Strategies for immortalization of primary hepatocytes

Novel Immortalized Human Multipotent Mesenchymal Stromal Cell Line for Studying Hormonal Signaling

Multipotent mesenchymal stromal cells (MSCs) integrate hormone and neuromediator signaling to coordinate tissue homeostasis, tissue renewal and regeneration. To facilitate the investigation of MSC biology, stable immortalized cell lines are created (e.g., commercially available ASC52telo). However, the ASC52telo cell line has an impaired adipogenic ability and a depressed response to hormones, including 5-HT, GABA, glutamate, noradrenaline, PTH and insulin compared to primary cells. This markedly reduces the potential of the ASC52telo cell line in studying the mechanisms of hormonal control of MSC's physiology. Here, we have established a novel immortalized culture of adipose tissue-derived MSCs via forced telomerase expression after lentiviral transduction. These immortalized cell cultures demonstrate high proliferative potential (up to 40 passages), delayed senescence, as well as preserved primary culture-like functional activity (sensitivity to hormones, ability to hormonal sensitization and differentiation) and immunophenotype up to 17-26 passages. Meanwhile, primary adipose tissue-derived MSCs usually irreversibly lose their properties by 8-10 passages. Observed characteristics of reported immortalized human MSC cultures make them a feasible model for studying molecular mechanisms, which regulate the functional activities of these cells, especially when primary cultures or commercially available cell lines are not appropriate.

Microscale tissue engineering of liver lobule models: advancements and applications

The liver, as the body's primary organ for maintaining internal balance, is composed of numerous hexagonal liver lobules, each sharing a uniform architectural framework. These liver lobules serve as the basic structural and functional units of the liver, comprised of central veins, hepatic plates, hepatic sinusoids, and minute bile ducts. Meanwhile, within liver lobules, distinct regions of hepatocytes carry out diverse functions. The in vitro construction of liver lobule models, faithfully replicating their structure and function, holds paramount significance for research in liver development and diseases. Presently, two primary technologies for constructing liver lobule models dominate the field: 3D bioprinting and microfluidic techniques. 3D bioprinting enables precise deposition of cells and biomaterials, while microfluidics facilitates targeted transport of cells or other culture materials to specified locations, effectively managing culture media input and output through micro-pump control, enabling dynamic simulations of liver lobules. In this comprehensive review, we provide an overview of the biomaterials, cells, and manufacturing methods employed by recent researchers in constructing liver lobule models. Our aim is to explore strategies and technologies that closely emulate the authentic structure and function of liver lobules, offering invaluable insights for research into liver diseases, drug screening, drug toxicity assessment, and cell replacement therapy.

Bioreactors, scaffolds and microcarriers and in vitro meat production-current obstacles and potential solutions

In vitro meat production presents a potential viable alternative for meat consumption, which could provide the consumer with a product indistinguishable from the original, with very similar nutritional and culinary values. Indeed, the alternative products currently accessible often lack comparable nutritional value or culinary attributes to their animal-derived counterparts. This creates challenges for their global acceptance, particularly in countries where meat consumption holds cultural significance. However, while cultured meat research has been progressing rapidly in recent years, some significant obstacles still need to be overcome before its possible commercialization. Hence, this review summarizes the most current knowledge regarding the history of cultured meat, the currently used cell sources and methods used for the purpose of in vitro meat production, with particular focus on the role of bioreactors, scaffolds and microcarriers in overcoming the current obstacles. The authors put the potential microcarrier and scaffold-based solutions in a context, discussing the ways in which they can impact the way forward for the technology, including the use of considering the potential practical and societal barriers to implementing it as a viable food source worldwide.

Exosomal MicroRNA and Protein Profiles of Hepatitis B Virus-Related Hepatocellular Carcinoma Cells

Infection with hepatitis B virus (HBV) is a main risk factor for hepatocellular carcinoma (HCC). Extracellular vesicles, such as exosomes, play an important role in tumor development and metastasis, including regulation of HBV-related HCC. In this study, we have characterized exosome microRNA and proteins released in vitro from hepatitis B virus (HBV)-related HCC cell lines SNU-423 and SNU-182 and immortalized normal hepatocyte cell lines (THLE2 and THLE3) using microRNA sequencing and mass spectrometry. Bioinformatics, including functional enrichment and network analysis, combined with survival analysis using data related to HCC in The Cancer Genome Atlas (TCGA) database, were applied to examine the prognostic significance of the results. More than 40 microRNAs and 200 proteins were significantly dysregulated (p < 0.05) in the exosomes released from HCC cells in comparison with the normal liver cells. The functional analysis of the differentially expressed exosomal miRNAs (i.e., mir-483, mir-133a, mir-34a, mir-155, mir-183, mir-182), their predicted targets, and exosomal differentially expressed proteins (i.e., POSTN, STAM, EXOC8, SNX9, COL1A2, IDH1, FN1) showed correlation with pathways associated with HBV, virus activity and invasion, exosome formation and adhesion, and exogenous protein binding. The results from this study may help in our understanding of the role of HBV infection in the development of HCC and in the development of new targets for treatment or non-invasive predictive biomarkers of HCC.

Integrated analysis of lncRNA/circRNA-miRNA-mRNA in the proliferative phase of liver regeneration in mice with liver fibrosis

BACKGROUND

Non-coding RNAs play important roles in liver regeneration; however, their functions and mechanisms of action in the regeneration of fibrotic liver have not been elucidated. We aimed to clarify the expression patterns and regulatory functions of lncRNAs, circRNAs, miRNAs, and mRNAs in the proliferative phase of fibrotic liver regeneration.

METHODS

Based on a mouse model of liver fibrosis with 70% hepatectomy, whole-transcriptome profiling was performed using high-throughput sequencing on samples collected at 0, 12, 24, 48, and 72 h after hepatectomy. Hub genes were selected by weighted gene co-expression network analysis and subjected to enrichment analysis. Integrated analysis was performed to reveal the interactions of differentially expressed (DE) lncRNAs, circRNAs, miRNAs, and mRNAs, and to construct lncRNA-mRNA cis- and trans-regulatory networks and lncRNA/circRNA-miRNA-mRNA ceRNA regulatory networks. Real-Time quantitative PCR was used to validate part of the ceRNA network.

RESULTS

A total of 1,329 lncRNAs, 48 circRNAs, 167 miRNAs, and 6,458 mRNAs were differentially expressed, including 812 hub genes. Based on these DE RNAs, we examined several mechanisms of ncRNA regulatory networks, including lncRNA cis and trans interactions, circRNA parental genes, and ceRNA pathways. We constructed a cis-regulatory core network consisting of 64 lncRNA-mRNA pairs (53 DE lncRNAs and 58 hub genes), a trans-regulatory core network consisting of 103 lncRNA-mRNA pairs (18 DE lncRNAs and 85 hub genes), a lncRNA-miRNA-mRNA ceRNA core regulatory network (20 DE lncRNAs, 12 DE miRNAs, and 33 mRNAs), and a circRNA-miRNA-mRNA ceRNA core regulatory network (5 DE circRNAs, 5 DE miRNAs, and 39 mRNAs).

CONCLUSIONS

These results reveal the expression patterns of lncRNAs, circRNAs, miRNAs, and mRNAs in the proliferative phase of fibrotic liver regeneration, as well as core regulatory networks of mRNAs and non-coding RNAs underlying liver regeneration. The findings provide insights into molecular mechanisms that may be useful in developing new therapeutic approaches to ameliorate diseases that are characterized by liver fibrosis, which would be beneficial for the prevention of liver failure and treatment of liver cancer.

