Drug Inhibition of SARS-CoV-2 Replication in Human Pluripotent Stem Cell-Derived Intestinal Organoids

A prospects tool in virus research: Analyzing the applications of organoids in virus studies

Organoids have emerged as a powerful tool for understanding the biology of the respiratory, digestive, nervous as well as urinary system, investigating infections, and developing new therapies. This article reviews recent progress in the development of organoid and advancements in virus research. The potential applications of these models in studying virul infections, pathogenesis, and antiviral drug discovery are discussed.

COVID-19 drug discovery and treatment options

The coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused substantial morbidity and mortality, and serious social and economic disruptions worldwide. Unvaccinated or incompletely vaccinated older individuals with underlying diseases are especially prone to severe disease. In patients with non-fatal disease, long COVID affecting multiple body systems may persist for months. Unlike SARS-CoV and Middle East respiratory syndrome coronavirus, which have either been mitigated or remained geographically restricted, SARS-CoV-2 has disseminated globally and is likely to continue circulating in humans with possible emergence of new variants that may render vaccines less effective. Thus, safe, effective and readily available COVID-19 therapeutics are urgently needed. In this Review, we summarize the major drug discovery approaches, preclinical antiviral evaluation models, representative virus-targeting and host-targeting therapeutic options, and key therapeutics currently in clinical use for COVID-19. Preparedness against future coronavirus pandemics relies not only on effective vaccines but also on broad-spectrum antivirals targeting conserved viral components or universal host targets, and new therapeutics that can precisely modulate the immune response during infection.

Organoids as preclinical models of human disease: progress and applications

In the field of biomedical research, organoids represent a remarkable advancement that has the potential to revolutionize our approach to studying human diseases even before clinical trials. Organoids are essentially miniature 3D models of specific organs or tissues, enabling scientists to investigate the causes of diseases, test new drugs, and explore personalized medicine within a controlled laboratory setting. Over the past decade, organoid technology has made substantial progress, allowing researchers to create highly detailed environments that closely mimic the human body. These organoids can be generated from various sources, including pluripotent stem cells, specialized tissue cells, and tumor tissue cells. This versatility enables scientists to replicate a wide range of diseases affecting different organ systems, effectively creating disease replicas in a laboratory dish. This exciting capability has provided us with unprecedented insights into the progression of diseases and how we can develop improved treatments. In this paper, we will provide an overview of the progress made in utilizing organoids as preclinical models, aiding our understanding and providing a more effective approach to addressing various human diseases.

Development trends of human organoid-based COVID-19 research based on bibliometric analysis

Coronavirus disease 2019 (COVID-19), a global pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has posed a catastrophic threat to human health worldwide. Human stem cell-derived organoids serve as a promising platform for exploring SARS-CoV-2 infection. Several review articles have summarized the application of human organoids in COVID-19, but the research status and development trend of this field have seldom been systematically and comprehensively studied. In this review, we use bibliometric analysis method to identify the characteristics of organoid-based COVID-19 research. First, an annual trend of publications and citations, the most contributing countries or regions and organizations, co-citation analysis of references and sources and research hotspots are determined. Next, systematical summaries of organoid applications in investigating the pathology of SARS-CoV-2 infection, vaccine development and drug discovery, are provided. Lastly, the current challenges and future considerations of this field are discussed. The present study will provide an objective angle to identify the current trend and give novel insights for directing the future development of human organoid applications in SARS-CoV-2 infection.

SARS-CoV-2 replicates in the human testis with slow kinetics and has no major deleterious effects ex vivo

IMPORTANCE

SARS-CoV-2 is a new virus responsible for the Covid-19 pandemic. Although SARS-CoV-2 primarily affects the lungs, other organs are infected. Alterations of testosteronemia and spermatozoa motility in infected men have raised questions about testicular infection, along with high level in the testis of ACE2, the main receptor used by SARS-CoV-2 to enter host cells. Using an organotypic culture of human testis, we found that SARS-CoV-2 replicated with slow kinetics in the testis. The virus first targeted testosterone-producing Leydig cells and then germ-cell nursing Sertoli cells. After a peak followed by the upregulation of antiviral effectors, viral replication in the testis decreased and did not induce any major damage to the tissue. Altogether, our data show that SARS-CoV-2 replicates in the human testis to a limited extent and suggest that testicular damages in infected patients are more likely to result from systemic infection and inflammation than from viral replication in the testis.

Organoids to Remodel SARS-CoV-2 Research: Updates, Limitations and Perspectives

The novel COVID-19 pneumonia caused by the SARS-CoV-2 virus poses a significant threat to human health. Scientists have made significant efforts to control this virus, consequently leading to the development of novel research methods. Traditional animal and 2D cell line models might not be suitable for large-scale applications in SARS-CoV-2 research owing to their limitations. As an emerging modelling method, organoids have been applied in the study of various diseases. Their advantages include their ability to closely mirror human physiology, ease of cultivation, low cost, and high reliability; thus, they are considered to be a suitable choice to further the research on SARS-CoV-2. During the course of various studies, SARS-CoV-2 was shown to infect a variety of organoid models, exhibiting changes similar to those observed in humans. This review summarises the various organoid models used in SARS-CoV-2 research, revealing the molecular mechanisms of viral infection and exploring the drug screening tests and vaccine research that have relied on organoid models, hence illustrating the role of organoids in remodelling SARS-CoV-2 research.

