In the grip of a heart attack (also known as myocardial infarction), heart muscle cells are killed by oxygen deprivation. Unable to replace cells, the heart is left with a scar, a region which affects its ability to pump properly and poses a risk of further health problems. Researchers are now looking at zebrafish to study scars because, unlike humans, they can replace damaged heart cells. Pictured here zebrafish heart muscle cells (stained purple) have experienced something like a heart attack which has killed off some cells (the black cleft). Around the damaged area a protein called Tenascin-C (stained green) is playing a healing role. Triggered in response to injury it appears near the edges of healthy cells. Researchers think that, at least in zebrafish, Tenascin-C helps replace dead cells with new heart cells.
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