High efficient differentiation of functional hepatocytes from porcine induced pluripotent stem cells

The progress of induced pluripotent stem cells derived from pigs: a mini review of recent advances

Pigs (Sus scrofa) are widely acknowledged as an important large mammalian animal model due to their similarity to human physiology, genetics, and immunology. Leveraging the full potential of this model presents significant opportunities for major advancements in the fields of comparative biology, disease modeling, and regenerative medicine. Thus, the derivation of pluripotent stem cells from this species can offer new tools for disease modeling and serve as a stepping stone to test future autologous or allogeneic cell-based therapies. Over the past few decades, great progress has been made in establishing porcine pluripotent stem cells (pPSCs), including embryonic stem cells (pESCs) derived from pre- and peri-implantation embryos, and porcine induced pluripotent stem cells (piPSCs) using a variety of cellular reprogramming strategies. However, the stabilization of pPSCs was not as straightforward as directly applying the culture conditions developed and optimized for murine or primate PSCs. Therefore, it has historically been challenging to establish stable pPSC lines that could pass stringent pluripotency tests. Here, we review recent advances in the establishment of stable porcine PSCs. We focus on the evolving derivation methods that eventually led to the establishment of pESCs and transgene-free piPSCs, as well as current challenges and opportunities in this rapidly advancing field.

Ameliorative effect of licorice extract against the detrimental effect of glyphosate-based pesticide: Toxicity and health

This study sheds the light on the potential of licorice (Glycyrrhiza glabra) root aqueous extract as a cornerstone for mitigating and detoxifying the residues of the widely used agricultural Glyphosate-based pesticides (GBPs). This study examined the GBPs toxic effects on kidney, liver, thyroid functions, and apoptosis using 50 adult male albino rats. All rats were divided into 5 groups, with 10 each. Control: served as untreated rats. GBP: rats were treated with 1 mL glyphosate solution 24 % orally for three weeks. The glyphosate-treated rats were gavaged with licorice root aqueous extractsolution (100, 200, and 300 mg/mLdistilled water, respectively) daily for three weeks. Licorice root aqueous extract solution (300 mg/mL distilled water) yielded notable reductions in liver, kidney enzymes, albumin, and AFP levels within the serum. Immunological tests, including immunohistochemical evaluations of caspase-3 and TNF-α expressions revealed a dose-dependent attenuation of apoptosis and inflammation with licorice intervention. This will provide a valuable perspective for agricultural practices future and paving the way for a more sustainable approach for using GBPs in animal agriculture industries.

The Efficiency of Stem Cells (SCs) Differentiation into Functional Hepatocytes for Treating Liver Disorders: A Systematic Review

Stem cells provided new opportunity to treat various diseases, including liver disorders. Stem cells are unspecialized cells, stimulating influential research interest be indebted to their multipotent self-renewal capacity and differentiation characteristics into several specialized cell types. Many factors contribute to their differentiation into different cell types such as insulin producing cells, osteoblast, and hepatocytes. Accordingly, wide range methods and materials have been used to transform stem cells into hepatocytes, but effectiveness of differentiation is different and depends on several factors such as cell-to-cell adhesion, cell-to-cell contact, and cell biological change. Search was done in PubMed, Scopus, and WOS to evaluate results of studies about stem cells differentiation for higher efficacy. Among more than 28000 papers, 51 studies were considered eligible for more evaluations. Results indicated that most studies were performed on mesenchymal stem cells compared with other types. Acute liver failure was the most investigated liver disorder, and tissue engineering was the most investigated differentiation methods. Also, functional parameters were the most evaluated parameters in assessing differentiation efficacy. We summarize recent advances in increasing efficiency of stem cells differentiation using varied materials, since promising results of this review, further studies are needed to assess efficiency and safety of these cells transplantation in some liver disease treatment.

