The Protein Fountain of Youth

Sixty years ago some ghoulish scientists connected the circulatory systems of old and young mice and discovered that the young blood made the older mice look and act young again.

Ever since then, physiologists have been searching for the magic factor that might be the cause of this remarkable effect. Last year a team led by two prominent American scientists, Amy Wagers and Richard Lee, announced that they had isolated one causal agent: a protein called GDF11. Wagers, Lee and colleagues

reported that blood levels of GDF11 drop in mice as the animals get older and that injecting old mice with GDF11 can partially reverse age-related thickening of the heart. . . . Wagers and collaborators also reported that GDF11 can rejuvenate the rodents’ muscles and brains.

But the first teams to attempt replication of this result could not confirm it:

The Novartis group concluded from a different assay that GDF11 levels in blood actually rise with age in rats and people. And in their lab, GDF11 injections inhibited muscle regeneration in young mice.

Today's news is that Wagers et al. are sticking to their guns:

To back up their earlier results, Wagers and collaborators again show in the new paper that daily GDF11 injections can shrink heart muscle in both old and new mice. 

But wait, there's more:

But this time they note another observation: The mice also lost weight.

I expect a black market in clandestine GDF11 to spring up overnight. Shadowy guys in the dark corners of bars and clubs will carry GDF11 instead of cocaine or oxycontin, crazy minor celebrities will go on talk shows to talk about their miracle cure, dubious doctors in Mexico and the Philippines will start offering tourists treatments with what they claim is GDF11, and eventually pharmaceutical companies will bring a drug to market and earn billions. I remains dubious, though, that it will really add years to anyone's life.