Ever used a stopwatch to record time for a certain activity? You must have observed a reset button that will make the clock hands go back to zero so that you can record time for the next activity. What if I told you there is a stopwatch in our cells when we are in the embryo stage? Apparently, science reports the existence of a reset button in embryonic cells too.
Cells accumulate change over time but offspring doesn’t show any such features of change even though it is formed from parental cells. The germ cells essentially are immortal and have gone back to ‘zero’ as pointed by Yukiko Yamashita, an MIT developmental biologist. Interestingly, the germ cells do age but they reset their age after fertilization. There is evidence of a rejuvenation event that occurs in human and mouse cells, whereby their biological age is reset during embryogenesis. This reset time has been termed as ‘ground zero’ which marks the onset of aging in organisms.
Vittorio Sebastiano, a developmental biologist at Standford University, understands that this idea of the biological clock might be the key to effectively treat arthritis or Parkinson’s disease. The process could probably be replicated in normal cells to initiate rejuvenation. Vadim Gladyshev, a geneticist at Harvard Medical School, along with his colleagues, was studying the ages of mouse embryos in their early developmental stage. The idea was to use molecular biomarkers such as genetic changes, altered gene expression, and metabolic components, to approximate an organism’s age. They found that the age of mouse embryos stayed constant after fertilization but their age decreased at one point as if they are becoming young to reach ‘ground zero’. Once reached, the biological age began to increase from there.
Data on human embryos was unavailable due to lack of research on them but Gladyshev suggested the presence of a similar clock reset in human embryos too. However, this is still the beginning of solving another mystery regarding the mechanism of this process. Yamashita does have a slight doubt whether the initial results are actually true. There may be some miscalculations from the biomarkers depicting epigenetic changes. It may as well be something else which is why it is necessary to dig deeper and conduct future related studies. That may pave the way to counteract a lot of age-related disorders we encounter today.