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.
Though little is known about this critical period, it is a major cause of miscarriage and birth abnormalities.
Prof. Jacob Hanna from the Weizmann Institute of Science tells me, “It’s a black box and that’s not a cliche – our knowledge is very limited.”
Starting point
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.
Prof. Hanna claims that this is the first time a textbook image of a human day-14 embryo has been created.
Naive stem cells were used as the beginning material instead of sperm and an egg, and they were reprogrammed 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 from these stem cells:
Epiblast cells develop into the embryo proper (or foetus) while trophoblast cells develop into the placenta and hypoblast cells into the sustaining extraembryonic mesoderm cells of the yolk sac.
The scientists carefully combined 120 of these cells in a specific ratio before stepping aside to observe.
About 1% of the mixture started the process of building itself spontaneously into a structure that resembles, but differs from, a human embryo.
I give the cells a lot of credit; all you need is the proper mixture and the appropriate habitat, and it just takes off, says Prof. Hanna. “What a remarkable phenomenon.”
The embryo models were allowed to mature and expand until 14 days after fertilization, when they were equivalent to an embryo. This is the legal threshold for typical embryo research in several nations.
I can still hear Prof. Hanna’s passion during the late-night video conversation as she takes me on a 3D tour of the “exquisitely fine architecture” of the embryo model.
I can see the embryo being encircled by the trophoblast, which is the precursor to the placenta. Furthermore, it contains the spaces, referred to as lacuna, that fill with the mother’s blood to carry nutrients to the infant.
There is a bilaminar embryonic disc, which is one of the essential characteristics of this stage of embryo development, as well as a yolk sac, which plays some of the functions of the liver and kidneys.
Being logical
Scientists are hoping that using embryo models will enable them to better comprehend hereditary or genetic illnesses, see the earliest stages of organ development, and explain how various cell types originate.
This study has already demonstrated that the early placenta cells must be able to envelop the embryo in order for other components to develop.
Even the idea of increasing in vitro fertilization (IVF) success rates by assisting in the understanding of why certain embryos fail or using the models to examine the safety of medications during pregnancy has been floated.
The Francis Crick Institute’s Prof. Robin Lovell Badge, who studies embryo development, tells me that these embryo models “do look pretty good” and “do look pretty normal.”
“I think it’s good, I thinks it’s done very well, it’s all making sense, and I’m pretty impressed with it,” he says.
However, he continues, the present 99% failure rate needs to be reduced. Infertility or miscarriage would be difficult to comprehend if the model frequently failed to put itself together.
legally different
The study also calls into question whether embryo development after the 14-day mark can be imitated.
Even in the UK, this would not be against the law because embryo models and embryos have different legal statuses.
According to Prof. Lovell-Badge, “some will welcome this, while others won’t like it.”
Additionally, the more ethical concerns that these models raise, the closer they resemble a genuine embryo.
Although they are embryo models rather than actual human embryos, they are quite similar to them.
So, should they be handled similarly to a typical human embryo, or is it possible to treat them with a little more laxity?
It was “a very significant piece of research,” according to Prof. Alfonso Martinez Arias from Pompeu Fabra University’s department of experimental and health sciences.
The research “has, for the first time, achieved a faithful construction of the complete structure [of a human embryo] from stem cells” in the laboratory, he claimed. This “opens the door for studies of the events that lead to the formation of the human body plan.”
The researchers emphasize that utilizing these embryo models to induce pregnancy would be unethical, unlawful, and practically impossible because doing so would go beyond the point at which an embryo could effectively implant into the lining of the womb.