The pharmacology and mechanisms of traditional Chinese medicine in promoting liver regeneration: A new therapeutic option

BACKGROUND

The liver is renowned for its remarkable regenerative capacity to restore its structure, size and function after various types of liver injury. However, in patients with end-stage liver disease, the regenerative capacity is inhibited and liver transplantation is the only option. Considering the limitations of liver transplantation, promoting liver regeneration is suggested as a new therapeutic strategy for liver disease. Traditional Chinese medicine (TCM) has a long history of preventing and treating various liver diseases, and some of them have been proven to be effective in promoting liver regeneration, suggesting the therapeutic potential in liver diseases.

PURPOSE

This review aims to summarize the molecular mechanisms of liver regeneration and the pro-regenerative activity and mechanism of TCM formulas, extracts and active ingredients.

METHODS

We conducted a systematic search in PubMed, Web of Science and the Cochrane Library databases using "TCM", "liver regeneration" or their synonyms as keywords, and classified and summarized the retrieved literature. The PRISMA guidelines were followed.

RESULTS

Forty-one research articles met the themes of this review and previous critical studies were also reviewed to provide essential background information. Current evidences indicate that various TCM formulas, extracts and active ingredients have the effect on stimulating liver regeneration through modulating JAK/STAT, Hippo, PI3K/Akt and other signaling pathways. Besides, the mechanisms of liver regeneration, the limitation of existing studies and the application prospect of TCM to promote liver regeneration are also outlined and discussed in this review.

CONCLUSION

This review supports TCM as new potential therapeutic options for promoting liver regeneration and repair of the failing liver, although extensive pharmacokinetic and toxicological studies, as well as elaborate clinical trials, are still needed to demonstrate safety and efficacy.

Integration of ATAC-Seq and RNA-Seq reveals FOSL2 drives human liver progenitor-like cell aging by regulating inflammatory factors

BACKGROUND

Human primary hepatocytes (PHCs) are considered to be the best cell source for cell-based therapies for the treatment of end-stage liver disease and acute liver failure. To obtain sufficient and high-quality functional human hepatocytes, we have established a strategy to dedifferentiate human PHCs into expandable hepatocyte-derived liver progenitor-like cells (HepLPCs) through in vitro chemical reprogramming. However, the reduced proliferative capacity of HepLPCs after long-term culture still limits their utility. Therefore, in this study, we attempted to explore the potential mechanism related to the proliferative ability of HepLPCs in vitro culture.

RESULTS

In this study, analysis of assay for transposase accessible chromatin using sequencing (ATAC-seq) and RNA sequencing (RNA-seq) were performed for PHCs, proliferative HepLPCs (pro-HepLPCs) and late-passage HepLPCs (lp-HepLPCs). Genome-wide transcriptional and chromatin accessibility changes during the conversion and long-term culture of HepLPCs were studied. We found that lp-HepLPCs exhibited an aged phenotype characterized by the activation of inflammatory factors. Epigenetic changes were found to be consistent with our gene expression findings, with promoter and distal regions of many inflammatory-related genes showing increased accessibility in the lp-HepLPCs. FOSL2, a member of the AP-1 family, was found to be highly enriched in the distal regions with increased accessibility in lp-HepLPCs. Its depletion attenuated the expression of aging- and senescence-associated secretory phenotype (SASP)-related genes and resulted in a partial improvement of the aging phenotype in lp-HepLPCs.

CONCLUSIONS

FOSL2 may drive the aging of HepLPCs by regulating inflammatory factors and its depletion may attenuate this phenotypic shift. This study provides a novel and promising approach for the long-term in vitro culture of HepLPCs.

Immortalized cell lines derived from dental/odontogenic tissue

Stem cells derived from dental/odontogenic tissue have the property of multiple differentiation and are prospective in tooth regenerative medicine and cellular and molecular studies. However, in the face of cellular senescence soon in vitro, the proliferation ability of the cells is limited, so studies are hindered to some extent. Fortunately, immortalization strategies are expected to solve the above issues. Cellular immortalization is that cells are immortalized by introducing oncogenes, human telomerase reverse transcriptase genes (hTERT), or miscellaneous immortalization genes to get unlimited proliferation. At present, a variety of immortalized stem cells from dental/odontogenic tissue has been successfully generated, such as dental pulp stem cells (DPSCs), periodontal ligament cells (PDLs), stem cells from human exfoliated deciduous teeth (SHEDs), dental papilla cells (DPCs), and tooth germ mesenchymal cells (TGMCs). This review summarized establishment and applications of immortalized stem cells from dental/odontogenic tissues and then discussed the advantages and challenges of immortalization.

Bioengineering liver microtissues for modeling non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) has become the world's most common chronic liver disease. However, due to the lack of reliable in vitro NAFLD models, drug development studies have faced many limitations, and there is no food and drug administration-approved medicine for NAFLD treatment. A functional biomimetic in vitro human liver model requires an optimized natural microenvironment using appropriate cellular composition, to provide constructive cell-cell interactions, and niche-specific bio-molecules to supply crucial cues as cell-matrix interplay. Such a suitable liver model could employ appropriate and desired biochemical, mechanical, and physical properties similar to native tissue. Moreover, bioengineered three-dimensional tissues, specially microtissues and organoids, and more recently using infusion-based cultivation systems such as microfluidics can mimic natural tissue conditions and facilitate the exchange of nutrients and soluble factors to improve physiological function in the in vitro generated constructs. This review highlights the key players involved in NAFLD initiation and progression and discussed the available cells and matrices for in vitro NAFLD modeling. The strategies for optimizing the liver microenvironment to generate a powerful and biomimetic in vitro NAFLD model were described as well. Finally, the current challenges and future perospective for promotion in this subject were discussed.

Telomerase-mediated immortalization of human vaginal wall fibroblasts derived from patients with pelvic organ prolapse

BACKGROUND

Extracellular matrix (ECM) remodeling is the most important pathomechanism of pelvic organ prolapse (POP). Fibroblasts are the key to ECM regulation. The passaging capacity of human vaginal wall fibroblasts (hVWFs) is limited in vitro . Here, we aimed to immortalize hVWFs through the introduction of human telomerase reverse transcriptase (hTERT).

METHODS

Primary cells were derived from the vaginal wall tissue of patients with POP. Cellular senescence was detected via senescence-associated β-galactosidase staining. We employed a lentiviral transfection vector to stably express hTERT in hVWFs at passage 3, generating immortalized hVWFs (i-hVWFs). We then assessed cellular proliferation via the CCK-8 and EdU assays as well as cellular migration via wound healing assays. G-banded chromosome karyotypic analysis was performed to evaluate chromosomal karyotype stability. Finally, cellular tumorigenesis capacity was assessed in nude mice. A two-tailed Student's t test was used to compare differences between the two groups.

RESULTS

Our results showed that senescence of primary hVWFs significantly increased from passage seven. From passage 11, hVWFs showed a significantly higher senescence percentage than i-hVWFs. During the continuous passage, i-hVWFs presented stability in proliferation, migration capacity, expression of ECM regulation-related genes, and chromosome karyotype. In vivo tumorigenesis was absent in i-hVWFs.

CONCLUSIONS

The senescence of hVWFs significantly increased from the seventh passage, and we successfully used hTERT to immortalize hVWFs derived from patients with POP. Studies on POP that require a long-lived hVWF line will benefit from our technique.

Differentiated mouse kidney tubuloids as a novel in vitro model to study collecting duct physiology

Kidney tubuloids are cell models that are derived from human or mouse renal epithelial cells and show high similarities with their in vivo counterparts. Tubuloids grow polarized in 3D, allow for long-term expansion, and represent multiple segments of the nephron, as shown by their gene expression pattern. In addition, human tubuloids form tight, functional barriers and have been succesfully used for drug testing. Our knowledge of mouse tubuloids, on the other hand, is only minimal. In this study, we further characterized mouse tubuloids and differentiated them towards the collecting duct, which led to a significant upregulation of collecting duct-specific mRNAs of genes and protein expression, including the water channel AQP2 and the sodium channel ENaC. Differentiation resulted in polarized expression of collecting duct water channels AQP2 and AQP3. Also, a physiological response to desmopressin and forskolin stimulation by translocation of AQP2 to the apical membrane was demonstrated. Furthermore, amiloride-sensitive ENaC-mediated sodium uptake was shown in differentiated tubuloids using radioactive tracer sodium. This study demonstrates that mouse tubuloids can be differentiated towards the collecting duct and exhibit collecting duct-specific function. This illustrates the potential use of mouse kidney tubuloids as novel in vitro models to study (patho)physiology of kidney diseases.

