Abstract 3874: Monitoring immune-tumor cell interactions in 3D microfluidic models with optical metabolic imaging and molecular profiling
Authors: Rehman Shujah H. , Ayuso Jose M. , Virumbrales-Munoz Maria Maria , McMinn Patrick H. , Beebe David J. , Skala Melissa C. 
Published: September 2020

Abstract
The tumor microenvironment is defined by nutrient starvation, waste product accumulation, hypoxia, and acidosis, which collectively contribute towards immune exhaustion and suppression. Models that mimic the tumor microenvironment will be instrumental to develop new therapies that improve immune response. Microfluidic models can mimic the tumor metabolic microenvironment to elucidate mechanisms that lead to weakened tumor immunity and to new tumor immunotherapies. We developed microfluidic models where cancer cells were cultured as a dense mass embedded in a 3D matrix. The microfluidic platform has lateral channels that are lined with endothelial cells to mimic the tumor vasculature. These vessels can be perfused with immune cells or drugs that extravasate into the tumor mass. Immune cells were isolated from the tumor mass within these microfluidic models and gene expression was analyzed to quantify changes in immune cell function under tumor metabolic microenvironment conditions. Optical metabolic imaging of NADH and FAD autofluorescence with 2-photon microscopy monitored metabolic dynamics during tumor-immune cell interactions. Immunotherapy drugs were also perfused through the microfluidic devices to measure drug efficacy. Changes in immune cell function after drug exposure were analyzed by optical metabolic imaging to examine metabolic dynamics, alongside fluorescence microscopy to visualize cytotoxicity changes. Natural killer cells exhibited directional migration towards the tumor, which indicates that natural killer cells can detect the presence of the tumor several hundreds of microns away. Real-time microscopy revealed that natural killer cells destroyed tumor cells at the tumor periphery and notably at the innermost tumor core. Gene expression analysis of immune cells and tumor cells cultured in the microfluidic model reveals that the tumor cells have created an environment consistent with immunosuppression, immune exhaustion, and nutrient starvation. Metabolic imaging reveals that immune cells exposed to the tumor microenvironment have an altered metabolic profile, specifically decreased redox ratio that persists even under normal culture conditions. The microfluidic model provides a system to examine immune cytotoxicity, metabolic dynamics during tumor-immune interactions, and the impact of immunotherapies in enhancing immune cytotoxicity. Optical metabolic imaging and microfluidic models provide novel insight into metabolic dynamics with tumor cell and immune cell interactions within the tumor metabolic microenvironment. Future studies will expand this technology towards studying immune exhaustion and dysfunction in other immune therapies.
Citation Format: Shujah H. Rehman, Jose M. Ayuso, Maria Maria Virumbrales-Munoz, Patrick H. McMinn, David J. Beebe, Melissa C. Skala. Monitoring immune-tumor cell interactions in 3D microfluidic models with optical metabolic imaging and molecular profiling [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3874.