Israeli scientists at the Weizmann Institute say they've used stem cells to make an "embryo model" that mimics a 14-day-old embryo without using sperm, an egg, or a womb.1
The researchers say they're trying to understand the activity that takes place in the first weeks of development and gain additional insight into the causes of birth defects and miscarriages. They used naïve stem cells, which have the potential to become any type of tissue in the body.2
Chemicals were then used to turn them into four types of cells found in the earliest stages of the human embryo: epiblast cells, which become the embryo proper; trophoblast cells, which become the placenta; hypoblast cells, which become the yolk sac; and extraembryonic mesoderm cells.1
This follows Weizmann Institute Prof. Jacob Hanna's work with a rival group at Cambridge University, in which they found that similar models could be derived from mouse stem cells. They announced the creation of a 14-day-old human embryo model in June; however, Weizmann's research is the first to be peer-reviewed.3
Fourteen days is the legal threshold for using embryos for research; however, "embryo models" — which are comparable, but not identical to, human embryos 14 days after fertilization — aren't governed by the same laws.2
The researchers said they hope this discovery will lead to new ways of growing transplant organs and offer a way around experiments that cannot be performed on live embryos.2
Narrative A, as provided by The Atlantic. Just because something is scientifically possible doesn't mean it's ethically or legally sound. While still in its early stages, this research potentially paves the way to synthetic wombs, which are problematic: Mothers and fathers are supposed to create babies together, and mothers carry them in their wombs — just as every other animal does — because it builds an unmatched connection between parent and child.
Narrative B, as provided by Scientific American. While concerns regarding this research are legitimate, we need to be cautious not to cross into the realm of unhelpful hyperbole and misleading generalizations. Ultimately, these model embryos are just that: models. They aren't equivalent to real human embryos and bring a host of benefits: from assisting in infertility research and potentially saving premature babies to paving the way to growing transplant organs, this research deserves serious consideration.
Cynical narrative, as provided by Quanta Magazine. While this discovery is promising, it raises a plethora of questions that touch on the broader issue of the indisputable fact that science has surpassed our ability to govern ethical limits. This particular research blurs the line between what does and doesn't qualify as a human being, and until a clear ethical and legal framework is established, a pause should be considered.