Thinking About the Human Neuron Mouse

bioethics.net :: Thinking About the Human Neuron Mouse: "Thinking About the Human Neuron Mouse
by Henry T. Greely, Mildred K. Cho, Linda F. Hogle, Debra M. Satz
2007. The American Journal of Bioethics 7(5):27

Dr. Irving Weissman, a professor in the departments of pathology and development biology at Stanford, approached one of us in February 2000 with ethical questions about interesting experiments he was considering. The most interesting experiment would begin with an inbred strain of mouse that attempted to form brains during very early fetal development, but, several days before birth, died as a result of the death of most or all of the developing neurons in their brains (the glial cells that make up about 90 percent of the brain are unharmed). Weissman proposed to transplant human brain stem cells into the fetal mice, just before their own neurons died. His hope was to produce a living mouse with a functioning brain made up of mouse glial cells and human-derived neurons. This mouse could then be used to study human neurons in vivo in a laboratory animal, similar to the way the SCID-hu mouse, which he had helped developed in the late 1980s, allowed the study of the human immune system inside laboratory mice. ...

This article is a revised version of our report, updated to reflect nearly five years of debate about the ethical issues surrounding the creation and use of human/non-human chimeras. That debate has taken place in scholarly journals, important policy reports, and the halls of Congress. We believe our analysis has interest as one of the earliest efforts to come to grips with the implications of this scientific research and as an example of a "benchside consult," an effort to provide ethics-based advice on research in progress. More importantly, we also believe that it remains, with slight modifications, a useful approach to such experiments. Our report focuses on transplanting human neural progenitor cells into non-human brains and so falls well within whatever boundaries define "neuroethics," but it also has broader implications for the creation of other kinds of human/non-human chimeras, including some with non-biological components.

This article begins by describing the debate over human/non-human chimeras. It then focuses on our case study, Weissman's proposed experiments aimed at creating what we have called the "human neuron mouse." It provides some background on the experiments and discusses their potential benefits and their risks and costs before providing our recommendations to Dr. Weissman (and, now, others contemplating similar experiments). The article ends with some broader conclusions about the ethics of research with human/non-human chimeras. ...