Sex Cells! Addressing Sex Differences in Pre-Clinical Research

By Ann Bonham, PhD

Janine Clayton and Francis Collins published an important commentary in Nature yesterday on the need to address sex differences in preclinical research that relies on cell and animal models. They outline some of the steps the National Institutes of Health (NIH) will take to address this issue and are clearly counting on the community to join in developing these reforms.

“The NIH plans to address the issue of sex and gender inclusion across biomedical research multi-dimensionally — through programme oversight, review and policy, as well as through collaboration with stakeholders including publishers. This move is essential, potentially very powerful and need not be difficult or costly,” they write.

I especially like their comments for several reasons: First, they see the issue through their lenses as scientists and science leaders and directed their comments to practicing scientists. Although detractors might claim “the science just isn’t there,” Clayton and Collins surveyed the evidence and persuasively laid out the case that “the science is there.” Further, they make a compelling case to change longstanding research practices, incorporating what too often is a critically missing variable: the role of sex variation from cells or animals in influencing results. The commentary demonstrates that the NIH and the medical research community can adapt to advance the very best science quickly and thoughtfully, underscoring the fact that scientists and the science community are best suited to set the nation’s research priorities and policies.

The Clayton–Collins commentary brings to mind the recent report, “Sex-Specific Medical Research: Why Women’s Health Can’t Wait,” from the Mary Horrigan Connors Center for Women’s Health & Gender Biology at Brigham and Women’s Hospital. That report examines clinical studies and calls for a more expansive conception of the types of research that pertain to women’s health. The authors discuss the evidence that compelled reform of FDA’s regulatory approval processes to better reflect the influence of sex differences on proposed medications in clinical trials. The NIH has long incorporated important requirements that encourage more consideration of sex and gender differences in clinical research, partly as a result of legislation but also of community action. That clinical research in turn has provided some of the evidence cited by Clayton and Collins on why scientists need to consider more closely the effects of sex differences in cellular and animal research.

Both the Clayton and Collins commentary and the Brigham and Women’s Connors Center report underscore how deeply the nation depends upon and trusts the medical and scientific establishment to think critically about its own research, its standards and processes, and the effectiveness with which it serves patients and the nation.

As a scientist, I understand very well that implementing these changes require time and money and that all resources are under stress. But scientists are committed to the very best science, and the discoveries that will undoubtedly be made about critical sex-dependent differences will advance the health of women and men dramatically.

If we act quickly to change research practices to include sex differences where relevant, support the reforms set forth by the NIH, and join Clayton and Collins in developing ways to address these concerns, we demonstrate yet again that the medical research community is not only worth the investment, but worthy of it.

Bonham AnnAnn Bonham, PhD, is chief scientific officer at the Association of American Medical Colleges. She can be reached at

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