Changes in metabolic pathways are often associated with the development of various pathologies including cancer, inflammatory diseases, obesity and metabolic syndrome. Identification of the particular metabolic events that are dysregulated may yield strategies for pharmacologic intervention. However, such studies are hampered by the use of classic cell media that do not reflect the metabolite composition that exists in blood plasma and which cause non-physiological adaptations in cultured cells. In recent years two groups presented media that aim to reflect the composition of human plasma, namely human plasma-like medium (HPLM) and Plasmax. Here we describe that, in four different mammalian cell lines, Plasmax enhances mitochondrial respiration. This is associated with the formation of vast mitochondrial networks and enhanced production of reactive oxygen species (ROS). Interestingly, cells cultivated in Plasmax displayed significantly less lysosomes than when any standard media were used. Finally, cells cultivated in Plasmax support replication of various RNA viruses, such as hepatitis C virus (HCV) influenza A virus (IAV), severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) and several others, albeit at lower levels and with delayed kinetics. In conclusion, studies of metabolism in the context of viral infections, especially those concerning mitochondria, lysosomes, or redox systems, should be performed in Plasmax medium.

Reactive oxygen species (ROS) play a major role in the regulation of various processes in the cell. The increase in their production is a factor contributing to the development of numerous pathologies, including inflammation, fibrosis, and cancer. Accordingly, the study of ROS production and neutralization, as well as redox-dependent processes and the post-translational modifications of proteins, is warranted. Here, we present a transcriptomic analysis of the gene expression of various redox systems and related metabolic processes, such as polyamine and proline metabolism and the urea cycle in Huh7.5 hepatoma cells and the HepaRG liver progenitor cell line, that are widely used in hepatitis research. In addition, changes in response to the activation of polyamine catabolism that contribute to oxidative stress were studied. In particular, differences in the gene expression of various ROS-producing and ROS-neutralizing proteins, the enzymes of polyamine metabolisms and proline and urea cycles, as well as calcium ion transporters between cell lines, are shown. The data obtained are important for understanding the redox biology of viral hepatitis and elucidating the influence of the laboratory models used.