Synthesising life: Getting closer to creating artificial humans?

Science fiction is fast morphing into reality. The latest such achievements are artificial embryos. Here's a look at the problems, pitfalls and potentials of this breakthrough

Set in 2540 CE, Brave New World — a dystopian novel by English author Aldous Huxley — opens with a sequence at “Central London Hatchery and Conditioning Centre”, where young students are being introduced to the “Bokanovsky’s Process”. “One egg, one embryo, one adult — normality. But a bokanovskified egg will bud, will proliferate, will divide. From eight to ninety-six buds, and every bud will grow into a perfectly formed embryo, and every embryo into a full-sized adult. Making ninety-six human beings grow where only one grew before. Progress,” explains the novel that was published way back in 1932.

Now, we live in an era where science fiction is fast morphing into reality. Among the latest such achievements are artificial embryos. In recently published studies, two teams of scientists independently reported that they created synthetic mouse embryos — without using eggs or sperm cells — for 8.5 days, longer than ever before (full gestation in mice is about 20 days). They used stem cells, which have the ability to develop into many different cell types.

These embryos developed distinct organs: A beating heart, a gut tube, and even neural folds.

Researchers, led by Magdalena Zernicka-Goetz, professor of mammalian development and stem cell biology at the University of Cambridge in the UK, whose study was published in Nature, now hope to move from mouse embryos to creating models of natural human pregnancies — many of which fail in the early stages. The other similar study — published in Cell — was carried out by a team of researchers from the Weizmann Institute of Science in Israel; they were led by stem-cell biologist Jacob Hanna.

Actually, Professor Zernicka-Goetz’s team used a technique developed by Hanna et al. The latter developed an incubator that kept the embryos from Day 5 to Day 11 (the embryos resided in glass vials that rotated; ventilation was provided, too).

The process is far from perfect: Only a small fraction of stem cells developed precursors to organs (also they didn’t entirely mimic a natural embryo). Still, these successful experiments allow scientists to see organ development in unprecedented detail.

According to Marianne Bronner, a professor of biology at the California Institute of Technology in Pasadena (as reported by CNN), these studies tackle a challenge scientists face studying mammalian embryos in utero. “These (artificial embryos) develop outside of the mother and therefore, can be easily visualised through critical developmental stages that were previously difficult to access,” Dr Bronner said. They are also easier to manipulate using genome-editing tools.

Developmental biologist Lewis Wolpert once said: “It is not birth, marriage or death, but gastrulation which is truly the most important time in your life.” But embryonic transformations, occurring about 16 or 17 days after fertilisation, or gastrulation, are still largely a black box of human development.

Cell dynamics are critical in the early days of gestation because an embryo evolves from a bundle of identical cells to a miniature body. A small mistake can lead to a miscarriage or life-long consequences for the child. So, researchers want to study and find out whether there is any way to prevent problems from arising.

But translating the aforementioned work into humans is easier said than done. Several teams of researchers have tried to develop human stem cells into blastocysts, a rapidly dividing ball of cells but, so far, there is no success regarding organ formation, which happens a month after fertilisation.

Also, in the case of in vitro fertilisation, an embryo — derived from fertilisation of eggs by sperm — has to be implanted in the parent by this stage, so scientists have limited visibility into the processes.

There are ethical pitfalls, too. One key question is whether synthetic structures be called embryos.

The International Society for Stem Cell Research, based in the US, had been against culturing human embryos beyond Day 14 — around the time when “primitive streak’ appears, marking the start of gastrulation. But in 2021, it eased guidelines to allow research with “compelling scientific rationale”. India, too, follows a similar norm.

Given these limitations, it is important to understand the above-mentioned synthetic structures are not embryos. Though they replicate certain aspects of embryonic development, they do not fully reproduce the cellular architecture of natural embryos.

Synthetic human embryos can also allow scientists to circumvent ethical issues around gene editing. With such methods, they shall have a deeper insight into how reprogramming happens.

In Brave New World, such methods were being used for nefarious purposes, for producing citizens for a futuristic World State who were environmentally engineered into an intelligence-based social hierarchy. Hopefully, scientists and policymakers in the real world shall thwart such sinister motives when we, humans, become God.