First successful use of expanded umbilical-cord blood units to treat leukemia

Scientists at Fred Hutchinson Cancer Research Center have cleared a major technical hurdle to making umbilical-cord-blood transplants a more widely-used method for treating leukemia and other blood cancers.

In a study published in the Jan.17 edition of Nature Medicine, Colleen Delaney, M.D., and colleagues describe the first use of a method to vastly expand the number of stem/progenitor cells from a unit of cord blood in the laboratory that were then infused into patients resulting in successful and rapid engraftment.

The relatively small number of stem cells in cord blood units (about one-10th the number a patient receives from a conventional transplant) has been a reason that cord blood transplants take much longer to engraft than standard stem cell transplants from donors. The longer the engraftment takes, the higher the risk is that immunocompromised patients will acquire life-threatening infections because they have essentially no white blood cells to fight them.

Despite the numbers disadvantage, cord blood is a promising source of stem cells to replace diseased blood and immune systems in stem cell transplantation because the donated cells don't need to be perfectly matched to the patient. The lack of a suitable match is why about 30 percent of patients overall who need a stem cell transplant to treat cancers such as leukemia can't find suitable donors. Among racial-minority patients the number who cannot find suitable donors is about 95 percent.

The use of expanded cord blood cells could decrease the risk of early death, which is higher in patients receiving a cord-blood transplant without expanded cells. Further clinical trials and technological improvements are needed to verify the efficacy of cord blood transplants that use expanded cells, the authors said.

"The real ground-breaking aspect of this research is that we have shown that you can manipulate stem/progenitor cells in the lab with the goal of increasing their numbers. When given to a person, these cells can rapidly give rise to white blood cells and other components of the blood system," said Delaney, an assistant member in the Hutchinson Center's Clinical Research Division and an assistant professor in the Department of Pediatrics at the University of Washington School of Medicine

The stem cell expansion was possible by activating the Notch signaling pathway in the stem cells. This approach was developed by Irwin Bernstein, M.D., a member of the Hutchinson Center's Clinical Research Division, and was initially published in Nature Medicine in 2000. A decade of work ensued resulting in successful translation of the laboratory findings to patients in a clinical setting. ...

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