Generation of expandable human pluripotent stem cell-derived hepatocyte-like liver organoids

Two-dimensionally cultured functional hepatocytes generated from human induced pluripotent stem cell-derived hepatic organoids for pharmaceutical research

Human induced pluripotent stem (iPS) cell-derived hepatocyte-like cells (HLCs) are expected to replace primary human hepatocytes (PHHs) as a new stable source of hepatocytes for pharmaceutical research. However, HLCs have lower hepatic functions than PHHs, require a long time for differentiation and cannot be prepared in large quantities because they do not proliferate after their terminal differentiation. To overcome these problems, we here established hepatic organoids (iHOs) from HLCs. We then showed that the iHOs could proliferate approximately 105-fold by more than 3 passages and expressed most hepatic genes more highly than HLCs. In addition, to enable their widespread use for in vitro drug discovery research, we developed a two-dimensional culture protocol for iHOs. Two-dimensionally cultured iHOs (iHO-Heps) expressed most of the major hepatocyte marker genes at much higher levels than HLCs, iHOs, and even PHHs. The iHO-Heps exhibited glycogen storage capacity, the capacity to uptake and release indocyanine green (ICG), albumin and urea secretion, and the capacity for bile canaliculi formation. Importantly, the iHO-Heps had the activity of major drug-metabolizing enzymes and responded to hepatotoxic drugs, much like PHHs. Thus, iHO-Heps overcome the limitations of the current models and promise to provide robust and reproducible pharmaceutical assays.

Therapeutic potential of stem cell-derived somatic cells to treat metabolic dysfunction-associated steatotic liver disease and diabetes

Developments in basic stem cell biology have paved the way for technology translation in human medicine. An exciting prospective use of stem cells is the ex vivo generation of hepatic and pancreatic endocrine cells for biomedical applications. This includes creating novel models 'in a dish' and developing therapeutic strategies for complex diseases, such as metabolic dysfunction-associated steatotic liver disease (MASLD) and diabetes. In this review, we explore recent advances in the generation of stem cell-derived hepatocyte-like cells and insulin-producing β-like cells. We cover the different differentiation strategies, new discoveries, and the caveats that still exist regarding their routine use. Finally, we discuss the challenges and limitations of stem cell-derived therapies as a clinical strategy to manage metabolic diseases in humans.

Engineering a dynamic extracellular matrix using thrombospondin-1 to propel hepatocyte organoids reprogramming and improve mouse liver regeneration post-transplantation

Hepatocyte organoids (HOs) hold significant potential for constructing bioartificial liver construction, toxicology research, and liver failure therapies. However, challenges such as difficulties in induced pluripotent stem cells (iPSCs) harvest and differentiation, safety concerns of tumor-derived matrices, and limited primary cell regulation hinder clinical applications. In this study, we developed a non-tumor-derived decellularized extracellular matrix (dECM) system with tunable mechanical properties and viscoelasticity to enhance stem cell proliferation and organoid functionality using thrombospondin-1 (THBS1). Nanoindentation and transcriptomic analysis revealed that THBS1 mediates adaptation and remodeling between organoids and ECM proteins, exhibiting native tissue-like viscoelasticity and up-regulated reprogramming transcriptional factors KLF4 and SOX2 via the YAP/TAZ pathway. Transplanting HOs presenting reprogramming effects into a 70 % hepatectomy model demonstrated improved liver regeneration, underscoring the potential of the THBS1-based dynamic ECM system in organoids manipulation and liver regeneration.

Modeling hepatic steatosis with human adult stem cell-derived liver organoids

Metabolic dysfunction-associated steatotic liver disease (MASLD) remains the most common chronic liver disease worldwide, and appropriate in vitro models are of great significance for investigating pathogenesis and drug screening of MASLD. In this study, human expandable cholangiocyte organoids were derived from adult stem cells of normal liver tissue. After differentiation, liver organoids (LOs) exhibited the functional characteristics and genomic features of mature hepatocytes. To induce steatosis, LOs were incubated with a gradient concentration oleic acid, and it was found that the model could recapitulate the development of lipid accumulation and inflammation. In addition, the drug sensitivity of the hepatic steatosis model was further verified through anti-steatosis drug testing. In summary, LOs have great potential for disease modeling, and the results indicate that the hepatic steatosis model may serve as a useful tool for exploring the molecular mechanisms and drug screening of MASLD.

Bile acid-FXR signaling facilitates the long-term maintenance of hepatic characteristics in human iPSC-derived organoids

Human induced pluripotent stem cells (iPSCs) can be differentiated into hepatocyte-like cells (iPS-Heps); however, maintaining the long-term proliferation and hepatic characteristics of iPS-Heps remains a challenge. In this study, we aimed to develop a human iPSC-derived hepatic organoid (iHO) culture system that effectively retains hepatic characteristics long term. Our original culture strategy, using bile acids and their receptor (farnesoid X receptor [FXR]) agonists, yielded human iHOs capable of long-term culture with a distinctive "grape-like" structure. Comprehensive analysis showed that these iHOs maintained hepatocyte-like phenotypes, even after multiple passages, whose gene expression profiles were consistent with those of fetal hepatocytes. In addition, the overexpression of small heterodimer partner (SHP), a downstream gene of FXR, in iHOs negatively regulated genes related to the intestine and cholangiocytes. Our data demonstrated that bile acid-FXR signaling promotes both the hepatic characteristics and proliferative potential of iHOs, offering promising potential for future applications in regenerative medicine and as a disease model.

UFMylation safeguards human hepatocyte differentiation and liver homeostasis by regulating ribosome dissociation

Ribosomal UFMylation contributes to ribosome heterogeneity and is associated with ribosome-associated quality control at the endoplasmic reticulum. However, the specific pathophysiological functions of ribosomal UFMylation remain unknown. In this study, we systematically demonstrate the significance of UFMylation in the differentiation and maturation of hepatocytes using human embryonic stem cell-derived hepatocyte-like cells and liver bud organoids as experimental platforms. We also develop a strategy to identify UFMylated substrates and confirm that RPL26 is a substrate in the liver. Additionally, we discover that mice with the Rpl26 c.395A>G (p.K132R) mutation are more susceptible to steatosis induced by a high-fat diet. Further investigations reveal a key role of CDK5RAP3 and RPL26 UFMylation in regulating ribosome dissociation. Our findings suggest that ribosome UFMylation serves as an important safeguard for liver development and homeostasis and may represent a potential therapeutic target for nonalcoholic fatty liver disease.

Liver organoids uncover tire-derived 6-PPDQ-induced hepatotoxicity of: A preliminary application of environmental toxicology and safety assessment

The novel pollutant, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine quinone (6-PPDQ) leaked out of the tire and has attracted extensive concerns due to its high lethal toxicity of salmon. However, the potential hepatotoxicity of 6-PPDQ exposure and its mechanisms are unknown. As a novel 3D cell culture, liver organoids (LOs) are more similar to real organ invitro in structure and function, which showed great potential for toxicity assessment. Herein, stable LOs were generated and their applicability on hepatotoxicity assessment was evaluated with four hepatotoxic compounds. The negative effect of 6-PPDQ was explored in LOs, live/dead staining visually demonstrated the damage to the liver, and the changes of ATP, LDH, ALT, and AST effectively reflected its hepatotoxicity. Meanwhile, machine learning-based quantitative assessments of LOs morphology changes provided objective data on area, circularity, and luminance changes, enabling sensitive detection of 6-PPDQ-induced hepatotoxicity. Furthermore, transcriptomic analysis revealed that the pathways related to DNA replication and repairment, cancers, and inflammation were significantly involved in the process of 6-PPDQ-induced liver injury; Disease enrichment analysis highlighted an increased risk of chronic liver diseases, and biliary atresia were validated by Cholyl-Lys-Fluorescein (CLF). Moreover, molecular docking analysis identified potential molecular targets of 6-PPDQ, including Slc6a9, Yes1, and Nos2. This study underscored the potential of LOs for toxicological studies and highlighted the toxic effects of 6-PPDQ on the liver, suggesting the need for further investigations to understand its long-term impact on human health.

