During her PhD, Maj-Britt Buchholz worked on an innovative idea: could breast milk be the key to improve breast cancer research? But her PhD was more than experiments; it was also about navigating the academic world, growing as a person and following her passion. Maj-Britt defended her thesis on March 24, 2025.

To understand how the mammary gland works, researchers need living human cells. The overall aim of my PhD was to make a mammary gland model of healthy cells, she explains. A humanized one because there's quite big differences to animal models. More accurate models like this could help scientists learn how breast cancer develops, test treatments, and even explore future possibilities for tissue regeneration. But obtaining breast tissue from healthy donors is complicated. Maj-Britt found an innovative solution: using breast milk.

Creating a tiny mammary gland
From the cells in breast milk, Maj-Britt was able to grow organoids, tiny clusters of cells that mimic real tissue of the mammary gland. The organoid contained amongst others the two most important types of cells. Basal cells help push the milk out, while luminal secretory cells produce and release the milk when they are squeezed, she explains. Being the first to create an organoid from breast milk, Maj-Britt and her colleagues offer a new way to study mammary gland function without requiring surgery or invasive procedures.

A breast-on-a-chip

Artistic representation: A 3D designed milk bottle containinga bouquet of mammary glands which is composed of imaging data of the breast-on-a-chip model.
After she developed organoids, Maj-Britt experimented with different biofabrication techniques to create a breast-on-a-chip model. This device connects organoids with tiny channels that allow fluids to flow through, simulating milk movement. What was really clear is that the mechanical stimulation from fluid flow affects the organization of epithelial cells, she explains. We found that when cells are exposed to fluid flow, they arrange themselves into an inner layer of luminal cells and an outer layer of basal cells. Without this flow, the cells remain randomly distributed. This finding mirrors what happens during breastfeeding, when the infant’s suckling influences the flow of milk and cellular organization.

Applications in breast cancer research
Maj-Britt’s models are valuable for studying breast cancer. A key goal is to understand how breast cancer develops in a healthy environment and to test new treatments, she says. As part of her research, she tested how different cancer treatments affected both healthy and tumor cells.  We saw that cellular immunotherapies specially targeted the cancer cells while leaving healthy tissue unharmed. And that’s an important confirmation. Testing treatments with organoids and breast-on-a-chip could contribute to more precise, less harmful cancer treatments.

Source : https://www.uu.nl/en/news/using-breast-milk-to-understand-the-mammary-gland