Using liver models generated from human-induced pluripotent stem cells (iPSCs) for evaluating chemical-induced modifications and disease across liver developmental stages

The liver is a pivotal organ regulating critical developmental stages of fetal metabolism and detoxification. Though numerous studies have evaluated links between prenatal/perinatal exposures and adverse health outcomes in the developing fetus, the central role of liver to health disruptions resulting from these exposures remains understudied, especially concerning early development and later-in-life health outcomes. While numerous in vitro methods for evaluating liver toxicity have been established, the use of iPSC-derived hepatocytes appears to be particularly well suited to contribute to this critical research gap due to their potential to model a diverse range of disease phenotypes and different stages of liver development. The following key aspects are reviewed: (1) an introduction to developmental liver toxicity; (2) an introduction to embryonic and induced pluripotent stem cell models; (3) methods and challenges for deriving liver cells from stem cells; and (4) applications for iPSC-derived hepatocytes to evaluate liver developmental stages and their associated responses to insults. We conclude that iPSC-derived hepatocytes have great potential for informing liver toxicity and underlying disease mechanisms via the generation of patient-specific iPSCs; implementing large-scale drug and chemical screening; evaluating general biological responses as a potential surrogate target cell; and evaluating inter-individual disease susceptibility and response variability.

Effect of glycyrrhizic acid and 18β-glycyrrhetinic acid on the differentiation of human umbilical cord-mesenchymal stem cells into hepatocytes

BACKGROUND

End-stage liver disease is a global health complication with high prevalence and limited treatment options. Cell-based therapies using mesenchymal stem cells (MSCs) emerged as an alternative approach to support hepatic regeneration. In vitro preconditioning strategies have been employed to strengthen the regenerative and differentiation potential of MSCs towards hepatic lineage. Chemical compounds of the triterpene class; glycyrrhizic acid (GA) and 18β-glycyrrhetinic acid (GT) possess diverse therapeutic properties including hepato-protection and anti-fibrosis characteristics. They are capable of modulating several signaling pathways that are crucial in hepatic regeneration. Preconditioning with hepato-protective triterpenes may stimulate MSC fate transition towards hepatocytes.

AIM

To explore the effect of GA and GT on hepatic differentiation of human umbilical cord-MSCs (hUC-MSCs).

METHODS

hUC-MSCs were isolated and characterized phenotypically by flow cytometry and immunocytochemistry for the expression of MSC-associated surface molecules. Isolated cells were treated with GA, GT, and their combination for 24 h and then analyzed at three time points; day 7, 14, and 21. qRT-PCR was performed for the expression of hepatic genes. Expression of hepatic proteins was analyzed by immunocytochemistry at day 21. Periodic acid Schiff staining was performed to determine the functional ability of treated cells.

RESULTS

The fusiform-shaped morphology of MSCs in the treatment groups in comparison with the untreated control, eventually progressed towards the polygonal morphology of hepatocytes with the passage of time. The temporal transcriptional profile of preconditioned MSCs displayed significant expression of hepatic genes with increasing time of differentiation. Preconditioned cells showed positive expression of hepatocyte-specific proteins. The results were further corroborated by positive periodic acid Schiff staining, indicating the presence of glycogen in their cytoplasm. Moreover, bi-nucleated cells, which is the typical feature of hepatocytes, were also seen in the preconditioned cells.

CONCLUSION

Preconditioning with glycyrrhizic acid, 18β-glycyrrhetinic acid and their combination, successfully differentiates hUC-MSCs into hepatic-like cells. These MSCs may serve as a better therapeutic option for degenerative liver diseases in future.

Generation of Hepatobiliary Cell Lineages from Human Induced Pluripotent Stem Cells: Applications in Disease Modeling and Drug Screening

The possibility to reproduce key tissue functions in vitro from induced pluripotent stem cells (iPSCs) is offering an incredible opportunity to gain better insight into biological mechanisms underlying development and disease, and a tool for the rapid screening of drug candidates. This review attempts to summarize recent strategies for specification of iPSCs towards hepatobiliary lineages -hepatocytes and cholangiocytes-and their use as platforms for disease modeling and drug testing. The application of different tissue-engineering methods to promote accurate and reliable readouts is discussed. Space is given to open questions, including to what extent these novel systems can be informative. Potential pathways for improvement are finally suggested.

