Gene therapy tackles hair loss.

It may be the stiffest challenge ever faced by the popular video-game hero Sonic the Hedgehog. Scientists suggest that a gene named after the combative character could prove a potent weapon in the battle against a fearsome foe: baldness.

During embryonic development, the gene sonic hedgehog participates in the formation of the brain, heart, lung, skeleton, and many other tissues and organs. It's also active in the embryo as hair follicles arise.

To test sonic hedgehog's role in hair growth, investigators used a virus to slip the gene into mouse hair follicles. Since they had dyed blond each animal's naturally black fur, the scientists could monitor new hair growth by looking for all-black hairs. The added gene triggered quiescent follicles into producing normal-looking hair, Ronald G. Crystal of Cornell University's Weill Medical College in New York and his colleagues report in the Oct. 1 JOURNAL OF CLINICAL INVESTIGATION.

Since sonic hedgehog activity may promote certain skin cancers, it's unclear whether an approach based on the gene is a safe way to tackle hair loss, caution the scientists. Moreover, in some forms of baldness, the follicles completely degenerate. Testing the gene-therapy strategy on human skin grafted onto mice would be a reasonable follow-up experiment, says Andrzej Dlugosz of the University of Michigan in Ann Arbor, who wrote a commentary accompanying the report.