Rather than using a fertilised egg, researchers from Cambridge University artificially grew an embryo in a three-dimensional structure by combining two types of stem cells – those that would develop into an embryo and those that would normally develop into the placenta. They found that the arrangement of cell development was very similar to the development of a usual mouse embryo.
While the media described the possibility of artificially formed human life soon becoming a reality, this is very early-stage research. Aside from the strict regulations about embryo research, the technical challenges of developing artificially formed human life are immense.
Reports about artificially created "designer babies" remain the stuff of science fiction.
A more down-to-earth implication of this research is that it may help provide more information about the early stages of pregnancy, which could eventually lead to new fertility treatments.
Where did the story come from?
The study was carried out by researchers from the University of Cambridge and Akdeniz University, Turkey.
The study was funded by the Wellcome Trust and the European Research Council and was published in the peer-reviewed journal Science.
The UK media reporting of the story was generally accurate, describing the methods used by the researchers in this exploratory lab study.
The Guardian reported: "Artificial mouse cells grown from outside the body in a blob of gel shown to morph into primitive embryos, roughly equivalent to one third of way through pregnancy", making clear that this was a study carried out in mice and not humans.
What kind of research was this?
This was an experimental laboratory study in mice that aimed to mimic interactions in the development of an embryo by combining the early embryonic stem cells with the cells that form the placenta within a 3D scaffold to try to develop an artificial embryo. This scaffold is a gel that allowed the structure to grow in three dimensions
While these laboratory studies are good at discovering new biological processes and ways of mimicking them, it must be remembered that they are often – as in this case – very early-stage research that cannot yet be applied to humans. Laboratory research involving human embryos is strictly controlled and regulated.
What did the research involve?
The study looked at the development of mouse embryos combining embryonic stem cells and cells that form the placental tissue, rather than starting from a fertilised egg.
The researchers took mouse embryonic stem cells (ES cells) and trophoblast stem (TS) cells, which are cells that are used to develop the placenta in normal pregnancy, and put them in a scaffold in a gel culture that allowed them to develop together.
What were the basic results?
They found that as the cells multiplied, structures made from the ES and TS cells developed in the 3D scaffold.
Following the seven days, the TS cells, which will go on to become the placenta, grew in a separate section to the ES cells – which will form the embryo.
Of all the structures they created, 22% were made from both ES and TS cells, 61% from ES cells only and 17% from TS cells only.
The ES and TS cells developing together in a 3D scaffold arranged themselves into a structure very similar to a natural embryo.
The ES cells further split into two groups, one cluster called the mesoderm would normally go on to develop into the heart, bones and muscles. The other section would normally go on to develop into the brain, eyes and skin.
They found that the timing and spatial arrangement of the cell development was very similar to the development of a usual mouse embryo.
How did the researchers interpret the results?
The authors conclude that "our study demonstrates the ability of distinct stem cell types to self-assemble in vitro (in laboratory settings) to generate embryos whose morphogenesis, architecture and constituent cell types resemble natural embryos".
This early-stage research offers a good insight into the development of mouse embryos and the sequence of biological steps that take place up to the point of implantation in the womb and immediately afterwards. They could provide an insight into the early stages of human life.
However, this does not mean that the creation of artificial human life is now possible:
- The study was carried out on mice stem cells, which have a very different biological make-up to humans so the processes may not be identical with human cells.
- While the artificial mouse embryo seemed to behave like a natural one, it is unlikely it could develop to a healthy foetus, as other components – such as the yolk sac that provides nutrition – were missing.
- Not all embryonic and trophoblast structures developed and the biological reason for this is not known.
Most importantly, experiments involving human embryos or embryonic tissues are strictly regulated in the UK. Current legislation prohibits the development of embryos beyond a limit of 14 days.
As Professor James Adjaye, Chair of Stem Cell Research and Regenerative Medicine at Heinrich Heine University says: "As always, these types of experiments using human stem cells are regulated but there is no 'universal regulatory body'. Each country has its own regulatory body, which will ultimately decide on whether human [embryonic and trophoblast stem cell] embryos can be generated and for how long they can be left in the petri dish to develop further. Of course, there should be an international dialogue on the regulation of such experiments."
It is reported that the research team behind this work now plans to carry out similar work using human cells – a move that is sure to attract more media controversy.