Scientists have used stem cells to create the closest approximation of a human embryo ever in a lab. It's a scientific milestone, and an ethical minefield."Our goal is not to create life," said Magdalena Żernicka-Goetz when the results of her research were published in the science journal Nature in late June 2023.

Also Read | Future Humans Born in a Petri Dish?.

But Żernicka-Goetz, a developmental biologist, and her team at the University of Cambridge had grown something very close to what could one day become a human being.

Also Read | UFO Sighting in July 2023: From Emergence of ‘World's First UFO Crash’ Report to Sightings of ‘Alien Spaceship’, Here Are Top UFO-Related Events That Happened This Month.

"Synthetic human embryos created in groundbreaking advance," reported The Guardian newspaper, the day Żernicka-Goetz presented the results of her research at a conference in Boston.

The headline effectively fired a starting gun for a media frenzy. The Cambridge study was published as a preprint more or less at exactly the same time as the findings from a rival team in Israel.

As international media pounced upon ethical issues associated with the research, the coverage conjured up images of Frankenstein's monsters.

Both teams had succeeded in growing embryo-like structures more advanced than any previous efforts made entirely from human stem cells.

The synthetic embryos developed to a stage equivalent to that of natural embryos at about 14 days after fertilization.

An ethical dilemma in embryonic research

We can put people on the moon and dive to the depths of the ocean, but we know very little about the earliest stages of human life.

Researchers couldn't get at this early period in our development without endangering a human life.

So, they are restricted to using animal embryos or human model embryos in their research. These can help researchers understand the causes of miscarriages, genetic conditions and congenital organ defects.

Żernicka-Goetz says she hopes her work will further our understanding of what's known as the "black box" period of human development. But critics are concerned that the way she's going about it is like her playing God.

This is the dilemma in embryonic research: the best research models are the ones that get as close to the real thing as possible.

"For scientific purposes, you want the model to be as like the original as possible. But the closer you get to the original, the closer you get to the ethical problems that drove you away to begin with," says Hank Greely, a law professor at Stanford and an expert on ethical, legal, and social issues in the biosciences. So, a model that's too much like a human embryo, is too much.

Scientists prefer the term 'embryo-like structures'

The findings of the Israeli research team, led by Jacob Hanna, sent a chill down his spine, says Jesse Veenvliet of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden.

As a developmental biologist, Veenvliet can recognize an embryo-like structures straight away, and know that it's not real. Not so with the ones from the Israeli team. "They look fantastic," acknowledges Veenvliet.

Yet like many stem cell researchers, Veenvliet stresses that "these models cannot really be described as embryos." He prefers the term "embryo-like structures" — a distinction also made by the International Society for Stem Cell Research (ISSCR) in late June.

The biologist argues that the duck test —­ that if it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck — doesn't apply in the field of embryology.

But biomedical ethics expert Hank Greely disagrees. "If it can make a baby, it's an embryo," says Greely.

Scientists, he says, are determined to tell us it's "no embryo, no embryo, no embryo". Which makes sense, in his opinion: they want to keep on doing their research.

Short-lived synthetic embryos

Closer inspection reveals that the models do differ from human embryos, says Veenvliet. For example, he says, they skip implantation in the lining of the womb. Which means they are incapable of life. And life was never the intention.

Research with animal embryos is a step further. In early April 2023 researchers in Shanghai succeeded in creating blastoids from the stem cells of macaque monkeys.

A blastoid is a stem cell-based model of a pre-implantation embryo.

When researchers put these "synthetic embryos" into the uteruses of adult monkeys, some showed the initial signs of pregnancy, although this pregnancy-like response was short-lived. So, they failed to create artificial life.

The 14-day rule in embryonic stem cell research

Legally, embryonic research is one big gray area. Most countries, including China, the United Kingdom and Canada, allow laboratory research on human embryos for up to 14 days.

Such experiments are completely forbidden in other countries, including Germany, Turkey and Russia.

Brazil and France do not set a time limit, while in the US, restrictions vary from one federal state to another.

The 14-day rule is based on bioethical recommendations in the Warnock Report, which was published in 1984.

Gastrulation, a milestone stage in human development, takes place roughly 14 days after fertilization. During this phase, a single-layered embryo transforms into a multi-layered structure that eventually gives rise to tissues, organs and systems in the body. The 14th day is also important because that's when the embryo is individuated and can no longer become a twin.

In the 1980s, the 14-day rule made sense. It allayed ethical concerns of the day, and allowed scientists scope to advance their research. It seemed technically out of reach to culture human embryos beyond about five days, anyway.

Science has come a long way since then, as demonstrated by Magdalena Żernicka-Goetz's and Jacob Hanna's research. But since their embryo-like models do not mature into humans, many scientists believe the 14-day rule is out-of-date.

In 2021, the International Society for Stem Cell Research proposed relaxing the 14-day rule. Veenvliet says he would welcome such a move.

The first time researchers were able to grow human embryos outside the uterus and keep them alive was almost exactly 30 years after the 14-day rule was introduced. Even if, for example, the period were extended to 21 days — which is when the heart begins to form — the next breakthrough could take another 30 years.

Double standard: Germany's embryo protection law

In Germany, embryo research is completely banned under the Embryo Protection Act of 1991. But there are thousands upon thousands of unwanted embryos in the country, left-overs from couples who have undergone artificial insemination. You're allowed to kill them, freeze or "cryopreserve" them, or throw them out, but you're not allowed to use them in research, explains lawyer Jochen Taupitz.

But then on the other hand, scientists are allowed to import embryonic stem cells from abroad and use them in research. And that, says Taupitz, is a clear double standard.

Taupitz says he hopes someone will finally take issue with the ban on embryonic research, but says that that can only happen with a review by Germany's Federal Constitutional Court. And the only way to get there is if someone breaches the law by doing illegal research. That would give the issue some momentum, he says. But until now, no one has dared risk it.

This article was originally published in German.

(The above story first appeared on LatestLY on Jul 26, 2023 09:00 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).