New Injection Reduces Chromosome Errors in Older Eggs by Half

Researchers have discovered a promising method to significantly reduce chromosomal errors in older human eggs, potentially enhancing the success rates of in vitro fertilization (IVF) for women over 35. The study, presented at the European Society of Human Reproduction and Embryology conference in London, revealed that an mRNA injection could halve the risk of aneuploidy, a condition where eggs have an abnormal number of chromosomes, which can lead to miscarriage and genetic disorders such as Down’s syndrome.

Addressing Chromosomal Imbalances

Aneuploidy is a common issue in older women’s eggs, with rates rising dramatically with age. In women in their late 30s, more than 65% of eggs are aneuploid, according to Agata Zielinska from Ovo Labs in Germany. This condition stems from the degradation of a protein called shugoshin-1, which is crucial for maintaining chromosome stability during meiosis, the process where egg and sperm cells divide their genetic material.

The research team, led by Zielinska, found that older eggs have reduced levels of shugoshin-1, leading to premature chromosome separation. By injecting the eggs with mRNA coding for shugoshin-1, the team was able to bolster the protein’s levels, thereby enhancing the structural integrity of chromosome pairs.

Promising Results in Human and Animal Trials

The study involved collecting 111 immature eggs from women aged 22 to 43 undergoing IVF or egg banking. Eggs treated with the mRNA injection showed a notable decrease in premature chromosome separation—from 53% in untreated eggs to 29% in treated ones. In eggs from women over 35, aneuploidy rates dropped from 65% to 44% with treatment, although researchers noted the reduction wasn't statistically significant due to the small sample size.

Experiments also extended to mouse models, where the approach successfully prevented aneuploidy. These treated mouse eggs were fertilized and developed into healthy offspring, showing no adverse effects on embryo or pup health. These findings suggest potential for human application, pending further trials.

Future Implications for IVF

Zielinska and her team are now preparing to test their approach in human IVF treatments. This would involve using immature eggs, which is a manageable adjustment to existing procedures. The treatment, dubbed EmbryoProtect, aims to provide a cost-effective enhancement to IVF, particularly for older women, potentially costing a fraction of a full IVF cycle.

Marcos Iuri Roos Kulmann from Nilo Frantz Reproductive Medicine in Brazil, who was not involved in the research, expressed optimism about the potential of this treatment to address a major cause of IVF failure. As research progresses, the hope is that this innovative approach will become a standard part of fertility treatments, offering new hope for many aspiring parents.