‘Rejuvenated’ eggs raise hopes for improved IVF outcomes

Scientists say they have ‘rejuvenated’ human eggs, in work that could improve IVF success rates for older women.

The team reports that an age-related defect causing genetic errors in embryos may be reversed by supplementing eggs with a key protein.

In eggs donated by fertility patients, microinjection of the protein cut the share showing the defect from 53 per cent to 29 per cent.

The findings were presented at the British Fertility Conference in Edinburgh by researchers from the Max Planck Institute for Multidisciplinary Sciences in Göttingen.

The technique is being commercialised by Ovo Labs, co-founded by professor Melina Schuh, who led the research.

The approach targets problems in meiosis, the process where eggs halve their genetic material before fertilisation.

In older eggs, chromosome pairs can loosen and separate too soon, leading to embryos with too many or too few chromosomes, known as aneuploidy.

The researchers found levels of a protein called Shugoshin 1, which helps hold chromosome pairs together, decline with age. Microinjections appeared to restore this “molecular glue” and reduce errors.

Professor Schuh said: “Overall we can nearly halve the number of eggs with [abnormal] chromosomes. That’s a very prominent improvement.

“Most women in their early 40s do have eggs, but nearly all of the eggs have incorrect chromosome numbers. This was the motivation for wanting to address this problem.

“What is really beautiful is that we identified a single protein that, with age, goes down, returned it to young levels and it has a big effect.

We are just restoring the younger situation again with this approach.

Declining egg quality is a major reason IVF success rates fall steeply with age.

UK figures show an average birth rate of 35 per cent per embryo transferred for patients under 35, dropping to 5 per cent for women aged 43 to 44.

Dr Agata Zielinska, co-founder and co-chief executive of Ovo Labs, said: “Currently, when it comes to female factor infertility, the only solution that’s available to most patients is trying IVF multiple times so that, cumulatively, your likelihood of success increases.

“What we envision is that many more women would be able to conceive within a single IVF cycle.”

The approach would not extend fertility beyond menopause.

The team is in talks with regulators about a clinical trial.

Dr Güneş Taylor, of the University of Edinburgh, who was not involved, said: “This is really important work because we need approaches that work for older eggs because that’s the point at which most women appear.

“If there’s a one-shot injection that substantially increases the number of eggs with properly organised chromosomes, that gives you a better starting point.”