Polarisation and functional characterisation of hepatocytes derived from human embryonic and mesenchymal stem cells

Hepatic Polarized Differentiation Promoted the Maturity and Liver Function of Human Embryonic Stem Cell-Derived Hepatocytes via Activating Hippo and AMPK Signaling Pathways

Hepatocytes exhibit a multi-polarized state under the in vivo physiological environment, however, human embryonic stem cell-derived hepatocytes (hEHs) rarely exhibit polarity features in a two-dimensional (2D) condition. Thus, we hypothesized whether the polarized differentiation might enhance the maturity and liver function of hEHs. In this study, we obtained the polarized hEHs (phEHs) by using 2D differentiation in conjunct with employing transwell-based polarized culture. Our results showed that phEHs directionally secreted albumin, urea and bile acids, and afterward, the apical membrane and blood-bile barrier (BBIB) were identified to form in phEHs. Moreover, phEHs exhibited a higher maturity and capacitity of cellular secretory and drug metabolism than those of non-phEHs. Through transcriptome analysis, it was found that the polarized differentiation induced obvious changes in gene expression profiles of cellular adhesion and membrane transport in hEHs. Our further investigation revealed that the activation of Hippo and AMPK signaling pathways made contributions to the regulation of function and cellular polarity in phEHs, further verifying that the liver function of hEHs was closely related with their polarization state. These results not only demonstrated that the polarized differentiation enhanced the maturity and liver function of hEHs, but also identified the molecular targets that regulated the polarization state of hEHs.

Implanted subcutaneous versus intraperitoneal bioscaffold seeded with hepatocyte-like cells: functional evaluation

Background and objectives

The X-linked bleeding disorder, hemophilia A, is caused by defective production of factor VIII (FVIII). Hemophilic patients require regular FVIII infusions. Recombinant factor replacement poses the safest line of therapy. However, its main drawbacks are high expenses and the higher liability for formation of inhibitors. Recent studies confirmed the ability of bone marrow-derived stem cells to secrete FVIII. This study aims to generate bioscaffold from decellularized liver and subsequently seed it with trans-differentiated human stem cells into hepatic-like cells. This scaffold can then be implanted intraperitoneally or subcutaneously to provide FVIII.

Methods

After generation of the bioscaffold, seeding of discoid scaffolds with trans-differentiated human hepatocyte-like cells was performed. Then, the generated organoid was implanted into peritoneal cavity or subcutaneous tissue of experimental rats.

Results

Serum human FVIII was significantly increased in rats subjected to subcutaneous implantation compared intraperitoneal implantation. Immunostaining for detecting Cytokeratin 19 and human anti-globulin confirmed the presence of mature human hepatocytes that were significantly increased in subcutaneous implanted scaffold compared to the intraperitoneal one.

Conclusion

Implantation of decellularized bioscaffold seeded with trans-differentiated stem cells in rats was successful to establish production of FVIII. Subcutaneous implantation showed higher FVIII levels than intraperitoneal implantation.

Advanced Techniques and Awaited Clinical Applications for Human Pluripotent Stem Cell Differentiation into Hepatocytes

Liver transplantation is currently the only curative treatment for several liver diseases such as acute liver failure, end-stage liver disorders, primary liver cancers, and certain genetic conditions. Unfortunately, despite improvements to transplantation techniques, including live donor transplantation, the number of organs available remains insufficient to meet patient needs. Hepatocyte transplantation has enabled some encouraging results as an alternative to organ transplantation, but primary hepatocytes are little available and cannot be amplified using traditional two-dimensional culture systems. Indeed, although recent studies have tended to show that three-dimensional culture enables long-term hepatocyte culture, it is still agreed that, like most adult primary cell types, hepatocytes remain refractory to in vitro expansion. Because of their exceptional properties, human pluripotent stem cells (hPSCs) can be amplified indefinitely and differentiated into any cell type, including liver cells. While many teams have worked on hepatocyte differentiation, there has been a consensus that cells obtained after hPSC differentiation have more fetal than adult hepatocyte characteristics. New technologies have been used to improve the differentiation process in recent years. This review discusses the technical improvements made to hepatocyte differentiation protocols and the clinical approaches developed to date and anticipated in the near future.

