Nanomedicine: Analyzing Sex

The Challenge

Nanomedicine is a burgeoning branch of medicine that employs nanoscale materials, such as biocompatible nanoparticles and nanorobots, for the prevention and treatment of disease (Hajipour et al., 2021; van der Meel et al., 2019; Lloyd-Parry et al., 2018). The hope is that nanomedicine can deliver more precise and less invasive treatments. Several nanomedicines are already being used to treat sex-specific cancers, such as ovarian and prostate cancer. For female-specific cancers, new research shows that the menstrual cycle can change how nanoparticles are distributed in the body and, thus, the efficacy of some cancer treatments.

Method: Analyzing Sex

It is well-known that sex differences in genetics, epigenetics, hormones, and body size affect how sexed bodies respond to and process drugs of all kinds (Mauvais-Jarvis et al., 2021; see also Case Study: Prescription Drugs). More research is now needed on how best to research this complex of biological factors in nanomedicines.

View General Method

 

Gendered Innovation: Studying How the Menstrual Cycle Changes the Effectiveness of Nanoparticles in Cancer Treatment

Since the 1990s, clinicians and researchers have used nanoparticles as drug delivery systems. Nanoparticles are thought to have several advantages over “free” drug delivery, including, for example, more targeted delivery or controlled release. One common application is cancer treatment, and several nanomedicines are already being used to treat female-specific cancers like ovarian cancer (Anselmo & Mitragotri, 2016, 2019).

In a new study on mice, Poley et al. (2020) have shown that the female estrus cycle (the mouse equivalent of the menstrual cycle) affects how nanoparticles are distributed within the reproductive system. During ovulation, nanoparticles administered intravenously were twice as like to accumulate in the ovaries. This kind of accumulation was more likely for nanoparticles smaller than 100 nanometers (nm).

The changes in nanoparticle bioaccumulations during the estrus cycle can change their efficacy in delivering chemotherapeutic agents for cancer treatment. This can have positive or negative effects. For example, when the researchers administered chemotherapeutic nanomedicines to treat breast cancer during ovulation, the particles accumulated more readily in the reproductive system rather than at the tumor site and, thus, lowed treatment efficacy. By contrast, the treatment of ovarian cancer improved during ovulation, since ovulation enhanced the accumulation of the chemotherapeutic nanoparticles in the ovaries, at the site of the tumor. The accumulation in the ovaries, however, also increased their toxic effects and resulted in decreased fertility in mice.

The research shows that biomedical researchers and clinicians should consider menstrual cycle stage and nanoparticle size to maximize the effectiveness of chemotherapeutic nanoparticles and to minimize their effect on fertility (when relevant). More broadly, this research suggests the importance of sex differences and reproductive cycles to the study of pharmaceuticals more generally, including nanoparticles.

Prostate Cancer

Nanoparticle therapies may also improve treatment of prostate cancer. Zhang et al. (2019) have reviewed the promise and challenges of these therapies.