Researchers destroyed a human-monkey cell embryo on the 20th day, but reopened the debate about the legal status of what would have grown from such an embryo.
Scientists transplanted human cells into macaque embryos and grew them in the lab for 20 days. According to scientists, this experiment will help solve the problem of a severe shortage of transplantable organs, as well as gain a better understanding of early human development, disease progression, and aging.
The research was led by Professor Juan Carlos Izpisua Belmonte of the Salk Institute in the United States, who helped create the first human-pig hybrid in 2017. During the experiment, they introduced human stem cells, which can develop into any human tissue, into macaque embryos. Previously, similar mixed-species embryos, or chimeras, had been created using sheep and pig embryos.
The research, conducted by an American-Chinese group of scientists, has reignited a debate about the ethics of such experiments. Professor Belmonte, for his part, says that the study, published in the journal Cell, fully complies with existing ethical and legal standards. “The use of chimeras will help us to conduct medical and biological research not only at the earliest stage of life, but also at the latest. Ultimately, we conduct these studies to understand and improve human health,” he said.
But some scientists are concerned about these studies. Dr. Anna Smythor, a professor and researcher in biomedical ethics at Norwich Medical School at the University of East Anglia, points out that although the embryos were destroyed after 20 days in this case, other scientists could continue to grow the chimera and it is unknown what that might lead to. She and other scientists are calling for public discussion of the consequences of creating human-animal chimeras.
We explain quickly, simply, and clearly what happened, why it matters, and what happens next.
Episodes The end of the story: Promotional Podcasts. “The scientists behind this research claim that these chimeric embryos open up new possibilities because we cannot do certain kinds of experiments on humans. But how do we answer the question of whether chimeric embryos are human?” says Anna Smaydor.
Professor Julian Savulescu, director of the Oxford Uehiro Centre for Practical Ethics and co-director of the Oxford Centre for Ethics and Humanities, agrees that the study “opens Pandora’s box for chimeras that are not human”. “This time the embryos were destroyed on the 20th day of development. But growing chimeras as a source of human organs is only a matter of time,” says Professor Julian Savulescu.
Continuing these studies is necessary, but it is crucial to discuss their implications in public and to determine the ethical and legal status of chimeras containing human and animal cells, scientists say.