Researchers Create Synthetic Human Embryos Without Sperm or Eggs

A lab technician in Seoul on March 11, 2020. ED JONES/AFP via Getty Images

Scientists have created synthetic human embryos from stem cells without using eggs or sperm in a development that raises challenging moral and legal questions.

Synthetic embryos, also known as embryo models, are not equal to actual human embryos. Instead, they look similar to the early stages of human development and show no signs of the beginnings of a brain or a beating heart. However, it contains cells that typically end up forming the placenta, yolk sac, and the embryo. The development of synthetic human embryos was revealed at the International Society for Stem Cell Research’s annual meeting in Boston on Wednesday by professor Magdalena Zernicka-Goetz from the University of Cambridge and the California Institute of Technology.

The research has not been peer-reviewed and is yet to be published, Zernicka-Goetz said at the event.

“I just wish to stress that they are not human embryos,” Zernicka-Goetz said to CNN. “They are embryo models, but they are very exciting because they are very looking similar to human embryos and very important path towards discovery of why so many pregnancies fail, as the majority of the pregnancies fail around the time of the development at which we build these embryo-like structures.”

The synthetic human embryos were grown from single human embryonic stem cells that were made to develop into three distinct tissue layers. At present, the synthetic model embryos are restricted to test tubes.

According to Zernicka-Goetz, her research is not aimed at creating life but at preventing the loss of life. She and her team had earlier created model embryos from mouse stem cells that had shown the initial states of a brain and heart.

The development has raised concerns about its implications. “Synthetic human embryos created. This falls outside the boundary of current ethical and moral consideration and legality,” Peter Dain, an activist with the U.K.’s Reform Party, said in a June 15 post on Twitter.

“Many human developments, with AI being another, are now overtaking the ability of society to respond and assimilate,” he added.

Moral, Legal Implications

When it comes to human embryo research, most nations follow the 14-day rule, which limits an embryo created through the fertilization of an egg to be grown only for 14 days.

However, synthetic embryos like those developed by Zernicka-Goetz and her team using stem cells are not legally embryos and thus not bound by these same rules, which raises questions about their legality.

“On the one hand, models of human embryos made of stem cells might offer an ethical and more readily available alternative to the use of IVF-derived [in-vitro fertilization] human embryos,” Prof James Briscoe, from the Francis Crick Institute, said in an interview with BBC.

“On the other hand, 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.”

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

Some people are already raising questions about the spiritual nature of these synthetic embryos. “Let’s get metaphysical: Where does its soul and spirit come from?” Derek P. Gilbert, an author and host at SkyWatchTV, said in a June 15 tweet.

From Synthetic Embryos to Grown Animals

While experiments with synthetic embryos are ongoing, the question of whether they can grow up into living creatures still remains.

Synthetic embryos of mice that Zernicka-Goetz and her team earlier created were implanted into female mice wombs but failed to develop into grown creatures.

Similarly, researchers from China have experimented with implanting synthetic embryos created from monkey cells into the wombs of female monkeys. This, too, had failed.

In an interview with MIT Technology Review in April, Jianping Fu, a bioengineer at the University of Michigan in Ann Arbor, admitted that things might change quite soon.

“Given how rapidly the field has been moving over the last few years … I’ve become more and more concerned about how close we are to generating a complete human embryo model with the potential to develop into a viable human embryo or fetus. This is not some far-fetched, remote possibility,” he said.