If only we could regrow our broken bones like Harry Potter, Skele-gro style. Or, at the very least, heal up like a limb-regenerating newt. Alas, we humans possess no such abilities. Though our bodies can mend broken bones, the older we get, the shoddier that patch job gets. As for cartilage — the crucial cushioning that keeps our bones from rubbing together — once that’s gone, it’s gone for good.

But a new discovery by researchers could change that outlook. A team from Stanford University