Scientists at Israel’s Weizmann Institute working with Australian scientists have used the hormone neuregulin to re-grow heart tissue damaged by a heart attack or heart disease. See this rare positive report in the normally anti-Israel UK Guardian. Also published in Nature Cell Biology.
http://www.theguardian.com/science/2015/apr/07/heart-muscle-cells-regrown-in-medical-research-breakthrough http://www.nature.com/ncb/journal/vaop/ncurrent/full/ncb3149.html