Transformative embryo research: Who gets to contribute?

The publication of a landmark study using base editing in human embryos has received positive coverage in the scientific community and press (see BioNews 1345 and 1349). Understandably, discussion has focused on the technology and the findings. However, another important issue has received less attention – without the altruistic donation of eggs, sperm and embryos, such research would not have been possible.

The study, published in Nature, uses base editing (see BioNews 848, 924, 1035 and 1285) to investigate the role of the gene NANOG in the earliest stages of human development. Named after Tír na nÓg, the mythical Celtic 'Land of the Young', NANOG was originally identified as playing a role in maintaining stem cells in a youthful, unspecialised state (see BioNews 210).

By creating embryos specifically for research and using base editing to inhibit NANOG gene function, the researchers showed that it also plays an essential role in enabling the group of cells that will ultimately form the fetus to develop.

These findings establish NANOG as a key regulator of early human embryonic development, and further the understanding of why some embryos may fail to develop or progress to the stage at which they can implant and result in a pregnancy. The study also demonstrates that base editing is a more precise approach for investigating gene function in human embryos than earlier genome editing methods.

An important aspect of the study is that it relied on the donation of human eggs for research. Using intracytoplasmic sperm injection (ICSI), the base editing components were introduced into the egg alongside the sperm at fertilisation, allowing embryo development to be studied during the earliest stages.

Speaking at a press briefing organised by the Science Media Centre, Professor Kathy Niakan – the study's corresponding author – emphasised that the research depended on the altruism of patients who choose to donate eggs for ethically approved research, within one of the world's most tightly regulated systems. Professor Niakan also said she hoped the study would raise awareness that fertility clinics can offer patients the opportunity to donate eggs, sperm and embryos for research, ensuring that anyone who wishes to contribute has the chance to do so.

Only about one in five UK fertility clinics currently offer patients the option to donate embryos or gametes to research, when these are no longer required for storage or IVF treatment. This means that whether fertility patients can contribute to research – or are even aware that this is a possibility – can often depend simply on where they received treatment, rather than on their own wishes.

As has been highlighted on more than one occasion at the PET (Progress Educational Trust) Annual Conference – by Professor Niakan herself (see BioNews 1219 and 1220), by Professor Geraldine Hartshorne (see BioNews 1268) and by others – opportunities for donation to research could be expanded if more clinics were willing to undertake a small amount of additional administration. The process could also be streamlined through broader consent arrangements and centralised research embryo banks.

Egg freezing has grown rapidly in the UK, with around 5580 egg-freezing cycles undertaken in 2024, compared with 2567 in 2019. While many people will eventually use their stored eggs, others will not. A substantial proportion remains unused after years in storage or is never used. For some, allowing eggs to perish feels appropriate. However, others may welcome the opportunity to donate eggs for ethically approved research, if that option were available and presented sensitively.

Establishing donation pathways for research does require additional consent processes, agreements with research centres and transport logistics. However, these represent relatively modest additions to existing clinic workflows, rather than fundamental changes to clinical practice. Research grants may include funding to support transport, and cryogenic courier companies have indicated a willingness to work with clinics and research institutions where batching research shipments can reduce costs.

In the longer term, broader consent models and centralised research storage hubs could simplify the system further, reducing the administrative burden on clinics while improving access for researchers (see BioNews 1234 and 1334). However, such policy discussions need not prevent progress now.

Clinics should not need to wait for legislative reform, or for a licensing requirement to offer research donation, before giving patients more choice when ending storage. Instead, clinics could discuss research donations alongside other end-of-storage options, enabling people to make informed choices that reflect their values. This study demonstrates that donated eggs can advance our understanding of human development – a fundamental step towards improving fertility treatment.