Doctors at Fred Hutchinson Cancer Research Center have successfully increased the stem cell numbers from cord blood and used the expanded numbers of cord blood stem cells in patient transplants. Stored cord blood was thawed and stem cell growth stimulated using an engineered protein that stimulates the "Notch" signaling pathway in the cells. Notch signaling is a key regulator of cell growth and development. Senior author Dr. Irwin Bernstein has been working on this approach using Notch signaling for at least a decade. The new results reported in Nature Medicine show that stimulation of the stem cells resulted in an average 164-fold increase in the number of CD34+ cells, a type of hematopoietic (blood forming) stem cell critical in adult stem cell transplants.

The study also reports preliminary results of an ongoing Phase I clinical trial. Ten patients received cord blood stem cell transplants incorporating the expanded stem cells. On average, it took half as long (14 days) for the transplanted cells to engraft, compared to using non-expanded cord blood stem cells. Seven of the 10 patients are still alive with no evidence of disease.

Dr. Colleen Delaney, lead author, pointed out:

"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."

Finding a donor match for an adult stem cell transplant can be difficult. Cord blood is increasingly being used as an alternative to bone marrow adult stem cell transplants. Through 2009, more than 20,000 unrelated (donor) cord blood stem cell transplants have been performed worldwide. Cord blood stem cells can be effective even when there is some mismatch between transplant donor and recipient. But the numbers of adult stem cells in a unit of cord blood can be low. This new result using Notch signaling to expand the numbers of stem cells in a cord blood unit is a significant step in making transplants more widely available.