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

Advances in drug-induced liver injury research: in vitro models, mechanisms, omics and gene modulation techniques

Drug-induced liver injury (DILI) refers to drug-mediated damage to the structure and function of the liver, ranging from mild elevation of liver enzymes to severe hepatic insufficiency, and in some cases, progressing to liver failure. The mechanisms and clinical symptoms of DILI are diverse due to the varying combination of drugs, making clinical treatment and prevention complex. DILI has significant public health implications and is the primary reason for post-marketing drug withdrawals. The search for reliable preclinical models and validated biomarkers to predict and investigate DILI can contribute to a more comprehensive understanding of adverse effects and drug safety. In this review, we examine the progress of research on DILI, enumerate in vitro models with potential benefits, and highlight cellular molecular perturbations that may serve as biomarkers. Additionally, we discuss omics approaches frequently used to gather comprehensive datasets on molecular events in response to drug exposure. Finally, three commonly used gene modulation techniques are described, highlighting their application in identifying causal relationships in DILI. Altogether, this review provides a thorough overview of ongoing work and approaches in the field of DILI.

Recent applications of three-dimensional bioprinting in drug discovery and development

The ability of three-dimensional (3D) bioprinting to fabricate biomimetic organ and disease models has been recognised to be promising for drug discovery and development as 3D bioprinted models can better mimic human physiology compared to two-dimensional (2D) cultures and animal models. This is useful for target selection where disease models can be studied to understand disease pathophysiology and identify disease-linked compounds. Lead identification and preclinical studies also benefit from 3D bioprinting as 3D bioprinted models can be utilised in high-throughput screening (HTS) systems and to produce efficacy and safety data that closely resembles clinical observations. Although no published applications of 3D bioprinting in clinical trials were found, there are two clinical trials planning to evaluate the predictive ability of 3D bioprinted models by comparing human and model responses to the same chemotherapy. Overall, this review provides a comprehensive summary of the latest applications of 3D bioprinting in drug discovery and development.

3D bioprinting of liver models: A systematic scoping review of methods, bioinks, and reporting quality

Background

Effective communication is crucial for broad acceptance and applicability of alternative methods in 3R biomedical research and preclinical testing. 3D bioprinting is used to construct intricate biological structures towards functional liver models, specifically engineered for deployment as alternative models in drug screening, toxicological investigations, and tissue engineering. Despite a growing number of reviews in this emerging field, a comprehensive study, systematically assessing practices and reporting quality for bioprinted liver models is missing.

Methods

In this systematic scoping review we systematically searched MEDLINE (Ovid), EMBASE (Ovid) and BioRxiv for studies published prior to June 2nd, 2022. We extracted data on methodological conduct, applied bioinks, the composition of the printed model, performed experiments and model applications. Records were screened for eligibility and data were extracted from included articles by two independent reviewers from a panel of seven domain experts specializing in bioprinting and liver biology. We used RAYYAN for the screening process and SyRF for data extraction. We used R for data analysis, and R and Graphpad PRISM for visualization.

Results

Through our systematic database search we identified 1042 records, from which 63 met the eligibility criteria for inclusion in this systematic scoping review. Our findings revealed that extrusion-based printing, in conjunction with bioinks composed of natural components, emerged as the predominant printing technique in the bioprinting of liver models. Notably, the HepG2 hepatoma cell line was the most frequently employed liver cell type, despite acknowledged limitations. Furthermore, 51% of the printed models featured co-cultures with non-parenchymal cells to enhance their complexity. The included studies offered a variety of techniques for characterizing these liver models, with their primary application predominantly focused on toxicity testing. Among the frequently analyzed liver markers, albumin and urea stood out. Additionally, Cytochrome P450 (CYP) isoforms, primarily CYP3A and CYP1A, were assessed, and select studies employed nuclear receptor agonists to induce CYP activity.

Conclusion

Our systematic scoping review offers an evidence-based overview and evaluation of the current state of research on bioprinted liver models, representing a promising and innovative technology for creating alternative organ models. We conducted a thorough examination of both the methodological and technical facets of model development and scrutinized the reporting quality within the realm of bioprinted liver models. This systematic scoping review can serve as a valuable template for systematically evaluating the progress of organ model development in various other domains. The transparently derived evidence presented here can provide essential support to the research community, facilitating the adaptation of technological advancements, the establishment of standards, and the enhancement of model robustness. This is particularly crucial as we work toward the long-term objective of establishing new approach methods as reliable alternatives to animal testing, with extensive and versatile applications.

