Animal-human embryos: monster or marvel?

The first ethical issue actually concerns the human stem cells. Some people object to the use of cells obtained from human embryos in research, because they believe that each embryo is a human life that should be respected. However, very few countries actually allow the creation of embryos for this specific purpose; the UK also permits the addition of rabbit mitochondria to human eggs to facilitate fertilization. Most embryonic stem cells used in research are actually derived from existing cell lines, and no (more) embryos need to be destroyed to produce these cells. For many non-religious people, the use of human embryos in research is justified by the potential benefits for people who are affected by disease, both now and in the future. In any case, most hybrid embryos are now created using induced pluripotent cells rather than those derived from embryos.

Some people also object to the use of animals and animal embryos in research. They argue that humans have no right to instrumentalize animals in this way, when doing so causes them pain and suffering. Again, however, most people agree that using animals for research is justified if it yields benefit for humans. Another ethical issue concerns the possibility of creating an animal with human features, such as a pig with a human face, for example, or producing animals that might be intelligent like humans. However, this is a misunderstanding of what is going on in this research: it does not aim to produce actual living animals that are carried to term, but only to conduct research on embryos and sometimes fetuses. There is no prospect of human-looking animals being produced.

One notable exception to this rule is research into using hybrid embryos to produce animals whose organs can be used for transplantation. Scientists in Japan and the United States have succeeded in using stem cells from rats to grow rat organs inside mice embryos. More recently, human organs were grown inside pigs. The next step will be to actually transplant one such organ into a human before beginning clinical trials. The advantage of this approach is that the organ can be grown using a patient’s stem cells so that it will be compatible when transplanted, and the patient will therefore not have to take immunosuppressant drugs. Of course, there is a shortage of organs for transplantation, so any new source of organs is useful. One quirk of the Swiss law on embryonic stem cells is that it does not cover induced pluripotent stem cells derived from humans, meaning that the creation of human organs for transplant inside pigs is accidentally legal, even if no-one is actually doing such research in Switzerland.

The example of growing human organs inside pigs using stem cells brings us on to the last major ethical issue: the so-called «slippery slope». This argument is used in many contexts, including assisted suicide and privatization of healthcare, but in biotechnology it is used to argue that a particular advance is just the first step towards «Frankenstein science» or «playing God». The implication is that if we permit the creation of chimaera embryos, we will soon be allowing everyone to create designer babies and engage in eugenics. Although Switzerland is a very progressive country with regard to assisted dying, its citizens generally seem to have a more conservative attitude with regard to biotechnological advances. At the Institute we recently asked patients about how they perceive synthetic biology, and many were very skeptical about genetic modification until the actual science and potential benefits were explained. Once they understood that many of their fears were misplaced, and that such treatments could be beneficial, their attitudes became more positive. We should not forget that developing treatments to treat sick patients is a fundamentally ethical endeavor.