In a move that is undoubtedly going to raise all sorts of ethical and scientific questions, scientists have now successfully grown human-monkey chimeric embryos for up to 20 days. The international team of scientists was led by gene expression expert Juan Carlos Izpisua Belmonte from the Salk Institute in California, according to RT.
Along with his team, he "implanted human stem cells into primate embryos which then grew for up to up to 20 days."
While the experiment toes many ethical lines, the potential benefits of helping humans understand evolution and biology seem to have outweighed the negatives - for the time being, at least.
Belmonte said: “As we are unable to conduct certain types of experiments in humans, it is essential that we have better models to more accurately study and understand human biology and disease. An important goal of experimental biology is the development of model systems that allow for the study of human diseases under in vivo conditions.”
The monkey embryos were injected with human stem cells 6 days after they were created, which can "yield multiple different types of tissue, both embryonic and non- or extra-embryonic tissues," the report notes.
The human cells were still found in 132 chimera embryos 24 hours after implantation. 109 embryos continued to develop after 9 days. After day 19, only 3 embryos remained. After 20 days, all of the embryos had been destroyed.
Researchers were able to examine the resultant embryos to determine "which communication pathways between the monkey and human cells were viable in the generation of future chimeras and which were not."
The team said it gave the “utmost attention to ethical considerations… by coordinating closely with regulatory agencies” during their research.
Technology developed by Weizhi Ji and his team at Kunming University of Science and Technology in Yunnan, China has made the attempts at chimeras - which have been ongoing since the 1970's - possible.