Search

Redox homeostasis is determinant in the modulation of quiescence/self-renewal/differentiation of stem cell lines. The aim of this study consisted of defining the impact of redox modifications on cell fate in a human hepatic progenitor line. To achieve this, the HepaRG cell line, which shows oval ductular bipotent characteristics, was used. The impact of redox status on the balance between self-renewal and differentiation of HepaRG cells was investigated using different methodological approaches. A bioinformatic analysis initially proved that the trans-differentiation of HepaRG toward bipotent progenitors is associated with changes in redox metabolism. We then exposed confluent HepaRG (intermediate differentiation phase) to oxidized (H2O2) or reduced (N-acetylcysteine) extracellular environments, observing that oxidation promotes the acquisition of a mature HepaRG phenotype, while a reduced culture medium stimulates de-differentiation. These results were finally confirmed through pharmacological modulation of the nuclear factor (erythroid-derived 2)-like 2 (NRF2), a principal modulator of the antioxidant response, in confluent HepaRG. NRF2 inhibition led to intracellular pro-oxidative status and HepaRG differentiation, while its activation was associated with low levels of reactive species and de-differentiation. In conclusion, this study shows that both intra- and extracellular redox balance are crucial in the determination of HepaRG fate. The impact of redox status in the differentiation potential of HepaRG cells is significant on the utilization of this cell line in pre-clinical studies. [ABSTRACT FROM AUTHOR]

The identification of key regulators in hepatic progenitor cells differentiation is determinant for organ regeneration and may improve stem cell transplantation for end-stage liver disease. Mesenchymal, embryonic and pluripotent stem cells have been investigated as potential sources for hepatic differentiation, but their unstable function and atypical morphology limit the usefulness for cell treatment. The human bipotent liver progenitor cell line HepaRG is applied for toxicity screening, viral hepatitis research, hepatocyte differentiation and transplantation testing. Since redox-dependent signaling molecules are involved in the regulation of stem cell self-renewal and differentiation, we studied the role of Nrf2 – the main transcription factor involved in the oxidative stress response – in HepaRG transdifferentiation. Nrf2 was upregulated in undifferentiated HepaRG, which exhibited higher free radical production as compared to transdifferentiated cells. Pharmacological and genetic inhibition of Nrf2 led to morphological, phenotypical and functional patterns characteristic of transdifferentiated elements. To conclude, we show a determinant role of Nrf2 in the process of HepaRG transdifferentiation, suggesting that this redox-dependent transcription factor represents a potential target to regulate the commitment of undifferentiated hepatic progenitor cells into specific lineages. [ABSTRACT FROM AUTHOR]