Scientists recently reported a major milestone in the creation of human-animal hybrids. Researchers from the Salk Institute for Biological Studies and colleagues, seen above, injected human stem cells into monkey embryos in vitro. Several of the chimera embryos survived for 19 days. Eventually, these hybrid animals could be used for testing new drugs or to grow organs for transplant into humans without the high risk of rejection. Unsurprisingly, the research has sparked some debate among scientists. Meanwhile, my sensationalistic use of the image above does nothing to help calm public concern about the matter but, well, how could I not. From Nature:
Some question the need for such experiments using closely related primates — these animals are not likely to be used as model animals in the way that mice and rodents are. Non-human primates are protected by stricter research ethics rules than are rodents, and they worry such work is likely to stoke public opposition.
"There are much more sensible experiments in this area of chimaeras as a source of organs and tissues," says Alfonso Martinez Arias, a developmental biologist at Pompeu Fabra University in Barcelona, Spain. Experiments with livestock animals, such as pigs and cows, are "more promising and do not risk challenging ethical boundaries", he says. "There is a whole field of organoids, which can hopefully do away with animal research."
Izpisua Belmonte says that the team does not intend to implant any hybrid embryos into monkeys. Rather, the goal is to better understand how cells of different species communicate with each other in the embryo during its early growth phase[…]
Meanwhile, international guidelines are catching up to the field's advances — next month, the International Society for Stem Cell Research (ISSCR) is expected to publish revised guidelines for stem-cell research. These will address non-human-primate and human chimaeras, says [Case Western Reserve University bioethicist Insoo] Hyun, who is leading an ISSCR committee discussing chimaeras. That group's guidelines currently prohibit researchers from letting human–animal chimaeras mate.
image: Wikipedia (public domain)