Chimeras: The Next Moral Battle You’ve Never Heard About

human_embryonic_stem_cells_only_aIn Greek mythology, a chimera was an animal to be feared. Homer and Hesiod described chimeras as fire-breathing hybrid creatures composed of a mixture of animal parts – part lion, part goat, part dragon.

The federal government is now considering whether it will fund medical research that would create part-human, part-animal chimeras – research that the United States Conference of Catholic Bishops calls “grossly unethical.”

The National Institutes of Health (NIH), the federal agency charged with funding and promoting biomedical research, issued a temporary moratorium on funding human-animal chimera experiments last September until it could consider the potential ethical ramifications of such research. Although NIH had not funded human-animal chimera research before issuing the moratorium, other agencies have funded similar research, including the California Institute for Regenerative Medicine, California’s state stem cell agency.

NIH recently proposed lifting parts of its moratorium, and it expects to decide before January whether it will begin funding human-animal chimera research. Among the proposed changes include limitations on the types of chimera research it will fund, as well as establishing a steering committee dedicated to providing input on research proposals and monitoring experimental designs.

The proposed changes suggest NIH is creating “a much more permissive environment” when it comes to researching human-animal hybrids, according to one neuroscientist quoted in Science.

But many scientists and ethicists are concerned about the ethical ramifications of creating human-animal hybrids.

“The effort to incubate organs in farm animals is ethically charged because it involves adding human cells to animal embryos in ways that could blur the line between species,” said Antonio Regalado, senior editor for biomedicine for MIT Technology Review.

According to Regalado, chimera research utilizes “advancements in stem-cell biology and gene-editing techniques”:

“By modifying genes, scientists can now easily change the DNA in pig or sheep embryos so that they are genetically incapable of forming a specific tissue. Then, by adding stem cells from a person, they hope the human cells will take over the job of forming the missing organ, which could then be harvested from the animal for use in a transplant operation.”

Some scientists believe that the research might also lead to breakthroughs in Alzheimer’s or cancer treatments.

There exists the possibility, however, that once human stem cells are added to animal embryos, the human stem cells may affect the hybrid animal’s development – possibly even giving hybrid animals some degree of human consciousness or cognitive abilities.

Researchers cannot guarantee that human stem cells intended to create a human pancreas in a pig, for example, will not end up in the chimera’s brain or endow it with human eggs and sperm, enabling it to reproduce part-human offspring.

In its proposal, NIH concedes that “there could be either a substantial contribution or a substantial functional modification to the animal brain by the human cells.”

One year after NIH issued its funding moratorium, ethicists are still wrestling with moral dilemmas like whether these cross-species chimeras should be given legal rights if they develop some form of human cognitive abilities.

“You’re getting into unsettling ground that I think is damaging to our sense of humanity,” said Stuart Newman, professor at New York Medical College.

Some of the human tissue and stem cells used in creating human-animal chimeras are harvested from aborted fetal tissue and human embryos, raising other moral questions.

The United States Conference of Catholic Bishops (USCCB) says that chimera research results in the “creation and manipulation of new beings,” neither fully human nor animal, “whose very existence blurs the line between humanity and animals”:

“For if one cannot tell to what extent, if any, the resulting organism may have human status or characteristics, it will be impossible to determine what one’s moral obligations may be regarding that organism.”

Human-animal chimera research is currently being performed in labs that receive funding from sources other than the federal government.

Editors for MIT Technology Review estimate that “about 20 pregnancies of pig-human or sheep-human chimeras have been established during the last 12 months in the U.S.” One lab profiled by MIT Technology Review allows its chimeras to grow only to 28 days of gestation because researchers do not yet know how the human cells would contribute to the animal’s development.

Human life deserves to be protected in all stages of life, but human-animal chimera research creates animals that are partially human to be experimented upon or harvested for organs. NIH should realize the enormous risks to human dignity associated with this type of research and rescind its proposal to lift its moratorium.


This post was originally published by the Family Policy Institute of Washington.