Infection and immunity on a chip: a compartmentalised microfluidic platform to monitor immune cell behaviour in real timeElectronic supplementary information (ESI) available. See DOI: 10.1039/c4lc01438c

Cells respond to their environments and self-organise into multicellular assemblies with dedicated functions. The migratory and homing response of cells to soluble ligands can be studied by using different techniques, but for real time studies of complex multicellular self-organisation, novel and simpler systems are required. We fabricated a flexible open access microsystem and tested the design by studying cell recruitment from an immune cell reservoir towards an infectious compartment. The two compartments were connected by a network of bifurcated microchannels allowing diffusion of signalling molecules and migration of cells. Bacterial filters were incorporated in the design to prevent bacteria and activated cells from entering the network, permitting migration only from the recruitment reservoir. The fabricated microsystem allows real-time continuous monitoring of cellular decision-making based on biologically produced gradients of cytokines and chemokines. It is a valuable tool for studying cellular migration and self-organisation in relation to infections, autoimmunity, cancer, stem cell homing, and tissue and wound repair. Immunity on a chip: modeling and designing immune reactions in vitro to study immune responses on a chip as well as unraveling physiological processes under a microscope.