Generation of Functional Immortalized Human Corneal Stromal Stem Cells

In addition to their therapeutic potential in regenerative medicine, human corneal stromal stem cells (CSSCs) could serve as a powerful tool for drug discovery and development. Variations from different donors, their isolation method, and their limited life span in culture hinder the utility of primary human CSSCs. To address these limitations, this study aims to establish and characterize immortalized CSSC lines (imCSSC) generated from primary human CSSCs. Primary CSSCs (pCSSC), isolated from human adult corneoscleral tissue, were transduced with ectopic expression of hTERT, c-MYC, or the large T antigen of the Simian virus 40 (SV40T) to generate imCSSC. Cellular morphology, proliferation capacity, and expression of CSSCs specific surface markers were investigated in all cell lines, including TNFAIP6 gene expression levels in vitro, a known biomarker of in vivo anti-inflammatory efficacy. SV40T-overexpressing imCSSC successfully extended the lifespan of pCSSC while retaining a similar morphology, proliferative capacity, multilineage differentiation potential, and anti-inflammatory properties. The current study serves as a proof-of-concept that immortalization of CSSCs could enable a large-scale source of CSSC for use in regenerative medicine.

Primary-like Human Hepatocytes Genetically Engineered to Obtain Proliferation Competence as a Capable Application for Energy Metabolism Experiments in In Vitro Oncologic Liver Models

Simple Summary

Fatty liver disease is an increasing health concern in Westernized countries. A fatty liver can lead to hepatocellular carcinoma (HCC), a type of liver cancer arising from hepatocytes, the major cells of the liver. How HCC may develop from the fatty liver is not known, and good cellular systems to investigate this are lacking. Recently, hepatocytes that can multiply continuously have been generated and suggested for hepatocyte research. In this study, we compared these continuously multiplying human hepatocytes to normal human hepatocytes and liver cancer cells, both within the state of fatty liver or not. We identified that these multiplying hepatocytes displayed many similarities to the liver cancer cells in terms of energy metabolism and concluded that these hepatocytes could be a pre-cancer model for liver cancer research and would be a valuable tool for HCC research.

Abstract

Non-alcoholic fatty liver disease (NAFLD), characterized by lipid accumulation in the liver, is the most common cause of liver diseases in Western countries. NAFLD is a major risk factor for developing hepatocellular carcinoma (HCC); however, in vitro evaluation of hepatic cancerogenesis fails due to a lack of liver models displaying a proliferation of hepatocytes. Originally designed to overcome primary human hepatocyte (PHH) shortages, upcyte hepatocytes were engineered to obtain continuous proliferation and, therefore, could be a suitable tool for HCC research. We generated upcyte hepatocytes, termed HepaFH3 cells, and compared their metabolic characteristics to HepG2 hepatoma cells and PHHs isolated from resected livers. For displaying NAFLD-related HCCs, we induced steatosis in all liver models. Lipid accumulation, lipotoxicity and energy metabolism were characterized using biochemical assays and Western blot analysis. We showed that proliferating HepaFH3 cells resemble HepG2, both showing a higher glucose uptake rate, lactate levels and metabolic rate compared to PHHs. Confluent HepaFH3 cells displayed some similarities to PHHs, including higher levels of the transaminases AST and ALT compared to proliferating HepaFH3 cells. We recommend proliferating HepaFH3 cells as a pre-malignant cellular model for HCC research, while confluent HepaFH3 cells could serve as PHH surrogates for energy metabolism studies.

Hepatic Models in Precision Medicine: An African Perspective on Pharmacovigilance

Pharmaceuticals are indispensable to healthcare as the burgeoning global population is challenged by diseases. The African continent harbors unparalleled genetic diversity, yet remains largely underrepresented in pharmaceutical research and development, which has serious implications for pharmaceuticals approved for use within the African population. Adverse drug reactions (ADRs) are often underpinned by unique variations in genes encoding the enzymes responsible for their uptake, metabolism, and clearance. As an example, individuals of African descent (14–34%) harbor an exclusive genetic variant in the gene encoding a liver metabolizing enzyme (CYP2D6) which reduces the efficacy of the breast cancer chemotherapeutic Tamoxifen. However, CYP2D6 genotyping is not required prior to dispensing Tamoxifen in sub-Saharan Africa. Pharmacogenomics is fundamental to precision medicine and the absence of its implementation suggests that Africa has, to date, been largely excluded from the global narrative around stratified healthcare. Models which could address this need, include primary human hepatocytes, immortalized hepatic cell lines, and induced pluripotent stem cell (iPSC) derived hepatocyte-like cells. Of these, iPSCs, are promising as a functional in vitro model for the empirical evaluation of drug metabolism. The scale with which pharmaceutically relevant African genetic variants can be stratified, the expediency with which these platforms can be established, and their subsequent sustainability suggest that they will have an important role to play in the democratization of stratified healthcare in Africa. Here we discuss the requirement for African hepatic models, and their implications for the future of pharmacovigilance on the African continent.

In vitro models for non-alcoholic fatty liver disease: Emerging platforms and their applications

Non-alcoholic fatty liver disease (NAFLD) represents a global healthcare challenge, affecting 1 in 4 adults, and death rates are predicted to rise inexorably. The progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. However, no medical treatments are licensed for NAFLD-NASH. Identifying efficacious therapies has been hindered by the complexity of disease pathogenesis, a paucity of predictive preclinical models and inadequate validation of pharmacological targets in humans. The development of clinically relevant in vitro models of the disease will pave the way to overcome these challenges. Currently, the combined application of emerging technologies (e.g., organ-on-a-chip/microphysiological systems) and control engineering approaches promises to unravel NAFLD biology and deliver tractable treatment candidates. In this review, we will describe advances in preclinical models for NAFLD-NASH, the recent introduction of novel technologies in this space, and their importance for drug discovery endeavors in the future.

In vitro models for non-alcoholic fatty liver disease: Emerging platforms and their applications

Non-alcoholic fatty liver disease (NAFLD) represents a global healthcare challenge, affecting 1 in 4 adults, and death rates are predicted to rise inexorably. The progressive form of NAFLD, non-alcoholic steatohepatitis (NASH), can lead to fibrosis, cirrhosis, and hepatocellular carcinoma. However, no medical treatments are licensed for NAFLD-NASH. Identifying efficacious therapies has been hindered by the complexity of disease pathogenesis, a paucity of predictive preclinical models and inadequate validation of pharmacological targets in humans. The development of clinically relevant in vitro models of the disease will pave the way to overcome these challenges. Currently, the combined application of emerging technologies (e.g., organ-on-a-chip/microphysiological systems) and control engineering approaches promises to unravel NAFLD biology and deliver tractable treatment candidates. In this review, we will describe advances in preclinical models for NAFLD-NASH, the recent introduction of novel technologies in this space, and their importance for drug discovery endeavors in the future.

