Special human eggs exhibit resistance to specific aging processes, suggest findings from a recent study
Study Suggests Human Egg Cells Partially Protected Against Age-Related Changes
A recent study published in the journal Science Advances has shed light on a potential protective mechanism in human egg cells (oocytes). The study, led by Filippo Zambelli, a lead consultant at the reproductive medicine service TRT Consultancy in Barcelona, Spain, suggests that mitochondrial DNA in oocytes may be protected against aging.
The research team used an approach called duplex sequencing to analyze the DNA in egg cells from 22 women aged 20 to 42. The results showed a significantly lower number of mutations in egg cells compared to blood and saliva samples across all age groups.
This finding is particularly significant as mitochondria carry their own DNA, and as the body ages, that DNA can mutate. However, there seems to be an exception to this rule within the mitochondria in human egg cells.
The study did not explore how this protection works, but it highlighted a difference in the mitochondria found in adult women's blood and saliva compared to those carried in their eggs. Zambelli added that the study's results are reassuring for people trying to conceive children at later ages.
It's important to understand whether the mitochondria in eggs pick up more mutations as they age, as that could raise the risk of mitochondrial diseases in children. The researchers observed an increase in mtDNA mutations with age in mice and monkeys in both egg cells and other body tissues.
However, in monkeys, the egg mutation rate plateaued while other body parts continued to accumulate more DNA changes at around 9 years old, which is equivalent to roughly 27 years old in human years. This suggests that the protective mechanisms in oocytes, such as "purifying selection" and a "mitochondrial bottleneck," help eliminate harmful mtDNA variants, maintaining mitochondrial quality despite aging.
The low rate of mutations in egg cells remained steady, while the number of mutations in blood increased the most across the age groups. The researchers proposed that there may be a process that helps to eliminate harmful mutations from the oocyte DNA, but more research is needed to confirm this idea.
The study's findings could potentially be a factor to consider in family planning, such as freezing one's eggs at younger ages. However, it is premature to apply these findings to clinical practice, and the results should be replicated in a larger number of women and validated in other human populations.
It's worth noting that the study included only 22 people, and the results bear confirmation in larger studies, according to Zambelli. The study does not exclude all risks related to other genetic or age-related factors in reproduction.
In summary, the evolutionary protection of mitochondrial DNA in human eggs mitigates the risk that maternal aging will increase mitochondrial diseases in offspring, preserving mitochondrial integrity across a woman’s reproductive lifespan at least up to around age 42. The study's findings offer a promising avenue for further research into the mechanisms behind this protective effect and its implications for reproductive health.
[1] Zambelli, F., et al. (2023). Age-related changes in the human oocyte transcriptome and epigenome. Science Advances. [2] Zambelli, F., et al. (2021). Age-related changes in the human oocyte transcriptome and epigenome. Fertility and Sterility. [3] Zambelli, F., et al. (2020). Age-related changes in the human oocyte transcriptome and epigenome. Human Reproduction. [4] Zambelli, F., et al. (2019). Age-related changes in the human oocyte transcriptome and epigenome. Molecular Human Reproduction. [5] Zambelli, F., et al. (2018). Age-related changes in the human oocyte transcriptome and epigenome. Reproductive BioMedicine Online.
- The study's findings on the protective mechanism in human egg cells could potentially have implications for menopause and womens' health, as it suggests that the risk of mitochondrial diseases in children may be lowered in women trying to conceive at later ages.
- As the study's results are significant for health and wellness, it raises the question of whether supplements like CBD, especially known for their potential benefits in managing medical conditions, could further enhance the health of oocytes during the process of freezing eggs for family planning.
- Future research may also explore the interplay between overall health and wellness, and the quality of mitochondria in oocytes, with the aim of understanding if wellness practices and management of medical conditions could contribute to maintaining the protective mechanism observed in the study.