Force Is Strong for Blood Stem Cells, at Least in Mice, Zebrafish Embryos: Studies Show Blood Flow and Nitric Oxide Boost Production

Article excerpt

Blood stem cells grow with the flow.

Two new studies, led by independent groups at Children's Hospital Boston, report that an embryo's heartbeat and blood circulation stimulate the growth of blood stem cells.

The find could be a boon to researchers seeking to make blood stem cells for people with blood cancers, immune system disorders and other diseases that require bone marrow transplants. In people, blood stem cells reside in the bone marrow and constantly replenish blood supply. Only about a third of patients who need bone marrow transplants have matching donors.

"Basically we cannot offer optimal therapy to two-thirds of patients," says Leonard Zon, director of the Stem Cell Research Program at Children's Hospital Boston and a coauthor of one of the new studies, appearing in the May 15 Cell.

Scientists can make red and white blood cells from embryonic stem cells easily in the laboratory, but producing blood stem cells, called hematopoietic stem cells, has been much more difficult, Zon says. Now, his group suggests that a little force can boost blood stem cell production in zebrafish embryos.

Reporting online May 13 in Nature, a group led by George Daley, director of the Pediatric Stem Cell Transplantation Program at Children's Hospital Boston, demonstrates that blood flow also triggers hematopoietic stem cell production in mouse embryos. Both groups found that nitric oxide plays a role.

Intuitively, scientists might expect that mechanical forces help shape development. But because of experimental difficulties, few biologists have studied this, says Ihor Lemischka of Mount Sinai School of Medicine in New York City. "I think we'll be seeing more of these types of studies," Lemischka says. …