A reconfigurable microscale assay enables insights into cancer-associated fibroblast modulation of immune cell recruitment.

Innate immune cell infiltration into neoplastic tissue is the first line of defense against cancer and can play a deterministic role in tumor progression. Here, we describe a series of assays, using a reconfigurable microscale assay platform (i.e. Stacks), which allows the study of immune cell infiltration in vitro with spatiotemporal manipulations. We assembled Stacks assays to investigate tumor-monocyte interactions, re-education of activated macrophages, and neutrophil infiltration. For the first time in vitro, the Stacks infiltration assays reveal that primary tumor-associated fibroblasts from specific patients differ from that associated with the benign region of the prostate in their ability to limit neutrophil infiltration as well as facilitate monocyte adhesion and anti-inflammatory monocyte polarization. These results show that fibroblasts play a regulatory role in immune cell infiltration and that Stacks has the potential to predict individual patients' cancer-immune response.

Reconfigurable open microfluidics for studying the spatiotemporal dynamics of paracrine signalling.

The study of intercellular signalling networks requires organotypic microscale systems that facilitate the culture, conditioning and manipulation of cells. Here, we describe a reconfigurable microfluidic cell-culture system that facilitates the assembly of three-dimensional tissue models by stacking layers that contain preconditioned microenvironments. By using principles of open and suspended microfluidics, the Stacks system is easily assembled or disassembled to provide spatial and temporal manoeuvrability in two-dimensional and three-dimensional assays of multiple cell types, enabling the modelling of sequential paracrine-signalling events, such as tumour-cell-mediated differentiation of macrophages and macrophage-facilitated angiogenesis. We used Stacks to recapitulate the in vivo observation that different prostate cancer tissues polarize macrophages with distinct gene-expression profiles of pro-inflammatory and anti-inflammatory cytokines. Stacks also enabled us to show that these two types of macrophages signal distinctly to endothelial cells, leading to blood vessels with different morphologies. Our proof-of-concept experiments exemplify how Stacks can efficiently model multicellular interactions and highlight the importance of spatiotemporal specificity in intercellular signalling.