NIH places moratorium on human-animal chimera development

From our student Amanda Hazy – a blog post for the class.

In late September, NIH declared a funding moratorium on research working toward creation of human-animal chimeras. Recent research in this field has attempted to use animals to generate human organs for transplantation by injecting early animal embryos with human stem cells to direct organ development. However, many question whether it is ethical to create “human-animals” and use them in research, while others are concerned about the potential for human cells to reach the animal’s brain and impart some level of human consciousness. NIH has halted funding until the ethical and moral aspects of the debate can be fully assessed. What are your thoughts on the risks and/or the potential of human-animalchimeras?

1) Can scientists perform research with human-animal chimeras and still maintain the principles of human dignity and animal welfare? And do animals receiving human stem cells truly have the potential to become “half-human” vs. simply serving as “incubators” for organ development?

2) Do the potential for organ development and the need for transplantable organs outweigh the ethical questions surrounding this research? Or is this type of work truly necessary considering advances in other sources of organs such as pigs, etc.?


  1. It is at this point that I am great full that the people on the board will not be fans of cartoons. In cartoons, chimeras are portrayed as sadists, cannibals, and masochist beasts. But in actuality, each chimera project will have their own meanings. One may want to increase the lifetime of their pets or their healthiness, others may finally wish to evolve chimps into the speaking era, and others will jump off the deep end and plan to give gills to bears.
    It is not possible to ban the entire research of chimeras, but steps must be taken to only give approval to the research that may benefit the animals.

  2. To me, restraint in this area seems quite prudent. We are not yet quite skilled enough to know all of the downstream consequences of gene editing. The body is such a complex and emergent organism that any edits to the blastocyst of a pig (for example) to put in human heart DNA (as was posited in class) for organ transplantation would very likely cause some other unintended consequence, either for the pig, or for the human who received the altered heart. The ease of the CRISPR-Cas technique far outstrips our knowledge of the consequences of that technique. The almost-daily news that some section of what was considered “junk” DNA was not quite so junky after all, and the rise of epigenetics show that we as a society and as scientists still have a lot to learn about the genome, the role of environment, and the role of symbiotic relationships to the health and construction of the human body.

    I think the possible deleterious unknown effects of gene editing in such a way to both the host animal and any human into which those organs might be implanted is both the more worrying and more likely problematic event than accidentally creating a pig with human or human-like intelligence. Many animals already approach human intelligence — Great Apes, Elephants, Dolphins — and yet we still treat them as significantly beneath us in moral consideration. The US only just ended its experimentation on chimpanzees, our nearest relative in the animal kingdom. Also, if improving the brain power of a pig is a moral problem… why?

    1. I agree–I think the greatest risk of human-animal chimera research is not really the risk of creating a cartoon-like animal-person or even an animal with human intelligence or consciousness. The danger is in the long-term effects this process could have on both the animals and the human organs in them. As you pointed out and as we discussed in class, there are many more layers to the genome and genetic regulation than we currently understand. We still haven’t identified every individual gene that is mapped/related to development of specific organs, much less their epigenetic markers and other forms of regulation. With that said, I don’t see our limited knowledge as a reason to halt this research, I see it as a reason to proceed carefully. The centerpoint of all research is the existence of unanswered questions. Research using human-animal chimeras could provide a source of human organs for transplant in the future, but even if it doesn’t, the information it would give about the processes and effects of gene editing and organ development will be beneficial to other areas of research. I think the research should move forward, but with careful guidance and oversight by researchers, veterinarians, and others who can ensure the welfare of the animals and people concerned.

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