Ethical Regulations Proposed for Human-Animal Hybrids

A group of UK bioethicists has proposed the first regulatory framework for creating and experimenting with human-animal hybrids, also known as chimeras.

The Chimera on a red-figure Apulian plate, ca 350–340 BCE (Musée du Louvre)
The Chimera on a red-figure Apulian plate, ca 350–340 BCE (Musée du Louvre)

The intermixing of biological material (genes, cells and tissue) between humans and non-human animals to form hybrid creatures — also known as chimeras — is now fully realizable. Just last year, bio-engineers successfully bred a mouse (from stem cells) which then developed a pancreas comprised of rat-derived cells. While this rodent chimera did not create very much public outcry, it represents just the beginning of greater — and more ethically problematic — creations, such as a monkey with human neurons in its brain.

Despite our ever-advancing ability to created human-animal hybrids, ethical rules governing the creation and use of such animals in laboratory settings have been lacking. Now, however, a working group of the Medical Research Council’s National Institute for Medical Research in London has drawn up the first “regulatory framework” in anticipation of such clinical experiments. The framework is outlined in the group’s July 22 published document Animals Containing Human Material and calls for the UK to take the lead in establishing safeguards for future chimera experiments.

The purpose of the framework, as stated by members of the Council’s working group, is not to hold up important research, such as medical research, but to prevent researchers from over-stepping “publicly acceptable” boundaries in the future. For example, the aforementioned case of a monkey with human brain cells, though potentially useful for human cognition/neuroscience research, would most likely be deemed unacceptable from an ethical standpoint.

Taking this example further, the report cites one example of a chimera that would be off limits: the creation of a non-human primate with sufficient human brain cells to give it “human-like” behavior, such as greater reasoning ability or self-awareness (though most great apes show signs of self-awareness, and even basic reasoning skills). This  hypothetical, artificially created capability would confer moral status onto the primate (akin to our own “moral status”) and thus preclude any “invasive” (surgical) research or experimentation on the primate (in most countries).

chimeras, the blotched mouse
Some chimeras, like the blotched mouse shown, are created through genetic modification techniques like gene targeting (NIMH).

The report also advises banning (“for now”) the creation of embryos from any mixture of human and non-human embryonic or pluripotent (undifferentiated) stem cells, along with animals possessing human-derived egg or sperm cells. These latter cases could potentially generate a true human-animal chimera.

Animals containing human material (ACHM)

However, certain chimaerical creations would not be banned, pending approval by a special ethical commission. These would include modification of the brains of (non-primate) animals to give them some human-like function that can then be studied.

For example, introducing neural stem cells into the brain of a monkey to determine if they could viably replace lost neurons would be beneficial in treating Parkinson’s disease, and so, this type of experimentation would be permissible under the guidelines (note: the use of “non-human” primates in biomedicine is ethically controversial; the report seems to waver a bit on barring said primates from all such research). Also permitted would be the development of human-derived sperm or egg cells in an animal in which there is no chance of fertilization.

The working group included experts in philosophy, ethics, social sciences, law, and biomedicine, and was chaired by chaired by human geneticist Martin Bobrow of the University of Cambridge. The group recommends that the UK government establish an expert body to consult and advise on ACHMs and to perform reviews of current research proposals/experiments on a regular basis. The group’s proposals are likely to be incorporated into legislation within the coming year.

Ilya Ivanovich Ivanov
Ilya Ivanovich Ivanov August 1, 1870-March 20, 1932) was a Russian and Soviet biologist who specialized in the field of artificial insemination and the interspecific hybridization of animals. He was involved in controversial attempts to create a human-chimpanzee ("humanzee") hybrid. The experiments failed.

The ACHM report concludes that no additional oversight of the biomedical field (vis a vis ACHMs) is needed, since a wide variety of transgenic animals (mice, goats, sheep, pigs, etc.) have already been created containing human genes in order to study various human diseases, or, in the case of pigs, to grow human organ tissue for later harvesting and transplantation. Such transgenic creatures are already regulated by animal welfare authorities (in the UK), according to the report.

Author’s comment:

I am not sure to what degree “animal welfare authorities” regulate the creation and treatment of transgenic animals here in the U.S. Regardless, it is not clear to me how the transgenic pig’s welfare is “protected”, given this use, regardless of the benefit to humans.

That said, I acknowledge that biomedical research is a difficult ethical sphere to deal with; we want to eradicate human diseases and suffering — as well as the suffering and mistreatment of animals–yet these two goals clash in the biomedical lab. Obviously, human self-interest will dictate most of the ethical “weighting” we give to experimental animals.

[updated paragraph] In vivo testing is, in many cases, essential for crafting effective medicines and treatments. Human testing is ethically more problematic (for us) and costly from a legal standpoint. That leaves us with non-human animals.

A good ethical starting point would be the mandating that any animal used in a laboratory experiment be used but once, and that, if it survives (to the extent that it is functional according to its nature), it be “retired” from all future testing. In the event that it is somehow diminished or malformed by said experiment, then the animal should be humanely euthanized following clear and compassionate criteria.

[updated paragraph] This approach will not, I believe, add excessive cost to a given research project, as long as animal models such as mice and rats — which have a prodigious reproduction rate — are used. The use of other, larger mammals for testing grows more costly (a good reason for phasing out or cutting back on their use) and ethically objectionable. But, what is the cost of humane treatment of test animals? Perhaps this cost (of time) should be figured into future research budgets (as mandated by the respective authoritative body. Now that would be a true progression in bio-ethics.

[updated paragraph] Lastly, I will note that this report, apart from the previous mention of transgenic animals (already created routinely), does not address the possibility of non-human animal chimeras that are far more altered-looking than mice with rat genes (there are some phylogenetic limits here, of course); what is the ethical boundary here?

Some source material for this article came from the Nature News article:  Regulations proposed for animal–human chimaeras by Alison Abbott

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