Researchers led by Buck Institute for Research on Aging and the Georgia Institute of Technology found the way of reversing adult stem cell aging in humans. The finding could give rise to new treatments of diseases that arise as people age. The results of the study were published in the journal Cell Cycle.
Adult stem cells that are responsible for tissues renovation in an adult body undergo age-related damage which results in lowering their ability to divide and give rise to new specialized cells, and, thus, in weakening tissue regenerating processes. The researchers dug into mechanisms that drive adult human stem cell division, proliferation and differentiation, and found how to turn back the biological clock.
The team hypothesized that mechanisms underlying stem cell aging are different to those in specialized cells. As the latter age, the shortening of telomeres, or caps at the end of chromosomes, occurs. In contrast, stem cells are known to keep their telomeres from shortening.
Therefore, the researchers had to look in the different direction for changes in the DNA that are responsible for aging process. They collected adult stem cells from young individuals, divided them in two parts and subjected one part to a long-time passaging in culture. The latter exhausted the ability of stem cells to divide and was used as a model of the aging process. Then the researchers compared the two groups of cells in terms of genomic sites where DNA damage was accumulated.
They found that DNA damage that occurred as a result of aging was accumulated mainly in the genome parts known as retrotransposons, once thought to be non-functioning “junk DNA”. In young stem cells, the transcription activity of these elements was suppressed which helped to keep their renovating potential at a high level, while old stem cells could not prevent transcription of damaged DNA areas. This was the explanation of the aging processes in stem cells.
The researchers were able to suppress forming of toxic transcripts from damaged DNA areas in retrotransposons in culture and reverse stem cell aging processes. They not only managed to bring cells to their pre-culture state, but also to bring them properties of early developmental stages–pluripotent stem cells that are found in embryos.
The team plans to study to what extent rejuvenated stem cells can be used in clinical practice. If they succeed, the key to curing age-relating diseases can be found.