mRNA Injection Reduced Chromosome Errors in Lab Human Eggs but Result Not Statistically Significant in Older Donors

Researchers injected mRNA encoding the shugoshin-1 protein into human eggs and recorded lower rates of premature chromosome separation than in untreated eggs from the same donors. @NewScientist reported that the team collected 111 spare immature eggs from more than 30 women aged 22 to 43 who were undergoing egg banking or IVF. They injected the mRNA into some eggs and left others untreated.

Premature chromosome separation occurred in 53 per cent of the untreated eggs and in 29 per cent of the treated eggs. In eggs from nine donors over age 35, the average aneuploidy rate reached 65 per cent in untreated eggs and 44 per cent in treated eggs. The reduction was not statistically significant, which the researchers attributed to the small sample size.

Shugoshin-1 protein levels are substantially lower in older mouse and human eggs than in younger ones. The protein helps maintain the molecular glue that holds chromosome pairs together during meiosis. When the glue degrades, chromosomes can separate unevenly before fertilisation.

Aneuploidy affects 10 to 25 per cent of eggs in women in their early 30s and more than 65 per cent of eggs in women in their late 30s. The same mRNA approach prevented aneuploidy in mouse eggs that were fertilised and produced healthy offspring. No side effects were observed in the mouse or human studies.

Agata Zielinska presented the findings at the European Society of Human Reproduction and Embryology conference in London on 6 July. The researchers named the therapy EmbryoProtect and said they are working toward human testing by adapting standard IVF procedures to use immature eggs.