Broken bones heal with young blood, how remains a mystery
![mouse bone X-ray](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2015/05/mr_youngblood_free.png?fit=860%2C460&ssl=1)
Surgically linking the circulatory system of old mice (gray) to young mice (yellow) boosts healing of broken bones (X-ray at right), compared with linking two old mice together (left).
G.S. Baht et al/Nature Communications 2015