Liver Organoids From Hepatocytes of Healthy Humans and Non-alcoholic Fatty Liver Disease (NAFLD) Patients Display Multilineage Architecture and can be Used to Develop an In Vitro Model of Steatohepatitis

Background/Aim

Non-alcoholic fatty liver disease (NAFLD) is a global health concern with limited treatment options. The paucity of predictive i n v itro models in preclinical settings seems to be one of the limitations of identifying effective medicines. We therefore aimed to develop an i n v itro model that can display the key hallmarks of NAFLD, such as steatosis, inflammation, and fibrosis.

Methods

An in vitro model of steatohepatitis was developed using organoids prepared from hepatocytes of healthy individuals from a commercial source (HLOs) and the liver tissues collected from needle biopsies of NAFLD patients (HLONAFLD) using defined culture conditions. HLOs were treated with palmitic acid for 72 h to develop an i n v itro model of steatohepatitis, while HLONAFLD served as a natural model of steatohepatitis. Metformin and saroglitazar were used to validate the liver organoid model of steatohepatitis. Saroglitazar was also evaluated in the high-fat, high-fructose (HF-HF) diet-induced model of NAFLD using C57BL/6 mice to validate the findings from the i n v itro model.

Results

HLOs and HLONAFLD exhibited bipotent properties, showing the expression of markers of hepatocytes, ductal cells, and also stem cells. Furthermore, they demonstrated the expression of nonparenchymal cell markers such as stellate cells (CD166) and Kupffer-like cells (CD68 and EMR1). The steatohepatitis models developed using these organoids displayed markers associated with steatosis, inflammation and fibrosis, which were decreased by metformin and saroglitazar.

Conclusion

The in vitro models developed in our lab employing HLOs and HLONAFLD display all three key hallmarks of NAFLD: steatosis, inflammation, and fibrosis without the necessity for coculture with other nonparenchymal cells. The implementation of the HLONAFLD-based model is also expected to provide a more realistic assessment of test substances to develop therapeutics for NAFLD.

Experimental Models to Investigate PNPLA3 in Liver Steatosis

Patatin-like phospholipase domain-containing 3 (PNPLA3) was the first gene identified through genome-wide association studies to be linked to hepatic fat accumulation. A missense variant, encoding the PNPLA3-148M allele, has since been shown to increase the risk for the full spectrum of steatotic liver disease (SLD), from simple steatosis to steatohepatitis, cirrhosis, and hepatocellular carcinoma. Despite extensive validation of this association and ongoing research into its pathogenic role, the precise mechanisms by which PNPLA3-148M contributes to the progression of SLD remain poorly understood. In this review, we evaluate preclinical in vitro and in vivo models used to investigate PNPLA3 and its involvement in SLD, with particular emphasis on metabolic dysfunction-associated steatotic liver disease. We assess the strengths and limitations of these models, as well as the challenges arising from species differences in PNPLA3 expression and function between human and murine systems.

Transdifferentiation of Integrin Beta 1 High+ Skin Progenitor Cells Into Functional Hepatocytes

A highly reproducible and functional liver model that closely resembles the human liver plays a crucial role in drug development, disease research, personalized medicine, and regenerative medicine. This study aimed to establish an in vitro liver model using skin epidermal progenitor cells (EPCs), which are easily accessible and exhibit a high proliferative capacity. Skin EPCs with high integrin beta 1 expression demonstrated multipotent differentiation potential, capable of differentiating into adipocyte- and neuron-like cells in vitro. Furthermore, when exposed to high concentrations of activin A, along with Wnt3a and BMP4, these cells efficiently differentiated into definitive endoderm, exhibiting high FOXA2 expression. Under our culture conditions, they further differentiated into functional hepatocytes. These differentiated cells exhibited high albumin secretion, CYP activity, and drug metabolism capabilities similar to those observed in vivo. In conclusion, this study highlights the potential of EPCs to differentiate into functional hepatocytes, providing a feasible and scalable source of hepatocytes for drug screening, liver disease modeling, and potential cell-based therapies.

Development of a microarray microfluidic chip mass spectrometry platform based on UV curable 3D hepatocellular sphere bio-ink for rapid screening inhibitors of advanced glycosylation end products from natural compounds

Advanced glycation end products (AGEs) are the unwanted by-products of excessive sugar intake, and their generation and accumulation promote aging and disease occurrence. However, the lack of robust biology model and platform for fast evaluating AGE generation and accumulation under intervention of drugs hampers AGEs-targeted therapeutic development. This work described a novel biological high AGEs recombinant extracellular matrix 3D human hepatocellular spheres model was built, under the same cell numbers, this 3D hepatocellular spheres expressed more AGEs over an order of magnitude than monolayer culture cells. Combined with UV curable gelatin methacryloyl (GelMA), biological 3D human hepatocellular sphere were made into a extruded type bio-ink with high AGEs, simply encapsulated in a hepatic lobule shaped micro array polymethyl methacrylate (PMMA) microfluidic chip successfully. Due to this biomimetic fluid microreactor environment, our biological microfluidic chip enables effectively determine the inhibition capacity of compounds on endogenous AGE accumulation with a high sensitivity and in a short time, total determination workflow less than 2.5 h, it takes 1/200 of the time required by mainstream methods. The evaluation results showed that alisol B 23-monoacetate and chlorogenic acid were potential natural AGEs inhibitors. Moreover, the integration of high AGEs bio-ink and microfluidic chip provides a promising tool for AGE-related drug discovery and liver disease research.

Cell therapies and liver organogenesis technologies: Promising strategies for end-stage liver disease

End-stage liver disease represents a critical hepatic condition with high mortality, for which liver transplantation remains the only effective treatment. However, the scarcity of suitable donors results in numerous patients dying while awaiting transplantation. Novel strategies, including cell therapies and technologies mimicking liver organogenesis, offer promising alternatives for treating end-stage liver disease by potentially providing new sources of liver grafts. Recently, significant progress has been made in this field, including stem cell transplantation, hepatocyte transplantation, in vitro liver tissue generation, and liver replacement technologies. Several clinical studies have demonstrated that stem cell transplantation and hepatocyte transplantation can prolong patient survival and serve as a bridge to liver transplantation. Furthermore, in vitro liver tissue generation technologies, such as liver organoids and three-dimensional bioprinting, can generate hepatic tissues with sophisticated structures and functions, making them promising transplantation materials. Notably, liver replacement technologies hold considerable potential for producing biologically functional and transplantable liver grafts. In this review, we discuss the fundamental principles and recent advancements in cell therapies and liver organogenesis technologies while also addressing the challenges and future prospects in this rapidly evolving field.