Food safety considerations and research priorities for the cultured meat and seafood industry

Cell-cultured meat and seafood offer a sustainable opportunity to meet the world's increasing demand for protein in a climate-changed world. A responsible, data-driven approach to assess and demonstrate safety of cell-cultured meat and seafood can support consumer acceptance and help fully realize the potential of these products. As an initial step toward a thorough demonstration of safety, this review identifies hazards that could be introduced during manufacturing, evaluates applicability of existing safety assessment approaches, and highlights research priorities that could support safe commercialization. Input was gathered from members of the cultured meat and seafood industry, researchers, regulators, and food safety experts. A series of workshops were held with 87 industry representatives and researchers to create a modular manufacturing process diagram, which served as a framework to identify potential chemical and biological hazards along the steps of the manufacturing process that could affect the safety of a final food product. Interviews and feedback on draft documents validated the process diagram and supported hazard identification and evaluation of applicable safety methods. Most hazards are not expected to be novel; therefore, safety assessment methods from a range of fields, such as conventional and novel foods, foods produced from biotechnology, pharmaceuticals, and so forth, are likely to be applicable. However, additional assessment of novel inputs or products with significant differences from existing foods may be necessary. Further research on the safety of the inputs and associated residues, potential for contamination, and development of standardized safety assessment approaches (particularly animal-free methods) is recommended.

In-vitro meat: a promising solution for sustainability of meat sector

The in-vitro meat is a novel concept in food biotechnology comprising field of tissue engineering and cellular agriculture. It involves production of edible biomass by in-vitro culture of stem cells harvested from the muscle of live animals by self-organizing or scaffolding methodology. It is considered as efficient, environmental friendly, better ensuring public safety and nutritional security, as well as ethical way of producing meat. Source of stem cells, media ingredients, supply of large size bioreactors, skilled manpower, sanitary requirements, production of products with similar sensory and textural attributes as of conventional meat, consumer acceptance, and proper set up of regulatory framework are challenges faced in commercialization and consumer acceptance of in-vitro meat. To realize any perceivable change in various socio-economic and environmental spheres, the technology should be commercialized and should be cost-effective as conventional meat and widely accepted among consumers. The new challenges of increasing demand of meat with the increasing population could be fulfill by the establishment of in-vitro meat production at large scale and its popularization. The adoption of in-vitro meat production at an industrial scale will lead to self-sufficiency in the developed world.

Screening and identification of dominant monoclonal HepG2 cell strain with 1.3-fold HBV genome

BACKGROUND

Hepatitis B virus (HBV) infection model in vitro is the basis for studying HBV life cycle and pathogenesis and for drug screening. With the clinical anti-HBV therapy entering the new trend of "functional cure" and "complete cure", there is an urgent need for cell models that can stably simulate the transcription mechanism of covalently closed circular DNA (cccDNA) and the role of hepatitis B virus X protein (HBx). The 1.3-fold HBV genome contains all the biological information of HBV. It can start the transcription process by its own promoter, support the formation of cccDNA, and complete viral replication, which is closest to the life cycle of HBV in vivo. Lentivirus transfection is a technology that takes lentivirus as vector and introduces foreign molecules such as DNA and RNA into eukaryotic cells, which can form stable transfection.

AIM

To construct a HepG2 cell model with 1.3-fold HBV genome by lentivirus transfection technology, and to screen and identify the dominant monoclonal strain that can stably and efficiently express HBV biomarkers.

METHODS

A lentiviral plasmid containing 1.3-fold HBV genome information was constructed, and the recombinant lentivirus culture was used to infect HepG2 cells at the optimal multiplicity of infection (MOI). Blasticidin (BSD) was used to select HepG2 cell strains (1.3-fold HBV-HepG2) stably integrating the 1.3-fold HBV genome, and then the HBV in the cell model was identified by PCR. HepG2 cells stably carrying the 1.3-fold HBV genome were cultured and nine candidate positive monoclones were selected. The flanking sequences of each monoclonal cell were sequenced to determine the insertion position of the corresponding HBV genome in the genome of HepG2 cells. The most dominant monoclones were selected according to the expression levels of HBsAg and HBeAg. The expression levels and stability of HBsAg, HBeAg, HBx, cccDNA, and HBV DNA in HepG2 cells stably carrying the 1.3-fold HBV genome were compared.

RESULTS

The lentiviral plasmid plenti-bsd-1.3-fold HBV was used to infect HepG2 cells at an MOI of 30. After 72 h, BSD (final concentration 1 μg/mL) was added for screening. After 15-20 d of continuous culture, stable 1.3-fold HBV-HepG2 cell line was obtained. HBV DNA sequence was then identified by PCR. Among the nine selected candidate positive monoclones, A14, in which the 1.3-fold HBV genome was inserted into the HepG2 genome at 1:166461695-166461715 (named HepGA14), had the highest expression levels of HBsAg and HBeAg at 24.28 IU/mL and 39.62 NCU/mL, respectively. HepGA14 can stably and highly express HBV biomarkers. Compared with HepG2.2.15 cell line, the expression levels of HBx and cccDNA in Hepga14 dominant monoclonal line in 1-20 passages were significantly higher (P < 0.05).

CONCLUSION

We have successfully constructed and screened HepGA14, a dominant monoclonal HepG cell strain with HBV 1.3-fold genome, which lays a good foundation for further research of HBV-host relationship and pathogenesis as well as for drug screening.

Generation, Characterization, and Application of Inducible Proliferative Adult Human Epicardium-Derived Cells

RATIONALE

In recent decades, the great potential of human epicardium-derived cells (EPDCs) as an endogenous cell source for cardiac regeneration has been recognized. The limited availability and low proliferation capacity of primary human EPDCs and phenotypic differences between EPDCs obtained from different individuals hampers their reproducible use for experimental studies.

AIM

To generate and characterize inducible proliferative adult human EPDCs for use in fundamental and applied research.

METHODS AND RESULTS

Inducible proliferation of human EPDCs was achieved by doxycycline-controlled expression of simian virus 40 large T antigen (LT) with a repressor-based lentiviral Tet-On system. In the presence of doxycycline, these inducible EPDCs (iEPDCs) displayed high and long-term proliferation capacity. After doxycycline removal, LT expression ceased and the iEPDCs regained their cuboidal epithelial morphology. Similar to primary EPDCs, iEPDCs underwent an epithelial-to-mesenchymal transition (EMT) after stimulation with transforming growth factor β3. This was confirmed by reverse transcription-quantitative polymerase chain reaction analysis of epithelial and mesenchymal marker gene expression and (immuno) cytochemical staining. Collagen gel-based cell invasion assays demonstrated that mesenchymal iEPDCs, like primary EPDCs, possess increased invasion and migration capacities as compared to their epithelial counterparts. Mesenchymal iEPDCs co-cultured with sympathetic ganglia stimulated neurite outgrowth similarly to primary EPDCs.

CONCLUSION

Using an inducible LT expression system, inducible proliferative adult human EPDCs were generated displaying high proliferative capacity in the presence of doxycycline. These iEPDCs maintain essential epicardial characteristics with respect to morphology, EMT ability, and paracrine signaling following doxycycline removal. This renders iEPDCs a highly useful new in vitro model for studying human epicardial properties.

Host-targeted Interventions as an Exciting Opportunity to Combat Malaria

Terminal and benign diseases alike in adults, children, pregnant women, and others are successfully treated by pharmacological inhibitors that target human enzymes. Despite extensive global efforts to fight malaria, the disease continues to be a massive worldwide health burden, and new interventional strategies are needed. Current drugs and vector control strategies have contributed to the reduction in malaria deaths over the past 10 years, but progress toward eradication has waned in recent years. Resistance to antimalarial drugs is a substantial and growing problem. Moreover, targeting dormant forms of the malaria parasite Plasmodium vivax is only possible with two approved drugs, which are both contraindicated for individuals with glucose-6-phosphate dehydrogenase deficiency and in pregnant women. Plasmodium parasites are obligate intracellular parasites and thus have specific and absolute requirements of their hosts. Growing evidence has described these host necessities, paving the way for opportunities to pharmacologically target host factors to eliminate Plasmodium infection. Here, we describe progress in malaria research and adjacent fields and discuss key challenges that remain in implementing host-directed therapy against malaria.

