Oppose NIH funding for human-animal hybrids

August 17, 2016

Submit comments by September 6, 2016 to oppose taxpayer funding for inserting human stem cells into animal embryos.

Instructions to submit comments to NIH:

  • Cut and paste the below text to NIH at http://grants.nih.gov/grants/rfi/rfi.cfm?ID=57.
  • You may enter the comments in either of the two text fields on the form.
  • You may modify your comments in any way, but please keep comments polite and respectful. All comments will be publicly posted by NIH.
  • Fill in your name and other requested fields. 
  • You may use CAARE as an organization if you choose, but no organizational affiliation is necessary.
  • Comment fields are limited to 500 words.

I object to NIH’s decision to proceed with funding for human-animal chimera research. The notion that such research is going to lead to cures and treatments for human disease is totally unfounded on 21st century science. Animals and humans are complex biological systems, having evolved over millions of years to have very specific characteristics. This species disparity has accounted for a very high failure rate of research translation from animals to humans.

Living organisms are adaptive systems, constantly responding to nuances in the environment, and within their own bodies. Once we put human cells or genes into an animal, the biological environment has a profound influence, regardless of the type of cell or biological material inserted.

Moreover, I object to the exclusion of rats and mice from brain modification experiments. This omission is totally unjustified. Regardless of their small size, rats and mice are mammals, demonstrated to have complex intelligence, emotions and perceptions. Their prevalence in research, occupying at least 90% of all current research, indicates that this exemption is one of convenience, and not science, welfare, or ethics.

NIH admits that uncertainty over human-animal hybrids experiments raises ethical and animal welfare concerns. As a taxpayer, I do not agree to have my tax dollars fund this line of research.

 For decades, scientists have been transplanting cells and genes from humans into animals. But now with the explosive growth of stem-cell and gene-editing technologies, they are seizing the opportunity to place a human stem cell into the embryo of an animal and develop it into a human-animal hybrid. These are termed “chimeras,” from the ancient Greek word for a mythical creature made of mixed species.


Human DNA in the brain o f a mouse embryo

Last year, the National Institutes of Health (NIH) imposed a moratorium on funding chimera models due to “ethical and animal welfare concerns arising from the  uncertain effects of growing human stem cells in animals.”

But on August 4, NIH proposed to end this moratorium and allow the controversial practice to receive federal funding.

Submit your comments to NIH to let them know that you oppose taxpayer funding for human-animal hybrids. Comments are being accepted through September 6th.

NIH will establish a committee to provide additional oversight for certain categories of chimera research that includes late-stage primate embryos and experiments that can substantially modify the brains of animals. None of these restrictions will apply to rats and mice.


Some scientists who support using chimera models are pushing the idea that they will contribute to a greater understanding of human disease.

Others are planning to use the technique to see if human organs can be grown in animals for human transplants. This kind of research is already underway with private funding. Scientists at University of California, Davis have put human stem cells into pigs to see if they will grow a human pancreas.

In contrast to tampering with human-animal hybrids, stem cell techniques in human biology offer great potential for medical advances.

The discovery that adult skins cells can be reprogrammed into induced pluripotent stem cells (iPCs) is providing unsurpassed ability to study human disease. Pluripotent cells have the ability to differentiate into any cell type in the body. Sophisticated cell culture models created using cells from patients with diseases such as Parkinson’s, Alzheimer’s – and virtually any disorder – can reveal genetic and molecular pathways with amazing precision.


New opportunities in regenerative medicine are using pluripotent cells and 3D bioprinting to manufacture tissues created from human cells that already can generate viable tissue. Grown from the patient’s own cells, they are superior to those grown in a human-animal hybrid and can minimize problems with tissue rejection. More research in this area promises to yield whole organs for transplant.

Apart from the superiority of human-based stem cell research, valid concerns exist over the cognitive experience of human-animal hybrids. Animals already possess a high level of consciousness that includes complex emotions and profound experiences of pain and pleasure. We have no way to know what effect the combination of human and animal cognition might produce.mouse_pups.jpg

Experimenters at University of Rochester injected the brains of newborn mouse pups with human embryonic glial cells, which provide support for neurons. Many died, but in those that survived, the human glial cells proliferated extensively, “Taking over the mouse brains completely”. Tests showed that the humanized mice performed up to four times better on memory tests.

While we can only speculate what effects these sorts of manipulations have on animals, it is clear that we are moving into areas with potentially frightening consequences.


Anytime we put human cells into an animal hoping to study human biology, it’s a lost opportunity to use the latest technology for human-relevant research that enables us to truly delve into the deep mysteries of human biology – and a foray into new areas of animal suffering.

Citizens for Alternatives to Animal Research (CAARE), is a 501(c)(3) non-profit organization, established to highlight and promote research without animals.

Please donate to support CAARE’s mission to reduce animal suffering by disseminating information about the power and progress of research without animals.