Protein may aid stroke recovery.

A drug best known for kick-starting bone marrow to make red blood cells has reversed brain damage due to strokes in test mice.

William D. Hill, a neuroscientist at the Medical College of Georgia in Augusta, and his colleagues surgically induced strokes in the mice, reducing the animals' propensity to explore an unfamiliar environment. Mice subsequently given injections of the protein erythropoietin increased their explorations over the next 4 weeks, whereas mice given saline injections showed a smaller boost, Hill says.

Other recent studies have shown that erythropoietin can protect some brain cells from injury. However, it's still unclear how the drug might heal parts of the brain temporarily starved of blood--as in a blood-clot-induced stroke, Hill says.

One possible explanation arises from another study in which researchers found that erythropoietin can protect endothelial progenitor cells, which build and repair blood vessels. Erythropoiefin triggers production of an enzyme, copper-zinc superoxide dismutase, that fights damage to those cells from oxygen, says molecular biologist Tongrong He of the Mayo Clinic in Rochester, Minn.

Both groups presented their findings at a recent meeting of the American Stroke Association in New Orleans.--N.S.