Analysis of an Integrated Human Multiorgan Microphysiological System for Combined Tolcapone Metabolism and Brain Metabolomics

Human-on-a-chip systems are rapidly advancing due to the availability of human stem cells from a variety of tissues, but publications have utilized mostly simple methods of biochemical analysis. Here, we apply mass spectrometry to a sophisticated multiorgan human-on-a-chip system for the comprehensive study of tolcapone metabolite profiling and metabolomics. The developed human-on-a-chip includes seven interacting microphysiological systems (MPSs), brain, pancreas, liver, lung, heart, gut, and endometrium, with a mixer chamber for systemic circulation and tolcapone dose. We investigated tolcapone metabolism by analyzing the circulating medium using mass spectrometry. Twelve tolcapone metabolites were identified, three of which are newly reported. These metabolites demonstrated that oxidation, reduction, and conjugation reactions were the most important routes of tolcapone metabolism. In parallel, metabolomics in brain MPS evaluated the tolcapone influences on endogenous pathways in human brain. Untargeted metabolomics identified 18 key biomarkers significantly changed in human brain MPS after tolcapone dosing, which were mainly associated with perturbation of tryptophan and phenylalanine metabolism (BH4 cycle), glycerophospholipid metabolism, energy metabolism, and aspartate metabolism. This is the first example of successfully combining drug metabolism, metabolomics, and cell engineering to capture complex human physiology and the multiorgan interactions; the results we present here could be a step toward using analytical chemistry to advance the utilization of human-on-a-chip for testing both drug efficacy and toxicity in a single system.