Scientists have reported the creation of the cells that help build the body's supply of blood and arteries. They have been derived from human embryonic stem cells, and have been produced in substantial numbers.
These cells have shown promise in lab animal treatment of diabetes, heart disease and wounds.
A team led by Shi-Jiang Lu of Advanced Cell Technology in Worcester, Mass., reported the creation of these precursor cells, known as "hemangioblasts," in the journal Nature Methods.
Says ACT's Robert Lanza: "We have been hunting these elusive cells for years.
"We're calling them 'ambulance' cells. They're very smart. We inject them into veins, and they head to repair sites," Lanza added.
Hemangioblasts, which develop early in embryonic development, were first isolated from early human embryos, last month and the procedure was documented in the journal Blood, by the researchers from Mount Sinai School of Medicine.
ACT is best known for its announcement in 2001 of an unsuccessful attempt to create a line of stem cells from a cloned human embryo. Embryonic stem cells are precursors to almost every tissue in the body.
In the new study, the ACT team reports growing billions of hemangioblasts from eight human embryonic stem cell types. They report using them to treat diabetic rats, as well as damaged blood vessels in mice.
Says Valerie Kouskoff of the United Kingdom's Paterson Institute for Cancer Research: "Overall, I would say that this is a very promising study". At the same time she cautions that all transplantations were performed in mice and rats, not people, and were short-term.
Lanza agrees but says that if safety studies show progress, his team may seek approval for human testing in 2008.
In theory, hemangioblasts could create large numbers of "universal donor" blood cells for transfusions in emergencies, according to the scientists.