Israeli Scientists Create Artificial Human Embryos Without Sperm or Eggs

Dr. Jacob Hanna, a specialist in molecular genetics at Israel's Weizmann Institute of Science, holds a vial containing five-day-old synthetic mouse embryos grown in an electronically controlled ex-utero roller culture platform, in a lab in the Israeli central city of Rehovot on Aug. 4, 2022. Ahmad Gharabli/AFP via Getty Images

Researchers from Israel’s Weizmann Institute of Science have created complete human “embryo models” without using sperm or eggs, growing them outside of the womb for 14 days.

Embryo models, also known as synthetic embryos, are not equivalent to actual human embryos. Instead, they look similar to early stages of human development but show no signs of the beginnings of a brain or beating heart. Researchers succeeded in creating “embryo models” that were developed from skin cells taken from an adult.

After extraction, the skin cell was subjected to certain biological and chemical processes that transformed it back into a stem cell, which then developed outside the womb until it hit the stage of a human embryo at 14 days.

The synthetic embryos contained “all the structures and compartments characteristic of this stage, including the placenta, yolk sac, chorionic sac, and other external tissues that ensure the models’ dynamic and adequate growth,” according to a Sept. 6 post by the institute.

The research is crucial since very little is known about the early stages of an embryo as they are difficult to study.

“The drama is in the first month, the remaining eight months of pregnancy are mainly lots of growth,” said Professor Jacob Hanna.

“But that first month is still largely a black box. Our stem cell-derived human embryo model offers an ethical and accessible way of peering into this box. It closely mimics the development of a real human embryo, particularly the emergence of its exquisitely fine architecture.”

Mr. Hanna pointed out that several failures of pregnancy occur in the first few weeks. And most of the time, affected women may not even be aware that they are pregnant.

It is during these first weeks that many of the birth defects develop, some of which may only be discovered at a much later date.

“Our models can be used to reveal the biochemical and mechanical signals that ensure proper development at this early stage, and the ways in which that development can go wrong,” he said.

Weizmann’s human embryo models can shed light on the causes of several birth defects and types of infertility as well as lead to the development of technologies to grow organs and tissues for transplant, the institute claimed.

It also opens up paths to conduct research that would be impossible on natural embryos, it said. For instance, the embryo models can be used to determine the effects of exposure to drugs or other substances on the development of the fetus.

Legal and Moral Issues

The embryo models grew outside of the womb for eight days, reaching a developmental stage that is equivalent to 14 days of natural human embryonic development after fertilization. This is the point at which natural embryos get the internal structures necessary to eventually evolve into body organs.

Fourteen days is also the legal cut-off date for embryonic research in many countries. Weizmann Institute’s work also raises the question of whether embryo development can be mimicked after the 14-day limit.

Dr. Jacob Hanna, a specialist in molecular genetics at Israel's Weizmann Institute of Science, injects a solution used for cell and tissue dissociation into a tray in a lab in the Israeli central city of Rehovot on Aug. 4, 2022. Ahmad Gharabli/AFP via Getty Images

Such a move may not be illegal in some nations as embryo models are legally distinct from natural embryos. The more similar such models are to the natural process, the more ethical dilemmas such research pose.

“The closer stem-cell-derived models of human embryos mirror human embryos, the more important it is to have clear regulations and guidelines for how they are used,” Professor James Briscoe from the Francis Crick Institute told the BBC.

He stressed the need to proceed “cautiously, carefully, and transparently” in the field so as to avoid any “chilling effect” among the public.

There is also the question of whether synthetic human embryos should be given the same status and rights, including protections, which are granted to natural embryos.

Some argue that normalizing the creation of synthetic embryos for research purposes may end up trivializing human life by seeing it as a commodity or resource. Manipulation of such synthetic embryos also involves questions about human dignity and respect for life.

The technology opens up concerns about genetic engineering and potential applications in cloning, which are already morally complicated issues.

Though there have been attempts at making human embryo models in the past, they could not be considered “genuinely accurate” as they lacked critical cell types like those that end up forming placenta, according to the Weizmann Institute’s post.

Moreover, these models did not have the “structural organization” of a regular embryo and showed no “dynamic ability” that they could evolve to the next developmental stage.

The human embryo models developed by the research team at Weizmann have an “authentic complexity,” it said.

The research “has, for the first time, achieved a faithful construction of the complete structure [of a human embryo] from stem cells” in the lab, Professor Alfonso Martinez Arias from the Pompeu Fabra University, Spain, told the BBC.

As such, it opens the door “for studies of the events that lead to the formation of the human body plan,” he said.