Hepatotoxicity evaluation method through multiple-factor analysis using human pluripotent stem cell derived hepatic organoids

Prediction of the potential for drug-induced liver injury (DILI) in the early stages of drug development is important. We developed an organoid-based and functional endpoint method for accurate prediction of DILI. To this end, hepatic organoids (HOs) derived from human pluripotent stem cells (hPSCs) were cocultured with hepatic stellate cells (HSCs) and THP-1 macrophages in Matrigel domes to mimic the cellular and physiological environment of the human liver. To validate our hepatotoxicity prediction model, we selected 12 hepatotoxic reference compounds. As indicators, we used factors related to mechanisms of hepatotoxicity and markers thereof, including factors related to oxidative stress and proinflammatory cytokines. We plotted radar graphs and calculated the relative areas of polygons to analyze the effects of drugs with different degrees of hepatotoxicity. The drugs in the severe DILI group significantly increased the levels of factors related to oxidative stress (ROS, GSSH, and catalase) compared to those in the no and mild DILI groups. The drugs in the severe group significantly increased the levels of inflammation-related factors (IL-1, IL-6, and IL-10). The drugs in the mild and severe groups highly significantly increased the activities of ALT and AST and the level of ALB compared to those in the no DILI group. In summary, the drugs in the severe DILI group had significantly greater effects on the factors analyzed than those in the no DILI group. Therefore, our hepatotoxicity evaluation method is suitable for predicting DILI in the early stages of drug development.

Pancreatic 3D Organoids and Microfluidic Systems-Applicability and Utilization in Surgery: A Literature Review

Background: Pancreatic organoids are a rapidly advancing field of research with new discoveries being made every day. A literature review was performed to answer the question of how relevant 3D pancreatic organoids are for surgery. Materials and Methods: We started our investigation by identifying articles in PubMed within the last 5 years using the keywords (("pancreatic organoid", OR "organ-on-a-chip", OR "pancreatic chip" OR "3D culture methods") AND pancreatic surgery). Only English articles were included in this literature review. This literature review was performed in a non-systematic way; articles were chosen without a predetermined protocol of inclusion and were based on the aim of the review. Results and Conclusions: There are many promising innovations in the field of 3D cultures. Drug sensitivity testing in particular holds great potential for surgical application. For locally advanced PDAC, EUS-FNB obtained cancer tissue can be cultured as organoids, and after 4 weeks, neoadjuvant treatment could be adjusted for each patient individually. Utilizing this approach could increase the number of R0 resections and possibly cure the disease. Furthermore, microfluidic devices, as a platform for pancreatic islet pre-transplant evaluation or cultivation of beta cells derived from HiPSC in vitro, promise broad application of islet transplantation to T1DM patients in the near future.

From gut to liver: organoids as platforms for next-generation toxicology assessment vehicles for xenobiotics

Traditional toxicological assessment relied heavily on 2D cell cultures and animal models of study, which were inadequate for the precise prediction of human response to chemicals. Researchers have now shifted focus on organoids for toxicological assessment. Organoids are 3D structures produced from stem cells that mimic the shape and functionality of human organs and have a number of advantages compared to traditional models of study. They have the capacity to replicate the intricate cellular microenvironment and in vivo interactions. They offer a physiologically pertinent platform that is useful for the researchers to monitor cellular responses in a more realistic manner and evaluate drug toxicity. Additionally, organoids can be created from cells unique to a patient, allowing for individualized toxicological research and providing understanding of the inter-individual heterogeneity in drug responses. Recent developments in the use of gut and liver organoids for assessment of the xenobiotics (environmental toxins and drugs) is reviewed in this article. Gut organoids can reveal potential damage to the digestive system and how xenobiotics affect nutrient absorption and barrier function. Liver is the primary site of detoxification and metabolism of xenobiotics, usually routed from the gut. Hence, these are linked and crucial for evaluating chemical or pollutant induced organ toxicity, forecasting their metabolism and pharmacokinetics. When incorporated into the drug development process, organoid models have the potential to improve the accuracy and efficiency of drug safety assessments, leading to safer and more effective treatments. We also discuss the limitations of using organoid-based toxicological assays, and future prospects, including the need for standardized protocols for overcoming reproducibility issues.

A New Perspective on Precision Medicine: The Power of Digital Organoids

Precision medicine is a personalized medical model based on the individual's genome, phenotype, and lifestyle that provides tailored treatment plans for patients. In this context, tumor organoids, a 3-dimensional preclinical model based on patient-derived tumor cell self-organization, combined with digital analysis methods, such as high-throughput sequencing and image processing technology, can be used to analyze the genome, transcriptome, and cellular heterogeneity of tumors, so as to accurately track and assess the growth process, genetic characteristics, and drug responsiveness of tumor organoids, thereby facilitating the implementation of precision medicine. This interdisciplinary approach is expected to promote the innovation of cancer diagnosis and enhance personalized treatment. In this review, the characteristics and culture methods of tumor organoids are summarized, and the application of multi-omics, such as bioinformatics and artificial intelligence, and the digital methods of organoids in precision medicine research are discussed. Finally, this review explores the main causes and potential solutions for the bottleneck in the clinical translation of digital tumor organoids, proposes the prospects of multidisciplinary cooperation and clinical transformation to narrow the gap between laboratory and clinical settings, and provides references for research and development in this field.

3D tumor cultures for drug resistance and screening development in clinical applications

Tumor drug resistance presents a growing challenge in medical practice, particularly during anti-cancer therapies, where the emergence of drug-resistant cancer cells significantly complicates clinical treatment. In recent years, three-dimensional (3D) tumor culture technology, which more effectively simulates the in vivo physiological environment, has gained increasing attention in tumor drug resistance research and clinical applications. By mimicking the in vivo cellular microenvironment, 3D tumor culture technology not only recapitulates cell-cell interactions but also more faithfully reproduces the biological effects of therapeutic agents. Consequently, 3D tumor culture technology is emerging as a crucial tool in biomedical and clinical research. We summarize the benefits of 3D culture models and organoid technology, explore their application in the realm of drug resistance, drug screening, and personalized therapy, and discuss their potential application prospects and challenges in clinical transformation, with the aim of providing insights for optimizing cancer treatment strategies and advancing precision therapy.

Optimization of culture conditions to generate vascularized multi-lineage liver organoids with structural complexity and functionality

Hepatic organoids (HOs), primarily composed of hepatobiliary cells, do not represent the pathogenesis of liver diseases due to the lack of non-parenchymal cells. Multi-lineage liver organoids (mLOs) containing various cell types found in the liver offer a promising in vitro disease model. However, their structural complexity remains challenging to achieve due to the difficulty in optimizing culture conditions that meet the growth need of all component cell types. Here, we demonstrate that cystic HOs generated from hPSCs can be expanded long-term and serve as a continuous source for generating complex mLOs. Assembling cystic HOs with hPSC-derived endothelial and hepatic stellate cell-like cells under conventional HO culture conditions failed to support the development of multiple cell types within mLOs, resulting in biased differentiation towards specific cell types. In contrast, modulating the cAMP/Wnt/Hippo signaling pathways with small molecules during assembly and differentiation phases efficiently generate mLOs containing both hepatic parenchymal and non-parenchymal cells. These mLOs exhibited structural complexity and functional maturity, including vascular network formation between parenchymal lobular structures, cell polarity for bile secretion, and the capacity to respond to fibrotic stimuli. Our study underscores the importance of modulating signaling pathways to enhance mLO structural complexity for applications in modeling liver pathologies.

