Scientists at Israel’s Weizmann Institute have uncovered a molecule called Agrin, that appears to control the cardiac repair process. It was discovered in the surrounding supportive tissue of the heart known as the extracellular matrix, or ECM. In lab tests, Agrin healed scar tissue in a month.

https://wis-wander.weizmann.ac.il/life-sciences/young-heart-restoring-cardiac-function-matrix-molecule

http://www.nature.com/nature/journal/v547/n7662/full/nature22978.html

http://www.timesofisrael.com/israeli-scientists-successfully-regenerate-damaged-hearts/