RPI engineers offer new insight into how tumors grow

Regional News

TROY, N.Y. (NEWS10) — Rensselaer Polytechnic Institute’s mechanical engineers say that as cancer and tumor cells move inside the human body, they communicate and are subject to mechanical forces. In order to understand how these actions affect cancer cell growth, spread, and invasion, a team of engineers at RPI is developing new models that mimic the body, which provide new insight into how and why tumors develop in certain ways.

In research published in Integrative Biology, a team of engineers from Rensselaer developed an in vitro — in the lab — lymphatic vessel model to study the growth of tumor emboli. Tumor emboli are collections of tumor cells within vessels that are frequently associated with increased metastasis and tumor recurrence.

“The growth of tumor emboli is important for the spread and metastasis of certain types of cancers. For example, inflammatory breast cancer has this growth pattern of just massive spread of emboli growing within dermal lymphatic vessels, in the breast, and it’s very aggressive in that way,” said Kristen Mills, an assistant professor of mechanical engineering at Rensselaer, who led this research. “This growth of tumor emboli hasn’t really been studied very much.”

Previous tumor models in the lab have used uncontrolled, three-dimensional cell modeling of tumor cells that don’t allow researchers to study the real interactions that happen. To more accurately mimic what happens in the body, Mills and her team modeled a lymphatic vessel in a lab using cylindrical gel channels. These channels were placed within either stiff or soft bioinert gel. This is so they can mimic the constraints tumor emboli may encounter in stiff, diseased tissue, or soft, healthy tissue.

To incorporate the varying growth behaviors of cells, the team used breast and colon cancer cells to model the emboli.

Researchers found that the model of a stiff tumor environment constrained both types of tumor emboli to the cylindrical channel, causing rapid growth of the emboli along the vessel. But, they found that the growth of the cancer cells was different, based on their type, in the softer matrix model, which mimics healthy colon or breast tissue.

The aggressive cells were not affected by the presence of the open channel and grew as a sphere, while the less aggressive cells first grew along the channel for several days before also forming a sphere. The researchers linked the differences in growth to the force capability of the cancer cells. Independent measurements indicated that the aggressive cancer cells were capable of exerting significantly more force than the less aggressive cells.

Growth along a vessel or channel is problematic, Mills said, because the cells within the tumor have constant access to life-sustaining nutrients through the vessel wall. When the tumor cells grow in a sphere and begin to bulge, she added, the cells in the center of that mass get farther and farther away from nutrients until they are cut off and eventually die. This information could be critical for therapeutic design and prescription.

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