The umbilical cord blood stem cells have been used to treat cancer patients whose bone marrow tissues have been wiped out by radiation or chemotherapeutic treatments. Several clinical trials have addresses the capacity of umbilical cord blood to reconstitute the bone marrow of cancer patients.
The first set of clinical trials have examined the use of umbilical cord blood in children. Gluckman and her colleagues reported the use of umbilical cord blood to treat children who had suffered from a variety of blood maladies. 74 patients were treated with umbilical cord blood. 63% of the patients survived one year after the procedure, and the rate of graft-versus-host disease (GVHD) was only 9%. Now this study showed that umbilical cord blood could be used to reconstitute the bone marrow, but how well does it work compared to bone marrow transplants?
To answer this question, Rocha and his colleagues compared kids who had received umbilical cord blood transplants with those who had received bone marrow transplants. 113 cord blood transplant patients were compared to 2052 bone marrow transplant recipients. In this study, the umbilical cord blood recipients took longer to have their bone marrow reconstituted, but the rate of graft-versus-host disease was lower. The survival rate of the two groups three years after the procedure was also about the same (64% for the umbilical cord blood recipients and 66% for the bone marrow recipients). Thus, umbilical cord blood seemed to work as well as bone marrow when it came to reconstituting the bone marrow.
Since the rates of GVH disease were so low, could umbilical cord blood that was not properly tissue matched to the recipient also work? The answer was yes. Once again Gluckman and her colleagues showed that the rate of GVH disease was rather low, and the rate of recovery in a group of 65 patients was quite high (87%). Such a treatment with unmatched bone marrow would be a disaster, since GVH disease would almost certainly result from such a treatment. The results of Gluckman’s small study were confirmed by a much larger study by Rubinstein and others in 1998.
Can cord blood be used to treat adults with similar maladies? Clinical studies have confirmed that the answer is yes. Survival rates from a host of clinical trials have ranged from 15%-70%, but clearly adults can benefit from umbilical cord blood transplantations. Once again, the rates of GVH disease were lower in umbilical cord blood recipients when compared to bone marrow recipients, but once again, the time required for bone marrow recovery was greater.
In Minnesota, Wagner and his colleagues pioneered the use of “double umbilical cord blood grafts” in which umbilical cord blood is taken from two different babies to treat an adult patient. This overcomes the limited volume and cell numbers in an umbilical collection from a single donor. These are only used for patients who are very ill, but studies have shown that patients who have received double umbilical cord blood grafts have a ten-fold lower decrease in the risk of relapse of blood cancers.
Thus over the past two decades, umbilical cord blood transplants have become rather attractive sources of material to reconstitute bone marrow. Although low cell numbers are still a chronic problem with them, the ability to culture and expand these cells in culture may give a new life to this useful treatment.