HiPSC-derived hepatocytes closely mimic the lipid profile of primary hepatocytes: A future personalised cell model for studying the lipid metabolism of the liver.

Mostafa Kiamehr,Reijo Laaksonen,Kim Ekroos,Laura Heiskanen,Anna Alexanova,Katriina Aalto‐Setälä,Leena E Viiri,Terhi Vihervaara,Reijo Käkelä,Dimple Kauhanen

doi:10.1002/jcp.27131

Abstract

Hepatocyte-like cells (HLCs) differentiated from human-induced pluripotent stem cells offer an alternative platform to primary human hepatocytes (PHHs) for studying the lipid metabolism of the liver. However, despite their great potential, the lipid profile of HLCs has not yet been characterized. Here, we comprehensively studied the lipid profile and fatty acid (FA) metabolism of HLCs and compared them with the current standard hepatocyte models:HepG2 cells and PHHs. We differentiated HLCs by five commonly used methods from three cell lines and thoroughly characterized them by gene and protein expression. HLCs generated by each method were assessed for their functionality and the ability to synthesize, elongate, and desaturate FAs. In addition, lipid and FA profiles of HLCs were investigated by both mass spectrometry and gas chromatography and then compared with the profiles of PHHs and HepG2 cells. HLCs resembled PHHs by expressing hepatic markers: secreting albumin, lipoprotein particles, and urea, and demonstrating similarities in their lipid and FA profile. Unlike HepG2 cells, HLCs contained low levels of lysophospholipids similar to the content of PHHs. Furthermore, HLCs were able to efficiently use the exogenous FAs available in their medium and simultaneously modify simple lipids into more complex ones to fulfill their needs. In addition, we propose that increasing the polyunsaturated FA supply of the culture medium may positively affect the lipid profile and functionality of HLCs. In conclusion, our data showed that HLCs provide a functional and relevant model to investigate human lipid homeostasis at both molecular and cellular levels.

Highlights

The liver plays an important role in the regulation of many physiological functions of the body, including lipid and carbohydrate metabolism, glycolytic/urea metabolism, plasma protein synthesis, and the detoxification of a wide variety of molecules (Si‐Tayeb et al, 2010)
To further investigate the metabolism of fatty acid (FA) in the hepatocyte‐like cell (HLC), primary human hepatocyte (PHH), and HepG2 cells, we studied the expression of five key genes involved in the synthesis pathways of FA by Quantitative PCR (qPCR)
The results revealed that FA synthase (FASN), a key gene in de novo FA synthesis, was expressed in the HLCs mostly at similar levels as in the PHHs (Figure 7a)

Summary

| INTRODUCTION

The liver plays an important role in the regulation of many physiological functions of the body, including lipid and carbohydrate metabolism, glycolytic/urea metabolism, plasma protein synthesis, and the detoxification of a wide variety of molecules (Si‐Tayeb et al, 2010). PHHs loose functionality relatively fast, and their liver‐ specific features progressively deteriorate, which hampers long‐term studies (Elaut et al, 2006; Godoy et al, 2013) To address these limitations, various human hepatoma cell lines, including HepG2 and Huh, have been used due to their ease of handling, unlimited life span, and stable phenotype. Hepatoma cell lines have failed to predict the numerous adverse hepatotoxic side effects of new drugs (Castell, Jover, Martínez‐Jiménez, & Gómez‐Lechón, 2006) Animal models, such as rats and mice, or animal primary hepatocytes have been widely used to study lipid metabolism and lipoprotein production in the liver (Kvilekval, Lin, Cheng, & Abumrad, 1994). | 3746 limitations of HLCs as a model for studying lipid metabolism are evaluated

| MATERIAL AND METHODS

| RESULTS

Findings

| DISCUSSION

| CONCLUSIONS