Emerging biotechnologies for engineering liver organoids

The engineering construction of the liver has attracted enormous attention. Organoids, as emerging miniature three-dimensional cultivation units, hold significant potential in the biomimetic simulation of liver structure and function. Despite notable successes, organoids still face limitations such as high variability and low maturity. To overcome these challenges, engineering strategies have been established to maintain organoid stability and enhance their efficacy, laying the groundwork for the development of advanced liver organoids. The present review comprehensively summarizes the construction of engineered liver organoids and their prospective applications in biomedicine. Initially, we briefly present the latest research progress on matrix materials that maintain the three-dimensional morphology of organoids. Next, we discuss the manipulative role of engineering technologies in organoid assembly. Additionally, we outline the impact of gene-level regulation on organoid growth and development. Further, we introduce the applications of liver organoids in disease modeling, drug screening and regenerative medicine. Lastly, we overview the current obstacles and forward-looking perspectives on the future of engineered liver organoids. We anticipate that ongoing innovations in engineered liver organoids will lead to significant advancements in medical applications.

Current hPSC-derived liver organoids for toxicity testing: Cytochrome P450 enzymes and drug metabolism

Drug-induced hepatotoxicity is the leading cause of attrition of drug candidates and withdrawal of marketed drugs owing to safety concerns. In most hepatotoxicity cases, the parent drugs are metabolized by cytochrome P450 (CYP) enzymes, generating reactive metabolites that bind to intracellular organelles and proteins, ultimately causing hepatocellular damage. A major limitation of animal models, which are widely used for toxicity assessment, is the discrepancy in CYP-mediated drug metabolism and toxicological outcomes owing to species differences between humans and animals. Two-dimensional (2D) hepatocytes were first developed as a promising alternative model using human pluripotent stem cells (hPSCs). However, their CYP expression was similar to that of the fetal liver, and they lacked CYP-mediated hepatic metabolism. CYP expression in hPSC-derived hepatic models is closely correlated with liver maturity. Therefore, liver organoids that are more mature than hPSC-derived hepatic models and mimic the structure and physiological functions of the human liver have emerged as new alternatives. In this review, we explored the role and essentiality of CYPs in human hepatotoxicity, their expression, and epigenetic regulation in hPSC-derived hepatocytes and liver organoids, as well as the current state of liver organoid technology in terms of CYP expression and activity, drug metabolism, and toxicity. We also discussed the current challenges and future directions for the practical use of liver organoids. In conclusion, we highlight the importance of methods and metrics for accurately assessing CYP expression and activity in liver organoids to enable the development of feasible models that reproduce hepatotoxicity in humans.

Global landscape of hepatic organoid research: A bibliometric and visual study

BACKGROUND

Hepatic organoid-based modelling, through the elucidation of a range of in vivo biological processes and the recreation of the intricate liver microenvironment, is yielding groundbreaking insights into the pathophysiology and personalized medicine approaches for liver diseases.

AIM

This study was designed to analyse the global scientific output of hepatic organoid research and assess current achievements and future trends through bibliometric analysis.

METHODS

Articles were retrieved from the Web of Science Core Collection, and CiteSpace 6.3.R1 was employed to analyse the literature, including outputs, journals, and countries, among others.

RESULTS

Between 2010 and 2024, a total of 991 articles pertaining to hepatic organoid research were published. The journal Hepatology published the greatest number of papers, and journals with an impact factor greater than 10 constituted 60% of the top 10 journals. The United States and Utrecht University were identified as the most prolific country and institution, respectively. Clevers H emerged as the most prolific author, whereas Huch M had the highest number of cocitations, suggesting that both are ideal candidates for academic collaboration. Research on hepatic organoids has exhibited a progressive shift in focus, evolving from initial investigations into model building, differentiation research in stem cells, bile ducts, and progenitor cells, to a broader spectrum encompassing lipid metabolism, single-cell RNA sequencing, and therapeutic applications. The phrases exhibiting citation bursts from 2022 to 2024 include "drug resistance", "disease model", and "patient-derived tumor organoids".

CONCLUSION

Research on hepatic organoids has increased over the past decade and is expected to continue to grow. Key research areas include applications for liver diseases and drug development. Future trends likely to gain focus include patient-derived tumour organoids, disease modelling, and personalized medicine.

Organoids from pluripotent stem cells and human tissues: When two cultures meet each other

Human organoids are a widely used tool in cell biology to study homeostatic processes, disease, and development. The term organoids covers a plethora of model systems from different cellular origins that each have unique features and applications but bring their own challenges. This review discusses the basic principles underlying organoids generated from pluripotent stem cells (PSCs) as well as those derived from tissue stem cells (TSCs). We consider how well PSC- and TSC-organoids mimic the different intended organs in terms of cellular complexity, maturity, functionality, and the ongoing efforts to constitute predictive complex models of in vivo situations. We discuss the advantages and limitations associated with each system to answer different biological questions including in the field of cancer and developmental biology, and with respect to implementing emerging advanced technologies, such as (spatial) -omics analyses, CRISPR screens, and high-content imaging screens. We postulate how the two fields may move forward together, integrating advantages of one to the other.

The Evolution of Anticancer 3D In Vitro Models: The Potential Role of Machine Learning and AI in the Next Generation of Animal-Free Experiments

The development of anticancer therapies has increasingly relied on advanced 3D in vitro models, which more accurately mimic the tumor microenvironment compared to traditional 2D cultures. This review describes the evolution of these 3D models, highlighting significant advancements and their impact on cancer research. We discuss the integration of machine learning (ML) and artificial intelligence (AI) in enhancing the predictive power and efficiency of these models, potentially reducing the dependence on animal testing. ML and AI offer innovative approaches for analyzing complex data, optimizing experimental conditions, and predicting therapeutic outcomes with higher accuracy. By leveraging these technologies, the next generation of 3D in vitro models could revolutionize anticancer drug development, offering effective alternatives to animal experiments.

Hepatobiliary organoid research: the progress and applications

Organoid culture has emerged as a forefront technology in the life sciences field. As "in vitro micro-organs", organoids can faithfully recapitulate the organogenesis process, and conserve the key structure, physiological function and pathological state of the original tissue or organ. Consequently, it is widely used in basic and clinical studies, becoming important preclinical models for studying diseases and developing therapies. Here, we introduced the definition and advantages of organoids and described the development and advances in hepatobiliary organoids research. We focus on applying hepatobiliary organoids in benign and malignant diseases of the liver and biliary tract, drug research, and regenerative medicine to provide valuable reference information for the application of hepatobiliary organoids. Despite advances in research and treatment, hepatobiliary diseases including carcinoma, viral hepatitis, fatty liver and bile duct defects have still been conundrums of the hepatobiliary field. It is necessary and crucial to study disease mechanisms, establish efficient and accurate research models and find effective treatment strategies. The organoid culture technology shed new light on solving these issues. However, the technology is not yet mature, and many hurdles still exist that need to be overcome. The combination with new technologies such as CRISPR-HOT, organ-on-a-chip may inject new vitality into future development.

