The shortage of human organs available for transplantation in the U.S. and around the world has led scientists to consider how to grow them in animals to be harvested later for transplants.
Advances in stem cell and gene editing technologies are enabling scientists to create human-animal organisms called chimeras. Scientists are now investigating how to modify an animal’s genome to interfere with the development of a particular organ. After that, animal cells and human stem cells would be combined, with the hope that the human cells could help produce the missing animal organ, allowing human organs to be made in animals with a patient’s own cells.
Researchers have already begun growing human pancreas cells in pig fetuses and have created sheep-human hybrid embryos as well. While these animals were not brought to term, the concept of creating human-animal chimeras raises several ethical and scientific issues.
Many are concerned with how human the human-animal hybrids could be. There is the possibility that human cells will be present in organs and tissues that the researchers hadn’t anticipated. If human cells end up in the brain of the chimeric animal, for instance, there is the possibility that the hybrid animal could acquire human mental cognition and consciousness, which raises serious bioethical issues.
Chimera research exploits animals and can potentially cause significant animal suffering. Presumptions and overconfidence by the scientific community about the potential of chimera research should not outweigh the cost and potential for harm.
There is no question that the shortage of human organs available for transplantation is a pressing issue. However, the creation of chimeric animals is not the best answer. A better solution is to modify existing organ donation programs to presume the intent to donate organs with the option to opt out. Not only is this approach more cost-effective, it spares both human and animal suffering.
Source: “Using domestic animals to make human organs,” The Economist, February 22, 2018
Illustration courtesy of Jeannie Phan