Bone marrow has long been thought to have a role in repairing damaged skin, and now UK and Japanese researchers think they’ve found the key to summoning stem cells from bone marrow to the site of damaged skin: a signal known as HMGB1. By tapping this signaling mechanism, researchers could develop new treatments for skin injuries like severe burns.

HMGB1 is like a “megaphone in the system,” researchers said, putting out a distress call when stem cells are needed. But that distress signal only goes out when initiated by certain conditions. Figuring out what those conditions are and then isolating the signal was the challenge for the researchers, based at King’s College London and Osaka University.