Without sperm, eggs, or a womb, scientists have created a being that closely resembles an early human fetus.
The Weizmann Institute team claims that their stem cell-created “embryo model” resembles a textbook illustration of a genuine 14-day-old embryo.
It even generated hormones that caused a laboratory pregnancy test to become positive.
The goal of embryo models is to offer a moral framework for comprehending the infancy of human existence.
A lot happens in the first few weeks after a sperm fertilizes an egg, going from a jumble of fuzzy cells to something that can eventually be seen on a baby ultrasound.
This crucial time is a major source of miscarriage and birth defects but poorly understood.
“It’s a black box and that’s not a cliche – our knowledge is very limited,” Prof Jacob Hanna, from the Weizmann Institute of Science, tells me.
Technically, morally, and legally complex are all aspects of embryo research. But a rapidly expanding field currently mimics the growth of an embryo naturally.
The Israeli team describes their work as the first “complete” embryo model for simulating all the important components that form in the early embryo, and it was published in the journal Nature.
“This is really a textbook image of a human day-14 embryo,” Prof Hanna says, which “hasn’t been done before”.
Instead of a sperm and egg, the starting material was naive stem cells which were reprogrammed to gain the potential to become any type of tissue in the body.
Chemicals were then used to coax these stem cells into becoming four types of cell found in the earliest stages of the human embryo:
About 1% of the mixture began the journey of spontaneously assembling themselves into a structure that resembles, but is not identical to, a human embryo.
“I give great credit to the cells – you have to bring the right mix and have the right environment and it just takes off,” Prof Hanna says. “That’s an amazing phenomenon.”