Do embryos have an age? Up until about 2 years of age, parent’s will refer to the age of their baby in terms of months rather than years. This is because babies are considered to begin their life journey at age 0. The simplicity of beginning at zero is not something that can be greatly debated. However, several studies have provided evidence for aging in eggs and sperm. This suggests that germline cells may actually have an age. A recent article in Science News discusses how studies are now suggesting that mouse embryos are capable of reversing their biological clock. This allows these cells to erase any signs of aging following fertilisation.
How could the age of the mouse embryos be predicted?
Molecular clocks were used to predict the age of the mouse embryos. These clocks measure changes in our epigenetics. Epigenetics refers to changes in gene expression that don’t involve alterations to the DNA sequence. This is important for understanding the effects of environmental factors particularly during early embryonic development. Nessa Carey highlights this in her book ‘The Epigenetics Revolution’: “Events that take place in the first three months of development, a stage when the foetus is really very small, can affect an individual for the rest of their life.”
Changes in the epigenetic markers throughout development provided evidence for changes in the biological age of the mouse embryos. Age initially remained constant following fertilisation, but there was a decrease after approximately 7 days. This allows a developing embryo to appear younger than the original fertilised egg. The mouse embryo biological age then began to increase at a specific point. This exact point during their development is yet to be determined. However, pinpointing the rejuvenation stage may provide hope for treating age-related diseases in the future.
What does this research mean for age-related diseases?
Age-related diseases, such as Parkinson’s or Alzheimer’s disease, are characterised by a progressive deterioration in symptoms. Focusing on how these cells exploit revival could allow scientists to harness this mechanism and transfer it into aging cells.
Ethical considerations complicate the situation for replicating the results in human embryos. This research was performed on mouse embryos so further investigation will be required to understand how this evidence may be adapted into human cells. This does however provide more evidence for understanding how two adults with an aged biological age can produce young offspring.
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*Disclaimer: This information is for educational purposes only