Mouse Hearts Undergo Pre-Teen Growth Spurt

If replicated in humans, the finding that heart cells have the capacity to divide long after birth could lead to regenerative treatments for heart disease.

AsianScientist (May 23, 2014) – A study published in Cell overturns more than a century of scientific theory, showing that heart cells are able to replicate in adolescence – at least in mice.

The study showed that the heart muscle cells of pre-adolescent mice undergo an intense 24 hour ‘burst’ of division in response to a surge in thyroid hormone. During this burst, the number of heart muscle cells increased by more than 40 percent, or roughly half a million cells. Furthermore, the authors noted that the increase in cell number correlated with an improved ability of the heart to recover after injury.

This response is essential for the heart to meet the increased circulatory needs of the body during a period of rapid growth in preadolescence, during which the heart increases almost four-fold in size.

The findings suggest that thyroid hormone therapy could stimulate the process, and may even enhance the heart’s ability to regenerate in patients with heart disease.

“Heart muscle cells retain the ability to divide and make new cells for a long time after birth, at least until preadolescence, equivalent to eight to ten years of age in humans,” says Professor Robert Graham, lead author of the study and executive director of the Victor Chang Cardiac Research Institute at the University of New South Wales.

“The implications of our findings could be huge, as it may give us a significant window of opportunity in which to repair the hearts of babies born with heart defects, or even to reactivate heart muscle cells damaged after a heart attack in adults.”

The scientists also believe the brevity of the burst may explain why it has previously gone undetected, taking place over just 24 hours in mice, equating to around five weeks in humans.

“I think this research has given us some really important and significant insights, including that the heart is not as static as we previously thought. It is actually a very dynamic organ, which is something we may be able to use to our advantage as we continue the fight against heart disease,” he says.

The article can be found at: Naqvi et al. (2014) A Proliferative Burst during Preadolescence Establishes the Final Cardiomyocyte Number.


Source: University of New South Wales; Photo: Dan Backman/Flickr/CC.

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