Molecule Multiplies Stem Cells in Human Cord Blood

By Suzanne Rostler

NEW YORK (Reuters Health) - A team of US researchers has for the first time expanded the number of stem cells derived from umbilical cord blood, raising the possibility that more adult patients will be able to receive this rich source of stem cells in the future.

Stem cells from adult bone marrow can develop into all types of blood and immune system cells, and bone marrow transplants are used to treat certain diseases, including leukemia. Blood collected from a newborn's umbilical cord is a richer source of these immature cells--which can give patients a "new" immune system--and the infant cells are less likely to attack the recipient's tissue, a potentially life-threatening complication of a transplant.

However, the number of blood cells collected from cords is usually insufficient for adult recipients. Studies have linked higher numbers of cells with the success of a transplant. For this reason, scientists have tried to grow cord blood-derived cells before transplanting them into patients.

In the current study, Dr. Irwin D. Bernstein from the Fred Hutchinson Cancer Research Center in Seattle, Washington and colleagues exposed human cord blood to a molecule, Delta-1, that activates an important pathway in the production of stem cells. The compound increased the number of stem cells more than 100-fold, they report in the October 21st issue of The Journal of Clinical Investigation.

"By manipulating the pathway we can manipulate the decisions stem cells make, so there might be general uses in engineering (hemopoietic) stem cells," he told Reuters Health.

Then, the researchers transplanted the cells into mice that had been bred to lack an immune system. The cells cultured with Delta-1 proved to be more powerful at boosting the immunity of mice than non-cultured cells or those that had been cultured with another compound, the study found.

"In clinical bone marrow transplantation, the frequent inability to find human stem cell donors fully or partially matched with the recipient...remains a problem," the researchers explain. "Thus, the significant expansion of...cells from cord blood stem cells observed in the present study points to the promise of enhancing the utility of human stem cell transplantation."

SOURCE: The Journal of Clinical Investigation 2002;110:1165-1174.