Cell and Tissue Therapy for the Treatment of Chronic Liver Disease

Liver disease is an important clinical problem, impacting 600 million people worldwide. It is the 11th-leading cause of death in the world. Despite constant improvement in treatment and diagnostics, the aging population and accumulated risk factors led to increased morbidity due to nonalcoholic fatty liver disease and steatohepatitis. Liver transplantation, first established in the 1960s, is the second-most-common solid organ transplantation and is the gold standard for the treatment of liver failure. However, less than 10% of the global need for liver transplantation is met at the current rates of transplantation due to the paucity of available organs. Cell- and tissue-based therapies present an alternative to organ transplantation. This review surveys the approaches and tools that have been developed, discusses the distinctive challenges that exist for cell- and tissue-based therapies, and examines the future directions of regenerative therapies for the treatment of liver disease.

Liver organoid as a 3D in vitro model for drug validation and toxicity assessment

The past decade has seen many advancements in the development of three-dimensional (3D) in vitro models in pharmaceutical sciences and industry. Specifically, organoids present a self-organising, self-renewing and more physiologically relevant model than conventional two-dimensional (2D) cell cultures. Liver organoids have been developed from a variety of cell sources, including stem cells, cell lines and primary cells. They have potential for modelling patient-specific disease and establishing personalised therapeutic approaches. Additionally, liver organoids have been used to test drug efficacy and toxicity. Herein we summarise cell sources for generating liver organoids, the advantages and limitations of each cell type, as well as the application of the organoids in modelling liver diseases. We focus on the use of liver organoids as tools for drug validation and toxicity assessment.

Creating cell lines for mimicking diseases

Cell lines can be good models for the disease they are derived from but can also be used to study general physiological and pathological processes. They can also be used to generate cell models of diseases when primary cultures are not available. Recent genome editing tools have been very promising tools toward creating cell models to mimic diseases in vitro. In this chapter, we highlight techniques used to obtain genome-edited cell lines, including cell line selection, transfection and gene editing tools available, together with methods of phenotype characterization and, lastly, a few examples of how in vitro disease models were created using CRISPR-Cas9.

In Vitro and In Vivo Models of Non-Alcoholic Fatty Liver Disease: A Critical Appraisal

Non-alcoholic fatty liver disease (NAFLD), including non-alcoholic fatty liver (NAFL) and non-alcoholic steatohepatitis (NASH), represents the hepatic manifestation of obesity and metabolic syndrome. Due to the spread of the obesity epidemic, NAFLD is becoming the most common chronic liver disease and one of the principal indications for liver transplantation. However, no pharmacological treatment is currently approved to prevent the outbreak of NASH, which leads to fibrosis and cirrhosis. Preclinical research is required to improve our knowledge of NAFLD physiopathology and to identify new therapeutic targets. In the present review, we summarize advances in NAFLD preclinical models from cellular models, including new bioengineered platforms, to in vivo models, with a particular focus on genetic and dietary mouse models. We aim to discuss the advantages and limits of these different models.

Current Perspective: 3D Spheroid Models Utilizing Human-Based Cells for Investigating Metabolism-Dependent Drug-Induced Liver Injury

Drug-induced liver injury (DILI) remains a leading cause for the withdrawal of approved drugs. This has significant financial implications for pharmaceutical companies, places increasing strain on global health services, and causes harm to patients. For these reasons, it is essential that in-vitro liver models are capable of detecting DILI-positive compounds and their underlying mechanisms, prior to their approval and administration to patients or volunteers in clinical trials. Metabolism-dependent DILI is an important mechanism of drug-induced toxicity, which often involves the CYP450 family of enzymes, and is associated with the production of a chemically reactive metabolite and/or inefficient removal and accumulation of potentially toxic compounds. Unfortunately, many of the traditional in-vitro liver models fall short of their in-vivo counterparts, failing to recapitulate the mature hepatocyte phenotype, becoming metabolically incompetent, and lacking the longevity to investigate and detect metabolism-dependent DILI and those associated with chronic and repeat dosing regimens. Nevertheless, evidence is gathering to indicate that growing cells in 3D formats can increase the complexity of these models, promoting a more mature-hepatocyte phenotype and increasing their longevity, in vitro. This review will discuss the use of 3D in vitro models, namely spheroids, organoids, and perfusion-based systems to establish suitable liver models to investigate metabolism-dependent DILI.

Effects of genetically modified human skin fibroblasts, stably overexpressing hepatocyte growth factor, on hepatic functions of cocultured C3A cells

Diseases leading to terminal hepatic failure are among the most common causes of death worldwide. Transplant of the whole organ is the only effective method to cure liver failure. Unfortunately, this treatment option is not available universally due to the serious shortage of donors. Thus, alternative methods have been developed that are aimed at prolonging the life of patients, including hepatic cells transplantation and bridging therapy based on hybrid bioartificial liver devices. Parenchymal liver cells are highly differentiated and perform many complex functions, such as detoxification and protein synthesis. Unfortunately, isolated hepatocytes display a rapid decline in viability and liver-specific functions. A number of methods have been developed to maintain hepatocytes in their highly differentiated state in vitro, amongst them the most promising being 3D growth scaffolds and decellularized tissues or coculture with other cell types required for the heterotypic cell-cell interactions. Here we present a novel approach to the hepatic cells culture based on the feeder layer cells genetically modified using lentiviral vector to stably produce additional amounts of hepatocyte growth factor and show the positive influence of these coculture conditions on the preservation of the hepatic functions of the liver parenchymal cells' model-C3A cells.

Controversies Surrounding the Origin of Hepatocytes in Adult Livers and the in Vitro Generation or Propagation of Hepatocytes

Epithelial cells in the liver (known as hepatocytes) are high-performance engines of myriad metabolic functions and versatile responders to liver injury. As hepatocytes metabolize amino acids, alcohol, drugs, and other substrates, they produce and are exposed to a milieu of toxins and harmful byproducts that can damage themselves. In the healthy liver, hepatocytes generally divide slowly. However, after liver injury, hepatocytes can ramp up proliferation to regenerate the liver. Yet, on extensive injury, regeneration falters, and liver failure ensues. It is therefore critical to understand the mechanisms underlying liver regeneration and, in particular, which liver cells are mobilized during liver maintenance and repair. Controversies continue to surround the very existence of hepatic stem cells and, if they exist, their spatial location, multipotency, degree of contribution to regeneration, ploidy, and susceptibility to tumorigenesis. This review discusses these controversies. Finally, we highlight how insights into hepatocyte regeneration and biology in vivo can inform in vitro studies to propagate primary hepatocytes with liver regeneration-associated signals and to generate hepatocytes de novo from pluripotent stem cells.

Dicamba elevates concentrations of S-adenosyl methionine but does not induce oxidative stress or alter DNA methylation in rainbow trout (Oncorhynchus mykiss) hepatocytes

Dicamba is a benzoic acid herbicide used to target woody and broadleaf weeds in industrial, domestic, and municipal spheres. Because of its widespread use, dicamba is frequently detected in surface waters near sites of application. However, little is known regarding the effects of dicamba on freshwater fishes. In the present study, primary cultures of hepatocytes from rainbow trout (Oncorhynchus mykiss) were exposed to either an environmentally relevant (0.22 or 2.2 μg L^-1) or supra-environmental (22 μg L^-1) concentration of dicamba for 48 h to investigate if oxidative stress is a mechanism of toxicity. mRNA abundances of genes involved in the response to oxidative stress, levels of lipid peroxidation, and concentrations of glutathione and s-adenosyl methionine (SAM) were quantified. Results indicate that dicamba does not induce oxidative stress. However, exposure to 2.2 μg L^-1 of dicamba did cause a 5.24-fold increase in concentrations of SAM. To investigate the mechanisms of increased SAM, effects of dicamba on global and genome-wide DNA methylation were quantified. Dicamba did not cause changes to DNA methylation. Overall, dicamba was not acutely toxic to hepatocytes and did not cause oxidative stress or changes in DNA methylation at environmentally relevant concentrations.