Blended electrospinning with human liver extracellular matrix for engineering new hepatic microenvironments

Tissue engineering of a transplantable liver could provide an alternative to donor livers for transplant, solving the problem of escalating donor shortages. One of the challenges for tissue engineers is the extracellular matrix (ECM); a finely controlled in vivo niche which supports hepatocytes. Polymers and decellularized tissue scaffolds each provide some of the necessary biological cues for hepatocytes, however, neither alone has proved sufficient. Enhancing microenvironments using bioactive molecules allows researchers to create more appropriate niches for hepatocytes. We combined decellularized human liver tissue with electrospun polymers to produce a niche for hepatocytes and compared the human liver ECM to its individual components; Collagen I, Laminin-521 and Fibronectin. The resulting scaffolds were validated using THLE-3 hepatocytes. Immunohistochemistry confirmed retention of proteins in the scaffolds. Mechanical testing demonstrated significant increases in the Young's Modulus of the decellularized ECM scaffold; providing significantly stiffer environments for hepatocytes. Each scaffold maintained hepatocyte growth, albumin production and influenced expression of key hepatic genes, with the decellularized ECM scaffolds exerting an influence which is not recapitulated by individual ECM components. Blended protein:polymer scaffolds provide a viable, translatable niche for hepatocytes and offers a solution to current obstacles in disease modelling and liver tissue engineering.

Mesenchymal Stem Cells: Miraculous Healers or Dormant Killers?

Mesenchymal Stem Cells (MSCs) are a heterogeneous population of fibroblast-like cells which maintain self-renewability and pluripotency to differentiate into mesodermal cell lineages. The use of MSCs in clinical settings began with high enthusiasm and the number of MSC-based clinical trials has been rising ever since. However; the very unique characteristics of MSCs that made them suitable to for therapeutic use, might give rise to unwanted outcomes, including tumor formation and progression. In this paper, we present a model of carcinogenesis initiated by MSCs, which chains together the tissue organization field theory, the stem cell theory, and the inflammation-cancer chain. We believe that some tissue resident stem cells could be leaked cells from bone marrow MSC pool to various injured tissue, which consequently transform and integrate in the host tissue. If the injury persists or chronic inflammation develops, as a consequence of recurring exposure to growth factors, cytokines, etc. the newly formed tissue from MSCs, which still has conserved their mesenchymal and stemness features, go through rapid population expansion, and nullify their tumor suppressor genes, and hence give rise to neoplastic cell (carcinomas, sarcomas, and carcino-sarcomas). Considering the probability of this hypothesis being true, the clinical and therapeutic use of MSCs should be with caution, and the recipients' long term follow-up seems to be insightful.

Impact of Three-Dimentional Culture Systems on Hepatic Differentiation of Puripotent Stem Cells and Beyond

Generation of functional hepatocytes from human pluripotent stem cells (hPSCs) is a vital tool to produce large amounts of human hepatocytes, which hold a great promise for biomedical and regenerative medicine applications. Despite a tremendous progress in developing the differentiation protocols recapitulating the developmental signalling and stages, these resulting hepatocytes from hPSCs yet achieve maturation and functionality comparable to those primary hepatocytes. The absence of 3D milieu in the culture and differentiation of these hepatocytes may account for this, at least partly, thus developing an optimal 3D culture could be a step forward to achieve this aim. Hence, review focuses on current development of 3D culture systems for hepatic differentiation and maturation and the future perspectives of its application.

