Your recipe for making synthetic embryos seems a bit magical. Why does it work?
It’s not magic. We start with naïve stem cells [inmaduras], which have all the information encoded in them, and we put them in conditions that are not very special: we give them nutrition, gas and we move them to make sure they don’t get hooked on each other. If you feed them, don’t drown them and prevent them from getting hooked, then they will release their potential on their own.
“The differences with human embryos are still too great. I do not consider them even abnormal embryos”
What do you think of the expression ‘synthetic embryos’?
The field is moving away from that expression, because it seems to imply that these cells are not intended to be embryos. The alternative expression ’embryo model’ has been proposed. The problem with this is that almost anything can be proposed as an embryo model. The work of [Magdalena] Żernicka-Goetz [científica que compite con Hanna por la paternidad de los embriones sintéticos] It has nothing resembling an embryo.
“Reproducing nine months of pregnancy outside the uterus is impossible”
Are your artifacts human embryos or not?
The differences with human embryos are still too great. I don’t consider them even abnormal embryos. If we were to develop them until the 21st or 22nd, we would see that there are many differences. I prefer to call them structured embryo-like entities. The difference may be reduced in the future, but it will take many years. Or it may not be reduced: it may not be a solvable technical issue, but rather an insurmountable difference.
“We cannot close the investigation on the subject for fear that someone will misuse it”
Do you intend to achieve pregnancy outside the womb?
It is not our goal and I believe it is not possible. Reproducing nine months of pregnancy outside the womb is impossible. How much could I imagine that we reached day 60 or 70 in humans.
So what do you want?
In the early stages of development, many pregnancies fail and many developmental diseases occur. Currently, it is not possible to do experiments in that phase. Embryonic material from abortions can be obtained but it is not enough to cover the hundreds of thousands of mouse embryos that we can study. Another objective would be to generate tissues [desde los embriones sintéticos], such as eggs for infertile women. This would be the main application to fertility. In no case are we trying to replace pregnancy.
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What ethical limits should this research have?
You have to trust the regulation. We cannot close research on the topic for fear that someone will misuse it, in the same way that we do not close research on viruses or nuclear physics because of their potential military use. Even in the case where a synthetic embryo is identical to a natural embryo, we should think about applications. If an adult is about to die because he cannot find a bone marrow donor, would it be ethical to take a cell from his skin, make a 50-day embryo and extract the tissues that would save his life? I don’t think a 50 day old embryo suffers pain or has cognition. Furthermore, we can introduce a genetic modification into the embryo so that it can never generate a brain or a heart, so that it can never be a human being. We are still far from these scenarios. There’s no need to panic, but it’s okay to start the discussion early.