A molecule best known for helping the body produce energy has a key role in the very first stage of life – when a fertilised egg implants in the uterus. This discovery could eventually help more embryos successfully anchor, opening up new possibilities in fertility treatment.
Sofie and Niels have spent years trying to have children. They have tried everything – waited, hoped. Time and again, they have gone through in vitro fertilisation, only to face the same heartbreak: the fertilised egg is transferred but fails to implant. Without forming crucial contact with the uterine lining, the embryo cannot develop into a fetus.
This situation is far from rare. Implantation fails for 30–50% of embryos transferred to the uterus during assisted reproduction. The egg does not attach, and pregnancy fails.
Doctors and researchers have long wondered why so many fertilised eggs fail to implant. Now, an international team led by Jan Jakub Żylicz and Karlien Van Nerum at the Novo Nordisk Foundation Center for Stem Cell Medicine (reNEW), University of Copenhagen, Denmark has identified a biological mechanism that may be crucial in determining whether the embryo anchors in the womb.
How a metabolic molecule steers the embryo’s fate
The new study, published in Nature Cell Biology, reveals an unexpected role for α-ketoglutarate (αKG). Until now, this molecule was believed to be involved solely in cellular metabolism – helping to process nutrients, recycle materials and eliminate waste.
Scientists have long known that αKG has a role in the citric acid cycle – a process that takes place in the mitochondria, the microscopic powerhouses of our cells, where sugar and fat are converted into energy. What is surprising is that αKG also appears to influence whether cells in the fertilised egg develop into the embryo itself or into the placenta.
“Our study shows that αKG affects the very first decision these stem cells make – whether they will become the fetus or help to form the trophectoderm, the supporting tissue that later becomes the placenta,” explains Jan Jakub Żylicz.
Elevated levels of αKG appear to tip the balance toward forming the trophectoderm – a critical shift, since this tissue enables the embryo to attach to the uterus and initiate pregnancy.
Laboratory experiments confirm the power of αKG
To investigate further, the researchers worked with naive human embryonic stem cells – cells that closely resemble those in a fertilised egg just days after conception. At this stage, the cells are not yet on a developmental path and can still potentially become either fetal or placental tissue.
The study focused on how these cells become trophectoderm. In a carefully designed step-by-step experiment, the team first observed the cells’ natural metabolic activity under standard conditions. Then, they added αKG externally – in different doses and at various stages – to determine how it influenced development.
Using both traditional two-dimensional cell cultures and three-dimensional embryo-like structures known as blastoids, Jan Jakub Żylicz and his team observed how the cells reacted. With advanced tools such as fluorescence microscopy, gene expression analysis and metabolic profiling, they tracked how the presence of αKG changed the cells’ structure, actions and gene activity.
Chemistry changes cell fate
The results were striking. Cells pretreated with αKG were significantly more likely to develop into trophectoderm. They exited their undifferentiated stem cell state more rapidly and actively suppressed genes that would otherwise keep them immature.
αKG also influenced the cells’ internal chemistry – including levels of acetyl coenzyme A, which is essential for maintaining certain genes in an active state. As the concentration of αKG dropped, the cells became more receptive to signals guiding them toward placental development.
This study underscores a broader concept: metabolism does not just provide energy but also helps to determine the role of cells in early development. This insight opens a new window into the molecular factors that shape human development – and indicates new opportunities in both fertility treatment and regenerative medicine.
From a hunch to a breakthrough
The team’s interest in αKG began with a hunch. In an earlier study, they had noticed an unusual spike in αKG in cells that were on their way to becoming placental tissue. The pattern was not random – it showed up consistently in multiple measurements, suggesting something more than coincidence.
What if αKG is not just a metabolic by-product but a molecular trigger? As the researchers looked closer, they began to understand just how powerful αKG could be: not merely a passive participant but an active switch capable of helping key developmental processes.
Wide-reaching potential
For now, the findings are part of fundamental research – aimed at understanding how nature works rather than solving a clinical problem right away. But the implications are already sparking new ideas.
According to Jan Jakub Żylicz, researchers are now incorporating these insights to improve the nutrient media used during in vitro fertilisation. The aim is to give more embryos a better chance to develop and successfully implant.
Even beyond fertility, the findings suggest something bigger: using cellular metabolism as a precision tool to steer how cells act and what they become. This could have transformative implications not only in reproductive medicine but also in regenerative therapies – directing cells to repair damaged tissues or restore organ function.
What began as a surprising result in the laboratory may one day become a tool that helps life take hold – quite literally: a discovery that could mean the difference between longing and reality for those hoping to start a family.
