Spanish researcher Juan Carlos Izpisua’s team, comprised of researchers from The Salk Institute in California, and Murcia Catholic University (UCAM), have created world’s first monkey-human chimeras. The study was largely funded by UCAM and carried out in China, as this type of research is illegal in Spain. Izpisua says that the hybrids could eventually be used to create human organs for transplant.
The scientists genetically modified monkey embryos to deactivate genes necessary for forming organs. They then injected human stem cells into the growing embryo. Those human cells are capable of generating any type of tissue. The experiment was stopped well before the chimera was ready to be born, as the scientists interrupted the pregnancies. Izpisua said the hybrid embryos will be destroyed after 14 days in accordance with international law.
International law has established a 14-day ‘red line’ for these types of experiments to prevent the embryos from developing human central nervous systems, which takes more than two weeks. Genome-editing is currently illegal in many countries because it is considered unethical and potentially harmful for both the individuals affected and future generations descended from the original experiments. The National Institutes of Health of the United States does not support the research of human-animal chimeras, but the Department of Defense and the Institute of Regenerative Medicine from California do.
Izpisua said in his announcement of the experiments, “We are now trying not only to move forward and continue experimenting with human cells and rodent and pig cells, but also with non-human primates.” This is not the first time he has made headlines with his experiments. In 2017, he and his team created the first human-pig hybrid.
Izpisua has also managed to successfully create chimeras of mice and rats. He and his team were able to use the CRISPR genetic editing technique to remove the genes necessary for the development of the heart, eyes, and pancreas in mouse embryos and inserted rat stem cells instead.