Scientists cross ethical boundaries—again
Researchers create monkey-human chimera embryos
Is it monkey? Is it man? Something else entirely? In what’s believed to be a first, an international team of scientists this week announced they’ve grown embryonic cells containing both human and monkey DNA. The research could put scientists one step closer to growing replacement human organs inside other animals, according to the study’s authors. While the experiment never reached beyond the embryonic stage, secular and religious critics alike warn of the dangers of creating hybrid creatures with mixed DNA.
The experiments took place in a Chinese laboratory where ethical standards are looser. The scientists call the embryos chimeras—creatures that contains cells from multiple species. The team injected 25 human stem cells each into 132 fertilized macaque monkey embryos. The chimeric lifeforms developed outside a womb in a lab. After 20 days, all of the chimeric embryos had died.
Developmental biologist and study co-author Juan Carlos Izpisua Belmonte told Nature that the goal of the research was to study how cells of different species might communicate and work together during early phases of growth. Izpisua Belmonte, who works for the Salk Institute for Biological Studies in California, previously participated in experiments with human-pig and human-cow chimeras. He said the researchers hope to develop a replacement for laboratory testing on animals or even methods of growing transplant-ready human organs.
But chimeric research faces fierce opposition from scientists and ethicists who say this type of genetic experimentation ought to be slowed or banned. David Prentice, vice president and research director of the pro-life Charlotte Lozier Institute, said scientists are on firm ethical ground when they experiment with injecting adult human stem cells into adult or even newly-born animals. “Not all mixing of human and animal cells is unethical. … The key is timing,” he said, but in this case, “The short answer is that what the researchers did is not ethical.”
He and Charlotte Lozier President Chuck Donovan have explained in the past that when the human cells are added so early in development, like in this case, they “could end up, well, anywhere in the developing animal. In the worst case, the human cells could end up in gonadal tissue and form human gametes (eggs or sperm) within the animal’s body.”
Prentice and other ethicists, such as Stanford’s Hank Greely, draw a distinction at a creature’s appearance, brain, and reproductive ability. Making a living and breathing chimera with blended features, the ability to pass along its genetics sexually, or develop a brain—and perhaps consciousness with it—crosses significant ethical boundaries.
The scientists that created the monkey-human chimeras say they have no intention to push that experimentation beyond the embryonic stage. But chimera experimentation is growing more common.
“Unfortunately, many scientists consider humans as just another experimental animal, especially unborn humans,” Prentice said. “Their ethical compass points to science and scientific knowledge as ultimate truth, and thus to them, anything that advances science is ethical.”