In a controversial move, scientists have created embryos that are partially human and partially monkey. According to Spanish daily El País, Juan Carlos Izpisúa Belmonte, a Spanish biologist operates a lab at Salk Institute, California, has been collaborating with researchers in China to conduct this controversial research. Their main goal is to produce “human-animal chimeras”, where human cells are added to the monkey embryos. Just a few days back, the Japanese government also approved experiments to be conducted on human-animal embryos.
The main motive behind this research is to create animals which possess organs such as liver or kidney that are composed of human cells. As a result, these animals could be used for sources for organ transplantation. The technique for creating chimeras is that human embryonic stem cells are injected into the embryos of another species which are a day-old. Researchers hope that with this addition the growth of human cells would take place with the embryo.
Previously, Izpisúa Belmonte tried to create human-animal chimeras with the addition of human cells to the pig embryos however, in that case, human cells did not take an effective hold. However as monkeys are closer to humans genetically, chances are more for the experiment to succeed. Researchers are using gene-editing technology so that the formation of certain kinds of cells can be disabled in the animal embryos and as a result, the human cells have a better chance of taking hold.
However, this is highly controversial in the United States. According to the National Institutes of Health, federal funds can never be used for the creation of mixed monkey-human embryos. Although China does not have such a rule which facilitates the research in that country.
Till now, a part-human and part-monkey has not taken birth. Estrella Núñez, an administrator and biologist at the Catholic University of Murcia, Spain told that the mixed embryos are only allowed to develop for a week or two in the laboratory, where they can be studied. Catholic University of Murcia is helping to fund this research. There have been no comments from the Salk Institute about this and Núñez has refused to comment till the final results are published.
Pablo Ross, a veterinary researcher at University of California, Davis, worked previously with Salk on pig-human chimeras. He said that it does not make any sense to try to grow human organs in the monkeys. As they are quite small, it takes a long time for their development. He thinks that the injection of human cells into the monkey embryos could resolve questions of evolutionary distance and interspecies barriers.