The historic announcement could be a turning point for research.
Scientists say that for the first time synthetic human embryos have been created, derived from stem cells without the need for eggs or sperm. The facilities represent very early stages in human development, which could enable vital studies of disorders such as recurrent miscarriages and genetic diseases. But questions have been asked about the legal and ethical implications, as the pace of scientific discovery outpaces legislation. The breakthrough was reported by the Guardian newspaper following a statement by Professor Magdalena Żernicka-Goetz, a developmental biologist at the University of Cambridge and Caltech, at the 2023 annual meeting of the International Society for Stem Cell Research. The findings have not yet been published in a peer-reviewed paper. It is understood that synthetic structures shape the beginnings of human development. They don’t yet contain a brain or a heart, for example, but they do include the cells that would be needed to form a placenta, yolk sac and embryo. Żernicka-Goetz told the conference that the structures grew just beyond the equivalent of 14 days of natural gestation for a human embryo in the womb. It is unclear whether it would be possible to allow them to mature further. It’s not about creating lab-grown babies. Rather, it is about lifting the lid on a period of human development that has hitherto been closed to scientists. The law currently only allows the cultivation of human embryos in the laboratory for up to 14 days. After this point, there is a window of time where developmental biology research is hampered, because scientists are only able to pick up the trail much later by studying pregnancy scans and donated embryos. It is hoped that synthetic embryo technology can help fill this gap. Reacting to the news, other experts in the field of stem cell research have stressed the importance of improving our understanding of embryonic development. “The ability to recapitulate early events in human development using stem cells in a dish is a major leap forward in cellular and reproductive technologies,” said Dr. Rodrigo Suarez of the University of Queensland in a statement. “The potential benefits are enormous, ranging from a better understanding of how early tissues self-organize during stages that would otherwise not be possible to study with current approaches, to elucidating the genetic and cellular requirements involved in early human development in health and disease. ».
Stem cell-derived embryos have previously been developed in mice – also by Żernicka-Goetz’s group – and monkeys, and many had speculated that the human equivalent could not happen. However, passing this scientific milestone also comes with a number of ethical and legal hurdles. One of the fundamental questions is: how similar are these structures to natural embryos? “If the whole intention is for these models to be very similar to normal embryos, then in a sense they should be treated in the same way. Currently in the legislation they are not. People are worried about this,” Professor Robin Lovell-Badge, head of stem cell biology and developmental genetics at the Francis Crick Institute, told the Guardian. “Although it is not yet clear how these synthetic embryos could develop or be used in research, if it is determined that they are not equivalent to human embryos, or it is possible to limit their development such that they do not acquire certain characteristics associated with law and ethical personality , could potentially be useful in research currently considered too risky to use human embryos,” said Dr Evie Kendal of Swinburne University of Technology in a statement. Evidence from similar animal research is mixed. When synthetic monkey embryos were implanted in female monkey uteri, most did not attach successfully and those that did did not develop into viable fetuses. The synthetic mouse embryos developed enough to begin forming a beating heart and brain before succumbing to the defects. Lovell-Badge explained to the Guardian that it is not clear whether there is a biological reason why these structures cannot develop beyond a certain point, or whether these problems are due to technical barriers that could theoretically be overcome. In 2022, the Australian National Health and Medical Research Council (NHMRC) licensed a technology developed at Monash University called iBlastoids. These are models of very early human embryos made from reprogrammed adult skin cells and are unable to develop into a mature fetus. Controversially, the NHMRC ruled that these facilities were subject to the same legal protections as normal human embryos, making them subject to the 14-day rule. This is just one example, but it highlights the complexities of this problem. What most experts seem to agree on is that there is an urgent need for regulators around the world to start catching up with the pace of these new developments so that we can more clearly define exactly what these synthetic embryos are – in legal sense – and how they can be used.