Medical breakthrough in heart regeneration

Media release: Scientists discover the heart can regenerate itself

9 May 2014

• Research overturns more than a century of scientific theory
• Finite number of heart muscle cells not decided just after birth – cells continue to regenerate until at least preadolescence
• Allows for a very rapid ‘burst’ of growth over 24 hour period

Scientists at the Victor Chang Cardiac Research Institute, in collaboration with colleagues at Emory University in the United States, have discovered for the first time that heart muscle cells retain the ability to replicate long after birth.

In a study published in Cell^[1], the scientists have overturned more than a century of scientific theory, which proposed that heart muscle cells in mammals stopped replicating just after birth, limiting the organs ability to repair itself after injury.

The study, carried out on mice, also showed that in response to a surge in thyroid hormone, heart muscle cells undergo an intense 24 hour ‘burst’ of division in preadolescence.

During this burst, the number of heart muscle cells increase by more than 40 per cent, or half a million cells, and compared with later in development, the ability of the heart to recover after injury was enhanced.

This response is essential for the heart to meet the increased circulatory needs of the body during a period of rapid growth in preadolescence, in 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 hearts ability to regenerate in patients with heart disease. The work also builds on a 2008 discovery^[2]

Professor Bob Graham, Executive Director, Victor Chang Cardiac Research Institute and Des Renford Professor of Medicine, University of New South Wales, with colleague Professor Ahsan Husain at Emory University, led the study.

“For over one hundred years it has been thought that the heart, much like the brain, stops being able to make new muscle cells soon after birth. In this study, we have overturned the dogma and shown this is not the case.

“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.

“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,” Professor Graham said.

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,” Professor Graham concluded.

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1. The Cell paper, ‘A Proliferative Burst During Preadolescence Establishes The Final Cardiomyocyte Number’
2. In Australia, this work was funded by the National Health & Medical Research Council, Heart Foundation, R.T Hall Estate and the Australian Research Council’s Stem Cells Australia

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For all media enquiries and interview requests, please contact:

Julia Timms
Head, Media & Communications
j.timms@victorchang.edu.au
0457 517 355