World first for Czech science: egg ageing can be reversed
03. 12. 2025
The signs of oocyte (egg) ageing can be reversed, and damage can be repaired. What was previously considered biologically impossible has been proven by an international research team led by reproductive biologist Helena Fulková from the Institute of Experimental Medicine of the Czech Academy of Sciences. The results, published in the journal Ageing Cell, raise new questions about the biology of ageing and open up space for the development of future therapeutic approaches.
With increasing age, females' reproductive capacity declines. Older eggs are more likely to have DNA damage and errors in chromosome division, which increases the risk of aneuploidy, or chromosome number abnormalities. These changes can cause embryo development to stop or lead to serious genetic disorders such as Down syndrome. A team of scientists has discovered that it is possible to repair the damage that accumulates in oocytes during ageing.
An analysis of eggs from older female mice showed a significantly higher rate of DNA damage – approximately 70% of chromosomes showed signs of double breaks, compared to only about 16% in oocytes from young mice. The scientists exposed the nuclei of old oocytes to the environment of young eggs, which they had stripped of their DNA. Young cells contain repair mechanisms that are significantly weakened in ageing oocytes. It turned out that in this environment, DNA damage in old eggs was significantly reduced, chromatin – the basic material of chromosomes composed of DNA and proteins—acquired a more flexible structure typical of younger cells, and chromosome division proceeded much more accurately—the number of chromosome abnormalities was reduced by almost half. These "rejuvenated" eggs were able to continue developing until the birth of healthy offspring with the same success rate as young individuals.
"Our results show that oocyte ageing is not irreversible and that egg quality can, in principle, be restored. For the first time, we have experimentally demonstrated that an older oocyte can restart DNA repair and proper chromosome division mechanisms in a young cellular environment. This not only raises new questions about the biology of ageing, but also opens up space for the development of future therapeutic approaches," explains team leader Helena Fulková from the Institute of Experimental Medicine of the Czech Academy of Sciences.
This fundamental discovery was made by chance while investigating the 3D structure of the cell nucleus in a project supported by the Czech Science Foundation and was further developed in the project The Future of Assisted Reproduction of the AV21 Strategy programme in collaboration with the Institute of Animal Science in Prague, the University of Teramo, and the University of Zurich.
This work fundamentally changes current theories about the ageing of sex cells and opens up opportunities for research into cell therapies that could reduce the risk of chromosomal defects in embryos, increase the success of assisted reproduction, and contribute significantly to the conservation of endangered species in the future.
Publication:
https://onlinelibrary.wiley.com/doi/10.1111/acel.70300
Contact:
Mgr. Helena Fulková, Ph.D.
helena.fulkova@iem.cas.cz
Petr Caletka
petr.caletka@iem.cas.cz
+420 725 797 600
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