Establishment and transcriptomic features of an immortalized hepatic cell line of the Chinese tree shrew

BACKGROUND

The Chinese tree shrew (Tupaia belangeri chinesis) is a rising experimental animal and has been used for studying a variety of human diseases, such as metabolic and viral infectious diseases.

METHODS

In this study, we established an immortalized tree shrew hepatic cell line, ITH6.1, by introducing the simian virus 40 large T antigen gene into primary tree shrew hepatocytes (PTHs).

RESULTS

The ITH6.1 cell line had a stable cell morphology and proliferation activity. This cell line could be infected by enterovirus 71 (EV71), but not hepatitis C virus (HCV), although the known HCV entry factors, including CD81, SR-BI, CLDN1 and OCLN, were all expressed in the PTHs and ITH6.1 of different passages. Comparison of the transcriptomic features of the PTHs and different passages of the ITH6.1 cells revealed the dynamic gene expression profiles during the transformation. We found that the DNA replication- and cell cycle-related genes were upregulated, whereas the metabolic pathway-related genes were downregulated in early passages of immortalized hepatocytes compared to the PTHs. Furthermore, expression of hepatocytes function-related genes were repressed in ITH6.1 compared to that of PTHs.

CONCLUSION

We believe these cellular expression alterations might cause the resistance of the ITH6.1 cell to HCV infection. This tree shrew liver cell line may be a good resource for the field.

KEY POINTS

• A tree shrew hepatic cell line (ITH6.1) was established. • ITH6.1 cells could be infected by EV71, but not HCV. • ITH6.1 had an altered expression profiling compared to the primary hepatocytes.

The Influence of Chronic Liver Diseases on Hepatic Vasculature: A Liver-on-a-chip Review

In chronic liver diseases and hepatocellular carcinoma, the cells and extracellular matrix of the liver undergo significant alteration in response to chronic injury. Recent literature has highlighted the critical, but less studied, role of the liver vasculature in the progression of chronic liver diseases. Recent advancements in liver-on-a-chip systems has allowed in depth investigation of the role that the hepatic vasculature plays both in response to, and progression of, chronic liver disease. In this review, we first introduce the structure, gradients, mechanical properties, and cellular composition of the liver and describe how these factors influence the vasculature. We summarize state-of-the-art vascularized liver-on-a-chip platforms for investigating biological models of chronic liver disease and their influence on the liver sinusoidal endothelial cells of the hepatic vasculature. We conclude with a discussion of how future developments in the field may affect the study of chronic liver diseases, and drug development and testing.

Creation and characterization of an immortalized canine myoblast cell line: Myok9

The availability of an in vitro canine cell line would reduce the need for dogs for primary in vitro cell culture and reduce overall cost in pre-clinical studies. An immortalized canine muscle cell line, named Myok9, from primary myoblasts of a normal dog has been developed by the authors. Immortalization was performed by SV40 viral transfection of the large T antigen into the primary muscle cells. Proliferation assays, growth curves, quantitative PCR, western blotting, mass spectrometry, and light microscopy were performed to characterize the MyoK9 cell line at different stages of growth and differentiation. The expression of muscle-related genes was determined to assess myogenic origin. Myok9 cells expressed dystrophin and other muscle-specific proteins during differentiation, as detected with mass spectrometry and western blotting. Using the Myok9 cell line, new therapies before moving to pre-clinical studies to enhance the number and speed of analyses and reduce the cost of early experimentation can be tested now. This cell line will be made available to the research community to further evaluate potential therapeutics.

Establishment and characterization of immortalized porcine neonatal hepatocytes without the use of viral components

Porcine hepatocytes are a promising option for xenotransplantation in light of the critical shortage of orthotopic donor livers. Because primary hepatocytes have limited ability to proliferate in vitro, several immortalized hepatocyte lines have been established. However, these cells have typically been generated using a virus-dependent transfection methodology and express viral oncogenes that introduce potential risks in clinical applications. In our study, we established immortalized porcine neonatal hepatocytes by introduction of a plasmid-based hTERT gene expression system by electroporation, without the use of viral components. We detected stable expression of hTERT by RT-PCR and Western blot. The immortalized hepatocytes exhibit a high growth rate, but retain the normal morphology of freshly isolated primary hepatocytes. To date, these immortalized hepatocytes have been expanded for over 80 passages. In addition, no significant differences were detected in glycogen synthesis, secretion of serum albumin, or lipid accumulation between the primary hepatocytes and our immortalized hepatocytes. The cells also exhibit serum-dependent growth and have no capacity for anchorage-independent growth in vitro, demonstrating that they have not been transformed in vitro. Our immortalized porcine hepatocytes will be useful for elucidating the pathogenesis of liver disease and developing efficient treatments. Furthermore, these immortalized hepatocytes may provide a safer source of cells for application in xenotransplantation, compared with immortalized cells generated using viral components.

Generation of hepatic spheroids using human hepatocyte-derived liver progenitor-like cells for hepatotoxicity screening

Rationale: The idiosyncratic drug-induced liver injury (iDILI) is a major cause of acute liver injury and a key challenge in late-stage drug development. Individual heterogeneity is considered to be an essential factor of iDILI. However, few in vitro model can predict heterogeneity in iDILI. We have previously shown that mouse and human hepatocytes can be converted to expandable liver progenitor-like cells in vitro (HepLPCs). However, the limited proliferation potential of human HepLPCs confines its industrial application. Here, we reported the generation of a novel hepatocyte model not only to provide unlimited cell sources for human hepatocytes but also to establish a tool for studying iDILI in vitro.

Methods: Human primary hepatocytes were isolated by modified two-step perfusion technique. The chemical reprogramming culture condition together with gene-transfer were then used to generate the immortalized HepLPC cell lines (iHepLPCs). Growth curve, doubling time, and karyotype were analyzed to evaluate the proliferation characteristics of iHepLPCs. Modified Hepatocyte Maturation Medium and 3D spheroid culture were applied to re-differentiate iHepLPCs.

Results: iHepLPCs exhibited efficient expansion for at least 40 population doublings, with a stable proliferative ability. They could easily differentiate back into metabolically functional hepatocytes in vitro within 10 days. Furthermore, under three-dimensional culture conditions, the formed hepatic spheroids showed multiple liver functions and toxicity profiles close to those of primary human hepatocytes. Importantly, we established a hepatocyte bank by generating a specific number of such cell lines. Screening for population heterogeneity allowed us to analyze the in vitro heterogeneous responses to hepatotoxicity induced by molecular targeted drugs.

Conclusions: In light of the proliferative capacity and the heterogeneity they represented, these iHepLPCs cell lines may offer assistance in studying xenobiotic metabolism as well as liver diseases in vitro.

Current Advances in Red Blood Cell Generation Using Stem Cells from Diverse Sources

Blood transfusions hold an indispensable part in the modern healthcare system. Up to date, the blood supply is largely dependent on donations. Unfortunately, collecting the clinical-grade blood products has become a challenging mission due to accelerated population aging, which not only increases the need for blood transfusions but also decreases the number of healthy donors. Moreover, individuals with severe hematological abnormalities or rare blood phenotypes need alternative therapeutic approaches instead of conventional blood transfusion. In these aspects, the concept of in vitro/ex vivo production of blood cells has been emerging and many attempts have been focused on manufacturing mature erythrocytes, so-called red blood cells (RBCs), the most common and important component among the blood derivatives. In this review, we provide a general overview regarding the current strategies for generating RBCs from various stem cell sources including pluripotent stem cells (PSCs) as well as circulating blood stem cells and the remaining challenges that must be overcome prior to their practical application.

HBV-related hepatocarcinogenesis: the role of signalling pathways and innovative ex vivo research models

BACKGROUND

Hepatitis B virus (HBV) is the leading cause of liver cancer, but the mechanisms by which HBV causes liver cancer are poorly understood and chemotherapeutic strategies to cure liver cancer are not available. A better understanding of how HBV requisitions cellular components in the liver will identify novel therapeutic targets for HBV associated hepatocellular carcinoma (HCC).