Large-Scale Production of Expandable Hepatoblast Organoids and Polarised Hepatocyte Organoids From hESCs Under 3D Static and Dynamic Suspension Conditions

To date, generating viable and functional hepatocytes in large scale remains challenge. By employing 3D suspension condition with the support of low concentration Matrigel, a novel culture system was developed to generate expandable hepatoblast organoids (HB-orgs) and mature polarised hepatocyte organoids (P-hep-orgs) from human embryonic stem cells (hESCs) in both dishes and bioreactors. scRNA-seq and functional assays were used to characterise HB-orgs and P-hep-orgs. hESC-derived HB-orgs could proliferate at least for 15 passages, leading to 1012 in total cells in 4 weeks. P-hep-orgs differentiated from HB-orgs displayed characteristics of mature hepatocytes with polarisation. Moreover, single-cell RNA sequencing exhibited that over 40% of cells in P-hep-orgs were highly fidelity with human primary hepatocytes. Eventually, large-scale production of P-hep-orgs could be generated from massively expanded HB-orgs within 1 week with similar number in bioreactors, which were achieved by the enhancements in energy metabolism contribute to the expansion of HB-orgs and maturation of P-hep-orgs in bioreactors. By providing a cost-efficient and robust platform, our study represents a significant step toward manufacturing large-scale functioning hESC-derived hepatocytes for cell-based therapeutics, disease modelling, pharmacology and toxicology studies.

High-Throughput Formation of Pre-Vascularized hiPSC-Derived Hepatobiliary Organoids on a Chip via Nonparenchymal Cell Grafting

Liver organoids have been increasingly adopted as a critical in vitro model to study liver development and diseases. However, the pre-vascularization of liver organoids without affecting liver parenchymal specification remains a long-lasting challenge, which is essential for their application in regenerative medicine. Here, the large-scale formation of pre-vascularized human hepatobiliary organoids (vhHBOs) is presented without affecting liver epithelial specification via a novel strategy, namely nonparenchymal cell grafting (NCG). Endothelial and mesenchymal cells are grafted to human hepatobiliary organoids (hHBOs) at the different liver epithelial differentiation stages without supplementing with nonparenchymal culture medium and growth factors. Endothelial grafting at the stage of hepatic maturation offers an optimal integration efficiency compared to the stage of hepatic specification. Additionally, grafting with mesenchymal proves crucial in endothelial invading and sprouting into the liver epithelial cells during the establishment of vhHBOs. Ectopic liver implants into mice further displayed integration of vhHBOs into mice vascular networks. Notably, transplanted vhHBOs self-organized into native liver tissue like hepatic zone and bile ducts, indicating their potential to regenerate damaged hepatic and bile duct tissues. It is believed that nonparenchymal cell grafting will offer a novel technical route to form a high-fidelity complex in vitro model for tissue engineering and regenerative medicine.

Liver organoids: Current advances and future applications for hepatology

The creation of self-organizing liver organoids represents a significant, although modest, step toward addressing the ongoing organ shortage crisis in allogeneic liver transplantation. However, researchers have recognized that achieving a fully functional whole liver remains a distant goal, and the original ambition of organoid-based liver generation has been temporarily put on hold. Instead, liver organoids have revolutionized the field of hepatology, extending their influence into various domains of precision and molecular medicine. These 3D cultures, capable of replicating key features of human liver function and pathology, have opened new avenues for human-relevant disease modeling, CRISPR gene editing, and high-throughput drug screening that animal models cannot accomplish. Moreover, advancements in creating more complex systems have led to the development of multicellular assembloids, dynamic organoid-on-chip systems, and 3D bioprinting technologies. These innovations enable detailed modeling of liver microenvironments and complex tissue interactions. Progress in regenerative medicine and transplantation applications continues to evolve and strives to overcome the obstacles of biocompatibility and tumorigenecity. In this review, we examine the current state of liver organoid research by offering insights into where the field currently stands, and the pivotal developments that are shaping its future.

Advances in liver organoids: replicating hepatic complexity for toxicity assessment and disease modeling

The lack of in vivo accurate human liver models hinders the investigation of liver-related diseases, injuries, and drug-related toxicity, posing challenges for both basic research and clinical applications. Traditional cellular and animal models, while widely used, have significant limitations in replicating the liver's complex responses to various stressors. Liver organoids derived from human pluripotent stem cells, adult stem cells primary cells, or tissues can mimic diverse liver cell types, major physiological functions, and architectural features. Recent advancements in the field have shown that some liver organoids have sufficient accuracy to replicate specific aspects of the human liver's complexity. This review highlights recent progress in liver organoid research, with a particular emphasis on their potential for toxicity assessment and disease modeling. The intrinsic advantages of liver organoids include higher sensitivity and suitability for long-term studies, which enhance the predictive value in drug and nanomaterial toxicity testing. The integration of liver organoids with microfluidic devices enables the simulation of the liver microenvironment and facilitates high-throughput drug screening. The liver organoids also serve as ideal platforms for studying liver diseases such as hepatitis, liver fibrosis, viral liver diseases, and monogenic diseases. Additionally, this review discusses the advantages and limitations of liver organoids along with potential avenues for future research.

Advances, challenges and future applications of liver organoids in experimental regenerative medicine

The liver is a vital organ responsible for numerous metabolic processes in the human body, including the metabolism of drugs and nutrients. After liver damage, the organ can rapidly return to its original size if the causative factor is promptly eliminated. However, when the harmful stimulus persists, the liver's regenerative capacity becomes compromised. Substantial theoretical feasibility has been demonstrated at the levels of gene expression, molecular interactions, and intercellular dynamics, complemented by numerous successful animal studies. However, a robust model and carrier that closely resemble human physiology are still lacking for translating these theories into practice. The potential for liver regeneration has been a central focus of ongoing research. Over the past decade, the advent of organoid technology has provided improved models and materials for advancing research efforts. Liver organoid technology represents a novel in vitro culture system. After several years of refinement, human liver organoids can now accurately replicate the liver's morphological structure, nutrient and drug metabolism, gene expression, and secretory functions, providing a robust model for liver disease research. Regenerative medicine aims to replicate human organ or tissue functions to repair or replace damaged tissues, restore their structure or function, or stimulate the regeneration of tissues or organs within the body. Liver organoids possess the same structure and function as liver tissue, offering the potential to serve as a viable replacement for the liver, aligning with the goals of regenerative medicine. This review examines the role of liver organoids in regenerative medicine.

Cellular Systems for Colorectal Stem Cancer Cell Research

Oncological diseases consistently occupy leading positions among the most life-threatening diseases, including in highly developed countries. At the same time, the second most common cause of cancer death is colorectal cancer. The current level of research shows that the development of effective therapy, in this case, requires a new grade of understanding processes during the emergence and development of a tumor. In particular, the concept of cancer stem cells that ensure the survival of chemoresistant cells capable of giving rise to new tumors is becoming widespread. To provide adequate conditions that reproduce natural processes typical for tumor development, approaches based on increasingly complex cellular systems are being improved. This review discusses the main strategies that allow for the study of the properties of tumor cells with an emphasis on colorectal cancer stem cells. The features of working with tumor cells and the advantages and disadvantages of 2D and 3D culture systems are considered.

In Vivo and In Vitro Models of Hepatic Fibrosis for Pharmacodynamic Evaluation and Pathology Exploration

Hepatic fibrosis (HF) is an important pathological state in the progression of chronic liver disease to end-stage liver disease and is usually triggered by alcohol, nonalcoholic fatty liver, chronic hepatitis viruses, autoimmune hepatitis (AIH), or cholestatic liver disease. Research on novel therapies has become a hot topic due to the reversibility of HF. Research into the molecular mechanisms of the pathology of HF and potential drug screening relies on reliable and rational biological models, mainly including animals and cells. Hence, a number of modeling approaches have been attempted based on human dietary, pathological, and physiological factors in the development of HF. In this review, classical and novel methods of modeling HF in the last 10 years were collected from electronic databases, including Web of Science, PubMed, ScienceDirect, ResearchGate, Baidu Scholar, and CNKI. Animal models of HF are usually induced by chemical toxicants, special diets, pathogenic microorganisms, surgical operations, and gene editing. The advantages and limitations of hepatic stellate cells (HSCs), organoids, and 3D coculture-based HF modeling methods established in vitro were also proposed and summarized. This information provides a scientific basis for the discovery of the pathological mechanism and treatment of HF.

