Despite its importance, the heart is one of the few tissues in the human body that can't repair damage very well – or at least, that's what has long been presumed. Scientists in Australia have now caught heart muscle cells freely regenerating after a heart attack.
When something impedes blood flow, the lack of oxygen kills heart cells. The organ can patch itself up with scar tissue, but this inelastic, fibrous tissue doesn't beat, making the heart less efficient. These irregularities can eventually lead to further attacks and heart failure in the future.
Mice seem to be lucky enough to have hearts that can regenerate, at least partly. Their cardiomyocytes (heart muscle cells) have been seen dividing again after a heart attack, but human heart cells aren't nearly so sprightly after injury.
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"Our research shows that while the heart is left scarred after a heart attack, it produces new muscle cells, which opens up new possibilities," says Robert Hume, first author of the study and cardiologist at the University of Sydney.
"Although this new discovery of regrowing muscle cells is exciting, it isn't enough to prevent the devastating effects of a heart attack. Therefore, in time, we hope to develop therapies that can amplify the heart's natural ability to produce new cells and regenerate the heart after an attack."
Previous research observing patients after heart surgery has hinted at the potential of heart muscle cells to regenerate after injury.
In this new study, Hume and colleagues examined living human heart tissue in a full heart from a donor declared brain-dead, as well as samples collected from patients during bypass surgery.
The team sequenced the RNA (readouts of DNA used to make proteins) and closely studied the proteins and metabolism of the tissue.
"We also characterized the [blood-deprived] environment that promoted this intrinsic cardiomyocyte cell division, identifying transcripts, proteins, and metabolites previously shown to induce [cell division] in rodent studies," the scientists write in a paper describing the work.
The hope is that these findings could lead to new regenerative therapies that could one day allow us to tackle the world's leading cause of death.
The research was published in the journal Circulation Research.