In heart failure, which is characterised by exercise intolerance, shortness of breath and oedema, the heart muscle is unable to pump a sufficient blood supply around the body. Cardiac muscle regeneration might thus restore function to a failing heart but how can cardiomyocyte regeneration be achieved? A zebrafish model of cardiac injury developed by Kenneth Poss and colleagues (see ) could provide valuable clues. It is known that adult zebrafish can regenerate cardiac muscle after surgical removal of about 20% of the ventricle. To study heart regeneration after larger injuries, the researchers created transgenic zebrafish in which destruction of more than 60% of the ventricular myocardium can be genetically induced. This massive myocardial loss triggers exercise intolerance in the fish, they report, but is completely reversed within 30 days through de-differentiation and proliferation of surviving cardiomyocytes. This new model of heart injury can now be used to understand why heart regeneration occurs in zebrafish – information that might help efforts to reverse human heart failure.
