Adult stem cells can be rejuvenated!
Scientists have turned back the aging clock of adult stem cells
LifeSciencesToday based on Georgia Tech materials:
Scientists Turn Back the Clock on Adult Stem Cells Aging
Scientists have proved that the aging process of adult stem cells responsible for the regeneration of worn or damaged tissues can be reversed. Perhaps this discovery will lead to the development of treatments for a number of diseases that develop as a result of tissue damage caused by human aging.
The ability to regenerate tissues and organs decreases with age. Modern ideas about the role of stem cells in the aging process are that living organisms are as old or as young as their tissue-specific adult stem cells are old or young. Therefore, the identification of molecules and understanding of the processes that allow adult stem cells to initiate self–renewal – to proliferate and then differentiate in order to rejuvenate damaged tissue - may be the key to regenerative medicine and, ultimately, to the cure of many age-related diseases.
A group of scientists led by experts from the Buck Institute for Research on Aging and the Georgia Institute of Technology conducted a study that showed which disorders limit the division of adult stem cells as they age, that is, what happens to their biological clock.
An article about the study (Inhibition of activated pericentromeric SINE/Alu repeat transcription in senescent human adult stem cells reinstates self-renewal) is published in the journal Cell Cycle.
"We have demonstrated the ability to reverse the aging process of human adult stem cells by interfering with the activity of non–protein coding RNAs originating from regions of the genome that were previously considered non-functional "genomic garbage," says Victoria Lunyak, associate professor at the Buck Institute.
It is adult stem cells that support the health of human body tissues by replacing old or damaged cells with new ones. They are multipotent, which means that an adult stem cell can replace any number of somatic cells of the tissue and organ to which it belongs. However, just like liver cells or any other organ, adult stem cells undergo age-related changes, and as the body ages, it is less able to replace damaged tissue with a new one. This leads to the development of a whole bunch of age-related diseases. But if scientists found a way to keep adult stem cells young, they could be used to restore heart muscle after a heart attack, heal wounds, correct metabolic syndrome, synthesize insulin in patients with type 1 diabetes, treat arthritis and osteoporosis, and regenerate bone tissue.
The researchers began with the assumption that DNA damage in the genome of adult stem cells should be radically different from age-related damage in normal cells of the body. As is known, in somatic cells, telomere shortening occurs – the protective end sections of chromosomes, while in adult stem cells, the length of telomeres does not change. Since most of the damage that occurs during aging is considered to be the result of telomere loss, scientists have concluded that another mechanism should be the key to aging adult stem cells.
Using computational methods for processing experimental data, they compared newly isolated adult stem cells of young people capable of self-renewal with cells of the same people who had undergone long-term passivation. This model of accelerated aging of adult stem cells depletes their regenerative capabilities.
"We found that in adult stem cells, most of the DNA damage and related changes in chromatin occur in regions of the genome known as retrotransposons," says King Jordan, associate professor at the Georgia Institute of Technology School of Biology. "Retrotransposons were previously considered non-functional elements of the genome and were classified as "junk DNA", but accumulating data indicate that they play an important role in the regulation of the genome."
While young adult stem cells were able to suppress the transcriptional activity of retrotransposons and coped with DNA damage, old adult stem cells were unable to suppress this process. This has a detrimental effect on the ability of stem cells to regenerate and triggers a process known as cellular aging.
"By suppressing the accumulation of toxic transcripts of retrotransposons, we were able to reverse the aging process of cultured human adult stem cells," Lunyak comments on the results of the work. "We managed not only to rejuvenate the "elderly" stem cells, but also, to our surprise, to return them to an earlier stage of development by activating "pluripotency factors" – proteins that play an important role in the self-renewal of undifferentiated embryonic stem cells."
In the near future, scientists plan to continue experiments and find out how rejuvenated adult stem cells are suitable for clinical tissue regeneration.
Portal "Eternal youth" http://vechnayamolodost.ru23.09.2011