Direct conversion of porcine primary fibroblasts into hepatocyte-like cells

The pig is an important model organism for biomedical research, mainly due to its extensive genetic, physiological and anatomical similarities with humans. Until date, direct conversion of somatic cells into hepatocyte-like cells (iHeps) has only been achieved in rodents and human cells. Here, we employed lentiviral vectors to screen a panel of 12 hepatic transcription factors (TF) for their potential to convert porcine fibroblasts into hepatocyte-like cells. We demonstrate for the first time, hepatic conversion of porcine somatic cells by over-expression of CEBPα, FOXA1 and HNF4α2 (3TF-piHeps). Reprogrammed 3TF-piHeps display a hepatocyte-like morphology and show functional characteristics of hepatic cells, including albumin secretion, Dil-AcLDL uptake, storage of lipids and glycogen and activity of cytochrome P450 enzymes CYP1A2 and CYP2C33 (CYP2C9 in humans). Moreover, we show that markers of mature hepatocytes are highly expressed in 3TF-piHeps, while fibroblastic markers are reduced. We envision piHeps as useful cell sources for future studies on drug metabolism and toxicity as well as in vitro models for investigation of pig-to-human infectious diseases.

The use of induced pluripotent stem cells in domestic animals: a narrative review

Induced pluripotent stem cells (iPSCs) are undifferentiated stem cells characterized by the ability to differentiate into any cell type in the body. iPSCs are a relatively new and rapidly developing technology in many fields of biology, including developmental anatomy and physiology, pathology, and toxicology. These cells have great potential in research as they are self-renewing and pluripotent with minimal ethical concerns. Protocols for their production have been developed for many domestic animal species, which have since been used to further our knowledge in the progression and treatment of diseases. This research is valuable both for veterinary medicine as well as for the prospect of translation to human medicine. Safety, cost, and feasibility are potential barriers for this technology that must be considered before widespread clinical adoption. This review will analyze the literature pertaining to iPSCs derived from various domestic species with a focus on iPSC production and characterization, applications for tissue and disease research, and applications for disease treatment.

Porcine cytochrome P450 3A: current status on expression and regulation

The cytochrome P450s (CYPs) constitute a family of enzymes maintaining vital functions in the body and are mostly recognized for their significant role in detoxification. Of the CYP subfamilies, CYP3A, is one of the most active in the clearance of drugs and other xenobiotics. During the last decades, much focus has been on exploring different models for human CYP3A regulation, expression and activity. In that respect, the growing knowledge of the porcine CYP3As is of great interest. Although many aspects of porcine CYP3A regulation and activity are still unknown, the current literature provides a basic understanding of the porcine CYP3As that can be used e.g., when translating results from studies done in the porcine model into human settings. In this review, the current knowledge about porcine CYP3A expression, regulation, activity and metabolic significance are highlighted. Future research needs are also identified.

Large Animal Models for the Clinical Application of Human Induced Pluripotent Stem Cells

Induced pluripotent stem cell (iPSC) technology offers a practically infinite and ethically acceptable source to obtain a variety of somatic cells. Coupled with the biotechnologies of cell therapy or tissue engineering, iPSC technology will enormously contribute to human regenerative medicine. Before clinical application, such human iPSC (hiPSC)-based therapies should be assessed using large animal models that more closely match biological or biomechanical properties of human patients. Therefore, it is critical to generate large animal iPSCs, obtain their iPSC-derived somatic cells, and preclinically evaluate their therapeutic efficacy and safety in large animals. During the past decade, the establishment of iPSC lines of a series of large animal species has been documented, and the acquisition and preclinical evaluation of iPSC-derived somatic cells has also been reported. Despite this progress, significant obstacles, such as obtaining or preserving the bona fide pluripotency of large animal iPSCs, have been encountered. Simultaneously, studies of large animal iPSCs have been overlooked in comparison with those of mouse and hiPSCs, and this field deserves more attention and support due to its important preclinical relevance. Herein, this review will focus on the large animal models of pigs, dogs, horses, and sheep/goats, and summarize current progress, challenges, and potential future directions of research on large animal iPSCs.

