Heart attacks, the leading cause of death worldwide, occur when blood supply to the heart is obstructed, depriving the heart muscle cells, or cardiomyocytes, of oxygen. In patients who recover, damaged muscle is replaced by scar tissue, which does not contract, thus permanently impeding the heart’s function. Yet, while damage to cardiomyocytes is irreversible in humans, zebrafish can regrow their cardiac muscle. New research suggests that, not only do they replace lost cardiomyocytes, but their heart cells can change fate to convert to cell types needed for repair. A section through a zebrafish heart (pictured) shows the process in action: cells in green, at the bottom of the heart, arose in the trabeculae, inner layers of the heart muscle, but are converting into cells of the external wall (in blue). This adaptability is another piece of the puzzle for scientists working towards possible future regenerative therapies in humans.
Written by Emmanuelle Briolat
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