A Microfluidic Chip Lets Scientists Observe Immune Cells Attack Cancer Cells One at a Time

Standard laboratory tests measure what happens to cancer cells on average—how many survive after exposure to immune cells, for example—but they obscure the details of individual interactions. A new microfluidic platform called CellTrap, developed at the Technical University of Munich (TUM), addresses that gap by isolating and observing single immune cell-cancer cell encounters in real time.

CellTrap consists of a microfluidic chip with a main channel that branches continuously into 1,024 small trapping chambers. Individual immune cells and cancer cells are drawn into these chambers, spatially fixed, and observed for up to 14 hours using time-lapse microscopy. The setup produces a range of conditions—cancer cells alone, immune cells alone, or varying ratios of immune to cancer cells—allowing researchers to capture the full diversity of cellular responses rather than an averaged result.

"With CellTrap, we can not only measure whether immune cells kill cancer cells, but also track when and under what conditions this occurs. This matters, because immune responses can vary so much from one cell to the next," said Ghulam Destgeer, senior author of the study published in RSC Advances. "And we deliberately kept the platform simple and affordable: it runs on a standard fluorescence microscope of the kind most labs already have, with no specialized equipment."

Initial experiments using a glioblastoma cell line showed that when multiple immune cells encounter a single cancer cell, the cancer cell is attacked more frequently and more intensely. The experiments also revealed that early activation signals in immune cells often predict whether a cell-damaging effect will occur later, making it possible to observe how early reactions within a single interaction relate to its eventual outcome. The team also tested CellTrap with two additional cancer cell lines: a chronic myeloid leukemia and an adenocarcinoma.

Understanding the precise timing of contact, activation, and cancer cell killing is considered critical for evaluating the effectiveness of immunotherapies—information that bulk assays cannot provide.

"The more we learn about what actually happens between individual cells, the better we can compare treatment strategies and develop new ones," Destgeer added. "And although we focused on immune and cancer cells, the platform isn't limited to them—almost any combination of cells can be loaded and observed in the chip."