Meet 'Gastruloid': The First Human Embryo-like Model From Stem Cells That Could Soon Save Many Babies From Developing Birth Defects

Human embryo goes through a process of gastrulation, which occurs during early development where isotropic cell groups transform into ensembles of tissue. Despite many restrictions in studying gastrulation, scientists have created an embryo-like blueprint for birth defect and disease detection from stem cells.

A team from the University of Cambridge gained new insight into the development period of gastrulation; what they call the 'black box' period. Due to ethical and legal issues that prohibit ex vivo observations, the scientists created a model that resembles an embryo. Laws prohibit scientists to culture embryos in a lab beyond two weeks, the point where gastrulation begins, making it impossible to study the black box period before the new study.

Alfonso Martinez-Arias, a geneticist from the university, said that their model 'produces part of the blueprint of a human...It's exciting to witness the developmental processes that until now have been hidden from view - and from study.'

During this black box period, three layers of cells form the ectoderm, mesoderm, and endoderm. These cells proceed to form the nervous system, muscles, and gut.

Gastruloids

Professor Martinez-Arias and the team set embryonic stem cells into 'small wells,' creating 'gastruloids.' Gastruloids resemble human embryos during the premature stages of development, around 18-21 days after being conceived.

The embryo models were then treated with chemical signals, proceed by lengthening along a head-to-tail axis. This activity triggered genes to form specific patterns which displayed a 'clear signature' for the development of various body parts. If it were a real embryo, the process would eventually result in specific body structures such as muscles, bones, and cartilages.

Naomi Moris, another geneticist from Cambridge, shared that '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.' The newly developed system may 'prove useful for studying what happens when things go wrong, such as in birth defects,' she continued.

The gastruloid model may help pinpoint specific causes of birth defects or diseases that begin during gastrulation such as alcohol consumption, harmful medication, substance abuse, and other forms of infections. Genetic disorders can also be more understood, as well as what causes infertility and miscarriages.

In-Cell NMR on a developing multicellular organism? How does this make sense? Only because embryonic development is highly synchronised and the ensemble behaviour of multiple 'objects' in the NMR tube is uniform! > watch zebrafish embryos develop pic.twitter.com/LOvqdqKDL1 — Selenko Lab (@philselenko) May 16, 2020

Human Models

Until recently, scientists have only conducted studies on mice and zebrafish embryo, which most likely have genetic differences with human cells during the gastrulation process. Moreover, non-human models respond differently to certain chemicals such as morning sickness medication for pregnant women. This results in clinical trials passing for animal models yet could be severely harmful to humans, causing birth defects.

Joyce Harper, a reproductive expert from the University College London and is not a co-author of the new study, knows that gastrulation is a highly critical stage in life development. ''But up until now, we have never been able to study it in humans [models]...this exciting work will allow many key studies to be done so we can learn about early human development and when it goes wrong,' she said.