Endocrine Abstracts

Primary human hepatocytes are considered the ‘gold standard’ to explore metabolic phenotype within the liver, however they come with limitations, such as donor variability, lack of proliferation and rapid phenotype loss. The human hepatoma cell line, HepG2, has been used extensively in cell-based metabolic studies but there are significant limitations including their malignant origin and inherent low rates of triglyceride secretion. The aim of this study was to investigate whether dimethyl sulfoxide (DMSO) supplementation in the cell media could enhance HepG2 cell metabolic functionality leading to development of an improved model that may more closely resemble primary human hepatocytes. HepG2 cells were cultured in cell media containing 1% DMSO for 7, 14, and 21 days and gene expression, protein levels, intracellular triglyceride content and triglyceride, urea and 3-OH-butyrate concentrations in the cell medium measured. mRNA expression of four markers of hepatocyte differentiation (albumin, HNF4A, transthyretin and α1-antithrypsin) increased with DMSO treatment to levels that were similar to those seen in primary cultures of human hepatocytes. In addition, mRNA expression of the tumor marker alpha-fetoprotein decreased. Furthermore, DMSO treatment decreased intracellular triglyceride content (control=205.1±16.1 nmol/mg, day 7=83.8±9.0 nmol/mg, day 14=82.3±10.5 nmol/mg, day 21=83.9±5.1 nmol/mg), while media triglyceride and 3-OH-butyrate levels increased in a time-dependent manner (TG: control=2.5±0.3 nmol/mg, day 7=1.4±0.1 nmol/mg, day 14=5.0±1.2 nmol/mg, day 21=6.2±2.0 nmol/mg; 3-OH-butyrate: control=4.5±2.3 μmol/mg, day 7=12.3±0.8 μmol/mg, day 14=12.1±0.8 μmol/mg, day 21=9.0±1.1 μmol/mg). Urea levels remained unchanged. Moreover, DMSO treatment decreased the mRNA expression of genes involved in lipid metabolism (ACC1, ACC2, DGAT1, DGAT2, FAS, SCD), but increased the levels of those implicated in glucose metabolism (PEPCK, G6PC). Changes in mRNA expression were mirrored by changes at the protein level as measured by western blotting. We have demonstrated that DMSO treatment changes the metabolic phenotype of HepG2 cells such that they more closely resemble primary human hepatocytes and has the potential to signficantly enhance currently available cell systems to study liver biology.