If you cut a piece of tissue from the heart of a salamander or zebrafish, they wild simply grow new heart tissue. Unfortunately, humans are unable to easily regenerate heart cells, and this males it difficult to recover from the permanent damage caused by heart attacks.
Fortunately, life scientists from the Weizmann Institute of Science in Israel and the Victor Chang Institute in Sydney have discovered a way to stimulate heart muscle cells in mammals to grow. This finding could have major implications for future heart attack sufferers.
Even though human blood, hair and skin cells renew themselves throughout life, cell division in the heart comes to a virtual standstill shortly after birth, according to Prof. Richard Harvey, from the Victor Chang cardiac research institute, and one of the authors of this research. Harvey said, “So there’s always been an intense interest in the mechanism salamanders and fish use which makes them capable of heart regeneration, and one thing they do is send their cardiomyocytes, or muscle cells, into a dormant state, which they then come out of to go into a proliferative state, which means they start dividing rapidly and replacing lost cardiomyocytes.”
Harvey continued: “There are various theories why the human heart can not do that, one being that our more sophisticated immune system has come at a cost, and because human cardiomyocytes are in a deeper state of quiescence, that has made it very difficult to stimulate them to divide.”
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By studying mice, Harvey and his colleagues found a way to overcome that regenerative barrier – at least in the rodents.
Harvey and others found that by stimulating a cell signaling pathway in the heart that is driven by a hormone called neuregulin, heart muscle cells divided in a spectacular way in both adolescent and adult mice. In humans, neuregulin expression is usually muted about one week after birth, and by about 20 weeks after birth in mice.
By triggering of the neuregulin pathway following a heart attack in mice, Harvey and others induced the replacement of lost muscle, which repaired the heart to a level close to that prior to the heart attack. Harvey said that he and other scientists should be able to determine with in the next five years if it is possible to replicate these results in humans.
“This is such a significant finding that it will harness research activities in many labs around the world, and there will be much more attention now on how this neuregulin-response could be maximised,” Harvey said.
“We will now examine what else we can use, other than genes, to activate that pathway, and it could be that there are already drugs out there, used for other conditions and regarded as safe, that can trigger this response in humans.”
When one of the blood vessels that provide blood to the heart muscle becomes blocked, the patient suffers a heart attack. Heart attacks or “myocardial infractions” cause billions of cardiomyocytes to die. Even if you survive a heart attack, you usually experience diminished quality of life because of it.
“The dream is that one day we will be able to regenerate damaged heart tissue, much like a salamander can regrow a new limb if it is bitten off by a predator,” Harvey said.
Molecular biologist Gabriele D’Uva lead this research, which was published in the scientific journal Nature Cell Biology.