Human embryo model is created from stem cells

Hyperaxion Jun 11, 2020

The structure resembles an embryo at 18 to 21 days and allows researchers to study the early stages of human development.

Scientists at the University of Cambridge, England, in collaboration with the Hubrecht Institute in the Netherlands, have developed a new model for studying one of the early stages of human development using embryonic stem cells. An article on the subject was published on Thursday (11), in the journal Nature.

Human embryo model is created from stem cells
(Credit: Naomi Moris / University of Cambridge).

The model resembles an embryo at 18 to 21 days of development and allows researchers to observe the processes underlying the formation of the body plan, the phase in which an animal’s embryo organizes its anatomy based on the phylum to which it belongs.

This step takes place thanks to the gastrulation process, in which three distinct layers of cells are formed. Later, they will give rise to all the main systems of the body: the ectoderm (outer layer of the embryo) will create the nervous system; the mesoderm, the muscles; and the endoderm, the intestine.

Until now, scientists have never observed gastrulation – many countries have regulations that prevent the cultivation of embryos older than 14 days. Still, studying this “black box” of the embryonic process is essential. According to experts, a better understanding of human gastrulation can shed light on many medical problems that arise during this period – some genetic disorders, for instance.

“This important finding will help us to understand the critical mechanisms of human body planning,” said Li Tianqing, a biologist at the Institute of Primate Translational Medicine in Yunnan, China, who was not part of the study, in an interview with Nature.

A human gastruloid growing at 24 hours (left), 48 hours (middle) and 72 hours (right).
A human gastruloid growing at 24 hours (left), 48 hours (middle) and 72 hours (right). (Credit: Naomi Moris / University of Cambridge).

Methodology

The researchers used human embryonic stem cells to generate a three-dimensional set of cells called gastruloids. These gastruloids are divided into three layers organized in a similar way to that created in the human body plan process.

To produce gastruloids in the laboratory, the team relied on previous experiments with mice embryonic stem cells. The researchers took two years to discover the right conditions for the development of human cells, but it worked.

The structure resembles an embryo between 18 and 21 days of development.
The structure resembles an embryo between 18 and 21 days of development. (Credit: Naomi Moris / University of Cambridge).

They used a compact “colony” of about 300 to 500 cells and treated them with a chemical called Chiron, which accelerated their development. The scientists then separated the cells and placed them into a well, so that they could grow even more.

The cells developed in 3D structures on their own and then spontaneously mimicked the gastrulation process. “This is a hugely exciting new model system, which will allow us to reveal and probe the processes of early human embryonic development in the lab for the first time,” said Naomi Moris, a researcher at the University of Cambridge, in a statement.

The gastroloid created in the laboratory.
The gastroloid created in the laboratory. (Credit: Naomi Moris / University of Cambridge).

It is worth mentioning that gastroloids do not have the potential to transform into a fully formed embryo, as they do not have brain cells or any of the tissues necessary for implantation in the uterus. According to the scientists, this means that they would never be able to progress to the fetal stage.

“Our system is a first step towards modelling the emergence of the human body plan, and could prove useful for studying what happens when things go wrong, such as in birth defects,” explained Moris.

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