The adverse effects of hypoxia on hiHep functions via HIF-1α/PGC-1α axis are alleviated by PFDC emulsion

Human-induced hepatocyte-like cells (hiHeps) are new cell sources for bio-artificial liver (BAL), as a potential treatment for acute liver failure (ALF), which calls for 10(10) cells at a minimum. However, high-density hiHeps loaded in BAL have a high demand for oxygen, leading to hypoxia during culture. At present, the effects of hypoxia on hiHep proliferation and functions are still unclear. Here, it was proved that hiHeps were hypoxic at day 8 of culture, even though the seeding density were 4 x 10(7) cells/cm(3) in the PET-loaded bioreactor. Hypoxia impaired hiHep functions, such as albumin secretion, urea synthesis and drug metabolism. HIF-1 alpha up-regulated its downstream genes related to glucose metabolism, including PDK-1, Glut1 and LDHA under hypoxia. Mean-while, HIF-1 alpha down-regulated the gene expressions of PGC-1 alpha, NRF-1, TFAM, TFB1M and TFB2M. This study found that PGC-1 alpha was a downstream mediator of HIF-1 alpha, and HIF-1 alpha/PGC-1 alpha axis repressed the protein expressions of CYP1A2 and CYP3A4. Our findings revealed that hypoxia affected the proliferation and functions of hiHeps via HIF-1 alpha/PGC-1 alpha axis, and showed that perfluorodecalin (PFDC) emulsion reversed the adverse effects of hypoxia during high-density perfusion culture.