News | Scientists 'rejuvenate' human eggs for the first time, potentially improving IVF success at older ages
Scientists have reported a key breakthrough described as "rejuvenating" human eggs. Adding a core protein that declines with age substantially reduced defects that cause chromosomal abnormalities in embryos, potentially improving in vitro fertilization (IVF) success in older women.
After microinjection into eggs donated by fertility clinic patients, the proportion with a key defect was almost halved. If confirmed in larger clinical trials, the approach could directly improve egg quality, a leading cause of IVF failure and miscarriage at older ages.
"Overall, we can almost halve the proportion of chromosomally abnormal eggs, which is a very substantial improvement," said Professor Melina Schuh, director at the Max Planck Institute for Multidisciplinary Sciences and co-founder of Ovo Labs. Her laboratory has studied egg biology for nearly 20 years.
Schuh said many women in their early 40s still have eggs, but "almost all have the wrong number of chromosomes." The findings were presented at the British Fertility Society meeting in Edinburgh and posted as a preprint on bioRxiv.
Age-related loss of egg quality underlies declining IVF success and rising chromosomal risks such as Down syndrome. UK data show an average live birth rate per embryo transfer of 35% below age 35, compared with 5% at ages 43–44. The average age of first fertility treatment in the UK now exceeds 35.
Ovo Labs co-founder and co-CEO Agata Zielinska said current care often relies on repeated IVF attempts to accumulate chances of success. "Our aim is to make it possible for more women to succeed in a single IVF cycle."
The technology targets a vulnerable stage of egg meiosis. The 23 pairs of X-shaped chromosomes must align and separate evenly after fertilization. In older eggs, chromosomes can loosen or separate too early, producing embryos with too many or too few chromosomes.
The team previously found that Shugoshin 1 acts as a "glue" stabilizing chromosome pairs and declines with age. Microinjecting Shugoshin 1 into mouse and human eggs reversed premature chromosome separation.
Among eggs donated through Bourn Hall fertility clinic in Cambridge, the defect fell from 53% in untreated eggs to 29% after injection. In eggs from women over 35 it fell from 65% to 44%, although the small sample meant this was not statistically significant.
"It is remarkable that restoring one age-depleted protein to youthful levels has such a clear effect," Schuh said. "We are not creating anything new; we are restoring the egg to a younger state."
The method cannot extend fertility after menopause because it does not replenish the egg reserve. Apart from intracytoplasmic sperm injection (ICSI), egg microinjection is rarely used clinically. The team expects no major safety concerns and has begun discussing trials with regulators. The next question is whether better egg quality produces embryos with fewer chromosomal abnormalities.
Dr Güneş Taylor of the University of Edinburgh, who was not involved, called the findings "very promising." She said a single injection that increases the number of eggs with correctly aligned chromosomes would give IVF a better starting point.
News | Scientists 'rejuvenate' human eggs for the first time, potentially improving IVF success at older ages
News | Scientists 'rejuvenate' human eggs for the first time, potentially improving IVF success at older ages
Scientists have reported a key breakthrough described as "rejuvenating" human eggs. Adding a core protein that declines with age substantially reduced defects that cause chromosomal abnormalities in embryos, potentially improving in vitro fertilization (IVF) success in older women.
After microinjection into eggs donated by fertility clinic patients, the proportion with a key defect was almost halved. If confirmed in larger clinical trials, the approach could directly improve egg quality, a leading cause of IVF failure and miscarriage at older ages.
"Overall, we can almost halve the proportion of chromosomally abnormal eggs, which is a very substantial improvement," said Professor Melina Schuh, director at the Max Planck Institute for Multidisciplinary Sciences and co-founder of Ovo Labs. Her laboratory has studied egg biology for nearly 20 years.
Schuh said many women in their early 40s still have eggs, but "almost all have the wrong number of chromosomes." The findings were presented at the British Fertility Society meeting in Edinburgh and posted as a preprint on bioRxiv.
Age-related loss of egg quality underlies declining IVF success and rising chromosomal risks such as Down syndrome. UK data show an average live birth rate per embryo transfer of 35% below age 35, compared with 5% at ages 43–44. The average age of first fertility treatment in the UK now exceeds 35.
Ovo Labs co-founder and co-CEO Agata Zielinska said current care often relies on repeated IVF attempts to accumulate chances of success. "Our aim is to make it possible for more women to succeed in a single IVF cycle."
The technology targets a vulnerable stage of egg meiosis. The 23 pairs of X-shaped chromosomes must align and separate evenly after fertilization. In older eggs, chromosomes can loosen or separate too early, producing embryos with too many or too few chromosomes.
The team previously found that Shugoshin 1 acts as a "glue" stabilizing chromosome pairs and declines with age. Microinjecting Shugoshin 1 into mouse and human eggs reversed premature chromosome separation.
Among eggs donated through Bourn Hall fertility clinic in Cambridge, the defect fell from 53% in untreated eggs to 29% after injection. In eggs from women over 35 it fell from 65% to 44%, although the small sample meant this was not statistically significant.
"It is remarkable that restoring one age-depleted protein to youthful levels has such a clear effect," Schuh said. "We are not creating anything new; we are restoring the egg to a younger state."
The method cannot extend fertility after menopause because it does not replenish the egg reserve. Apart from intracytoplasmic sperm injection (ICSI), egg microinjection is rarely used clinically. The team expects no major safety concerns and has begun discussing trials with regulators. The next question is whether better egg quality produces embryos with fewer chromosomal abnormalities.
Dr Güneş Taylor of the University of Edinburgh, who was not involved, called the findings "very promising." She said a single injection that increases the number of eggs with correctly aligned chromosomes would give IVF a better starting point.
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