Scientists created something that mimicked an early human fetus without the need for sperm, eggs or a uterus. According to the Weizmann Institute researchers, their “embryo model” created with stem cells resembles a 14-day-old embryo.
It even released hormones that came back positive on a pregnancy test in the lab. The goal of embryo models is to provide an ethical framework for understanding the early stages of human life.
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- Scientists create human embryo model without sperm or eggs
- Material for the start of the project.
- Through this discovery, IVF recovery rate will increase
- A legal distinction
Scientists create human embryo model without sperm or eggs
Credit: Weizmann Institute of Science
The first few weeks after a sperm fertilizes an egg are a time of tremendous changes, from a collection of unclear cells to something that can be seen on an ultrasound of the baby. This critical period is one of the leading causes of miscarriages and birth defects, although it is poorly understood.
“It’s a black box, and it’s not a cliché: our knowledge is very limited,” says Professor Jacob Hanna of the Weizmann Institute of Science.
Material for the start of the project.
Embryo research is complicated from a legal, ethical and technical point of view. However, there is now a rapidly growing profession that mimics the natural development of embryos. The Israeli team describes this study, published in the journal Nature, as the first “complete” embryo model that mimics all the main components that arise in the early embryo.
“This is a textbook image of a day 14 human embryo,” adds Professor Hanna, adding that “this has not been done before.”
Instead of sperm and eggs, naïve stem cells were used as starting material and were reprogrammed to have the ability to form any type of tissue in the body.
- Chemicals were then used to induce these stem cells to transform into four different types of cells seen in the early stages of the human embryo:
- The epiblastic cells develop into the actual embryo (or fetus).
- Trophoblast cells develop in the placenta.
- The hypoblast cells become the supporting yolk sac.
- extraembryonic mesoderm cells
The scientists stood back and watched as 120 cells combined in an exact proportion.
Credit: Nature/Weizmann Institute
About 1% of the mixture began to spontaneously organize into a structure that resembles, but is not identical to, a human embryo.
“I give a lot of credit to cells: if you give the right combination and have the right environment, everything takes off,” explains Professor Hanna. “That’s an amazing phenomenon.”
The embryo models were allowed to grow and develop until they were comparable to a fertilized embryo 14 days later. This is the legal limit in several countries for normal embryo research.
Through this discovery, IVF recovery rate will increase
Credit: Canva
The goal is for embryo models to help scientists explain how different types of cells form, witness the early stages of organ development, and understand hereditary or genetic diseases.
According to this study, other components of the embryo will form once the first cells of the placenta can surround it.
There is even talk of increasing IVF success rates by understanding why certain embryos fail or using models to evaluate whether drugs are safe during pregnancy.
Professor Robin Lovell Badge of the Francis Crick Institute, who studies embryonic development, tells me that these models “look pretty good” and “seem pretty normal.”
“I think it’s good; I think it’s very well done; it all makes sense and I’m quite impressed,” he says.
However, he adds, it would be necessary to improve the current failure rate of 99%. If the model failed to build itself most of the time, it would be difficult to understand what was wrong with miscarriage or infertility.
A legal distinction
The research also raises the question of whether embryonic development can be replicated beyond the 14-day stage. This would not be prohibited in the UK because embryo models are legally different from embryos. “Some will like it, but others won’t,” says Professor Lovell-Badge.
And the closer these simulations get to a genuine embryo, the more ethical problems they create. They are not normal human embryos; rather, they are models of embryos that are remarkably similar to them.
Credit: BBC
“Should we regulate them the same way we would a normal human embryo, or can we be a little more lax in how we treat them?”
Professor Alfonso Martínez Arias, from the Department of Experimental and Health Sciences at Pompeu Fabra University, described it as “very important research”.
“The work has achieved, for the first time, a faithful construction of the complete structure [of a human embryo] of stem cells” in the laboratory, “thus opening the door to studies of the events that lead to the formation of the human body plan,” he said.
The researchers stress that using these embryo models to generate a pregnancy would be unethical, illegal, and impossible: piecing all 120 cells together is beyond the point at which an embryo could safely implant itself in the lining of the uterus.
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Source: vtt.edu.vn