Growing lots of adult stem cells in the lab, for study or for a patient treatment, has been difficult in the past. While some groups have successfully grown large numbers of adult stem cells, many labs have difficulties keeping the cells growing for more than a few days. Now scientists at Weill Cornell have shown that culturing adult stem cells with endothelial cells, the cells that compose the innermost linings of blood vessels, is the key to growing unlimited amounts of adult stem cells. The research group reasoned that because endothelial cells line blood vessels and are often in contact with adult stem cells, these cells might play a significant role in the growth and maintenance of stem cells. Using a mouse model, the scientists were able to grow adult stem cells for weeks at a time and increase the number of cells over 400-fold. They also showed that even after one year, there was no indication of tumor formation from the adult stem cells. Senior author, Dr. Shahin Rafii, noted:

"This study will have a major impact on the treatment of any blood-related disorder that requires a stem cell transplant."

Previous work from Dr. Rafii's lab had demonstrated that endothelial cells are not "passive conduits"

for delivery of oxygen and nutrients but also produce novel stem-cell-active growth factors.

The breakthrough promises broad clinical benefits, from bone marrow transplantation to therapies for heart, brain, skin and lungs. If the system continues to be validated, physicians could use any source of hematopoietic (blood-forming) stem cells, grow large numbers, and bank the adult stem cells for transplantation into patients.

The paper is published in the journal Cell Stem Cell.