Systematic comparison of cellular adaptive stress response activation networks in hepatic stem cell-derived progeny and primary human hepatocytes

Various adaptive cellular stress response pathways are critical in the pathophysiology of liver disease and drug-induced liver injury. Human-induced pluripotent stem cell (hiPSC)-derived hepatocyte-like cells (HLCs) provide a promising tool to study cellular stress response pathways, but in this context there is limited insight on how HLCs compare to primary human hepatocytes (PHH). Here, we systematically compared the activation of four different stress pathways in PHH, HepG2 liver cancer cells, hiPSCs and different stages within the differentiation towards HLCs (definitive endoderm, hepatoblast, immature hepatocytes and HLCs). We exposed all different cell types in a concentration response to four different compounds that specifically activate the oxidative stress response (diethyl-maleate), unfolded protein response (tunicamycin), DNA damage response (cisplatin) and inflammatory signalling (TNF). We used targeted RNA-sequencing to map concentration response transcriptional similarities and differences using bench-mark concentration modelling for the various stress responses in the different test systems. We observed that HLCs are more sensitive to oxidative stress than PHH showing activation at ten-fold lower concentrations and induce a strong anti-oxidant response. Although similar UPR gene sets were activated in HLCs compared to PHH, PHH were about ten times more sensitive. Furthermore, HLCs were highly sensitive to inflammation conditions similar to HepG2 cells and in sharp contrast to hiPSC, which showed hardly any response. On the contrary, hiPSC and HepG2 were highly sensitive to DNA damage signalling while HLCs resisted a strong p53 DNA damage response upon exposure. Overall, the data indicate that despite limitation in full hepatocyte maturation, HLCs did gain specific adaptive cellular stress response networks that mimic those of PHHs.