Chimeric Models Facilitate Advances In Drug and Immune System Research
Researchers at the Salk Institute for Biological Studies recently created a chimeric mouse model for human liver disease to study drug efficacy. In this experiment, researchers developed a simple system that allows them to transplant human hepatocyte cells into immunodeficient mice, which could then be used to test how drugs affect the liver. Despite President Bush’s call for a ban on this type research in his 2006 State of the Union Address, federal funding from the National Institutes of Health supported this development. But research on chimeric models is drawing criticism from those who oppose the research on ethical grounds (subscription).
Although without using a chimeric model, researchers at Stanford University Medical School regenerated a mouse immune system by transplanting mouse blood-forming stem cells into mouse bone marrow. This research pioneered the use of toxins to remove the mouse immune system, where previously scientists had used high-risk chemotherapy or radiation. Although cause for celebration, principal investigator Irving Weissman explained that the downside is that the mouse is a poor mimic of the human immune system. A chimeric mouse model with an entirely human immune system would offer a solution. The potential of such a model was high enough to warrant a $17 million grant from the Gates foundation for research at Yale University and the Howard Hughes Medical Institute and a $1.9 million grant for research at Peking University in China.
Some policymakers are alarmed by a lack of national oversight of chimeric research. A recent Science Progress article pointed out that Senator Sam Brownback (R-KS) proposed a ban (S.1373) on the creation of human-nonhuman chimeras in 2005. This November, he and Senator Mary Landrieu (D-LA) introduced the Human-Animal Hybrid Prohibition Act 2007 (S-2358), which criminalizes the use of some chimeric organisms. Policymakers recognizing the important role chimeric models can play in laboratory research should work to ensure that properly regulated use of these important models can continue.
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