Current Treatment Regimens and Promising Molecular Therapies for Chronic Hepatobiliary Diseases

Chronic hepatobiliary damage progressively leads to fibrosis, which may evolve into cirrhosis and/or hepatocellular carcinoma. The fight against the increasing incidence of liver-related morbidity and mortality is challenged by a lack of clinically validated early-stage biomarkers and the limited availability of effective anti-fibrotic therapies. Current research is focused on uncovering the pathogenetic mechanisms that drive liver fibrosis. Drugs targeting molecular pathways involved in chronic hepatobiliary diseases, such as inflammation, hepatic stellate cell activation and proliferation, and extracellular matrix production, are being developed. Etiology-specific treatments, such as those for hepatitis B and C viruses, are already in clinical use, and efforts to develop new, targeted therapies for other chronic hepatobiliary diseases are ongoing. In this review, we highlight the major molecular changes occurring in patients affected by metabolic dysfunction-associated steatotic liver disease, viral hepatitis (Delta virus), and autoimmune chronic liver diseases (autoimmune hepatitis, primary biliary cholangitis, and primary sclerosing cholangitis). Further, we describe how this knowledge is linked to current molecular therapies as well as ongoing preclinical and clinical research on novel targeting strategies, including nucleic acid-, mesenchymal stromal/stem cell-, and extracellular vesicle-based options. Much clinical development is obviously still missing, but the plethora of promising potential treatment strategies in chronic hepatobiliary diseases holds promise for a future reversal of the current increase in morbidity and mortality in this group of patients.

Spliced exon9 ADRM1 promotes liver oncogenicity via selective degradation of tumor suppressor FBXW7

BACKGROUND & AIMS

The ubiquitin receptor ADRM1/Rpn13 governs the specificity of eukaryotic protein degradation. We first discovered a novel spliced variant of ADRM1 with a skipped exon 9, termed ADRM1-ΔEx9, in human hepatocellular carcinoma (HCC) by SMRT sequencing. This study aimed to elucidate this novel ubiquitin receptor's underlying biology and clinical implications in HCC.

METHODS

The role of ADRM1-ΔEx9 in early liver carcinogenesis was studied using human liver-derived non-tumoral organoids and a murine model with hydrodynamic in vivo transfection. ADRM1-ΔEx9 biology in HCC and its potential as a biomarker for predicting olaparib response were investigated using patient-derived tumor organoids and xenograft models. The underlying mechanism was delineated using the Proteome Profiler Human Ubiquitin Array.

RESULTS

ADRM1-ΔEx9, not its full-length counterpart, conferred human liver organoids with pro-survival advantages and led to more profound tumor formation in a hydrodynamic transfected murine model. Functional knockdown resulted in spontaneous apoptosis in cell lines and patient-derived organoids, highlighting a pivotal role for ADRM1-ΔEx9 in HCC oncogenicity. Mechanistically, the shortened C-terminus of ADRM1-ΔEx9 interacted with a different deubiquitinase partner (BAP1) to alter proteasome specificity. The new exon 8-10 fusion in ADRM1-ΔEx9 creates a de novo binding site for the tumor suppressor protein FBXW7, resulting in its selective proteasome-mediated degradation. The loss of FBXW7 protein in ADRM1-ΔEx9-expressing tumors underscores their sensitivity to the PARP inhibitor olaparib. Notably, findings on ADRM1-ΔEx9 in primary HCC tumors denote its overexpression in a subgroup of patients with inferior survival and a window of therapeutic opportunity through a synthetic lethal association with olaparib.

CONCLUSION

ADRM1-ΔEx9 redirects ubiquitin proteasome specificity to selectively degrade the tumor suppressor protein FBXW7. This promotes HCC tumor formation and provides a synthetic lethal link for PARP inhibitor therapy.

IMPACT AND IMPLICATIONS

Reduced tumor suppressor protein FBXW7 expression is pivotal in hepatocellular carcinoma (HCC) pathogenesis and other liver diseases. However, the regulatory mechanism governing FBXW7 protein expression remains elusive. Herein, we unveil a non-canonical spliced isoform of the ubiquitin receptor ADRM1 that selectively degrades FBXW7 protein, thereby promoting the premalignant transformation of hepatic cells and conferring growth advantages to HCC tumors. Furthermore, our results demonstrate that ADRM1-ΔEx9-expressing HCC tumors exhibited sensitivity to olaparib in a dose-dependent manner, implicating the potential use of olaparib in targeting ADRM1-ΔEx9-driven HCC growth.

Micronuclei as genotoxicity endpoint applied in the co-culture of two mammalian cell lines

There has been a shift from traditional animal models towards alternative methods. While 2D cell culture has a decade long tradition, more advances methods like 3D cultures, organoids, and co-culture techniques, which better mimic in vivo conditions, are not yet well established in every research area. Genotoxicity assessment is an integral part of toxicological testing or regulatory approval of pharmaceuticals and chemicals. The micronucleus assay is now a standard method in this context. In this systematic literature review, we aim to describe the state of the art of the application of co-cultures of two mammalian cell lines for micronucleus assessment. We summarized the cell types used, methods for co-culture, disease models and agents, as well as the application of additional genotoxicity endpoints and viability tests. Airway system cells were the most frequent, followed by macrophage-like cells, liver cells, and various others. Co-culture techniques involve either direct physical contact or separation by porous membranes. Within a limited number of investigations using other genotoxicity assays like the comet and γH2AX assays in parallel, the micronucleus assay performed well. Overall, the micronucleus test demonstrating its suitability in disease models and for a more complex substance testing beyond simple 2D cultures, encouraging a more widespread use in co-culture systems in the future.

Living biobank: Standardization of organoid construction and challenges

ABSTRACT

In multiple areas such as science, technology, and economic activities, it is necessary to unify the management of repetitive tasks or concepts by standardization to obtain the best order and high efficiency. Organoids, as living tissue models, have rapidly developed in the past decade. Organoids can be used repetitively for in vitro culture, cryopreservation, and recovery for further utilization. Because organoids can recapitulate the parental tissues' morphological phenotypes, cell functions, biological behaviors, and genomic profiles, they are known as renewable "living biobanks". Organoids cover two mainstream fields: Adult stem cell-derived organoids (also known as patient-derived organoids) and induced pluripotent stem cell-derived and/or embryonic stem cell-derived organoids. Given the increasing importance of organoids in the development of new drugs, standardized operation, and management in all steps of organoid construction is an important guarantee to ensure the high quality of products. In this review, we systematically introduce the standardization of organoid construction operation procedures, the standardization of laboratory construction, and available standardization documents related to organoid culture that have been published so far. We also proposed the challenges and prospects in this field.

Transcriptomic and proteomic sequencing unveils the role of vitamin D and metabolic flux shifts in the induction of human hepatic organoids

BACKGROUND

Hepatic organoids (HOs), validated through comparative sequencing with human liver tissues, are reliable models for liver research. Comprehensive transcriptomic and proteomic sequencing of HOs throughout their induction period will enhance the platform's utility, aiding in the elucidation of liver development's molecular mechanisms.

