Is the epicardium a good target for new drugs to encourage heart repair?

Epicardial activation and signalling during cardiovascular repair: comparing regenerative and non-regenerative models (renewal)

Heart muscle cannot repair itself after injury, e.g. after a heart attack, so scientists are working to repair it using new heart muscle cells. BHF Professor Paul Riley and colleagues (University of Oxford and University College London) have found they can turn cells in the outer layer of the heart (the epicardium) of mice into beating heart cells using a chemical called thymosin beta-4. These cells then integrated with existing healthy heart muscle. In mice, epicardial cells contribute to the development of the heart in the embryo but this ability is lost in adults. Thymosin beta-4 seemed to reactivate the cells by switching on embryonic genes. The researchers also screened over 16,000 drugs to see if they can activate epicardial cells. Thanks to the Mending Broken Hearts Appeal, the BHF has awarded a grant of just over £1.1m to Professor Riley to fully understand this ‘epicardium reactivation process’ to restore lost muscle and blood vessels following a heart attack. They will study adult zebrafish and newborn mice (which can completely regenerate their hearts following injury) to identify epicardial signals instrumental in driving heart repair. They will then apply these ‘regenerative’ epicardial signals to adult mouse hearts and human patient cells to see if they induce heart repair after injury. This research may uncover new drug molecules to boost heart repair over the next decade – which could make a huge difference to people with heart failure in the future.