Why You Should Consider Sex as a Biological Variable in Preclinical Research

Today, we attended a fascinating webinar hosted by Charles River Ireland on the topic “Why You Should Consider Sex as a Biological Variable in Preclinical Research.”

For our audience of in-vivo researchers, this is a familiar issue, but it's worth revisiting, especially given the low percentage of papers reporting results by sex.

Currently, more often than not, basic and preclinical biomedical research still predominantly focuses on male animals and cells. This over-reliance on male subjects can obscure our understanding of how sex influences health processes and outcomes.

Learning Goals of the Webinar:

• Understand the importance of using both male and female mice in research.
• Recognize the role of sex as a biological variable.
• Identify biases across various biological disciplines.

Ignoring sex in animal study designs and analyses leads to an incomplete understanding of biological functions, diseases, and treatments. Male and female mice exhibit different phenotypes and respond differently to therapies, and these differences are relevant to human clinical outcomes.

Substantial evidence from scientific literature supports the need to factor sex into research design and to report it when analyzing experimental results.

However, this consideration brings a challenge...

Testing both sexes requires more subjects, potentially conflicting with the 3Rs principle, which advocates for the reduction of animal use in research. Yet, ignoring sex as a variable can undermine the robustness and reproducibility of results.

How Can We Address This?

Careful planning and validation of experimental design are crucial. Researchers should incorporate both sexes in their studies or provide strong justification for single-sex studies. This approach ensures robust, reproducible results that account for biological variations.

Institutions also provide support.

Here are some helpful resources:

• NIH: https://orwh.od.nih.gov/sex-gender/orwh-mission-area-sex-gender-in-research/nih-policy-on-sex-as-biological-variable
• European Commission: https://research-and-innovation.ec.europa.eu/news/all-research-and-innovation-news/accounting-sex-and-gender-makes-better-science-european-commission-set-insist-steps-will-make-2020-12-11_en
• Canadian Institutes of Health Research: https://cihr-irsc.gc.ca/e/49346.html

Just to mention a few.

Incorporating sex as a biological variable is essential for advancing our understanding of health and disease.

By embracing this complexity, we can enhance the quality and applicability of our research, ultimately leading to better science and better health outcomes.

What is your view? Have you implemented both sexes in your research? We’d love to hear your opinion!

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