METHODS

We developed hepatic organoids (HOs) from embryonic stem cells (ESCs) through a de novo induction protocol, mimicking the stages of fetal liver development: ESCs to definitive endoderm (DE), then to foregut (FG), hepatoblasts (HB), and finally to HOs stage 1 (HO1), culminating in self-organizing HOs stage 2 (HO2) via dissociation and re-inoculation. The successful establishment of HOs was validated by immunofluorescence staining and RT-qPCR for specific markers. Comprehensive transcriptomic and proteomic sequencing and analysis were conducted on FG, HB, HO1, and HO2.

RESULTS

Our data suggest that several transcription factors (TFs) activated during the HB stage share overlapping target genes with the vitamin D receptor (VDR). Calcitriol, a direct activator of VDR, notably facilitated the FG to HB stage transition by activating VDR and enhancing key TFs, thereby promoting hepatic progenitor cell maturation. Furthermore, our findings revealed a significant transition towards glycolytic energy metabolism at the HO2 stage, characterized by increased glycolytic flux and reduced oxidative phosphorylation. Inhibition of glycolysis using 2-deoxy-D-glucose (2-DG) led to suppressed growth and differentiation at the HO2 stage. Analysis of signaling pathways indicated upregulation of the HIF-1 pathway, which is associated with glycolysis activation, as well as the MAPK and PI3K-AKT pathways, which regulate HIF-1α protein translation.

CONCLUSIONS

We elucidated a pivotal role for calcitriol in facilitating the transition from FG to HB by activating VDR and augmenting the expression of critical transcription factors (TFs). Besides, our research underscores a shift in metabolic pathways toward glycolytic energy metabolism in HO2 organoids. Overall, our multiomics approach reveals the intricate molecular regulation during the development of HOs.

Ethical frontiers in liver transplantation

Liver transplantation represents a pivotal intervention in the management of end-stage liver disease, offering a lifeline to countless patients. Despite significant strides in surgical techniques and organ procurement, ethical dilemmas and debates continue to underscore this life-saving procedure. Navigating the ethical terrain surrounding this complex procedure is hence paramount. Dissecting the nuances of ethical principles of justice, autonomy and beneficence that underpin transplant protocols worldwide, we explore the modern challenges that plaques the world of liver transplantation. We investigate the ethical dimensions of organ transplantation, focusing on allocation, emerging technologies, and decision-making processes. PubMed, Scopus, Web of Science, Embase and Central were searched from database inception to February 29, 2024 using the following keywords: "liver transplant", "transplantation", "liver donation", "liver recipient", "organ donation" and "ethics". Information from relevant articles surrounding ethical discussions in the realm of liver transplantation, especially with regards to organ recipients and allocation, organ donation, transplant tourism, new age technologies and developments, were extracted. From the definition of death to the long term follow up of organ recipients, liver transplantation has many ethical quandaries. With new transplant techniques, societal acceptance and perceptions also play a pivotal role. Cultural, religious and regional factors including but not limited to beliefs, wealth and accessibility are extremely influential in public attitudes towards donation, xenotransplantation, stem cell research, and adopting artificial intelligence. Understanding and addressing these perspectives whilst upholding bioethical principles is essential to ensure just distribution and fair allocation of resources. Robust regulatory oversight for ethical sourcing of organs, ensuring good patient selection and transplant techniques, and high-quality long-term surveillance to mitigate risks is essential. Efforts to promote equitable access to transplantation as well as prioritizing patients with true needs are essential to address disparities. In conclusion, liver transplantation is often the beacon of hope for individuals suffering from end-stage liver disease and improves quality of life. The ethics related to transplantation are complex and multifaceted, considering not just the donor and the recipient, but also the society as a whole.

Local Stiffness Measurement of Hepatic Steatosis Model Liver Organoid by Fluorescence Imaging-Assisted Probe Indentation

Mechanical stiffness of liver organoid is a key indicator for the progress of hepatic steatosis. Probe indentation is a noninvasive methodology to measure Young's modulus (YM); however, the inhomogeneous nature of the liver organoid induces measurement uncertainty requiring a large number of indentations covering a wide scanning area. Here, we demonstrate that lipid-stained fluorescence imaging-assisted probe indentation significantly reduces the number of measurements by specifying the highly lipid-induced area. Lipid-stained hepatic steatosis model liver organoid shows broad fluorescence distributions that are spatially correlated with a decreased YM on a lipid-filled region with bright fluorescence compared with that measured on a blank region with dark fluorescence. The organoid viability remained robust even after exposure to an ambient condition up to 6 h, showing that probe indentations can be noninvasive methods for liver organoid stiffness measurements.

Research progress in stem cell therapy for Wilson disease

Wilson disease (WD), also known as hepatolenticular degeneration, is an autosomal recessive disorder characterized by disorganized copper metabolism caused by mutations in the ATP7B gene. Currently, the main treatment options for WD involve medications such as d-penicillamine, trientine hydrochloride, zinc acetate, and liver transplantation. However, there are challenges that encompass issues of poor compliance, adverse effects, and limited availability of liver sources that persist. Stem cell therapy for WD is currently a promising area of research. Due to the advancement in stem cell directed differentiation technology in vitro and the availability of sufficient stem cell donors, it is expected to be a potential treatment option for the permanent correction of abnormal copper metabolism. This article discusses the research progress of stem cell therapy for WD from various sources, as well as the challenges and future prospects of the clinical application of stem cell therapy for WD.

Trends and challenges in organoid modeling and expansion with pluripotent stem cells and somatic tissue

The increasing demand for disease modeling, preclinical drug testing, and long waiting lists for alternative organ substitutes has posed significant challenges to current limitations in organoid technology. Consequently, organoid technology has emerged as a cutting-edge tool capable of accurately recapitulating the complexity of actual organs in physiology and functionality. To bridge the gaps between basic research and pharmaceutical as well as clinical applications, efforts have been made to develop organoids from tissue-derived stem cells or pluripotent stem cells. These developments include optimizing starting cells, refining culture systems, and introducing genetic modifications. With the rapid development of organoid technology, organoid composition has evolved from single-cell to multi-cell types, enhancing their level of biomimicry. Tissue structure has become more refined, and core challenges like vascularization are being addressed actively. These improvements are expected to pave the way for the construction of organoid atlases, automated large-scale cultivation, and universally compatible organoid biobanks. However, major obstacles remain to be overcome before urgently proof-of-concept organoids can be readily converted to practical applications. These obstacles include achieving structural and functional summarily to native tissue, remodeling the microenvironment, and scaling up production. This review aims to summarize the status of organoid development and applications, highlight recent progress, acknowledge existing limitations and challenges, and provide insights into future advancements. It is expected that this will contribute to the establishment of a reliable, scalable, and practical platform for organoid production and translation, further promoting their use in the pharmaceutical industry and regenerative medicine.

Accelerated production of human epithelial organoids in a miniaturized spinning bioreactor

Conventional static culture of organoids necessitates weekly manual passaging and results in nonhomogeneous exposure of organoids to nutrients, oxygen, and toxic metabolites. Here, we developed a miniaturized spinning bioreactor, RPMotion, specifically optimized for accelerated and cost-effective culture of epithelial organoids under homogeneous conditions. We established tissue-specific RPMotion settings and standard operating protocols for the expansion of human epithelial organoids derived from the liver, intestine, and pancreas. All organoid types proliferated faster in the bioreactor (5.2-fold, 3-fold, and 4-fold, respectively) compared to static culture while keeping their organ-specific phenotypes. We confirmed that the bioreactor is suitable for organoid establishment directly from biopsies and for long-term expansion of liver organoids. Furthermore, we showed that after accelerated expansion, liver organoids can be differentiated into hepatocyte-like cells in the RPMotion bioreactor. In conclusion, this miniaturized bioreactor enables work-, time-, and cost-efficient organoid culture, holding great promise for organoid-based fundamental and translational research and development.

