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Scientists create human blastocyst-like structure for the first time

 Last Update: 2021-03-26
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Scientists create human blastocyst-like structure for the first time

Open the "black box" of early human development to explore the reasons behind infertility and miscarriage

Scientists for the first time to create a human blastocyst-like structures scientists first create a human blastocyst-like structureopen early human development "black box" to explore the reasons behind infertility, miscarriage open early human development "black box" to explore the reasons behind infertility, miscarriage open early human development "black box "Explore the reasons behind infertility and miscarriage

On the 7th or 8th day of human development, the blastocyst will implant into the uterine wall.

This is the first time that scientists have constructed a complete human blastocyst-like structure in vitro.

"It is very difficult to study early human development.

Although scientists emphasize that the human-like blastocyst structure is only used for scientific research and cannot be used for reproduction, related research still challenges people’s understanding of what life is and when it started, and has brought about the “laboratory creation of humans”.

Laboratory manufacturing of "human-like blastocysts"

Everyone develops from a blastocyst.

From the fertilization of the egg into a blastocyst to its attachment to the implantation in the uterus, the earliest human development process is only about seven or eight days.

However, due to the lack of suitable models, people's understanding of human early embryonic development has been limited.

In 2018, scientists used mouse stem cells cultured in vitro to construct artificial mouse embryos for the first time.

However, conducting research on human embryos in the laboratory not only lacks materials, but also has ethical disputes.

Scientists have been eager to breed human-like embryos in the laboratory and open up the "black box" of human early embryonic development.

The two research groups started with different cells and got similar results, creating "cell balls" in the laboratory that resembled the early stages of human embryonic development.

They all found that the human blastocyst-like structure appeared after 6-8 days of culture, and its size, shape, and total number of cells were similar to those of natural blastocysts.

They also proved that these structures have important characteristics of human blastocysts—cells isolated from them can be used to generate multiple stem cell types.

"This is an important milestone.

Open the "black box" of early human development

"We are very excited!" Polo said at a press conference held in Nature on the evening of the 16th.

"These two studies are the first step in the construction of human blastocysts, and are of great value to the use of embryos to simulate human embryo development and related diseases.

Since it is difficult to obtain human fertilized embryos in general laboratories, embryo-like technology has its outstanding advantages.
For example, embryo-like characteristics are stable, unlimited number, strong uniformity, and easy to obtain.
Based on embryos, a drug screening model can also be established.
By screening drugs that are teratogenic to early embryo development, it can provide safety simulation tests for pregnant women's drugs that enter clinical applications.

Although the human blastocyst-like structure helps to open the "black box" of early human development, Wu Jun and Polo both stated that they are not equivalent to naturally formed blastocysts, and it is not yet possible to prove that such structures can be the same as real embryo sacs.
It develops into a more complex embryo structure, so these models cannot completely replace the study of human blastocysts.
However, large-scale experiments can be carried out through these structures, and then back to real embryos for confirmation, to improve efficiency and reliability of results.

In an interview with China Science Daily, Wu Jun also said that the current efficiency of obtaining this structure is also low.
Only about 10% to 20% of reprogrammed or transformed cells form human-like blastocyst-like structures.
He said that he and his team are continuing to optimize the method, hoping to develop a more efficient and stable platform for other researchers to use.

Treatment prospects coexist with ethical challenges

In recent years, the use of fertilized embryos or artificially constructed embryos constructed from stem cells in vitro is used as an in vitro model to study embryonic development and reproductive diseases.

Li Wei said that at present, there are many domestic research teams engaged in artificial embryo construction and embryo in vitro delayed culture research, including the Chinese Academy of Sciences Strategic Leading Technology Special (Class A) project "Organ Reconstruction and Manufacturing", which also conducts research in this area.
The forward-looking layout and funding.
The Wang Hongmei team of the Institute of Zoology of the Chinese Academy of Sciences and the Kunming University of Science and Technology team reported in Science last year that non-human primate embryos were cultured in vitro for the first time until 20 days after fertilization.

Chinese Academy of Sciences Chinese Academy of Sciences Chinese Academy of Sciences Chinese Academy of Sciences

"The work done by these domestic researchers is in a leading position internationally.
" Li Wei said.

At the same time, in terms of human blastocyst-like structure cultivation, on March 9 and 12 this year, the research team led by Yu Yang, an associate researcher at the Center for Reproductive Medicine, Peking University Third Hospital, and Magdalena Zernicka-Goetz, a developmental biologist at the California Institute of Technology, respectively A pre-printed article on this website BioRxiv reported that they used induced pluripotent stem cells to create structures similar to human blastocysts.
However, these studies have not yet been peer reviewed.

Although Wu Jun and other researchers emphasized that they followed the "14-day rule" in their research, and the relevant structure they produced was different from the naturally formed blastocyst, and could not be used to create human life.
However, related research still challenges people's cognition of what life is and when it started, and has triggered ethical controversy.

At present, people's "consensus" on the start of life is reached after the birth of the first IVF.

In 1978, the first infant Louis Brown who passed in vitro fertilization (IVF) was born.
A few months later, the "14-day rule" was proposed as a guiding principle, stipulating that scientists should not allow human embryos to develop in the laboratory for more than two weeks .
Since human embryos 14 days ago have not differentiated into nerves and other structures, they do not yet possess human characteristics, so ethical issues are not involved.
The "14-day rule" is considered to be one of the most internationally agreed rules in the field of reproductive science and medicine.

However, Li Wei said that compared with the delayed culture of fertilized embryos, the current artificially constructed embryos with stem cells can only reproduce a limited part of the embryonic development, which is a necessary condition for the birth of individual life, which is developmental totipotency.
Very far distance.
Therefore, they are considered not to have the same ethical status as fertilized embryos.

In the future, with the optimization of experiments, human blastocyst-like structures will be closer to human blastocysts.
What should their ethical status be and how should their use be regulated? In this regard, in Li Wei's view, the development of science is always accompanied by ethical disputes.
On the one hand, relevant research should be encouraged and supported, because it is of great value to understanding the mechanism of human development and related diseases; on the other hand, the accompanying ethical norms should also be determined by scientists, ethicists and policy makers.
Discuss and formulate together as soon as possible.

In this regard, Li Lei, who is engaged in molecular embryo developmental biology research, also holds the same view.
He believes that related research is still in its infancy.
The scientific community has basic moral bottom lines and ethical norms, as well as various laws and regulations.
There is no need to worry too much about the idea of "laboratory creation" to stop it.
.
"Isn't IVF a technology of human intervention? Millions of people have been born in 43 years since 1978.
"

Regarding the potential role of human blastocyst-like structure on assisted reproduction, Li Lei said, "It is still difficult to determine.
"

"Now, we have only taken the first step to understand human early embryos, and there are still many unfinished parts in deep understanding and exploration.
Improving this structure will allow us to better understand the process of life development, and to better understand the process of life development.
Respond to the corresponding disease.
" Wu Jun said.
(Source: Feng Lifei Xin Yu, China Science News)