Named the consequences of creating synthetic human embryos

Synthetic human embryos are created by scientists using an innovative approach. This breakthrough, on the one hand, could help research into genetic disorders, but, on the other hand, raises serious ethical and legal problems.

Scientists have created synthetic human embryos using stem cells, a groundbreaking achievement that avoids the need for eggs or sperm.

As The Guardian writes in an exclusive article, scientists say these model embryos, which resemble embryos in the earliest stages of human development, could provide crucial insight into the impact of genetic disorders and the biological causes of recurrent miscarriages.

However, the work also raises serious ethical and legal questions, as lab-grown objects fall outside the scope of current legislation in the UK and most other countries, The Guardian notes.

These structures do not have a beating heart or the rudimentary brain, but they include the cells that normally form the placenta, the yolk sac, and the embryo itself.

Professor Magdalena Jernica-Goetz of the University of Cambridge and Caltech spoke about her work in a plenary address Wednesday at the annual meeting of the International Society for Stem Cell Research in Boston.

“We can create models similar to the human embryo by reprogramming embryonic stem cells,” she said at the meeting.

In the short term, there is no prospect of clinical use of synthetic embryos. It would be illegal to implant them in the patient’s uterus, and it is not yet clear whether these structures have the potential to further mature beyond the earliest stages of development.

The motivation for the work is for scientists to understand the developmental period of the “black box,” so named because scientists are only allowed to culture embryos in the lab until the legal deadline of 14 days. They then trace the development much further, looking at pregnancy scans and embryos donated for research.

Robin Lovell-Bage, head of stem cell biology and developmental genetics at the Francis Crick Institute in London, said: “The idea is that if you actually model normal human embryonic development using stem cells, you can get a huge amount of information how we start development, what can go wrong without having to use early embryos for research.”

Previously, the Zernica-Goetz team and a rival group at the Weizmann Institute of Science in Israel showed that mouse stem cells can be stimulated to self-assemble into early embryonic structures with an intestinal tract, brain buds, and a beating heart. Since then, the race has begun to translate this work into human models, and several teams have been able to replicate the earliest stages of development.

The full details of the latest work from the Cambridge Institute of Technology lab have yet to be published in a journal article. But speaking at the conference, Zernitz-Goetz described culturing embryos to just over 14 days of natural embryo development.

The model structures, each grown from a single embryonic stem cell, have reached the beginning of a developmental stage known as gastrulation, when the embryo transforms from a continuous layer of cells into individual cell lines and forms the main axes of the body. At this stage, the embryo does not yet have a beating heart, intestines, or rudimentary brain, but the model showed the presence of primary cells, which are the precursor cells of the egg and sperm.

“Our human model is the first three-line model of the human embryo that defines amnion and germ cells, egg and sperm progenitor cells,” Zernica-Goetz told The Guardian ahead of her speech. “It’s beautiful and made entirely from embryonic stem cells.”

The event highlights how quickly the science in this area has outpaced the law, and scientists in the UK and elsewhere are already starting to develop voluntary guidelines to govern the handling of synthetic embryos.

“If the whole intention is for these models to be very similar to normal embryos, then in a sense they should be treated the same way,” says Robin Lovell-Bage. “Currently, this is not in the legislation. People are worried about this.”

There is also an important unanswered question about whether these structures, in theory, have the potential to turn into a living being, notes The Guardian. Synthetic embryos grown from mouse cells have been reported to look nearly identical to natural embryos. But when they were implanted in the wombs of female mice, they did not develop into living animals. In April, researchers in China created synthetic embryos from monkey cells and implanted them in the wombs of adult monkeys, some of which showed initial signs of pregnancy but none continued to develop for more than a few days. The scientists say it’s unclear whether the barrier to more advanced development is purely technical or has a more fundamental biological reason.

“That is very difficult to answer. It will be difficult to tell if they have an internal problem or if it’s just a technical one,” comments Lovell-Bage. This unknown potential has made the need for stronger legislation urgent, he said.