Current approaches to breast cancer research have their limitations when it comes to observing its behavior in live human tissue. There is something to be gained by studying cells in mice and the lab, but these methods still don't paint a complete picture. Researchers have now built a hydrogel scaffold that mimics the environment found within the human breast, allowing them to grow real mammary tissue and gain new insights into how tumors spread through this part of the body.

Generally speaking, researchers have had to rely on either transformed cell lines in a dish or human tumor cells planted into mice to further our understanding of breast cancer. But because actual tumor cells recruit their surrounding cells for progression, and mouse breast tissue has a different structure to that of human breast tissue, there is only so much these methods can tell us about how they behave in humans.

To get something closer to the real deal, scientists at the Whitehead Institute set out to grow human mammary glands in a dish, something that has been difficult to achieve so far. When the team had tried this previously, the common view was that mammary cells require other cells to support them, thus the difficulty in getting them to stay alive in the lab. But researchers Ethan Sokol and Daniel Miller suspected that the molecules secreted by those support cells might actually be the key driver of mammary cell growth, rather than the support cells themselves.

So they fashioned a scaffold out of hydrogel that closely replicates the extracellular matrix, or network of support molecules, found in the breast. Planting patient-derived primary human mammary cells into the scaffold saw the cells organize, grow and then finally differentiate into ducts and lobes found in breast tissue.

"I wouldn't have thought it possible that these tissues could grow with such complexity and to such a size," says Whitehead Member Piyush Gupta. "It's really quite remarkable."

The team has since put its scaffold to work and is already making discoveries about the development of mammary glands, one of which includes how human breast tissue grows differently to that of a mouse.

"Ours is a beautiful system, and it's a very good tool for someone who has questions about normal breast development or breast cancer, to see what happens when a gene is perturbed," says Sokol. "It's so amazing to watch the tissues grow."

The research was published in the journal Breast Cancer Research.