Scientists from the Salk Institute engineered a human-pig hybrid in the lab, apparently the first successful human-animal crossbreed. Injecting human stem cells into animal embryos, they created what is called a chimera, or a creature that consists of cells from two individuals from the same or distinct species. Through their research, scientists are hoping to develop lab-grown organs that will help save lives. The experiment demonstrates that human cells can survive and even grow in a non-human organism (at least in pigs). One of the stated motivations for the research is the statistics that each day 22 people who have been waiting for organ transplants die without a necessary organ. Scientists are hoping to grow custom organs inside animals to help address this issue.

The scientists created this human-animal chimera using induced pluripotent stem cells (“IPS”). The IPS technology consists of artificially created stem cells. The cells come from mature somatic cells and are reintegrated back into pluripotent stem cells. Somatic cells are those that make up the body of an organism. Pluripotent stem cells are characterized by their ability to differentiate amongst three germ layers, giving them the capacity to assist with replacing cells from damaged or sick tissues. In other words, pluripotent stems cells can transform into every form of human tissue.

There are a number of ethical concerns related to human-animal chimera research. One important ethical consideration is whether it is prima facie ethically unacceptable to do this type of research. In our society, humans and animals are treated differently. For example, humans are legal entities with legal status whereas animals are not legal entities. There are already regulations designed to minimize suffering of animals subject to experiments, and it is unclear what further regulations will govern human-animal chimera research.

Different countries have different legal standards when it comes to human-animal chimera research. For instance, one researcher named Nakauchi moved his research from Kyoto, Japan to Stanford, U.S.A. since there was Japanese opposition to the research. However, he found it difficult to gain federal funding from the U.S. Under French law, manufacturing a chimeric human embryo is illegal. German law prohibits mixing a human embryo with animal cells, but does not prohibit introducing human cells into an animal embryo. In the U.S., federal laws do not govern this issue. However, in 2005, the U.S. National Research Council and the Institute of Medicine recommended that human-animal chimera research should be limited and that human-animal chimeras should not be permitted to breed.

Other legal issues abound as well. Since human-animal chimeras consist of some human characteristics, it is unclear how human dignity and/or human rights laws will be handled with respect to chimeras. Additionally, there are legal implications regarding the funding for the human-animal chimera research. NIH announced that it was going to lift its moratorium on human-animal chimera research, which implies that more research will be done in this area.

Overall, the trend of doing human-animal chimera research poses important ethical, scientific, and legal implications.

Dora Duru

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