A metabolic compound can reverse the ageing process of eggs in mice and could lead to new non-invasive treatments for improving fertility in older women, according to new research.
The study conducted by researchers at the Universities of Queensland and New South Wales, both in Australia, published in the journal Cell Reports, showed that infertile mice provided with low doses of the molecule had notably better egg quality and were able to give birth to offspring during a breeding trial. If translatable to humans, this could significantly improve chances of older women to become pregnant without the need for several rounds of IVF.
'Quality eggs are essential for pregnancy success because they provide virtually all the building blocks required by an embryo,' said corresponding author and study lead, Professor Hayden Homer from the University of Queensland.
Professor Homer and his team identified a key molecule essential to metabolism and genome stability in oocytes: nicotinamide adenine dinucleotide (NAD+). In their study they restored declining levels of NAD+ in reproductively aged, infertile mice by supplying their drinking water with a precursor of the metabolite, called nicotinamide mononucleotide (NMN). The mice's cells used the precursor to produce NAD+, resulting in recovery of the quality of egg cells, which led to even older animals giving birth in follow-up breeding cycles.
When women are born, all their eggs are already formed and will age with them throughout life. Therefore, although a woman in her mid- to late-thirties may be physically healthy, her oocytes will likely be of lesser quality due to ageing, contributing to a lower chance of becoming pregnant and a higher risk of bearing children with chromosome disorders.
'This is an increasing issue as more women are embarking on pregnancy later in life, and one in four Australian women who undergo IVF treatment are aged 40 or older,' Professor Homer said.
The authors hope that their new strategy will translate into new infertility treatments in the future by reversing oocyte ageing. However, they pointed out that human clinical trials have to be conducted before they can make conclusions about safety.
Professor Homer commented: 'Our findings suggest there is an opportunity to restore egg quality and in turn female reproductive function using oral administration of NAD-boosting agents – which would be far less invasive than IVF. It is important to stress, however, that although promising, the potential benefits of these agents remains to be tested in clinical trials.