Lab-on-a-chip platform shows how immune cells attack cancer cells

Established laboratory tests mainly capture average values across many cells and show, for example, how many cancer cells survive after contact with immune cells. What happens in detail—how each cell reacts and interacts with others—remains hidden. However, to better understand the effectiveness of immunotherapies, the precise timing of a cell-cell interaction is often crucial: when contact, activation, and ultimately, the killing of the cancer cell occur.

How CellTrap Works

CellTrap consists of a microfluidic chip with a large main channel that branches out continuously. At the ends of the branching pathways are 1024 small trapping chambers into which the cells are drawn. Within the chambers, individual immune cells and cancer cells are selectively brought together, spatially fixed, and their interactions are observed over many hours — up to 14 hours — using a time-lapse microscope. This creates a wide variety of situations: cancer cells alone, immune cells alone, or various ratios of immune cells to cancer cells.

"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," says Ghulam Destgeer, Professor of Control and Manipulation of Microscale Living Objects at the TUM School of Computation, Information and Technology. “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 specialised equipment."

What individual cell contacts reveal

Initial experiments with a glioblastoma cell line — a type of brain tumour — confirm: When multiple immune cells encounter a single cancer cell, it is attacked more frequently and more intensely. Furthermore, it appears that early activation signals in immune cells often indicate that a cell-damaging effect will occur later. This allows, for the first time, the observation of how early reactions are related to the later outcome within the same cell-cell interaction. Beyond this glioblastoma line, the team also tested CellTrap with two further cancer cell lines: a chronic myeloid leukaemia and an adenocarcinoma.

"The more we learn about what actually happens between individual cells, the better we can compare treatment strategies and develop new ones," adds Destgeer. "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."