New method rapidly multiplies scarce stem cells

The stem cells in umbilical cord blood transplants have shown great promise in combating leukemia and other blood cancers.

They’re important because, like bone marrow, they have the ability to become all types of blood cells, and they don’t need to be perfectly matched to the transplant patient.

Dr. Colleen Delaney

But until recently there was one major roadblock that had not been surmounted by researchers. Typically, there aren’t enough stem cells in cord blood units—far fewer than in a conventional transplant—and researchers were unable to multiply them in the laboratory.

Fewer stem cells mean that cord blood transplants take hold much later than standard stem cell transplants from donors. When an engraftment takes too long, the risk of acquiring life-threatening infections is much higher for patients who essentially have no white blood cells to fight them.

In January, Hutchinson Center researchers reported a breakthrough using a method that vastly expanded the number of stem cells from a unit of cord blood. The stem cells were infused into patients, leading to rapid and successful engraftment.

“The real groundbreaking aspect of this research is that we have shown you can manipulate stem/progenitor cells in the lab with the goal of increasing their numbers,” said the Hutchinson Center’s Dr. Colleen Delaney, a lead investigator. “When given to a person, these cells can rapidly give rise to white blood cells and other components of the blood system.”

Delaney’s team used an approach to multiply the stem cells that was first developed by another Center researcher, Dr. Irwin Bernstein, a decade ago. Delaney and colleagues built upon Bernstein’s earlier work by engineering a protein that can be used in the lab to increase the number of stem cells into quantities on par with conventional transplant sources.

Cord blood overcomes another transplant obstacle: finding a donor. The lack of a suitable match is why about 30 percent of patients overall who need a stem cell transplant can’t find suitable donors. In some ethnicities, the number of patients who cannot find suitable donors is about 95 percent.