Broken bones heal with young blood, how remains a mystery

Young blood is good for old bones.

Elderly mice hooked up to the circulatory systems of young adult mice bounce back quickly from broken legs, researchers report May 19 in Nature Communications. The bone-healing finding is the latest in a chain of recent studies exposing the health benefits of young blood on different parts of the body. Last year, scientists discovered that a hit of young blood gave old mice a boost in brain power and even rejuvenated aging muscle cells.

Scientists haven’t yet pinpointed the mysterious helper that lurks in young blood. A molecule previously pegged as responsible for some fountain-of-youth properties may not be so impressive after all, a second new study suggests. The molecule, a protein called GDF11, actually makes muscles wither, researchers contend May 19 in Cell Metabolism.