New target identified for repairing the heart after heart attack

An immune cell is shown for the first time to be involved in creating the scar that repairs the heart after damage. Billions of cardiac muscle cells are lost during a heart attack. The human heart cannot replenish these lost cells, so the default mechanism of repair is to form a cardiac scar. While this scar works well initially to avoid ventricular rupture, the scar is permanent, so it will eventually lead to heart failure and the heart will not be able to pump as efficiently as before the damage caused by heart attack. Zebrafish, a freshwater fish native to South Asia, is known to be able to fully regenerate its heart after damage due to the formation of a temporary scar as new cardiac muscle cells are formed. Professor Paul Riley and his team at the University of Oxford have been striving to understand and compare the composition of the cardiac scar in different animals as part of ongoing efforts to investigate whether it can be modulated to become a more transient scar like that of the zebrafish, and therefore potentially avoid heart failure in heart attack patients. To do so, the researchers used three different models of studying heart repair and regeneration; the adult mouse heart, which behaves in a similar way to the human heart, the neonate mouse heart, which can regenerate up to 7 days after being born before losing that ability as the mouse ages, and the zebrafish which can regenerate the heart up to adulthood through forming a transient scar.