MAIN BODY

The development of HCC involves deregulation in several cellular signalling pathways including Wnt/FZD/β-catenin, PI3K/Akt/mTOR, IRS1/IGF, and Ras/Raf/MAPK. HBV is known to dysregulate several hepatocyte pathways and cell cycle regulation resulting in HCC development. A number of these HBV induced changes are also mediated through the Wnt/FZD/β-catenin pathway. The lack of a suitable human liver model for the study of HBV has hampered research into understanding pathogenesis of HBV. Primary human hepatocytes provide one option; however, these cells are prone to losing their hepatic functionality and their ability to support HBV replication. Another approach involves induced-pluripotent stem (iPS) cell-derived hepatocytes. However, iPS technology relies on retroviruses or lentiviruses for effective gene delivery and pose the risk of activating a range of oncogenes. Liver organoids developed from patient-derived liver tissues provide a significant advance in HCC research. Liver organoids retain the characteristics of their original tissue, undergo unlimited expansion, can be differentiated into mature hepatocytes and are susceptible to natural infection with HBV.

CONCLUSION

By utilizing new ex vivo techniques like liver organoids it will become possible to develop improved and personalized therapeutic approaches that will improve HCC outcomes and potentially lead to a cure for HBV.

A DMSO-free hepatocyte maturation medium accelerates hepatic differentiation of HepaRG cells in vitro

The most essential tools for studying drug hepatotoxicity, liver diseases, and bioartificial livers have always been models that can recapitulate liver physiology in vitro. The liver progenitor cell line HepaRG represents an effective surrogate of the primary hepatocyte. However, the differentiation of HepaRG relies on long-term induction using a high concentration of dimethyl sulfoxide (DMSO), which may compromise the research of drug metabolism and restrict the applicability of this hepatic model. Here, we present a novel hepatic maturation medium (HMM) for the differentiation of HepaRG, which is based on a cocktail of soluble molecules that mimick the in vivo environment. We showed that HMM could rapidly (about nine days) induce HepaRG differentiation into polarized hepatocytes with maturely metabolic functions. In addition, under three-dimensional culture conditions, the hepatic spheroids showed multiple liver functions and toxicity profiles close to those of primary human hepatocytes (PHH). Our work demonstrates the utility of HMM as an alternative to the DMSO-dependent differentiation protocol for HepaRG; moreover, these results facilitate the application of HepaRG.

Decellularization and recellularization of cornea: Progress towards a donor alternative

The global shortage of donor corneas for transplantation has led to corneal bioengineering being investigated as a method to generate transplantable tissues. Decellularized corneas are among the most promising materials for engineering corneal tissue since they replicate the complex structure and composition of real corneas. Decellularization is a process that aims to remove cells from organs or tissues resulting in a cell-free scaffold consisting of the tissues extracellular matrix. Here different decellularization techniques are described, including physical, chemical and biological methods. Analytical techniques to confirm decellularization efficiency are also discussed. Different cell sources for the recellularization of the three layers of the cornea, recellularization methods used in the literature and techniques used to assess the outcome of the implantation of such scaffolds are examined. Studies involving the application of decellularized corneas in animal models and human clinical studies are discussed. Finally, challenges for this technology are explored involving scalability, automatization and regulatory affairs.

Ornithine transcarbamylase downregulation is associated with poor prognosis in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-associated mortalities worldwide. The role of ornithine transcarbamylase (OTC) in HCC remains unclear. In the present study, the expression of OTC in HCC was analyzed based on datasets from the Gene Expression Omnibus database of the National Center for Biotechnology Information and further confirmed by immunohistochemistry, western blotting analysis and reverse transcription-quantitative polymerase chain reaction assays on clinical samples and cell lines. Furthermore, the associations between OTC expression and clinicopathological parameters as well as clinical outcome, including the overall and disease-free survival rates were analyzed. Finally, the effect of OTC on HCC cells was measured using proliferation, bromodeoxyuridine and colony-formation assays. Lower OTC expression was observed in HCC cells and tissues compared with primary human hepatocytes. Further investigation demonstrated that low expression of OTC in HCC was associated with larger tumor size and advanced grade. A Kaplan-Meier analysis revealed that patients with lower levels of OTC exhibited shorter overall and disease-free survival times. Notably, OTC silencing with RNA interference facilitated cell proliferation in HCC SK-Hep-1 and Huh-7 cells. However, overexpression of OTC led to inhibition of cell proliferation. In conclusion, the present study identified a novel role of OTC in HCC development, providing a potential novel therapeutic target for this disease.

Neutrophil extracellular trap components increase the expression of coagulation factors

Neutrophil extracellular traps (NETs) represent an important link between inflammation and thrombosis. Here, the present study aimed to investigate the influence of the NET components, DNA and histone H4, on hemostatic gene expression. A further aim was to confirm the influence of H4 on the expression of tissue factor (TF) and investigate a potential effect of DNA, and to test the involvement of miR-17/92 and its paralog miR-106b-25 in this regulation. In HepG2 cells, the mRNA levels of factor VII and factor XII, which are crucial in the activation of the coagulation cascade, and of serpin family F member 2 (encoding α2-antiplasmin) were significantly upregulated by DNA and H4; while the mRNA levels of factor V, which is essential for thrombin generation of protein S, a cofactor of protein C that also has the ability to inhibit the factor X activation pathway, and of serpin family C member 1 (encoding antithrombin, the main endogenous anticoagulant) were significantly upregulated only by H4. H4 and DNA also provoked an increase in hepatocyte nuclear factor 4α (HNF4A) mRNA expression that could be responsible for the increase in the expression of certain coagulant factors. In THP-1 cells, it was also demonstrated that H4 caused an increase in TF mRNA while decreasing several of the microRNAs (miRNA/miRs) of the cluster miR-17/92, which may in part explain the increase in the expression of TF. The present results suggest the ability of NET components to alter the hemostatic balance and a possible involvement of HNF4α and miRNAs in this regulation.

Establishment and characterization of an immortalized renal cell line of the Chinese tree shrew (Tupaia belangeri chinesis)

The Chinese tree shrew holds a great potential as a viable animal model in biomedical research, especially for infectious diseases and neuropsychiatric disorders. A thorough understanding of the innate immunity, which represents the first line that defends the host against viral infection, of the Chinese tree shrew, is needed. However, the progress is hindered by the lack of a proper cell line for research usage. In this study, we established a cell line that is applicable to the study of tree shrew innate immune responses against viral infections. The Chinese tree shrew primary renal cells (TSPRCs) were immortalized by simian virus 40 large T antigen (SV40LT) transduction, and the immortalized cells were termed TSR6 (tree shrew renal cell #6). TSR6 showed a similar morphology to TSPRCs and expressed the epithelial cell-specific marker cytokeratin 18 (KRT18). In addition, TSR6 could be transfected by transfection reagent and was suitable for CRISPR/Cas9-mediated gene editing. Infection of Newcastle disease virus (NDV) or herpes simplex virus 1 (HSV-1) in TSR6 induced the mRNA expression of tree shrew interferon-β (tIFNB1) and myxovirus resistance protein 1 (tMx1) in a dose- and time-dependent manner. Collectively, we successfully established a tree shrew renal cell line and demonstrated that this cell line was suitable for the study of the innate immune response to viral infections.

Treatment of AECHB and Severe Hepatitis (Liver Failure)

This chapter describes the general treatment and immune principles and internal management for AECHB and HBV ACLF, including ICU monitoring, general supportive medications/nutrition/nursing, immune therapy, artificial liver supportive systems, hepatocyte/stem cell, and liver transplant, management for special populations, frequently clinical complications and the utilization of Chinese traditional medicines.

