A “synthetic” mouse embryo with a brain, spinal cord, and beating heart was developed without the need for a fertilized egg or uterus by researchers in the US and UK.
Three distinct types of stem cells from a mouse embryo, which would typically develop into all the tissues needed in a growing embryo, were used to generate synthetic embryos, or “embryoids.”
A rotating flask of nutrients was used as the artificial growth medium into which the cells were subsequently transported. Embryos developed spontaneously from stem cells.
Only one in one hundred attempts was successful, but those that were, are, according to Professor Magdalena Zernicka-Goetz of the University of Cambridge in the UK and Caltech in Pasadena, California, “absolutely indistinguishable in many cases from natural embryos.”
Synthetic mouse embryos required only half the normal gestation period, or eight-and-a-half days, to exhibit equivalent development to that of a naturally developed mouse. The method used in such studies is crucial in creating research conditions which would allow for cruelty-free research without reliance on actual animals.
Working on a Model of a Human Embryo
The team is actively working on a model of a human embryo, but they emphasize that it is still in the early stages. Early mouse development and early human development differ significantly.
However, creating a human embryo artificially could be a significant advancement in infertility and common developmental diseases research.
Prof Zernicka-Goetz says, “The majority of human pregnancies are lost at the very early stages of our lives and IVF fails in 20 to 70 [percent] of cases.”
A lab-grown “model” embryo could be useful in providing answers to many concerns because donated human embryo supplies are limited and frequently of low quality.
The group is putting forth artificial embryoids that only mimic one component of an early human embryo, such as the heart or the tissue that develops into the placenta during implantation. A key factor in the lack of success of IVF pregnancies is failure at implantation.
The current law, which does not include creating embryos from stem cells, would need to be modified in order to allow for the creation of synthetic human embryos, at least in the UK.
The growth of human embryos in a laboratory after fourteen days is likewise prohibited by UK legislation. Most significant developmental processes shown in these “synthetic” mouse embryos don’t take place until much later. Experts argue that discussion of these legal and ethical issues should begin as soon as possible in light of this most recent discovery.
Prof. Alfonso Martinez Arias of Barcelona’s Universitat Pompeu Fabra, who was not involved in the study says, “The result does herald that, in the future, similar experiments will be done with human cells and that, at some point, will yield similar results.”
He also adds that “this should encourage considerations of the ethics and societal impact of these experiments before they happen.”