In 2007, Françoise Baylis and Jason Scott Robert published “Part-Human Chimeras: Worrying the Facts, Probing the Ethics” in The American Journal of Bioethics. Within their article, hereafter “Part-Human Chimeras,” the authors offer corrections on “Thinking About the Human Neuron Mouse,” a report published in The American Journal of Bioethics in 2007 by Henry Greely, Mildred K. Cho, Linda F. Hogle, and Debra M. Satz, which discussed the debate on the ethics of creating part-human chimeras. Chimeras are organisms that contain two or more genetically distinct cell lines. Both publications discuss chimeras with DNA from different species, specifically in response to studies in which scientists injected human brain cells into mice. “Part-Human Chimeras,” contributes to a chain of ethical and scientific discussion that occurred in the mid-2000s on whether people should be able to conduct research on chimeras, especially in embryos.

The basic goal of preclinical animal research is to improve understanding of human disease and treatment. Mandates for sex-inclusive research – both in preclinical animal work and in human clinical trials – have prompted discussions about the ethics and functionality of sex-inclusive research. Authors of peer review research articles and opinion pieces have varying opinions regarding sex-inclusive preclinical animals research. The arguments that support sex inclusion in animal research include: a) sex inclusive research in the preclinical animal model stage saves money further down the road in research, b) new understanding in hormonal variation in both male and female mice undercuts a notion that male mice are simpler research subjects, and c) sex-inclusive research is needed for improved treatment and diagnosis for male and female humans down the road. Arguments against inclusive research include: a) increased research cost and time, and b) sex-inclusive preclinical animal research is not useful, and may be harmful, to the development of personalized medicine. Weighing the different arguments present in the conversation regarding sex inclusive research, sex inclusive research is clearly important and necessary moving forward for cost efficiency, scientific discovery, and movement towards precision medicine.