Early clinical indicators of severe hepatitis B include acratia, gastrointestinal symptoms, a daily increase in serum bilirubin >1 mg/dL, toxic intestinal paralysis, bleeding tendency and mild mind anomaly or character change, and the presence of other diseases inducing severe hepatitis. Laboratory indicators include T-Bil, PTA, cholinesterase, pre-albumin and albumin. The roles of immune indicators (such as IL-6, TNF-α, and fgl2), gene polymorphisms, HBV genotypes, and gene mutations as early clinical indicators.

Intensive Care Unit monitor patients with severe hepatitis include intracranial pressure, infection, blood dynamics, respiratory function, renal function, blood coagulation function, nutritional status and blood purification process. Nursing care should not only include routine care, but psychological and special care (complications).

Nutrition support and nursing care should be maintained throughout treatment for severe hepatitis. Common methods of evaluating nutritional status include direct human body measurement, creatinine height index (CHI) and subject global assessment of nutrition (SGA). Malnourished patients should receive enteral or parenteral nutrition support.

Immune therapies for severe hepatitis include promoting hepatocyte regeneration (e.g. with glucagon, hepatocyte growth factor and prostaglandin E1), glucocorticoid suppressive therapy, and targeting molecular blocking. Corticosteroid treatment should be early and sufficient, and adverse drug reactions monitored. Treatments currently being investigated are those targeting Toll-like receptors, NK cell/NK cell receptors, macrophage/immune coagulation system, CTLA-4/PD-1 and stem cell transplantation.

In addition to conventional drugs and radioiodine, corticosteroids and artificial liver treatment can also be considered for severe hepatitis patients with hyperthyreosis. Patients with gestational severe hepatitis require preventive therapy for fetal growth restriction, and it is necessary to choose the timing and method of fetal delivery. For patients with both diabetes and severe hepatitis, insulin is preferred to oral antidiabetic agents to control blood glucose concentration. Liver toxicity of corticosteroids and immune suppressors should be monitored during treatment for severe hepatitis in patients with connective tissue diseases including SLE, RA and sicca syndrome. Patient with connective tissue diseases should preferably be started after the antiviral treatment with nucleos(t)ide analogues.

An artificial liver can improve patients’ liver function; remove endotoxins, blood ammonia and other toxins; correct amino acid metabolism and coagulation disorders; and reverse internal environment imbalances. Non-bioartificial livers are suitable for patients with early and middle stage severe hepatitis; for late-stage patients waiting for liver transplantation; and for transplanted patients with rejection reaction or transplant failure. The type of artificial liver should be determined by each patient’s condition and previous treatment purpose, and patients should be closely monitored for adverse reactions and complications. Bio- and hybrid artificial livers are still under development.

MELD score is the international standard for choosing liver transplantation. Surgical methods mainly include the in situ classic type and the piggyback type; transplantation includes no liver prophase, no liver phase or new liver phase. Preoperative preparation, management of intraoperative and postoperative complications and postoperative long-term treatment are keys to success.

Severe hepatitis belongs to the categories of “acute jaundice”, “scourge jaundice”, and “hot liver” in traditional Chinese medicine. Treatment methods include Chinese traditional medicines, acupuncture and acupoint injection, external application of drugs, umbilical compress therapy, drip, blow nose therapy, earpins, and clysis. Dietary care is also an important part of traditional Chinese medicine treatment.

Suitability of hepatocyte cell lines HepG2, AML12 and THLE-2 for investigation of insulin signalling and hepatokine gene expression

Immortal hepatocyte cell lines are widely used to elucidate insulin-dependent signalling pathways and regulation of hepatic metabolism, although the often tumorigenic origin might not represent the metabolic state of healthy hepatocytes. We aimed to investigate if murine cell line AML12 and human cell line THLE-2, which are derived from healthy liver cells, are comparable to hepatoma cell line HepG2 for studying acute insulin signalling and expression of gluconeogenic enzymes and hepatokines. Insulin responsiveness of AML12 and THLE-2 cells was impaired when cells were cultured in the recommended growth medium, but comparable with HepG2 cells by using insulin-deficient medium. THLE-2 cells showed low abundance of insulin receptor, while protein levels in HepG2 and AML12 were comparable. AML12 and THLE-2 cells showed only low or non-detectable transcript levels of G6PC and PCK1. Expression of ANGPTL4 was regulated similarly in HepG2 and AML12 cells upon peroxisome proliferator-activated receptor δ activation but only HepG2 cells resemble the in vivo regulation of hepatic ANGPTL4 by cAMP. Composition of the culture medium and protein expression levels of key signalling proteins should be considered when AML12 and THLE-2 are used to study insulin signalling. With regard to gluconeogenesis and hepatokine expression, HepG2 cells appear to be closer to the in vivo situation despite the tumorigenic origin.

Establishment and Evaluation of a Stable Bovine Thyroid Cell Line for Investigating Foot-and-Mouth Disease Virus

Foot-and-mouth disease virus (FMDV) has a wide host range. Its pathogenesis varies among hosts and types of viruses. Most investigations of pathogenesis have been performed on cattle and swine. However, FMDV research in cattle is hampered by the lack of a stable in vitro infection model. In this study, the stable bovine thyroid (BTY) cell line hTERT-BTY from primary BTY cells was established by telomerase reverse transcriptase over expression. The results of karyotype analysis and experiments on morphological and biological characteristics indicated that this cell line possessed the qualities of primary BTY cells, which could be extended indefinitely with stable morphology and steady growth rates. The hTERT-BTY cell line, has 60 chromosomes including 29 pairs of autosomes and 1 pair of sex chromosomes without structure aberrations. It can express thyroid-specific function genes thyroid-stimulating hormone receptor and sodium/iodide symporter in high abundance ratios. The cell line is sensitive to FMDV strains and is expected to be used as a powerful tool for FMDV clinical diagnosis, separation, detection and culture. Also, the different mRNA expression levels in infected and uninfected hTERT-BTY cells were analyzed in this study to identify the pathways of immunity using RNA-seq. The results suggested that the hTERT-BTY cell line could be regarded as an effective tool for the immune response exploration of FMDV. In conclusion, this study provided a useful tool for FMDV clinical diagnosis, separation, detection, and culture. The cell line also could serve as an in vitro model to study the mechanism underlying FMDV pathogenicity and host–virus interaction.

Reversibly immortalized hepatic progenitor cell line containing double suicide genes

A large number of functional hepatocytes is required for bioartificial liver therapy. Simian virus 40 T-antigen (SV40T) has been previously reported to improve the immortalized proliferation of primary hepatocytes to generate a sufficient number of cells; however, these long-term immortalized hepatocytes may induce further malignant transformation in vivo. In the present study, the SV40T immortalization gene and two suicide genes, herpes simplex virus thymidine kinase (HSV-tk) and cytosine deaminase (CD), were transducted into primary hepatocytes to construct a novel type of Cre/LoxP-mediated reversible immortalized hepatocyte line. Polymerase chain reaction analysis and western blotting confirmed that the SV40T, HSV-tk and CD genes were successfully inserted into hepatic progenitor cells and their expression was controlled by Cre/LoxP recombination. Total removal of SV40T could be achieved via the ganciclovir (GCV)/HSV-tk suicide system. Cells maintained their biosafety in vivo with CD gene expression and 5-fluoro-cytosine (5-FC) induced cell death. Following transplantation into the carbon tetrachloride (CCl₄) model group, the majority of cells had survived after 14 days post-implantation and a number of the cells had transported into the liver parenchyma. When compared with the CCl₄ model group, the transplanted cells repaired the liver biochemical index and pathological structure markedly. Thus, the present study reports a novel reversible immortalized hepatocyte with double suicide genes, which exhibited the cellular phenotype and recovery function of normal liver cells. This method maximally guaranteed the biological safety of immortalized hepatocytes for in vivo application, providing a reliable, safe and ideal cell material for the artificial liver technique.