Establishment and application of hepatic organoid model of hepatitis B virus infection / 中华传染病杂志

ABSTRACT

Objective:To establish the hepatic organoid of hepatitis B virus (HBV) infection on the basis of induced pluripotent stem cells (iPSC) and an inverted colloidal crystal polyethylene glycol scaffold (ICC), and to evaluate the antiviral effect of nucleoside drugs.Methods:iPSC was differentiated into hepatocyte-like cells (HLC), and inoculated into ICC to construct a hepatic organoid. The relative mRNA expressions of Nanog homeobox (NANOG), sex determining region Y-box (SOX) 2, SOX17, forkhead box protein A2 (FOXA2), alpha fetoprotein (AFP) and albumin (ALB) were detected by real time quantitative polymerase chain reaction (RT-qPCR). Confocal laser microscopy was used to photograph the three-dimension (3D) structure of organs. The expression of sodium taurocholate cotransporting polypeptide (NTCP) in HLC was analyzed by Western blot and immunofluorescence. HepG2.2.15 cells were used to extract HBV virus particles to infect hepatic organoid. The relative expression of HBV pregenome RNA (pgRNA) in cells was detected by RT-qPCR. The expressions of hepatitis B core antigen (HBcAg) and hepatitis B surface antigen (HBsAg) in cytoplasm were observed under confocal laser microscopy. A total of 0.5 μmol/L entecavir and 0.5 μmol/L lamivudine were used to treat the infected cells respectively. The relative expression of HBV pgRNA in infected and uninfected cells was detected by RT-qPCR. Independent sample t test and one-way analysis of variance were used for statistical analysis. Results:Within 21 days of iPSC differentiation, the mRNA expressions of NANOG and SOX2 in stem cells markers decreased ( F=158.90 and 8.31, respectivley; P<0.001 and P=0.002, respectively), while the mRNA expressions of SOX17 and FOXA2 in the endoderm increased first and then decreased ( F=37.23 and 82.57, respectively, both P<0.001). In the later stage of differentiation, the mRNA expressions of AFP and ALB in liver cells increased ( F=4.65 and 34.64, respectively, P=0.012 and P<0.001, respectively), and all differences were statistically significant. NTCP was highly expressed in differentiated cells detected by Western blot and fluorescence microscopy, the protein expression level was 0.803±0.099. Confocal laser microscopy confirmed that the differentiated cells expressed ALB and presented spherical structure in ICC. The expression of HBV pgRNA and the immunostaining of HBsAg and HBcAg confirmed that HBV successfully infected hepatic organoid. Three days after the application of entecavir and lamivudine, the HBV pgRNA level decreased significantly both in entecavir group (0.665±0.220) and lamivudine group (0.503±0.117) compared to the uninfected cells (3.347±0.454), and the differences were both statistically significant ( t=10.53 and 12.72, respectively, both P<0.001). Conclusions:HLC display hepatic specific genes ALB and NTCP. Hepatic organoids constructed with iPSC and ICC have human liver function and can be infected by HBV. Entecavir and lamivudine could effectively inhibit the replication of HBV in hepatic organoids.