Mapping Proteome and Lipidome Changes in Early-Onset Non-Alcoholic Fatty Liver Disease Using Hepatic 3D Spheroids.

Non-alcoholic fatty liver disease affects one-fourth of the world's population. Central to the disease progression is lipid accumulation in the liver, followed by inflammation, fibrosis and cirrhosis. The underlying mechanism behind the early stages of the disease is poorly understood. We have exposed human hepatic HepG2/C3A cells-based spheroids to 65 µM oleic acid and 45 µM palmitic acid and employed proteomics and lipidomics analysis to investigate their effect on hepatocytes. The treatment successfully induced in vivo hallmarks of NAFLD, as evidenced by intracellular lipid accumulation and increased ATP levels. Quantitative lipidome analysis revealed an increase in ceramides, LPC and saturated triglycerides and a decrease in the ratio of PC/PE, similar to the changes observed in patients' liver biopsies. The proteomics analysis combined with qPCR showed increased epithelial to mesenchymal transition (EMT) signalling. Activation of EMT was further validated by transcriptomics in TGF-ß treated spheroids, where an increase in mesenchymal cell markers (N-cadherin and collagen expression) was found. Our study demonstrates that this model system thus closely echoes several of the clinical features of non-alcoholic fatty liver disease and can be used to investigate the underlying molecular changes occurring in the condition.

3D-ViaFlow: A Quantitative Viability Assay for Multicellular Spheroids.

Three-dimensional cell culture became an essential method in molecular and cell biology research. Accumulating results show that cells grown in 3D, display increased functionality and are capable of recapitulating physiological functions that are not observed in classical in vitro models. Spheroid-based cell culture allows the cells to establish their own extracellular matrix and intricate intercellular connections promoting a tissue-like growth environment.In this paper we present the 3D-ViaFlow method that combines an optimised dual live-dead cell staining with flow cytometry to deliver a quantitative estimation of viability of cells in multicellular spheroids. The method is optimised for monolayer cultures and multicellular spheroids created from HepG2/C3A human hepatocytes or coculture of HepG2/C3A and endothelial cell line HMEC-1. It includes protocol for spheroids disassembling, labeling of cells with fluorescein diacetate and propidium iodide and instructions for flow cytometry gating optimized for analysis of heterogeneous cell populations form spheroids.

Method to Disassemble Spheroids into Core and Rim for Downstream Applications Such as Flow Cytometry, Comet Assay, Transcriptomics, Proteomics, and Lipidomics.

Cells cultured in a monolayer have been a central tool in molecular and cell biology, toxicology, biochemistry, and so on. Therefore, most methods for adherent cells in cell biology are tailored to this format of cell culturing. Limitations and disadvantages of monolayer cultures, however, have resulted in the ongoing development of advanced cell culturing techniques. One such technique is culturing cells as multicellular spheroids, that had been shown to mimic the physiological conditions found in vivo more accurately. This chapter presents a novel method for separation of the spheroid rim and core in mature spheroids (>21 days) for further analysis using advanced molecular biology techniques such as flow cytometry, viability estimations, comet assay, transcriptomics, proteomics and lipidomic. This fast and gentle disassembly of intact spheroids into rim and core fractions, and further into viable single-cell suspension provides an opportunity to bridge the gap from 3D cell culture to current state-of-the-art analysis methods.