Paris (AFP)
Scientists have developed a human embryo model from human embryonic stem cells that reproduces the early stages of its development in the laboratory, a three-dimensional advance that could prove useful in studying birth defects or other abnormalities , according to a study.
According to the teams from the University of Cambridge (Great Britain) and the Hubrecht Institute (Netherlands), whose work appeared Thursday in the scientific journal Nature, this pseudo-embryo model allows us to observe new processes underlying the formation of the human body, never directly observed before.
This system is "a first step towards modeling the emergence of the plan of the human body, and could prove useful to study what happens when things go wrong, as in birth defects," says Dr. Naomi Moris (Department of Genetics, University of Cambridge) co-author of the study.
The model developed by the researchers partially resembles an 18 to 21 day old embryo.
The "plan" of the human body, or blueprint for building the body, arises from a process called gastrulation, during which a structure is formed of three distinct layers of cells that will later constitute the different tissues of the body.
The period of gastrulation is considered the "black box" of human development because legal restrictions prevent the development of embryos in the laboratory beyond 14 days.
However, many birth defects occur during this period of embryonic development, from causes such as alcohol, drugs, chemicals, and infections. His study could also help understand medical problems like infertility, miscarriages and genetic disorders, add the researchers.
"Our model produces part of a human's plan," said Alfonso Martinez-Arias, of the Cambridge Department of Genetics, responsible for the study. "It's exciting to see the development processes that have so far been hidden from view - and under study."
To create and develop this model, the team collected tight aggregates of human cells grown in the laboratory and subjected them to chemicals to activate certain genes.
It is the first time that human stem cells have been used to create a three-dimensional model of a human embryo, after those made with mouse and zebrafish stem cells.
These embryonic drafts, the gastruloids, cannot become fully formed true embryos because they have neither brain cells nor the tissues necessary for their implantation in the uterus, underline the researchers. However, at 72 hours of development, they observed obvious signs of the events leading to the formation of muscles, bones and cartilage.
The study opens a "fantastic window" on the early formation of the human body, notes the professor of developmental biology at King's College London, Jeremy Green, who did not participate.
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