[Contribution to the world of 3D cell products created by bio 3D printing technology and to the life science field]

We have been making 3D tissues consist of cells only, based on the corporate philosophy of "contributing to dramatic advances in medical care through the practical application of innovative 3D cell stacking technology." Currently, in the field of regenerative medicine, we are working toward obtaining approval from the Ministry of Health, Labor and Welfare and commercializing large artificial organs that are made from patients' own cells and have functions such as nerve regeneration, osteochondral regeneration, and blood vessels. On the other hand, this three-dimensional cell stacking technology can be extended to technology for culturing cells in an environment similar to the human body, and is expected to serve as a new methodology for evaluating the effects of new products in various fields on living organisms. Therefore, we are planning a business to provide developers of pharmaceuticals, foods, cosmetics, etc. with a small device called "Functional Cell Device (FCD)" that reproduces some of the functions of human organs outside the body. As the first step, we have developed a three-dimensional liver construct (3D mini-liver). The in vitro human liver model has a wide range of usage, such as evaluation of hepatotoxicity of drugs, elucidation of drug metabolism mechanism, and model of liver disease. In this report, we will outline it together with actual examples in regenerative medicine.

Application of 3D Bioprinting in Liver Diseases

Liver diseases are the primary reason for morbidity and mortality in the world. Owing to a shortage of organ donors and postoperative immune rejection, patients routinely suffer from liver failure. Unlike 2D cell models, animal models, and organoids, 3D bioprinting can be successfully employed to print living tissues and organs that contain blood vessels, bone, and kidney, heart, and liver tissues and so on. 3D bioprinting is mainly classified into four types: inkjet 3D bioprinting, extrusion-based 3D bioprinting, laser-assisted bioprinting (LAB), and vat photopolymerization. Bioinks for 3D bioprinting are composed of hydrogels and cells. For liver 3D bioprinting, hepatic parenchymal cells (hepatocytes) and liver nonparenchymal cells (hepatic stellate cells, hepatic sinusoidal endothelial cells, and Kupffer cells) are commonly used. Compared to conventional scaffold-based approaches, marked by limited functionality and complexity, 3D bioprinting can achieve accurate cell settlement, a high resolution, and more efficient usage of biomaterials, better mimicking the complex microstructures of native tissues. This method will make contributions to disease modeling, drug discovery, and even regenerative medicine. However, the limitations and challenges of this method cannot be ignored. Limitation include the requirement of diverse fabrication technologies, observation of drug dynamic response under perfusion culture, the resolution to reproduce complex hepatic microenvironment, and so on. Despite this, 3D bioprinting is still a promising and innovative biofabrication strategy for the creation of artificial multi-cellular tissues/organs.

3D bioprinted liver tissue and disease models: Current advances and future perspectives

Three-dimensional (3D) bioprinting is a promising technology for fabricating complex tissue constructs with biomimetic biological functions and stable mechanical properties. In this review, the characteristics of different bioprinting technologies and materials are compared, and development in strategies for bioprinting normal and diseased hepatic tissue are summarized. In particular, features of bioprinting and other bio-fabrication strategies, such as organoids and spheroids are compared to demonstrate the strengths and weaknesses of 3D printing technology. Directions and suggestions, such as vascularization and primary human hepatocyte culture, are provided for the future development of 3D bioprinting.

In vitro long term differentiation and functionality of three-dimensional bioprinted primary human hepatocytes: application for in vivo engraftment

In recent decades, 3D in vitro cultures of primary human hepatocytes (PHH) have been increasingly developed to establish models capable of faithfully mimicking main liver functions. The use of 3D bioprinting, capable of recreating structures composed of cells embedded in matrix with controlled microarchitectures, is an emergent key feature for tissue engineering. In this work, we used an extrusion-based system to print PHH in a methacrylated gelatin matrix (GelMa). PHH bioprinted in GelMa rapidly organized into polarized hollow spheroids and were viable for at least 28 days of culture. These PHH were highly differentiated with maintenance of liver differentiation genes over time, as demonstrated by transcriptomic analysis and functional approaches. The cells were polarized with localization of apico/canalicular regions, and displayed activities of phase I and II biotransformation enzymes that could be regulated by inducers. Furthermore, the implantation of the bioprinted structures in mice demonstrated their capability to vascularize, and their ability to maintain human hepatic specific functions for at least 28 days was illustrated by albumin secretion and debrisoquine metabolism. This model could hold great promise for human liver tissue generation and its use in future biotechnological developments.

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.

