First-Ever Human-Monkey Chimera Embryos Created

The “What could possibly go wrong” file is so full, it may be time to give China its own manila folder for its experiments with human-animal chimeras that not only cross the ethical line – they wipe it out completely with genetically-altered erasers. The latest entry in the file is an experiment that attempts to reach the unholy grail of hybrids – human-monkey chimeras, created under the ‘good intentions’ guise of developing ways to address the severe shortage of human organs for transplants. Before you start pointing fingers at China’s Kunming University of Science and Technology, the leader of this experiment was an American from the Salk Institute in California who has also been involved in creating human-pig chimeras. Do we need to start TWO files?

“We studied the chimeric competency of human extended pluripotent stem cells (hEPSCs) in cynomolgus monkey (Macaca fascicularis) embryos cultured ex vivo. We demonstrate that hEPSCs survived, proliferated, and generated several peri- and early post-implantation cell lineages inside monkey embryos.”

Whoa!

In their new paper published in the journal Cell, American geneticist Juan Carlos Izpisua Belmonte and a team of researchers in China led by primate reproduction biologist Weizhi Ji announced they have successfully injected 25 human stem cells into developing five-day-old macaque monkey embryos, and of the 132 human-monkey chimera embryos created, 103 were still alive after 10 days and 3 survived for 20 days in lab dishes. That’s an impressive success rate when compared to Izpisúa Belmonte’s experiments with human-pig and other chimeras, and he tells Live Science it’s because “the evolutionary distance is smaller” between humans and monkeys.

“Generation of a chimera between human and non-human primate, a species more closely related to humans along the evolutionary timeline than all previously used species, will allow us to gain better insight into whether there are evolutionarily imposed barriers to chimera generation and if there are any means by which we can overcome them.”

In the press release, Izpisúa Belmonte even destroys the chalk used to draw the ethical line by revealing his experiments seek to hurdle the barriers to chimera generation. Right now, by doing the experiments in China, the only barriers he hasn’t hurdled are regulations in other countries. Alejandro De Los Angeles, a stem cell biologist at the Yale University School of Medicine who was not involved in the study, told Live Science:

“The embryos here were not transferred into a uterus, and thus could not lead to living chimeric animals or even fetuses. Implantation of human-monkey embryos would be ethically contentious and will need to be discussed by scientists, ethicists and the public before moving forward with such experiments.”

Right — just like the creation of these human-monkey embryos was … not. In fact, one of the big concerns about allowing human-monkey chimeras to live longer is that the human cells would migrate to the monkey brains and grow there, transferring humanness to them. Unfortunately, it appears some communications already occurred in the 20-day-old chimera embryos, according Izpisua Belmonte in the press release.

“From these analyses, several communication pathways that were either novel or strengthened in the chimeric cells were identified. Understanding which pathways are involved in chimeric cell communication will allow us to possibly enhance this communication and increase the efficiency of chimerism in a host species that’s more evolutionarily distant to humans.”

This is too much!

Even if we eliminate the more cinematic, sci-fi and dystopian scenarios from the “what could possibly go wrong” discussions, there are still plenty of other outcomes worth worrying about and preventing. As always, the reality is that these experiments are being conducted in China and those scenarios may have already played out, even though Izpisua Belmonte assures us that “it is our responsibility as scientists to conduct our research thoughtfully, following all the ethical, legal, and social guidelines in place.”

Sorry, Izpisua Belmonte. What if you’re in a place where there are no such guidelines? Isn’t that why you went to China?

How many more “What could possibly go wrong” files do we need? Is it time for a cabinet? A warehouse?

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