A heart attack without scarring on the heart?
Scientists have figured out how to restore heart tissue without stem cellsRIA News
Scientists have uncovered the cellular mechanism of restoring heart tissue in danio rerio fish and have shown that they do not need stem cells for this, which will help develop methods for regenerating heart tissue in humans, according to an article by researchers published on Thursday in the journal Nature (Chris Jopling et al., Zebrafish heart regeneration occurs by cardiomyocyte dedifferentiation and proliferation).
Danio rerio fish, which have long served scientists as a model animal, have one very striking feature – the removal of a fragment of their heart muscle leads to a slowdown in their activity, but over time the heart of the fish is fully restored and in less than a month the fish return to active life.
A group of scientists led by Juan Carlos Izpisua Belmonte from the Center for Regenerative Medicine in Barcelona in their work investigated the cellular mechanisms of regeneration of lost heart tissue in danio rerio. To do this, scientists have bred transgenic fish, whose heart tissue cells – cardiomyocytes – are easily distinguishable from other tissues due to the fluorescent protein embedded in them, glowing green.
After removing the fragment of the heart muscle, scientists expected that the newly formed heart tissue in its place would not glow green, since it would be formed from another type of cells – stem cells, but in fact it turned out that the regenerating fragment of the heart muscle, as well as intact, actively radiated a green glow.
This means that the restoration of heart tissue in danio rerio occurred without the use of stem cells, with the participation of adult cardiomyocytes only.
"Our results show that nature uses other ways for regeneration besides returning tissues to their original pluripotent state," said Ispisua Belmonte, quoted by the press service of the Solkovsky Institute for Biological Research in the United States.
Scientists in their work have shown that the remaining cardiomyocytes of danio rerio during regeneration partially returned to a young state, activating the production of proteins associated with cell reproduction, which are produced by progenitor cells.
The researchers note that the mammalian and human heart cannot go through these stages of regeneration and instead of new tissue, the place of the lost fragment of the heart muscle is occupied by scar tissue that is not capable of contraction. Nevertheless, scientists emphasize that before a person has heart palsy, his muscle cells go into a state of "hibernation" – a decrease in the amplitude of contractions in order to prevent self-destruction of tissues.
(Hibernation is not hibernation. Myocardial hibernation is called a decrease in the function of the heart muscle as a result of a decrease in its blood supply – VM.)
The same hibernation is observed in the cardiomyocytes of danio rerio, which leads scientists to assume that human heart cells are also "trying" to start regeneration, but for this they need some additional effort.
"We can no longer consider adult cells of the body as a static form, which ends the process of their maturation. If we can simulate in mammalian heart cells the process that is observed in danio rerio, we will understand why we still do not observe the regeneration of the heart in humans," Ispisua Belmonte summed up.
Portal "Eternal youth" http://vechnayamolodost.ru25.03.2010