Nav: Home

Stem cells organize themselves into pseudo-embryos

October 03, 2018

The definitive architecture of the mammalian body is established shortly after implantation of the embryo in the uterus. The antero-posterior, dorso-ventral and medio-lateral axes of the body become organized under the control of gene networks that coordinate the transcription of DNA in various regions of the embryo. Researchers from the University of Geneva (UNIGE), the University of Cambridge, UK, and the Federal Institute of Technology Lausanne (EPFL) now report the ability of mouse stem cells to produce pseudo-embryos that display similar capacities. Established from about 300 embryonic stem cells only, these structures, called gastruloids, show developmental features comparable to that of the posterior part of embryos aged from 6 to 10 days. The study, published in the journal Nature, shows that the three main embryonic axes are formed according to a gene expression program similar to that of embryos. Gastruloids thus possess a remarkable potential for the study of the early stages of normal or pathological embryonic development in mammals.

Studying the processes orchestrating the formation of early mammalian embryos is hampered by the difficulty in obtaining them. The team of Alfonso Martinez Arias, Professor at the Department of Genetics of the University of Cambridge, UK, recently discovered that, under certain conditions, murine embryonic stem cells can assemble into three-dimensional aggregates that keep elongating in culture. These entities called "gastruloids" display different characteristics of early stages of embryonic development.

Interdependent developmental processes

"To determine whether gastruloids organize themselves into bona fide embryonic structures, we characterized their level of genetic activation at different stages of development", explains Denis Duboule, Professor at the Department of Genetics and Evolution of the UNIGE Faculty of Sciences and at the Swiss Institute for Experimental Cancer Research of EPFL. The researchers identified and quantified the RNA transcribed from gastruloids and compared the expressed genes with those of mouse embryos at comparable stages of development.

"Gastruloids form structures similar to the posterior part of the embryo, whose development program is somewhat different from that of the head", says Leonardo Beccari, scientist in the Geneva group and co-first author of the study. These pseudo-embryos express genes characteristic of the various types of progenitor cells necessary for the constitution of future tissues. "The complexity of gene expression profiles increases over time, with the appearance of markers from different embryonic cell lineages, much like the profiles observed in control embryos", notes Naomi Moris, scientist from the Cambridge team and co-first author of the article.

Architect genes are activated as in the embryo

During the formation of the gastruloids' antero-posterior, dorso-ventral and medio-lateral axes, members of these teams could visualize an amazing property; the 'architect' Hox genes, which are normally activated in a precise sequential order in the embryo, were equally well activated in gastruloids grown in vitro. "The implementation of the Hox gene network over time, which mimicks that of the tail of the embryo, confirms the remarkably high level of self-organization of gastruloids", explains Mehmet Girgin, geneticist at EPFL and co-first author of the study.

These artificial pseudo-embryos will in some cases offer an alternative method to animal experimentation, in accordance with the 3Rs. The 3Rs principle (reduce, replace, refine) has established itself internationally as the foundation of the ethical approach applied to animal experimentation. It aims at reducing the number of animals used, refining experimental conditions to improve animal welfare, and eventually trying to replace animal models with other experimental methods whenever possible. Gastruloids will complement the use of animal embryos, thereby reducing their number in the study of mammalian embryonic development.
-end-


Université de Genève

Related Embryonic Stem Cells Articles:

New mechanisms that regulate pluripotency in embryonic stem cells are discovered
A study by researchers at the Center for Cell-Based Therapy, which is supported by FAPESP, identified microRNAs involved in pluripotency maintenance and cell differentiation.
Embryonic mammary gland stem cells identified
Research team led by Prof. Cédric Blanpain identified the mechanisms that regulate mammary gland development.
New insights into mechanisms regulating gene expression in embryonic stem cells
Researchers from Turku, Finland, have discovered new information about the mechanisms which maintain gene activity in human embryonic stem cells.
New tools to study the origin of embryonic stem cells
Researchers at Karolinska Institutet have identified cell surface markers specific for the very earliest stem cells in the human embryo.
Scientists approve the similarity between reprogrammed and embryonic stem cells
Researchers from the Vavilov Institute of General Genetics, Research Institute of Physical Chemical Medicine and Moscow Institute of Physics and Technology (MIPT) have concluded that reprogramming does not create differences between reprogrammed and embryonic stem cells.
Drug makes stem cells become 'embryonic' again
If you want to harness the full power of stem cells, all you might need is an eraser -- in the form of a drug that can erase the tiny labels that tell cells where to start reading their DNA.
Oncogene controls stem cells in early embryonic development
Many animal species delay the development of their embryos to ensure that their offspring is born at a favorable time.
Are embryonic stem cells and artificial stem cells equivalent?
Harvard Stem Cell Institute (HSCI) researchers at Massachusetts General Hospital and Harvard Medical School have found new evidence suggesting some human induced pluripotent stem cells are the 'functional equivalent' of human embryonic stem cells, a finding that may begin to settle a long running argument.
UCSF researchers control embryonic stem cells with light
UCSF researchers have for the first time developed a method to precisely control embryonic stem cell differentiation with beams of light, enabling them to be transformed into neurons in response to a precise external cue.
Protein plays unexpected role in embryonic stem cells
A protein long believed to only guard the nucleus also regulates gene expression and stem cell development.
More Embryonic Stem Cells News and Embryonic Stem Cells Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Our Relationship With Water
We need water to live. But with rising seas and so many lacking clean water – water is in crisis and so are we. This hour, TED speakers explore ideas around restoring our relationship with water. Guests on the show include legal scholar Kelsey Leonard, artist LaToya Ruby Frazier, and community organizer Colette Pichon Battle.
Now Playing: Science for the People

#568 Poker Face Psychology
Anyone who's seen pop culture depictions of poker might think statistics and math is the only way to get ahead. But no, there's psychology too. Author Maria Konnikova took her Ph.D. in psychology to the poker table, and turned out to be good. So good, she went pro in poker, and learned all about her own biases on the way. We're talking about her new book "The Biggest Bluff: How I Learned to Pay Attention, Master Myself, and Win".
Now Playing: Radiolab

Uncounted
First things first: our very own Latif Nasser has an exciting new show on Netflix. He talks to Jad about the hidden forces of the world that connect us all. Then, with an eye on the upcoming election, we take a look back: at two pieces from More Perfect Season 3 about Constitutional amendments that determine who gets to vote. Former Radiolab producer Julia Longoria takes us to Washington, D.C. The capital is at the heart of our democracy, but it's not a state, and it wasn't until the 23rd Amendment that its people got the right to vote for president. But that still left DC without full representation in Congress; D.C. sends a "non-voting delegate" to the House. Julia profiles that delegate, Congresswoman Eleanor Holmes Norton, and her unique approach to fighting for power in a virtually powerless role. Second, Radiolab producer Sarah Qari looks at a current fight to lower the US voting age to 16 that harkens back to the fight for the 26th Amendment in the 1960s. Eighteen-year-olds at the time argued that if they were old enough to be drafted to fight in the War, they were old enough to have a voice in our democracy. But what about today, when even younger Americans are finding themselves at the center of national political debates? Does it mean we should lower the voting age even further? This episode was reported and produced by Julia Longoria and Sarah Qari. Check out Latif Nasser's new Netflix show Connected here. Support Radiolab today at Radiolab.org/donate.