finding a match.

Members of the research team, along with Dr. Horowitz, were Pablo Rubinstein, M.D., placental blood program head, New York Blood Center; Joanne Kurtzberg, M.D., professor of pediatrics, Duke University; Cladd E. Stevens, M.D., M.P.H., and Andromachi Scaravadou, M.D., immunogenetics department, New York Blood Center; Mei-Jie Zhang, Ph.D., associate professor of biostatistics and Fausto Loberiza, M.D., M.S., assistant professor of health policy at the Medical College; and John E. Wagner, M.D. associate professor of pediatrics, University of Minnesota.

12-Dec-2001