There’s a worldwide organ shortage, and xenotransplantation has long been floated in major medical circles as an alternative solution. For some time, attempts at xenotransplantation meant putting chimpanzee kidneys in humans, which didn’t turn out to be successful in any way. The large problem with transplantation of any kind is that the immune system will most likely reject the donated organ, even if it’s human. So imagine how severe the rejection would be for an animal organ in a human body.
On the other side, animals contain viruses that are harmful to humans, and a number of dangerous diseases such as HIV, SARS, and MERS, have all jumped from animals to humans, causing concern that xenotransplantation “might save one person’s life and cause a plague that can kill 10,000 others coming from the human host. Medical science might eventually be able to get around some of the ethical and legal issues with advances in genome editing. Just a few months ago, scientists revealed the world’s first human and pig chimeras, or pig embryos injected with human stem cells. The pigs weren’t allowed to develop past the fetal stage and so, started to grow organs with human cells in them.
They set the stage for a world where we could grow human organs in other animals. One day, scientists may even be able to use stem cells to grow human organs in other animals. But all of this still comes with ethical and legal questions. Xenotransplantation actually has a long history beginning in the early 20th century. In 2003, a South Korean company called Maria Biotech announced its newest discovery of creating mouse embryos with human cells in them. The concept was that the mice could be born with human cells in all their tissues, and this would make them more accurate animal models for research, and avoiding the ethical issue of using animals for laboratory tests.
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However, a big problem came when a reporter asked whether there would truly be human cells in all the tissues. The answer was yes. Does that include human cells in ovaries and testes? Another yes. So what happens if two of these mice get together, and a human sperm meets a human egg in the Fallopian tube of a mouse? That question literally ended the project. The scenario described by the reporter was almost certainly impossible, but the incident represents some of the ethical questions around transplanting organs between species, or xenotransplantation.
Some medically sound transplants came in the 1960’s, with chimpanzee kidneys transplanted into 13 patients, one of whom lived for almost nine months. The decade also brought an attempt at transplanting a monkey heart, but the patient died immediately. More optimistically, one patient survived for 70 days after he received a baboon liver in 1992. In the 1980s, Danish scientist Steen Willadsen, a pioneer in cloning, combined portions of both sheep and goat embryos to made chimeras that were half sheep and half goat, colloquially called “geeps.”