First published June 1, 2005 - More info
Experts are making an effort to set up a national network of umbilical cord blood banks to coordinate collection and distribution of these cells. But they must first figure out how to establish and fund such a network so that physicians will be able to provide patients with suitable cells in a timely manner.
According to the Institute of Medicine (IOM), cord blood stem cell transplants have, in recent years, saved the lives of roughly 20,000 Americans with leukemia, lymphoma, sickle cell anemia, and several other illnesses. Umbilical cord blood is a useful source of hematopoietic progenitor cells, the same multipotent blood stem cells found in the bone marrow.
“[Cord blood] provides increased access to transplantation therapy for patients in need of a stem cell transplant who can’t identify a matched related or unrelated donor,“ said Joanne Kurtzberg, director of the Pediatric Blood and Marrow Transplant Program at Duke University.
Most patients who need a hematopoietic progenitor cell transplant do not have a relative whose cells are a suitable match and must rely on public bone marrow registries or umbilical cord banks. But there currently aren’t enough units of cord blood to meet the demand from the 11,700 Americans who could benefit from a transplant each year. As a result, thousands of patients die waiting for a match.
Because cord blood is readily available and virus free, Kurtzberg said, it’s convenient for patients who need to go to transplant rapidly and don’t have time to search for an unrelated adult donor.
Since the late 1980s, collection of newborn cord blood has increased sharply. By 2003, nearly 80,000 families in the US took advantage of any 1 of the 22 public banks that have been established to utilize cord blood. “Cord blood stem cells are a valuable addition to the armamentarium of transplantable tissues for transplant physicians,” Naomi Luban, director of Transfusion Medicine at Children’s National Medical Center in Washington, D.C., told the JCI.
There are major limitations to using cord blood, however. Kurtzberg points out that there is no central coordination, not enough federal funding to build adequate inventory, lack of standardization of banking criteria to ensure quality standards among banks, and lack of a single search registry listing all available unrelated donors for transplantation. “Currently transplant centers must approach multiple banks for each donor search,” she said.
Lawmakers introduced a bill that addressed these issues in both the House of Representatives and the Senate earlier this year. The bill is still pending and has been referred to the House Subcommittee on Health. It would help to establish a national umbilical cord blood stem cell bank network and authorize $15 million in federal funds during 2006 and $30 million during 2007 to subsidize efforts to collect, process, test, freeze, and store cord blood stem cells to be used in transplant treatments. The network would also support peer-reviewed research using these cells. “The proposal of the US Congress to earmark dollars to the establishment of a cord blood banking program represents an important advance in the field of hematopoietic stem cell transplantation,” said Vanderson Rocha, clinical coordinator of the Eurocord Project and board member of the Netcord organization.
The need for a central coordinating network is also the focus of a report released April 18, 2005 by the IOM. The report recommends that a new cord blood coordinating center — similar to the existing National Marrow Donor Program — be set up to ensure a standardized and interconnected national system to cost-effectively store and distribute these cells. The Bush administration is studying the IOM report but has not yet determined its next step.
The proposed center would strengthen the network of cord blood banks and allow physicians to meet the needs of more patients who require transplantation therapies with a high-quality stem cell product, Rocha said. To build an adequate supply of cord blood for transplantations, the IOM concluded that the nation would need about 100,000 donations, in addition to the useable 50,000 cord blood donations already in stock at various public cord blood banks around the country.
Increasing the amount of inventory would assure that more people find a suitable match. “The matched cells are useful because they are frozen, so one does not need to depend on a live donor’s availability,” Luban told the JCI. But, she adds, “One cannot go back to the donor for additional transplantable cells or for other donor-derived cells.”
Another factor that restricts the clinical utility of cord blood stem cells is that use of these cells to treat other patients, called allogenic transplantation, could be associated with recipient immune rejection against donor cells. According to Luban, the small volume and low percentage of cells expressing CD34, an antigen selectively expressed on human hematopoietic progenitor cells, are also limiting factors.
The limitations due to the fact that cord blood stem cells are rare can be resolved through new expansion techniques, said Jonathan Leor, head of the Neufeld Cardiac Research Institute at Sheba Medical Center in Tel Aviv. Based on his experience, Leor believes that there is a high probability that the cells obtained from cord blood could be expanded in vitro and used for myocardial repair and angiogenesis. Clinical trials are also underway to assess the effects of using 2 cord blood units for a single patient, Rocha said.
Most important, many recent clinical retrospective studies in children and in adults show that the results of unrelated cord blood cell transplants are similar to those of unrelated bone marrow transplants. “Transplantation in children tends to have a good outcome with a minimum dose of cells,” said Derwood Pamphilon, a consulting hematologist for the United Kingdom’s National Blood Service. Even in adults, he continued, a reasonable dose of cord blood cells, even with a minor degree of mismatch, gives an outcome much better than had been hoped for.