HepG2-NIAS cells, a new subline of HepG2 cells that can enhance not only CYP3A4 activity but also expression of drug transporters and form bile canaliculus-like networks by the oxygenation culture via a collagen vitrigel membrane

We reported the enhanced liver-specific function and structure of HepG2 cells by the oxygenation culture via a collagen vitrigel membrane (CVM). The cells were conditioned in our laboratory for a long period, so their characteristics may change from the original HepG2 cells registered in RIKEN cell bank (RCB) with the number of 1648 (HepG2-RCB1648 cells). We named the conditioned HepG2-RCB1648 cells in our laboratory as HepG2-NIAS cells. Here, we clarified the features of HepG2 cells with three different culture histories by analyzing their morphology and viability, CYP3A4 activity, the potential to form bile canaliculus-like structures, and the expression of drug transporters. On plastic, HepG2-NIAS cells grew as a monolayer without the formation of large aggregates involving dead cells that were observed in HepG2-RCB1648 cells and HepG2-RCB1886 cells. In the oxygenation culture via a CVM, the CYP3A4 activity of HepG2-NIAS cells increased to almost half level in direct comparison to that of differentiated HepaRG cells cultured on a collagen-coated plate; however, that of HepG2-RCB1648 cells and HepG2-RCB1886 cells was almost not detected. HepG2-NIAS cells formed bile canaliculus-like networks in which fluorescein was accumulated after the exposure of fluorescein diacetate, although HepG2-RCB1648 cells and HepG2-RCB1886 cells did not possess the potential. Also, immunohistological observations revealed that HepG2-NIAS cells remarkably enhanced the expression of drug transporters, NTCP, OATP1B1, OATP1B3, BSEP, MDR1, MRP2, and BCRP. These results suggest that HepG2-NIAS cells are a new subline of HepG2 cells useful for drug development studies. HepG2-NIAS cells were registered in RCB with the number of 4679.

Preclinical models of idiosyncratic drug-induced liver injury (iDILI): Moving towards prediction

Idiosyncratic drug-induced liver injury (iDILI) encompasses the unexpected harms that prescription and non-prescription drugs, herbal and dietary supplements can cause to the liver. iDILI remains a major public health problem and a major cause of drug attrition. Given the lack of biomarkers for iDILI prediction, diagnosis and prognosis, searching new models to predict and study mechanisms of iDILI is necessary. One of the major limitations of iDILI preclinical assessment has been the lack of correlation between the markers of hepatotoxicity in animal toxicological studies and clinically significant iDILI. Thus, major advances in the understanding of iDILI susceptibility and pathogenesis have come from the study of well-phenotyped iDILI patients. However, there are many gaps for explaining all the complexity of iDILI susceptibility and mechanisms. Therefore, there is a need to optimize preclinical human in vitro models to reduce the risk of iDILI during drug development. Here, the current experimental models and the future directions in iDILI modelling are thoroughly discussed, focusing on the human cellular models available to study the pathophysiological mechanisms of the disease and the most used in vivo animal iDILI models. We also comment about in silico approaches and the increasing relevance of patient-derived cellular models.

3D Bioprinting-Based Vascularized Tissue Models Mimicking Tissue-Specific Architecture and Pathophysiology for in vitro Studies

A wide variety of experimental models including 2D cell cultures, model organisms, and 3D in vitro models have been developed to understand pathophysiological phenomena and assess the safety and efficacy of potential therapeutics. In this sense, 3D in vitro models are an intermediate between 2D cell cultures and animal models, as they adequately reproduce 3D microenvironments and human physiology while also being controllable and reproducible. Particularly, recent advances in 3D in vitro biomimicry models, which can produce complex cell structures, shapes, and arrangements, can more similarly reflect in vivo conditions than 2D cell culture. Based on this, 3D bioprinting technology, which enables to place the desired materials in the desired locations, has been introduced to fabricate tissue models with high structural similarity to the native tissues. Therefore, this review discusses the recent developments in this field and the key features of various types of 3D-bioprinted tissues, particularly those associated with blood vessels or highly vascularized organs, such as the heart, liver, and kidney. Moreover, this review also summarizes the current state of the three categories: (1) chemical substance treatment, (2) 3D bioprinting of lesions, and (3) recapitulation of tumor microenvironments (TME) of 3D bioprinting-based disease models according to their disease modeling approach. Finally, we propose the future directions of 3D bioprinting approaches for the creation of more advanced in vitro biomimetic 3D tissues, as well as the translation of 3D bioprinted tissue models to clinical applications.