Non-alcoholic fatty liver disease (NAFLD) is a highly prevalent, progressive disorder and growing public health concern. To address this issue considerable research has been undertaken in pursuit of new NAFLD therapeutics. Development of effective, high-throughput in vitro models is an important aspect of drug discovery. Here, a micropatterned hepatocyte co-culture (MPCC) was used to model liver steatosis. The MPCC model (HEPATOPAC) involves hepatocytes and 3T3-J2 mouse stromal cells patterned onto a standard 96-well plate, increasing throughput and allowing the cultures to be handled and imaged like 2D cultures. These studies employed high content imaging (HCI) analysis to assess lipid content in cultures. HCI analysis of lipid accumulation allows large numbers of samples to be imaged and analyzed in a relatively short period of time compared to manual acquisition and analysis methods. Treatment of MPCC with free fatty acids (FFA), high glucose and fructose (HGF), or a combination o f both induces hepatic steatosis. MPCC treatment with ACC1/ACC2 inhibitors, as either a preventative or reversal agent showed efficacy against FFA induced hepatic steatosis. Drug induced steatosis was also evaluated. Treatment with valproic acid showed steatosis induction in a lean background, which was significantly potentiated in a fatty liver background. Additionally, these media treatments changed expression of fatty liver related genes. Treatment of MPCC with FFA, HGF, or a combination reversibly altered expression of genes involved in fatty acid metabolism, insulin signaling, and lipid transport. Together, these data demonstrate that MPCC is an easy to use, long-term functional in vitro model of NAFLD having utility for compound screening, drug toxicity evaluation, and assessment of gene expression changes.
Overall design: MPCC (HEPATOPAC) cultures were created using microfabrication processes to generate an organized co-culture containing cryopreserved primary human hepatocytes (PHH) from BioIVT (Baltimore, MD) and 3T3-J2 murine embryonic fibroblasts. Cryopreserved primary human hepatocytes from donor lot TWJ were thawed at 37°C, counted, and plated on collagen-patterned 96 or 24 well plates. The cells were allowed to adhere until the following day, when 3T3-J2 fibroblasts were introduced to the culture plates. The resulting culture contained multiple hepatocyte islands having a 500 μm diameter spaced 1200 μm apart, center-to-center; with 3T3-J2 murine fibroblasts filling the area surrounding the hepatocyte islands. MPCC cultures were stabilized in serum containing medium for 7 days. At maturity, approximately 3,100 hepatocytes and 15,000 fibroblasts were present/well in a 96 well plate and about 21,000 hepatocytes and 90,000 fibroblasts were present/well in a 24 well plate. Treatment was initiated on day 7 after initiation of culture manufacture.
Cells were treated with control medium containing 1.0g/L glucose, 1.1 µM insulin and 10% bovine serum or steatosis inducing media containing 0.5 mM free fatty acid (FFA) (Palmitate/Oleate 2:1, Sigma), 10g/L glucose and 1.0g/L fructose (HGF), or a combination of FFA and HGF with media exchanges every other day. Cells were treated with steatosis inducers continuously until day 7 of treatment or switched back to control media on day 4 for 3 days, until day 7 of treatment (reversal samples).
RT-PCR array using Qiagen Human Fatty Liver Array
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