We previously examined lipoprotein profile in PXB-cells, fresh primary human hepatocytes from humanized mouse livers, and demonstrated that they are suitable for screening anti-lipidemic agents. The accumulation of numerous oil droplets － a hallmark of non-alcoholic fatty liver disease (NAFLD)－was observed in PXB-cells immediately after their isolation from humanized murine livers 16 weeks after transplantation, but markedly decreased in an in vitro culture of more than 10 days. Some studies demonstrated that the size of very low density lipoproteins (VLDL) in the plasma of patients NAFLD or non-alcoholic steatohepatitis significantly increased, suggesting that increases in the size of VLDL have potential as a minimally invasive biomarker for the diagnosis and/or progression of NAFLD. To clarify whether hepatocytes with numerous oil droplets actually secret larger size of VLDL, we investigated intra- and extracellular lipid levels and lipoprotein profiles of PXB-cells isolated at several posttransplantation durations, which seem to be closely related to cytosolic oil droplet accumulations.