We can now create synthetic human embryos – embryoids – from stem cells, without the need for sperm or eggs.
Published in Nature in September, a research group from the Weizmann Institute in Israel reported ground-breaking findings describing how they had been able to create a day 14 post-implantation human embryoid.
Previously a ‘black box’ period, inaccessible to researchers as the early embryo undergoes key developmental processes whilst buried in the uterine wall, we now have a window into the earliest stages of life.
Human embryoids could provide a valuable tool both for the understanding of pathogenesis and the influence of potential pharmacotherapies on organised human tissues.
This latest advance is the latest in a journey of increasingly sophisticated embryoid models. The first evidence that embryoids can develop into different tissue types came from Wisconsin-Madison in 2021, which was soon followed in 2022 when researchers at the University of Sheffield successfully implanted an embryoid into the uterus of a mouse.
At the Weizmann’s Institute of Science mouse embryoids were successfully taken to 8.5 days of gestation, in the context of a normal complete gestational period of 20 days. At this stage the embryo has a beating heart, blood stem cell circulation, a brain with formed folds and an intestinal tract.
Even in the case of mice, certain experiments are unfeasible because they require thousands of embryos. However, with the advent of synthetic embryonic tissue built from the millions of embryonic cells that can be produced in a single lab incubator these experiments are now only possible but could become commonplace.
There are legal, regulatory, and ethical issues surrounds the generation of synthetic embryos. Embryoids are genetic clones of the source of the stem cell from which it originates. Since ‘Dolly the Sheep’ in the late 20th century, many different species have been successful cloned using somatic cell nuclear transfer.
Therefore, we have a good regulatory framework around animal clones. However, synthetic human embryos are a new phenomenon that requires special consideration.
Ethically, it could be suggested by some that the creation of human embryos constitutes an incursion into the realm of a creator. Are we ‘playing God’? Whilst not a rigorous objection to synthetic embryos it is one commonly held and will drive the pursuit of clear and rigorously enforced regulatory frameworks.
Currently, the assumption is that research on embryoids should come under the same laws as are applied to IVF embryos. However, this is not currently a legal requirement, and it is evident that this is not the approach being taken.
As it stands, human embryoids do not come under the remit of the 2008 Human Fertilization and Embryology Act, principally because the creation of embryoids was not anticipated at the time of its drafting.
The ultimate decision as to the status of an embryoid will determine their usefulness in research; should these embryos be considered in the same way as cultured cells then their potential applications would be far broader.
Dr Joe Taylor is Principal at Candesic and Dr Leonid Shapiro is Managing Partner at Candesic. Go to candesic.com
