Integrated Discrete Multiple Organ Co-culture (IdMOC) System for the Evaluation of Multiple Organ Drug Distribution, Drug Metabolism, and Organ Specific Drug Toxicity

The metabolic fate of a xenobiotic in vivo often involves multiple organs. However, investigation on drug metabolism is routinely performed using experimental systems derived from a single organ, especially liver-derived systems such as liver microsomes and hepatocytes. The Integrated Discrete Multiple Organ Co-culture (IdMOC™) system has been developed in our laboratory as an in vitro experimental system to overcome this major deficiency of single-organ systems. The IdMOC employs a wells-in-a well concept, with multiple inner wells located within a larger, containing well. Multiple cell types are firstly cultured individually in each inner well, followed by flooding and interconnection of the inner wells with an overlying medium. The IdMOC thereby models an organism with multiple organs that are connected by the systemic circulation. We report here the application of IdMOC in the co-culturing of major cell types of the major human organs: hepatocytes (liver), renal proximal tubule cells (kidney), neurons (nervous system), adipocytes (fat) and skeletal myocytes (skeletal muscle). Using IdMOC, in vitro pharmacokinetic/toxicokinetic studies can be performed via quantification of parent disappearance and metabolite formation in the medium, quantification of drug distribution in each cell type, as well as the evaluation of toxicity in each cell type. Results with model drug metabolizing enzyme substrates, transporter substrates, and organ-specific toxicant including midazolam (CYP3A substrate), L-glutamic acid gamma (4 – methoxy –beta naphthylamide) (GGT substrate), metformin (OCT1 substrate), simvastatin (SLCO1B1 substrate and skeletal muscle toxicant), and aflatoxin B1 (hepatotoxicant and hepatocarcinogen) are shown, using LC/MS/MS for the quantification of parent and metabolites and multiple endpoints (MTT metabolism, cellular ATP content, cellular GSH content) for cytotoxicity. The results demonstrate that IdMOC is as an effective in vitro experimental tool for the evaluation of multiple organ drug distribution, metabolism, and toxicity.