Up until now, the development of any mammal embryo required an egg and sperm cell. But a team of scientists has created “synthetic” mouse embryos without egg or sperm cells. This is a breakthrough in the field of genetic engineering that could potentially lay the groundwork for synthetic human embryos, despite thorny ethical implications.
The science and other stuff to know
As detailed in a paper published in the journal Nature, a team led by Magdalena Zernicka-Goetz at the University of Cambridge turned mouse stem cells into an embryo that was able to start growing a brain, heart, and other organs for over a week.
To create the synthetic embryos, or “embryoids,” Zernicka-Goetz and her team combined embryonic stem cells and two other types of stem cells – all from mice. They did this in a lab, using a particular type of petri dish that allowed the cells to communicate with each other and mimic what happens naturally during embryonic development.
While the embryoids they created weren’t all perfect, Zernicka-Goetz noted that the best ones were “indistinguishable” from natural mouse embryos. Besides forming a heart-like structure, they also developed head-like structures that included a brain. “This is really the first model that allows you to study brain development in the context of the whole developing mouse embryo,” she said.
Creating an embryo from cells other than sperm and egg and then growing them in a lab is an area of study that has developed significantly over the past few years.
Most of these studies are aimed at getting more insights into why the majority of human pregnancies are lost at an early stage, as well as why embryos created through In-Vitro Fertilization (IVF) sometimes fail. Moreover, according to the National Library of Medicine, among women who know they’re pregnant, up to 25 percent of those pregnancies often end in a miscarriage.
There are also practical health implications that could arise from such novel studies, such as the precise detection of fetal defects early in pregnancy. Advancements in this research could also help solve organ transplants and infertility problems.
The roots of this study go back decades, and Zernicka-Goetz said their next steps include trying to coax the synthetic mouse embryos to develop past 8 and a half days. The goal is to get the embryos to term, which is 20 days for a mouse.
This team isn’t technically the first to create a “synthetic” embryo from stem cells. Some scientists have already used human stem cells to develop “blastoids,” structures mimicking pre-embryo. These pre-embryo models offer an effective and ethical way to study human development and could lead to new discoveries in genetic engineering.