Porcine hepatocytes culture on biofunctionalized 3D inverted colloidal crystal scaffolds as an in vitro model for predicting drug hepatotoxicity

As drug-induced hepatotoxicity represents one of the most common causes of drug failure, three-dimensional (3D) in vitro liver platforms represent a fantastic toolbox to predict drug toxicity and thus reduce in vivo animal studies and lessen drug attrition rates. The aim of this study is to establish a functional porcine hepatocyte culture using a biofunctionalized 3D inverted colloidal crystal (ICC) hydrogel platform. The performances of non-adhesive bare poly(ethylene glycol)diacrylate (PEGDA) ICCs and PEGDA ICCs coated with either collagen type I or fibronectin have been investigated. Porcine hepatocytes viability, morphology, hepatic-specific functions and patterns of gene expression have been evaluated over a period of two weeks in culture to test diclofenac, a well-known hepatotoxic drug. Interestingly, cells in the fibronectin-functionalized scaffold exhibit different aggregation patterns and maintain better liver-specific function than those in bare ICCs and in collagen functionalized scaffold. We concluded that the 3D cell culture environment and the presence of extracellular matrix (ECM) proteins, especially fibronectin, facilitate hepatocyte viability and maintenance of the liver-specific phenotype in vitro, and enable us to predict hepatotoxicity.

As drug-induced hepatotoxicity represents one of the most common causes of drug failure, three-dimensional in vitro liver platforms represent a fantastic toolbox to predict drug toxicity and reduce in vivo studies and drug attrition rates.

Decellularized Liver Extracellular Matrix as Promising Tools for Transplantable Bioengineered Liver Promotes Hepatic Lineage Commitments of Induced Pluripotent Stem Cells

Liver transplantation is the last resort for liver failure patients. However, due to the shortage of donor organs, bioengineered liver generated from decellularized whole liver scaffolds and induced pluripotent stem cell (iPSC)-derived hepatocytes (iPSC-Heps) is being studied as an alternative approach to treat liver disease. Nevertheless, there has been no report on both the interaction of iPSC-Heps with a liver extracellular matrix (ECM) and the analysis of recellularized iPSC-Heps into the whole liver scaffolds. In this study, we produced porcine iPSC-Heps, which strongly expressed the hepatic markers α-fetoprotein and albumin and exhibited hepatic functionalities, including glycogen storage, lipid accumulation, low-density lipoprotein uptake, and indocyanine green metabolism. Supplementation of ECM from porcine decellularized liver containing liver-derived growth factors stimulated the albumin expression of porcine iPSC-Heps during differentiation procedures. The iPSC-Heps were reseeded into decellularized liver scaffolds, and the recellularized liver was cultured using a continuous perfusion system. The recellularized liver scaffolds were transplanted into rats for a short term, and the grafts expressed hepatocyte markers and did not rupture. These results provide a foundation for development of bioengineered liver using stem cell and decellularized scaffolds.

Pluripotent stem cells and livestock genetic engineering

The unlimited proliferative ability and capacity to contribute to germline chimeras make pluripotent embryonic stem cells (ESCs) perfect candidates for complex genetic engineering. The utility of ESCs is best exemplified by the numerous genetic models that have been developed in mice, for which such cells are readily available. However, the traditional systems for mouse genetic engineering may not be practical for livestock species, as it requires several generations of mating and selection in order to establish homozygous founders. Nevertheless, the self-renewal and pluripotent characteristics of ESCs could provide advantages for livestock genetic engineering such as ease of genetic manipulation and improved efficiency of cloning by nuclear transplantation. These advantages have resulted in many attempts to isolate livestock ESCs, yet it has been generally concluded that the culture conditions tested so far are not supportive of livestock ESCs self-renewal and proliferation. In contrast, there are numerous reports of derivation of livestock induced pluripotent stem cells (iPSCs), with demonstrated capacity for long term proliferation and in vivo pluripotency, as indicated by teratoma formation assay. However, to what extent these iPSCs represent fully reprogrammed PSCs remains controversial, as most livestock iPSCs depend on continuous expression of reprogramming factors. Moreover, germline chimerism has not been robustly demonstrated, with only one successful report with very low efficiency. Therefore, even 34 years after derivation of mouse ESCs and their extensive use in the generation of genetic models, the livestock genetic engineering field can stand to gain enormously from continued investigations into the derivation and application of ESCs and iPSCs.

