Earlier this month, scientists at the Guangzhou Institutes of Biomedicine and Health announced that they had successfully grown “humanized” kidneys inside pig embryos.
Scientists genetically modified the embryos to remove their ability to grow kidneys, then injected them with human stem cells. The embryos were then implanted into a pig and allowed to grow for up to 28 days.
The resulting embryos were composed mostly of pig cells (although some human cells were found throughout their bodies, including the brain). However, the embryonic kidneys were largely human.
This breakthrough suggests that it may soon be possible to generate human organs inside half-human “chimeric” animals. Such animals could be used in medical research or in transplanting organs for transplantation, which could save many human lives.
But the research is fraught with ethical risks. We may want to do things to these creatures that we would never do to humans, such as killing them to obtain body parts. The problem is that these chimeric pigs are not Just Pigs – they are also partly human.
If the human-pig chimera comes to an end, should we treat it as a pig, a human, or something else entirely?
This question may seem very easy. But what about the idea of creating monkeys with human brains?
Chimeras are just one challenge among many
Other areas of stem cell science raise similar difficult questions.
In June, scientists created “artificial embryos” – models of lab-grown embryos that closely resemble natural human embryos. Despite the similarities, it falls outside the legal definitions of a human fetus in the UK (where the study was conducted).
Like human and porcine chimeras, artificial embryos fall into two distinct categories: in this case, the stem cell model and the human embryo. It is not clear how they should be treated.
In the past decade, we have also seen the increasing development of human brain organoids (or “lab-grown mini-brains”).
Unlike artificial embryos, brain organoids do not mimic the development of an entire person. But it mimics the development of the part that stores our memories, thinks about our thoughts, and makes conscious experience possible.
Cortical Laboratories
Most scientists believe that current “mini-brains” are not conscious, but this field is developing rapidly. It is not far-fetched to believe that a cerebral organoid will one day “wake up.”
Further complicating the picture are entities that combine human neurons with technology – such as DishBrain, a biological computer chip made by Cortical Labs in Melbourne.
How should we deal with these? in the laboratory Brains? Like any other human tissue transplant, or like a human? Or maybe something in between, like a research animal?
A new ethical framework
It may be tempting to think that we should answer these questions by dividing these entities into one category or another: human or animal, fetus or model, human person or merely human tissue.
This approach would be a mistake. Confusion aroused by chimeras and embryonic models in the laboratory Brains show that these basic categories no longer make sense.
Read more: As scientists get closer to creating human and animal creatures, what are the concerns?
We create entities that are neither one nor the other. We cannot solve the problem by pretending otherwise.
We will also need good reasons to classify an entity one way or another.
Should we count the percentage of human cells to determine whether a chimera is an animal or a human? Or should it matter where the cells are located? What matters more, the brain or the buttocks? How can we solve this?
Moral status
Philosophers might say that these are questions about “moral status,” and they have spent decades deliberating about what kinds of creatures to whom we have moral duties, and how strong those duties are. Their work can help us here.
For example, utilitarian philosophers view moral standing as a matter of whether a creature has anything Interests (In this case, it has moral standing), and how strong those interests are (stronger interests are more important than weaker interests).
On this view, as long as the fetal or brain organoid model lacks consciousness, it will lack moral standing. But if it develops interests, we must take it into account.
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Likewise, if a chimera develops new cognitive abilities, we need to reconsider how we treat it. If the neurochimera cares as much for its own life as an ordinary human, then we should be as reluctant to kill it as we are to kill a human.
This is just the beginning of a larger discussion. There are other considerations of moral status, and other ways of applying it to the entities that stem cell scientists create.
But thinking about the moral situation puts us on the right path. It fixes our minds on what is morally important, and can start a much-needed conversation.
