Model of human embryo developed without sperm, eggs or a womb

In August of 2022, a synthetic mouse embryo was created by genetic engineering specialists at the University of Cambridge without the need of eggs or sperm. 

For up to a week, the stem cell-derived embryos were found to begin forming a heart, brain, and other organs.

Meanwhile, last June, an embryo-like model of the important post-implantation stage of human development was produced by scientists using human stem cells.

And those are just a few examples.

The first complete model

The new development, however, has resulted in the first "complete" embryo model for simulating all the important components that form in the early embryo, the researchers told the BBC.

The team claims that their stem cell-created embryo model resembles a genuine 14-day-old embryo.

"This is really a textbook image of a human day-14 embryo," Prof Jacob Hanna, from the Weizmann Institute of Science, the organization behind the new work, told the BBC. She added that this "hasn't been done before".

The development is so advanced that it even generated hormones that caused a laboratory pregnancy test to become positive.

The scientists say that the new embryo could now provide a moral framework for undertaking the crucial research necessary for understanding the infancy of human existence on a whole other level.

It is particularly useful in comprehending the time after a sperm fertilizes an egg, when cells first transform into what will one day be a human being.

This important period is largely responsible for miscarriages and birth abnormalities but is notoriously unexplained in science.

So how did the scientists achieve this new miracle?

They replaced sperm and eggs with naive stem cells and they reprogrammed them to acquire the ability to develop into any kind of bodily tissue.

Following that, chemicals were employed to induce the four cell types found in the earliest stages of the human embryo.

The scientists carefully combined 120 of these cells and proceeded to observe what happened.

Reaching the legal threshold for embryo research

They reported that about one percent of the solution began the process of building itself autonomously into a structure that resembles a human embryo, although it likely cannot function as one.

The researchers let the embryo models mature until the equivalent of 14 days following fertilization, the legal threshold for typical embryo research in several nations.

Although the new method can not be legally used to make babies, it can enable a better understanding of how genetic illnesses emerge and may be the key to finally providing an answer as to how various cell types originate.

The study was published in the journal Nature.