Breakthrough in Egg Rejuvenation for IVF Success

Researchers have reportedly “rejuvenated” human eggs, marking a significant advancement that could transform IVF success rates for older women.

This innovative study indicates that a defect associated with aging, which leads to genetic errors in embryos, might be reversible by introducing a vital protein. Fertility patients’ donated eggs, when microinjected with this protein, demonstrated nearly half the likelihood of showing defects compared to untreated counterparts.

If validated through broader trials, this method could enhance egg quality—often the main barrier to successful IVF and the reason for miscarriages in older women.

Professor Melina Schuh from the Max Planck Institute for Multidisciplinary Sciences in Göttingen, who co-founded Ovo Labs to commercialize this technique, expressed that they could nearly cut the number of eggs with chromosomal abnormalities by half, which is a significant improvement.

Schuh noted that while most women in their early 40s still have eggs, almost all of them carry incorrect chromosome numbers. This understanding was a driving force behind efforts to tackle the issue.

The findings will be showcased at the British Fertility Conference in Edinburgh and have also been published as a preprint paper.

The decline in egg quality significantly contributes to the declining success rates of IVF as women age, increasing the risk of chromosomal disorders like Down’s syndrome. According to recent UK data, those under 35 see an average birthrate of 35% per embryo, while it drops to just 5% for women aged 43–44. The average age at which women start IVF in the UK has surpassed 35.

Dr. Agata Zielinska, co-founder and co-CEO of Ovo Labs, commented that currently, the main option for women facing infertility is often repeated IVF attempts to improve chances. She envisions a future where many women could conceive successfully in just a single IVF cycle.

This new strategy focuses on a weakness in eggs relating to meiosis, where sex cells dispose of half their genetic material to fuse and create embryos.

During this process, eggs require their 23 pairs of X-shaped chromosomes to align along a single axis. Ideally, upon fertilization, these pairs would split evenly, resulting in a single cell with 23 chromosomes from the mother, complemented by the other half from the sperm.

However, older eggs often struggle with chromosome alignment, causing pairs to detach before fertilization. This misalignment results in chaos during cell division, leading to embryos with improper chromosome counts.

Schuh and her team previously discovered that Shugoshin 1, a protein that helps keep chromosome pairs intact, diminishes with age. In their recent experiments on mouse and human eggs, they found that microinjections of this protein seemed to manage the issue of early separation of chromosome pairs.

Using eggs from patients at the Bourn Hall fertility clinic in Cambridge, they observed a drop in defect rates from 53% in control eggs to 29% in treated eggs. A similar trend was noted among eggs from women over 35 (65% versus 44%), although that result wasn’t statistically significant due to a limited number of treated eggs from this group.

“What is really remarkable is that we pinpointed a single protein whose levels decline with age, restored them to youthful levels, and it made a considerable difference,” Schuh stated. “We are effectively reverting the situation back to a younger state.”

This method doesn’t extend fertility beyond menopause when egg reserves deplete.

Currently, aside from intra-cytoplasmic sperm injection (ICSI), other treatments involving microinjections into eggs are rare. The team anticipates no safety concerns and is in talks with regulators about potential clinical trials. A critical question remains whether the improvements in egg quality lead to embryos with fewer genetic errors.

Dr. Güneş Taylor from the University of Edinburgh, not part of the research, described the results as “really promising.” She emphasized the importance of finding solutions for older eggs, as that is when most women confront fertility challenges. A one-time injection that significantly boosts eggs with correctly organized chromosomes could provide a much better starting point.