If you become an embryo for a short time…
Scientists rejuvenated a mouse for the first time using gene therapy
Gene therapy, including a set of embryonic genes, rejuvenated some organs of elderly mice, which opens the way for the creation of rejuvenation techniques and human cells, according to an article published in the journal Cell (Ocampo et al., In Vivo Amelioration of Age-Associated Hallmarks by Partial Reprogramming).
"Our study shows that aging does not necessarily go one way irreversibly. This is a fairly flexible process that, under very specific conditions and with the appropriate tools, can be reversed," said Juan Belmonte from the Salk Institute in La Jolla (in a press release on the institute's website Turning back time: Salk scientists reverse signs of aging – VM).
Embryo cells and embryonic stem cells are virtually immortal from the point of view of biology – they can live almost indefinitely in an adequate habitat, and divide an unlimited number of times. In contrast, the cells of the adult human body gradually lose their ability to divide after 40-50 division cycles, entering the aging phase.
Why do cells do this? As scientists believe today, in this way cells protect themselves and the body as a whole from the development of cancer, stopping division at a time when the probability of mutations in their genome reaches a certain critical point.
Aging, as geneticists say, is accompanied by many changes in the vital activity of the cell, which actually turn it off from the normal functioning of the body. The accumulation of such "elderly" cells, as scientists believe today, is the reason for the development of characteristic physiological changes associated with the onset of old age.
Belmonte and his colleagues found that part of the aging process can be reversed by including those genes that are responsible for the "immortality" of embryonic and stem cells – Oct4, Sox2, Klf4 and cMYC. Nobel laureate Shinya Yamanaka used these same genes to turn "adult" skin cells into analogues of embryonic stem cells.
To do this, scientists created a special gene therapy that did not replace these genes or make additional copies of them inside the cell, but simply turned them on, changing the structure of the protein "packaging" of DNA that prevents the reading of Oct4, Sox2, Klf4 and cMYC in the nucleus of an adult cell.
These genes, as scientists explain, were turned on for a very short time – two or four days, enough for rejuvenation, but not enough for the cells to start dividing uncontrollably and turn into a cancerous tumor.
Having tested the work of this anti–aging therapy on cell cultures in vitro, the scientists tried to repeat the same operation on healthy elderly rodents and their relatives suffering from progeria - accelerated aging syndrome.
The results of these experiments, as Belmonte notes, were amazing – gene therapy extended the life of rapidly aging rodents by 30%, and increased the rate of regeneration of skeletal muscles and pancreas in elderly wild-type mice.
At the same time, scientists have not recorded an increase in the incidence of cancer, which suggests that the short-term inclusion of "Yamanaki genes" is relatively safe. On the other hand, do not expect that such rejuvenation courses will appear in clinics tomorrow. As scientists admit, not all the results of experiments on mice are successfully reproduced in human clinical trials, and even if such therapy works, it will take at least 10 years before it passes such tests.
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16.12.2016