Here we summarize 2020 publications where PXB-cells® were used in such application areas as lipid metabolism, toxicity, drug metabolism and hepatitis B.

Hata, K. et al. Biomed. Res. 2020; 41(1):33.

 “Lipoprotein profile and lipid metabolism of PXB-cells®, human primary hepatocytes from liver-humanized mice: proposal of novel in vitro system for screening anti-lipidemic drugs”

Extracellular apolipoproteins ApoB100 and ApoC3 in PXB-cells, HepG2 and HuH-7 cells
Extracellular apolipoproteins ApoB100 and ApoC3 in PXB-cells, HepG2 and HuH-7 cells

Hata et al. publication describes lipoprotein profile and lipid metabolism of PXB-cells®, showing their suitability to screen anti-lipidemic agents. The paper shows that PXB-cells® mainly release triglycerides and cholesterol as VLDL (like primary human hepatocytes) in contrast to two other hepatoma cell lines, which mainly release LDL. Fenofibrate (PPARα ligand) suppressed lipoprotein production from PXB-cells® in a dose-dependent manner. (VLDL – very low density lipoprotein; LDL – low density lipoprotein).

Next five publications discuss the use of PXB-cells® in toxicity-related applications (in 2D and in 3D formats).

Ikeyama, Y. et al. Toxicol in Vitro. 2020; 65: 104785.

Mitochondria toxicity assessment with PXB-cells and Cryopreserved Human Hepatocytes.
Mitochondria toxicity assessment with PXB-cells and Cryopreserved Human Hepatocytes. Image modified from the Graphical Abstract of the Ikeyama Y. et al. Toxicol. in Vitro 2020; 65: 104785

“Successful energy shift from glycolysis to mitochondrial oxidative phosphorylation in freshly isolated hepatocytes from humanized mice liver”

Ikeyama et al. showed that PXB-cells® in the galactose culture had a higher level of intracellular ATP than those in the glucose culture. This result was not observed in CHH lots: a total of 5 out of 6 CHH lots tested were not able to survive after sugar resource substitution with galactose. PXB-cells® showed high viability regardless the substitution of sugars. More detailed summary is available via the following link:

Ide, I. et al. Toxicol Mech Methods. 2020; 30(3):189-196.

“A novel evaluation method for determining drug induced hepatotoxicity using 3D bio-printed human liver tissue”

Ide et al. present the 3D bio-printed liver tissue with improved viability and enhanced gene expression of enzymes related to drug metabolism and transport. Both PHH and PXB-cells® were used for 3D tissue preparation. The following three genes were evaluated in PXB-cells® based 3D tissue: CYP1A2, OATP1B1 and CYP3A4. CYP1A2 and OATP1B1 have been reported to be difficult to maintain its long-term expression; and CYP3A4 is generally known as the most important drug metabolism related enzyme. Gene expression levels in 3D bio-printed liver tissue based on PXB-cells® were maintained for about 1 month.

Ishida, Y. et al. PLoS One. 2020; 15(9): e0239540.

Chemical structure of Aflatoxin B1
Chemical structure of Aflatoxin B1

 “Detection of acute toxicity of aflatoxin B1 to human hepatocytes in vitro and in vivo using chimeric mice with humanized livers

Ishida et al. paper highlights that the quality of PXB-cells® allows the study of long-term exposure (6 or 14 days) at a low dose and shows time-dependent cytotoxicity of relatively low levels of aflatoxin B1. We have reviewed this publication before:

Morita, K. et al. Sci Rep. 2020; 10(1):13139.

“Decomposition profile data analysis of multiple drug effects identifies endoplasmic reticulum stress‑inducing ability as an unrecognized factor”

Morita et al. focused on the ability of drugs to induce endoplasmic reticulum (ER) stress. Some drugs overwhelm relevant compensatory machinery and can cause drug-induced liver injury (DILI). Induction of ER stress was studies in MCF7 cells and compared to PXB-cells®, HepG2 and HuH7. PXB-cells® were selected because their normal metabolic activities and reactivity to compounds are relatively well preserved compared to those of hepatic cancer-derived cell lines (HepG2 and HuH7). Thus, the study of manifestations of ER stress induced by the candidate drugs was expected to be more relevant in PXB-cells®.