Cell-based therapies of liver diseases: age-related challenges

The scope of this review is to revise recent advances of the cell-based therapies of liver diseases with an emphasis on cell donor's and patient's age. Regenerative medicine with cell-based technologies as its integral part is focused on the structural and functional restoration of tissues impaired by sickness or aging. Unlike drug-based medicine directed primarily at alleviation of symptoms, regenerative medicine offers a more holistic approach to disease and senescence management aimed to achieve restoration of homeostasis. Hepatocyte transplantation and organ engineering are very probable forthcoming options of liver disease treatment in people of different ages and vigorous research and technological innovations in this area are in progress. Accordingly, availability of sufficient amounts of functional human hepatocytes is crucial. Direct isolation of autologous hepatocytes from liver biopsy is problematic due to related discomfort and difficulties with further expansion of cells, particularly those derived from aging people. Allogeneic primary human hepatocytes meeting quality standards are also in short supply. Alternatively, autologous hepatocytes can be produced by reprogramming of differentiated cells through the stage of induced pluripotent stem cells. In addition, fibroblasts and mesenchymal stromal cells can be directly induced to undergo advanced stage hepatogenic differentiation. Reprogramming of cells derived from elderly people is accompanied by the reversal of age-associated changes at the cellular level manifesting itself by telomere elongation and the U-turn of DNA methylation. Cell reprogramming can provide high quality rejuvenated hepatocytes for cell therapy and liver tissue engineering. Further technological advancements and establishment of national and global registries of induced pluripotent stem cell lines homozygous for HLA haplotypes can allow industry-style production of livers for immunosuppression-free transplantation.

Hepatic differentiation of porcine embryonic stem cells for translational research of hepatocyte transplantation

Porcine embryonic stem cells (ES) are considered attractive preclinical research tools for human liver diseases. Although several studies previously reported generation of porcine ES, none of these studies has described hepatic differentiation from porcine ES. The aim of this study was to generate hepatocytes from porcine ES and analyze their characteristics. We optimized conditions for definitive endoderm induction and developed a 4-step hepatic differentiation protocol. A brief serum-free condition with activin A efficiently induced definitive endoderm differentiation from porcine ES. The porcine ES-derived hepatocyte-like cells highly expressed hepatic markers including albumin and α-fetoprotein, and displayed liver characteristics such as glycogen storage, lipid production, and low-density lipoprotein uptake. For the first time, we describe a highly efficient protocol for hepatic differentiation from porcine ES. Our findings provide valuable information for translational liver research using porcine models, including hepatic regeneration and transplant studies, drug screening, and toxicology.

Two Effective Routes for Removing Lineage Restriction Roadblocks: From Somatic Cells to Hepatocytes

The conversion of somatic cells to hepatocytes has fundamentally re-shaped traditional concepts regarding the limited resources for hepatocyte therapy. With the various induced pluripotent stem cell (iPSC) generation routes, most somatic cells can be effectively directed to functional stem cells, and this strategy will supply enough pluripotent material to generate promising functional hepatocytes. However, the major challenges and potential applications of reprogrammed hepatocytes remain under investigation. In this review, we provide a summary of two effective routes including direct reprogramming and indirect reprogramming from somatic cells to hepatocytes and the general potential applications of the resulting hepatocytes. Through these approaches, we are striving toward the goal of achieving a robust, mature source of clinically relevant lineages.