Integrated respiratory toxicity of municipal wastewater to human bronchial epithelial cells and 3D bronchospheres

Respiratory symptoms have been reported in wastewater treatment workers and residents living close to sewage treatment plant. However, toxicological research about the respiratory hazards of municipal wastewater is scarce. The present study aims to gain insight into the comprehensive respiratory hazards induced by the contaminant mixtures in municipal wastewater. The integrated respiratory hazards of effluents from four secondary wastewater treatment plants (SWTPs), a tertiary wastewater treatment plant (TTP), and a constructed wetland (CW) were evaluated using normal human bronchial epithelial cells (NHBE) bioassay, and toxicity reduction efficiency of various treatment techniques was analyzed. Effluents caused cytotoxicity, oxidative damage, inflammation response with the increased levels of IL-6 and CXCL8, and impaired barrier integrity with decreased expressions of ZO-1 and occludin in NHBE. Further, the effluents inhibited the development of 3D bronchospheres, increased irregular surface and cell debris, and suppressed the formation of luminal structures. TTP E effluent significantly increased the expression of MUC5AC in bronchospheres. The integrated biomarker response (IBR) of the influent was removed by 40.2% at SWTPs, 18.2% at TTP, and 36.6% at CW, respectively. The IBR of the final effluents from SWTPs, TTP, and CW were 7.2, 7.7, and 7.7, respectively. Significant correlation with toxicity biomarkers was frequently observed for stearyl alcohol, o-cresol, phenanthrene, butylated hydroxytoluene, and dimethyl phthalate. The present study provided human relevant evidence concerning the adverse respiratory effects associated with discharge. The necessity for deep water treatment, performance optimization, and the potential means were suggested for improving water quality and protecting respiratory health.

Regenerative human liver organoids (HLOs) in a pillar/perfusion plate for hepatotoxicity assays

Human liver organoids (HLOs) differentiated from embryonic stem cells (ESCs), induced pluripotent stem cells (iPSCs), and adult stem cells (ASCs) can recapitulate the structure and function of human fetal liver tissues, thus being considered as a promising tissue model for liver diseases and predictive compound screening. However, the adoption of HLOs in drug discovery faces several technical challenges, which include the lengthy differentiation process with multiple culture media leading to batch-to-batch variation, short-term maintenance of hepatic functions post-maturation, low assay throughput due to Matrigel dissociation and HLO transfer to a microtiter well plate, and insufficient maturity levels compared to primary hepatocytes. To address these issues, expandable HLOs (Exp-HLOs) derived from human iPSCs were generated by optimizing differentiation protocols, which were rapidly printed on a 144-pillar plate with sidewalls and slits (144PillarPlate) and dynamically cultured for up to 20 days into differentiated HLOs (Diff-HLOs) in a 144-perfusion plate with perfusion wells and reservoirs (144PerfusionPlate) for in situ organoid culture and analysis. The dynamically cultured Diff-HLOs exhibited greater maturity and reproducibility than those cultured statically, especially after a 10-day differentiation period. In addition, Diff-HLOs in the pillar/perfusion plate were tested with acetaminophen and troglitazone for 3 days to assess drug-induced liver injury (DILI) and then incubated in an expansion medium for 10 days to evaluate liver recovery from DILI. The assessment of liver regeneration post-injury is critical to understanding the mechanism of recovery and determining the threshold drug concentration beyond which there will be a sharp decrease in the liver's regenerative capacity. We envision that bioprinted Diff-HLOs in the pillar/perfusion plate could be used for high-throughput screening (HTS) of hepatotoxic compounds due to the short-term differentiation of passage-able Exp-HLOs, stable hepatic function post-maturation, high reproducibility, and high throughput with capability of in situ organoid culture, testing, staining, imaging, and analysis.

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.

Cell therapy in Sjögren's syndrome: opportunities and challenges

Sjögren's syndrome (SS) is a chronic autoimmune disease caused by immune system disorders. The main clinical manifestations of SS are dry mouth and eyes caused by the destruction of exocrine glands, such as the salivary and lacrimal glands, and systemic manifestations, such as interstitial pneumonia, interstitial nephritis and vasculitis. The pathogenesis of this condition is complex. However, this has not been fully elucidated. Treatment mainly consists of glucocorticoids, disease-modifying antirheumatic drugs and biological agents, which can only control inflammation but not repair the tissue. Therefore, identifying methods to regulate immune disorders and repair damaged tissues is imperative. Cell therapy involves the transplantation of autologous or allogeneic normal or bioengineered cells into the body of a patient to replace damaged cells or achieve a stronger immunomodulatory capacity to cure diseases, mainly including stem cell therapy and immune cell therapy. Cell therapy can reduce inflammation, relieve symptoms and promote tissue repair and regeneration of exocrine glands such as the salivary glands. It has broad application prospects and may become a new treatment strategy for patients with SS. However, there are various challenges in cell preparation, culture, storage and transportation. This article reviews the research status and prospects of cell therapies for SS.

SALL2 regulates neural differentiation of mouse embryonic stem cells through Tuba1a

The spalt (Sal) gene family has four members (Sall1-4) in vertebrates, all of which play pivotal roles in various biological processes and diseases. However, the expression and function of SALL2 in development are still less clear. Here, we first charted SALL2 protein expression pattern during mouse embryo development by immunofluorescence, which revealed its dominant expression in the developing nervous system. With the establishment of Sall2 deficient mouse embryonic stem cells (ESCs), the in vitro neural differentiation system was leveraged to interrogate the function of SALL2, which showed impaired neural differentiation of Sall2 knockout (KO) ESCs. Furthermore, neural stem cells (NSCs) could not be derived from Sall2 KO ESCs and the generation of neural tube organoids (NTOs) was greatly inhibited in the absence of SALL2. Meanwhile, transgenic expression of E1 isoform of SALL2 restored the defects of neural differentiation in Sall2 KO ESCs. By chromatin immunoprecipitation sequencing (ChIP-seq), Tuba1a was identified as downstream target of SALL2, whose function in neural differentiation was confirmed by rescuing neural phenotypes of Sall2 KO ESCs when overexpressed. In sum, by elucidating SALL2 expression dynamics during early mouse development and mechanistically characterizing its indispensable role in neural differentiation, this study offers insights into SALL2's function in human nervous system development, associated pathologies stemming from its mutations and relevant therapeutic strategy.

Organoid as a promising tool for primary liver cancer research: a comprehensive review

Primary liver cancer (PLC) is one of the most common malignant gastrointestinal tumors worldwide. Limited by the shortage of liver transplantation donors and the heterogeneity of tumors, patients with liver cancer lack effective treatment options, which leads to rapid progression and metastasis. Currently, preclinical models of PLC fall short of clinical reality and are limited in their response to disease progression and the effectiveness of drug therapy. Organoids are in vitro three-dimensional cultured preclinical models with a high degree of heterogeneity that preserve the histomorphological and genomic features of primary tumors. Liver cancer organoids have been widely used for drug screening, new target discovery, and precision medicine; thus representing a promising tool to study PLC. Here, we summarize the progress of research on liver cancer organoids and their potential application as disease models. This review provides a comprehensive introduction to this emerging technology and offers new ideas for researchers to explore in the field of precision medicine.