Kohara, H. et al. Toxicol Sci. 2020; 173 (2), 347-361.

Cholestasis and DILI schematic
Cholestasis and DILI schematic

“High-throughput screening to evaluate inhibition of bile acid transporters using human hepatocytes isolated from chimeric mice”

Kohara et al. discuss that cholestasis resulting from hepatic bile acid efflux transporter inhibition may contribute to drug induced liver injury (DILI). Authors showed that in terms of gene expression comparison, PXB-cells resembled human liver tissue more closely than HepaRG or HepG2 cells at all time points tested and still became closer to human liver tissue throughout the culture period. The ADME gene expression of PXB-cells® became closer to that of human liver tissue over time, whereas PHHs did not become closer.

Three publications below use PXB-cells® in HBV research. Please, note that in some cases authors call PXB-cells® “primary human hepatocytes”, without mentioning their trade name (PXB-cells®).

Luo, J. et al. PLoS Pathog. 2020; 16(3):e1008459.

“… primary human hepatocytes (the PXB-cells), which do not divide in culture, more closely mimic the human hepatocytes in vivo than hepatoma cells, and of HepG2-NTCP cells…”

Role of Hepatitis B virus capsid phosphorylation in nucleocapsid disassembly and covalently closed circular DNA formation”

Luo et al. propose a model whereby rephosphorylation of HBc at both N-terminal domain and C-terminal domain (CTD) by the packaged CDK2 (cyclin-dependent kinase 2), following CTD dephosphorylation during nucleocapsid (NC) maturation, facilitates uncoating and CCC DNA formation by destabilizing mature NCs. (Authors used PXB-cells® for their study)

Matsunaga, S. et al. iScience. 2020; 23(3): 100867.

“Engineering Cellular Biosensors with Customizable Antiviral Responses Targeting Hepatitis B Virus”

Matsunaga et al. study establishes the concepts of ‘‘engineered immunity’’ where the synNotch (synthetic Notch) platform is utilized for cellular immunotherapy against viral infections. PXB-cells® were used to assess the antiviral activity of the IFNß-HiBiT (interferon ß tagged at their carboxy terminals with the 11-amino-acid luminescent tag HiBiT) produced by α-HBs SNR (anti-HBs synNotch receptor) cells. Reduced HBV DNA in the medium reflected the suppression of viral replication. These results indicate that α-HBs SNR cells can initiate an effective synthetic anti-viral innate immune response following the recognition of HBs antigen. Later, α -HBs SNR cells were incorporated with neutralizing antibody gene. Secreted antibody inhibited preS1 peptide-NTCP interaction and was also suppressed HBV infection in PXB cells®. 

Chen, S.-W. et al. Sci Rep. 2020; 10(1):14349.

“Modulation of hepatitis B virus infection by epidermal growth factor secreted from liver sinusoidal endothelial cells”

Chen et al. used PXB-cells® to study modulation of HBV infection by epidermal growth factor (EGF). With the increase of EGF dose, HBV infection (HBV DNA) initially enhanced in the FBS-free condition. HBV infection gradually reduced with further increase of EGF concentration. (In this publication PXB-cells® are referred as “primary human hepatocytes”).

Finally, the paper below is a nice summary characterizing PXB-cells® and showing long lasting high activity of metabolizing enzymes and transporters:

Yamasaki, C. et al. PLoS One. 2020; 15(9):e0237809.

“Culture density contributes to hepatic functions of fresh human hepatocytes isolated from chimeric mice with humanized livers: Novel, long-term, functional two-dimensional in vitro tool for developing new drugs”

Morphology of PXB-cells in culture
Morphology of PXB-cells in culture

Yamasaki et al. show the results of the evaluation of human albumin secretion, urea synthesis, cytochrome P450 (CYP) activities, and CYP, UGT, and transporter mRNA expression in PXB-cells® from three different donors. Authors prove PXB-cells® usability and high performance for at least three weeks after isolation. Localization and function of MRP2, NTCP, and BSEP in PXB-cells® was confirmed. It was shown that the high-density cells culture maintained high expressions of some transcriptional factors (HNF4α, PXR, and FXR).

Summary is prepared by Dr. S. Sapelnikova.