Clinical Trials in a Dish: A Perspective on the Coming Revolution in Drug Development

The pharmaceutical industry is facing unprecedented challenges as the cost of developing new drugs has reached unsustainable levels, fueled in large parts by a high attrition rate in clinical development. Strategies to bridge studies between preclinical testing and clinical trials are needed to reduce the knowledge gap and allow earlier decisions to be made on the continuation or discontinuation of further development of drugs. The discovery and development of human induced pluripotent stem cells (hiPSCs) have opened up new avenues that support the concept of screening for cell-based safety and toxicity at the level of a population. This approach, termed “Clinical Trials in a Dish” (CTiD), allows testing medical therapies for safety or efficacy on cells collected from a representative sample of human patients, before moving into actual clinical trials. It can be applied to the development of drugs for specific populations, and it allows predicting not only the magnitude of effects but also the incidence of patients in a population who will benefit or be harmed by these drugs. This, in turn, can lead to the selection of safer drugs to move into clinical development, resulting in a reduction in attrition. The current article offers a perspective of this new model for “humanized” preclinical drug development.

Microfluidic platforms for modeling biological barriers in the circulatory system

Microfluidic platforms have recently become popular as in vitro models because of their superiority in recapitulating microenvironments compared with conventional in vitro models. By providing various biochemical and biomechanical cues, healthy and diseased models at the organ level can be applied to disease progression and treatment studies. Microfluidic technologies are especially suitable for modeling biological barriers because the flow in the microchannels mimics the blood flow and body fluids at the interfaces of crucial organs, such as lung, intestine, liver, kidney, brain, and skin. These barriers have similar structures and can be studied with similar approaches for the testing of pharmaceutical compounds. Here, we review recent developments in microfluidic platforms for modeling biological barriers in the circulatory system.

A Drug-Induced Hybrid Electrospun Poly-Capro-Lactone: Cell-Derived Extracellular Matrix Scaffold for Liver Tissue Engineering

Liver transplant is the only treatment option for patients with end-stage liver failure, however, there are too few donor livers available for transplant. Whole organ tissue engineering presents a potential solution to the problem of rapidly escalating donor liver shortages worldwide. A major challenge for liver tissue engineers is the creation of a hepatocyte microenvironment; a niche in which liver cells can survive and function optimally. While polymers and decellularized tissues pose an attractive option for scaffold manufacturing, neither alone has thus far proved sufficient. This study exploited cell's native extracellular matrix (ECM) producing capabilities using two different histone deacetylase inhibitors, and combined these with the customizability and reproducibility of electrospun polymer scaffolds to produce a "best of both worlds" niche microenvironment for hepatocytes. The resulting hybrid poly-capro-lactone (PCL)-ECM scaffolds were validated using HepG2 hepatocytes. The hybrid PCL-ECM scaffolds maintained hepatocyte growth and function, as evidenced by metabolic activity and DNA quantitation. Mechanical testing revealed little significant difference between scaffolds, indicating that cells were responding to a biochemical and topographical profile rather than mechanical changes. Immunohistochemistry showed that the biochemical profile of the drug-derived and nondrug-derived ECMs differed in ratio of Collagen I, Laminin, and Fibronectin. Furthermore, the hybrid PCL-ECM scaffolds influence the gene expression profile of the HepG2s drastically; with expression of Albumin, Cytochrome P450 Family 1 Subfamily A Polypeptide 1, Cytochrome P450 Family 1 Subfamily A Polypeptide 2, Cytochrome P450 Family 3 Subfamily A Polypeptide 4, Fibronectin, Collagen I, and Collagen IV undergoing significant changes. Our results demonstrate that drug-induced hybrid PCL-ECM scaffolds provide a viable, translatable platform for creating a niche microenvironment for hepatocytes, supporting in vivo phenotype and function. These scaffolds offer great potential for tissue engineering and regenerative medicine strategies for whole organ tissue engineering.

Pluripotent stem cells to hepatocytes, the journey so far

Over the past several years, there has been substantial progress in the field of regenerative medicine, which has enabled new possibilities for research and clinical application. For example, there are ongoing efforts directed at generating functional hepatocytes from adult-derived pluripotent cells for toxicity screening, generating disease models or, in the longer term, for the treatment of liver failure. In the present review, the authors summarise recent developments in regenerative medicine and pluripotent stem cells, the methods and tissues used for reprogramming and the differentiation of induced pluripotent stem cells (iPSCs) into hepatocyte-like cells. In addition, the hepatic disease models developed using iPSC technologies are discussed, as well as the potential for gene editing.