Further advances to the production of synthetic reproductive cells and even organisms in 2023 could boost our understanding of human fertility and why many pregnancies don’t reach full term.
In 2022, such research was carried out in non-human animals, namely rodents. This marked a significant step forward, but also raised the question of whether these procedures would be safe in humans or even ethical.
, for reasons that are often unclear. To better understand the extent to which sperm abnormalities may be involved, 2022 saw researchers use rat stem cells to produce sperm that resulted in fertile offspring.
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This could be a step towards synthetic human sperm. That is probably many years in the future, however, as producing sperm from stem cells in a laboratory could theoretically lead to non-genetic abnormalities that affect offspring, says at the University of Cambridge.
The rat model technology isn’t advanced enough to detect if the synthetic sperm cells have any such abnormalities, he says. The sperm happened to produce healthy, fertile pups, but this may not always be the case, says Surani.
In 2022, another group of researchers used mice stem cells to produce a synthetic embryo with a beating heart and the beginnings of a brain.
Lead researcher at the California Institute of Technology says the team wanted to better understand how embryos grow in the first few weeks. In the early stage of embryonic development, mice and human cells share several features, , she says.
Producing synthetic non-human embryos is necessary because human embryos are in short supply, she says. They can be donated to science in some circumstances, for instance if an excess amount is produced during in vitro fertilisation (IVF). According to Zernicka-Goetz, however, such donations are relatively rare, making it difficult to repeat a study enough times to draw conclusions into why some pregnancies don’t reach a live birth.
A non-human embryo model is the best method we have to gauge how pregnancies that end in a miscarriage differ from those that don’t, such as how embryonic cells may change shape according to different pregnancy outcomes, says Zernicka-Goetz.
According to at the University of Cambridge, however, drawing conclusions from these models is similarly hard. Synthetic embryos typically die after about one week, as embryos need oxygen and the removal of waste products, which is difficult to achieve in an incubator, he says.
In 2023, Boroviak and his colleagues plan to publish research on the production of a synthetic placenta from marmoset stem cells.
Technological setbacks aside, the ethical questions around producing synthetic sperm and organisms are also vast.
“When people think of synthetic embryos, they think of synthetic babies,” says at the University of Oxford. Embryos could theoretically be genetically edited so that the resulting child is more intelligent than they otherwise would have been. only be available in more developed countries, worsening global inequalities.
In 2021, the International Society for Stem Cell Research , urging them not to use synthetic reproductive cells to help people have children as the technology isn’t known to be safe.
Synthetic embryos can only be used for research in the UK, not to establish a pregnancy. Researchers can also only culture human embryos in a laboratory for a maximum of 14 days after fertilisation.
The UK Human Fertilisation and Embryology Authority tells żěè¶ĚĘÓƵ that it plans to launch a consultation in early 2023 with the aim of updating laws around embryo research, possibly extending the number of days after fertilisation at which embryos can be studied.
at Stanford University, California, says the biggest issue surrounding synthetic embryos is whether they should be treated in the same way we treat excess IVF human embryos that are donated for research.
“Should synthetic embryos be treated to all human rights, including the right to life, at least in some people’s minds, or are they cell constructs?” he says.
According to Chan, policy-makers should get public input when attempting to answer these ethical questions. Synthetic embryo research invites questions around what it means to be human and could one day help to treat particularly sensitive conditions, such as infertility, she says.
“This kind of research is going to shape society and the society that we all live in,” she says.
