Development of a Hepatocyte Spheroid Culture Model for Drug Uptake, Metabolism and Transporter Studies

Abstract

The liver is a key organ in drug bioavailability including uptake, metabolism, and excretion as well as drug toxicity. Thus, a robust liver in vitro model that resembles in vivo micro environment with improved predictive capabilities is highly warranted. The focus in this thesis has been to develop and characterize a 3D liver spheroid model for the study of long-term drug uptake, metabolism, and transport. The bipotent progenitor cell line HepaRG has been used as it is known to express various liver specific markers and function in its differentiated state similar to primary human hepatocytes. Culturing these cells onto ultra-low attachment plates derived spheroid formation after 3 days independent of cellular concentration. Various staining techniques were used to investigate long-term sustainability of 2000 and 4000 cell spheroid culture. The gene expression analysis of the drug metabolizing cytochrome P450 (CYP) enzymes illustrated higher expression level in spheroid formation compared to 2D control while drug transporter, MRP2, hepatocyte markers Ki67, albumin, and CK19 all showed moderate to low expression. The HepaRG spheroid model showed promising results. The enzyme activity of CYP2C9, CYP2D6, and CYP3A4 was measurable throughout the whole cultivation period with a peak activity at day 7 while CYP1A2 showed no activity.