A research team at the University of Cambridge have grown artificial mouse embryos to help discover secrets behind early development


embryo1Image taken from pinsdaddy.com

By Hayley Fryer

Research into reproduction and development is a fast-paced field, with new discoveries being made all the time.

A few decades ago, the idea of forming an embryo from anything but an egg and a sperm cell would have seemed ludicrous.

In the mid ‘90s, Dolly the sheep was the first mammal to be cloned. This was a highly regarded and well-renowned experiment, as it was the first time a mammal was created without the need for sperm.

Since then, stem cells have been more readily used in reproductive medicine, being used to grow tissues and organs for use in research and therapeutic areas.

However, until now, stem cells have not been used to grow a full embryo.

A research team at the University of Cambridge have created a technique in which embryos can be created using a mixture of stem cells, eliminating the need for gametes such as egg and sperm.


The research

Growing embryonic and trophoblast stem cells together in a special medium can result in embryos which are very similar to natural mouse embryos

embryo2Image taken from the Zernicka-Goetz Lab, University of Cambridge

Embryonic stem cells are cells found in the inner cell mass of an embryo, which have the potential to differentiate into any cell type. These stem cells are very useful, and are often used in medical research.

Previously, stem cells have only been grown into a specific cell type, and growing stem cells into a full embryo without the use of an egg had not been done.

The research team, led by Magdalena Zernicka-Goetz, found a way to grow artificial mouse embryos from stem cells.

They did this by combining the embryonic stem cells with trophoblast stem cells, which produce the placenta. The mixture was grown on a specially designed gel matrix, and the stem cells grew together.

Four days after formation, the artificial embryos closely mimicked natural mouse embryos, and could self-organise without human interference.

These artificial embryos have already given some insights into certain embryonic developmental processes that were previously not understood. The scientists have identified morphogenetic events and signalling pathways involved in early developmental stages. The cells within the embryo can be monitored, and movements tracked, using fluorescent markers.

Cells are often hard to monitor in mammalian embryos, as they grow within their mother’s uterus. Therefore, these artificial embryos give scientists an exciting opportunity to research developmental processes that could previously not be examined.


How are artificial embryos different to clones?

Clones require an egg cell, whereas artificial embryos do not require any gametes.

embryo3image taken from the independent

Clones, like Dolly the sheep and many other animals, were first made at the end of the 20th century.

Therapeutic cloning creates a cloned embryo which has the same DNA as the donor cell. This embryo is used to produce embryonic stem cells, which can then be used in research exploring disease and developing disease treatments.

Cloned animals are made by removing the DNA from an egg cell, and inserting the DNA from a donor adult body cell into the ‘empty’ egg. The embryo is then grown, and can be made to differentiate into cells which can be used for research or therapeutic techniques.

The issue with cloning is that although it does not require any sperm, it does require an egg cell, which can be difficult to acquire.

The “artificial embryos” do not require egg or sperm gametes, and can therefore produce more tissues for research than cloning methods.


The future

It is hoped that this research may be able to be extended to human stem cells, to act as “a powerful tool for the future study of mammalian embryogenesis”

embryo4image taken from embryo.soad.umich.edu

This technique could prove hugely beneficial by giving insight into early-stage human development. Current research is restricted by a limited number of embryos donated from IVF treatment. Artificial embryos may allow scientists to do far more research, and discover more about our development.

There have been some criticisms of the research; Robin Lovell-Badge from the Francis Crick Institute in London told New Scientist that the embryos lacked other cell types which are needed to develop organs.

Zernicka-Goetz plans to add yolk sac cells in future experiments, to try and help develop these types of cells.


The paper: http://science.sciencemag.org/content/356/6334/eaal1810