Real-time quantitative fluorescence measurement of microscale cell culture analog systems

A microscale cell culture analog (mu CCA) is a cell-based lab-on-a-chip assay that, as an animal surrogate, is applied to pharmacological studies for toxicology tests. A mu CCA typically comprises multiple chambers and microfluidics that connect the chambers, which represent animal organs and blood flow to mimic animal metabolism more realistically. A mu CCA is expected to provide a tool for high-throughput drug discovery. Previously, a portable fluorescence detection system was investigated for a single mu CCA device in real-time. In this study, we present a fluorescence-based imaging system that provides quantitative real-time data of the metabolic interactions in mu CCAs with an emphasis on measuring multiple mu CCA samples simultaneously for high-throughput screening. The detection system is based on discrete optics components, with a high-power LED and a charge-coupled device (CCD) camera as a light source and a detector, for monitoring cellular status on the chambers of each mu CCA sample. Multiple samples are characterized mechanically on a motorized linear stage, which is fully-automated. Each mu CCA sample has four chambers, where cell lines MES-SA/DX5, and MES-SA (tumor cells of human uterus) have been cultured. All cell-lines have been transfected to express the fusion protein H2B-GFP, which is a human histone protein fused at the amino terminus to EGFP. As a model cytotoxic drug, 10 mu M doxorubicin (DOX) was used. Real-time quantitative data of the intensity loss of enhanced green fluorescent protein (EGFP) during cell death of target cells have been collected over several minutes to 40 hours. Design issues and improvements are also discussed.