Ageing
‘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.”
Women with two to three children live longest, while having more than four is linked to shorter lives, research on biological ageing suggests.
The study also found timing matters, with pregnancies roughly between ages 24 and 38 linked to more favourable ageing and longevity patterns.
Somewhat unexpectedly, childless women showed faster ageing than women with a few children, though this may be explained by other lifestyle or health factors.
Doctoral researcher Mikaela Hukkanen, who conducted the study, said: “From an evolutionary biology perspective, organisms have limited resources such as time and energy.
“When a large amount of energy is invested in reproduction, it is taken away from bodily maintenance and repair mechanisms, which could reduce lifespan.”
The research, conducted by the University of Helsinki and the Minerva Foundation Institute for Medical Research, followed nearly 15,000 female twins born between 1880 and 1957. Participants completed a questionnaire in 1975 and have been followed regularly since.
A novel aspect was measuring ageing biologically using epigenetic clocks, which detect ageing-related cellular changes by analysing chemical markers in blood samples. These can identify signs of biological ageing years before death.
The epigenetic analysis of more than 1,000 participants supported the mortality findings, showing women with many children or no children were biologically somewhat older than their chronological age.
Dr Miina Ollikainen, who led the study, said: “A person who is biologically older than their calendar age is at a higher risk of death. Our results show that life history choices leave a lasting biological imprint that can be measured long before old age.
“In some of our analyses, having a child at a young age was also associated with biological ageing.
“This too may relate to evolutionary theory, as natural selection may favour earlier reproduction that entails shorter overall generation times, even if it entails health-related costs associated with ageing.”
The researchers emphasised that the findings apply only at population level and do not demonstrate cause-effect relationships.
Dr Ollikainen added: “An individual woman should therefore not consider changing her own plans or wishes regarding children based on these findings.”
Women experience slightly worse recovery than men in the first year after stroke, with more difficulty with daily tasks such as eating, dressing and driving.
The differences persisted after adjusting for age, race and ethnicity, education and insurance status, according to the study.
The research, led by Chen Chen at the University of Michigan, examined recovery from ischaemic stroke, the most common type, which happens when blood flow to part of the brain is blocked.
“Stroke is a leading cause of disability in the US and with the ageing population, the number of stroke survivors is growing,” said Chen. “Since many people live with physical, cognitive and emotional challenges after stroke, it is important to find ways to improve recovery. Our study provides a better understanding of sex differences during stroke recovery.”
Researchers identified 1,046 people who experienced their first ischaemic stroke, average age 66. Recovery was tracked through records and interviews at three, six and 12 months, with neurological assessments, cognitive tests and quality-of-life questionnaires.
Participants were assessed on their ability to complete daily tasks, both simple and more complex, such as walking, bathing, cooking and doing housework.
Female participants had higher average scores than male participants, indicating poorer recovery, at three, six and 12 months. Female participants had an average score of 2.39 compared to 2.04 for male participants at three months. Scores for female participants decreased from three to 12 months, indicating some improvement, while male participants’ scores remained stable.
Chen noted the effect size was small. While there were no sex differences in other areas of recovery, both sexes improved in neurological function, which includes communicating and performing simple movements.
“Our results suggest that early and repeated assessments of a person’s ability to do daily tasks after stroke are needed, and particularly for female individuals, in order to reduce these differences in recovery,” said Chen. “When developing new interventions, these recovery patterns should be considered. Since the differences were mainly in activities such as doing heavy housework, shopping and carrying heavy weights, new interventions could include muscle-strengthening activities.”
A limitation was the lack of data on participants’ use of rehabilitation services.
The study was supported by the US National Institutes of Health.
Women with high psychosocial stress show early heart changes linked to cardiovascular disease, with no similar association in men, a recent study has found.
The findings support sex-specific effects of stress on cardiovascular health and suggest that risk assessment should include psychosocial factors and mental wellbeing.
Judy Luu is assistant professor at the Division of Clinical and Translational Research at McGill Faculty of Medicine.
She said: “From an epidemiological point of view, we have known for about two decades that stress is an important risk factor in cardiovascular health for people born female.
“But with this research stream, we’re really aiming to understand how stress physiologically impacts the heart.”
Cardiac MRI measures T1 and T2 in heart muscle, signals related to tissue composition and water; higher values can indicate early disease.
The study, conducted by researchers from McGill and Concordia universities in Canada, examined MRI heart scans of 219 adults aged 43 to 65, about half of whom were female.
The scans assessed T1 and T2 markers linked to early cardiac disease.
Participants were divided into two groups: those with at least one cardiovascular risk factor (such as diabetes, hypertension or smoking) but no heart disease, and healthy controls.
In both groups, women reporting high psychosocial stress had significantly higher T1 values than low-stress women.
T2 was also higher in the at-risk group only. No significant differences were seen between high- and low-stress men.
She added that the sex differences observed are not only a social question, but also a biological question.
Luu said: “Research points to the fact that there are biological differences in the way females physically handle stress.”
The next phase of the research will focus on blood markers and other biological explanations, such as hormones.
The team hopes the work can lead to better interventions to advance women’s heart health.
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