As publicly announced in June, three research teams from the UK, the US and Israel have independently succeeded in developing cell aggregates from human stem cells that very closely resemble the early human embryo.
These cell aggregates are considered the most faithful embryo models ever created. What’s new about them is that human embryonic development can be initiated using cells other than gametes (ova and sperm); these embryo models are created from a single person’s stem cells. Now the question is whether they should be used in research. After all, research on real human embryos is ethically controversial and tightly restricted in many countries. Research on these new models, on the other hand, is not yet regulated by law in many countries. Ethicist Alessandro Blasimme of ETH Zurich has been studying ethical issues in biomedicine for years. In a recent study published in the journal external pageCell Stem Cellcall_made, he specifically addressed the new embryo models derived from human stem cells.
ETH News: Why are these embryo models significant to science?
Alessandro Blasimme: We still know very little about the first phases of human embryonic development. Since research in this field is highly regulated in many countries, embryo models offer scientists a close alternative for studying embryonic development and also relevant problems that may occur in early pregnancy. For instance, how does an embryo implant in the uterus, and why are spontaneous miscarriages relatively common during this stage of pregnancy? Ultimately, such research could also lead to treatments for couples who are otherwise unable to have children. These extremely accurate models enable scientists to study embryonic life in a way that was simply not possible before.
In some countries, researchers are allowed to use real human embryos up to 14 days old. So far, the novel embryo models haven’t been kept in culture for more than 14 days either. What’s the benefit of these models when you can also do research on real embryos?
The researchers who developed human embryo models kept them in culture up to eight days probably due to current experimental limitations. Presumably, however, such embryo models will soon permit researchers to observe much later stages of embryogenesis. Two of the research groups involved in these experiments, were recently able to generate mouse embryo models from stem cells up to the organogenesis, meaning that they were able to observe a beating heart develop and a brain emerge in these models. A further benefit is that while natural human embryos are created using ova harvested from women, embryo models don’t require human egg cells.