Organoids: The current status and biomedical applications

Organoids are three-dimensional (3D) miniaturized versions of organs or tissues that are derived from cells with stem potential and can self-organize and differentiate into 3D cell masses, recapitulating the morphology and functions of their in vivo counterparts. Organoid culture is an emerging 3D culture technology, and organoids derived from various organs and tissues, such as the brain, lung, heart, liver, and kidney, have been generated. Compared with traditional bidimensional culture, organoid culture systems have the unique advantage of conserving parental gene expression and mutation characteristics, as well as long-term maintenance of the function and biological characteristics of the parental cells in vitro. All these features of organoids open up new opportunities for drug discovery, large-scale drug screening, and precision medicine. Another major application of organoids is disease modeling, and especially various hereditary diseases that are difficult to model in vitro have been modeled with organoids by combining genome editing technologies. Herein, we introduce the development and current advances in the organoid technology field. We focus on the applications of organoids in basic biology and clinical research, and also highlight their limitations and future perspectives. We hope that this review can provide a valuable reference for the developments and applications of organoids.

Intestinal organoids: A versatile platform for modeling gastrointestinal diseases and monitoring epigenetic alterations

Considering the significant limitations of conventional 2D cell cultures and tissue in vitro models, creating intestinal organoids has burgeoned as an ideal option to recapitulate the heterogeneity of the native intestinal epithelium. Intestinal organoids can be developed from either tissue-resident adult stem cells (ADSs) or pluripotent stem cells (PSCs) in both forms induced PSCs and embryonic stem cells. Here, we review current advances in the development of intestinal organoids that have led to a better recapitulation of the complexity, physiology, morphology, function, and microenvironment of the intestine. We discuss current applications of intestinal organoids with an emphasis on disease modeling. In particular, we point out recent studies on SARS-CoV-2 infection in human intestinal organoids. We also discuss the less explored application of intestinal organoids in epigenetics by highlighting the role of epigenetic modifications in intestinal development, homeostasis, and diseases, and subsequently the power of organoids in mirroring the regulatory role of epigenetic mechanisms in these conditions and introducing novel predictive/diagnostic biomarkers. Finally, we propose 3D organoid models to evaluate the effects of novel epigenetic drugs (epi-drugs) on the treatment of GI diseases where epigenetic mechanisms play a key role in disease development and progression, particularly in colorectal cancer treatment and epigenetically acquired drug resistance.

Human brain organoids to explore SARS-CoV-2-induced effects on the central nervous system

Severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19). In less than three years, an estimated 600 million infections with SARS-CoV-2 occurred worldwide, resulting in a pandemic with tremendous impact especially on economic and health sectors. Initially considered a respiratory disease, COVID-19, along with its long-term sequelae (long-COVID) rather is a systemic disease. Neurological symptoms like dementia or encephalopathy were reported early during the pandemic as concomitants of the acute phase and as characteristics of long-COVID. An excessive inflammatory immune response is hypothesized to play a major role in this context. However, direct infection of neural cells may also contribute to the neurological aspects of (long)-COVID-19. To mainly explore such direct effects of SARS-CoV-2 on the central nervous system, human brain organoids provide a useful platform. Infecting these three-dimensional tissue cultures allows the study of viral neurotropism as well as of virus-induced effects on single cells or even the complex cellular network within the organoid. In this review, we summarize the experimental studies that used SARS-CoV-2-infected human brain organoids to unravel the complex nature of (long)-COVID-19-related neurological manifestations.

Organoids/organs-on-a-chip: new frontiers of intestinal pathophysiological models

Organoids/organs-on-a-chip open up new frontiers for basic and clinical research of intestinal diseases. Species-specific differences hinder research on animal models, while organoids are emerging as powerful tools due to self-organization from stem cells and the reproduction of the functional properties in vivo. Organs-on-a-chip is also accelerating the process of faithfully mimicking the intestinal microenvironment. And by combining organoids and organ-on-a-chip technologies, they further are expected to serve as innovative preclinical tools and could outperform traditional cell culture models or animal models in the future. Above all, organoids/organs-on-a-chip with other strategies like genome editing, 3D printing, and organoid biobanks contribute to modeling intestinal homeostasis and disease. Here, the current challenges and future trends in intestinal pathophysiological models will be summarized.

Insights into organoid-based modeling of COVID-19 pathology

Since December 2019, various types of strategies have been applied due to the emergent need to investigate the biology and pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to discover a functional treatment. Different disease modeling systems, such as mini-organ technology, have been used to improve our understanding of SARS-CoV-2 physiology and pathology. During the past 2 years, regenerative medicine research has shown the supportive role of organoid modeling in controlling coronavirus disease 2019 (COVID-19) through optimal drug and therapeutic approach improvement. Here, we overview some efforts that have been made to study SARS-CoV-2 by mimicking COVID-19 using stem cells. In addition, we summarize a perspective of drug development in COVID-19 treatment via organoid-based studies.

Induced Pluripotent Stem Cell-Derived Organoids: Their Implication in COVID-19 Modeling

The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a significant global health issue. This novel virus's high morbidity and mortality rates have prompted the scientific community to quickly find the best COVID-19 model to investigate all pathological processes underlining its activity and, more importantly, search for optimal drug therapy with minimal toxicity risk. The gold standard in disease modeling involves animal and monolayer culture models; however, these models do not fully reflect the response to human tissues affected by the virus. However, more physiological 3D in vitro culture models, such as spheroids and organoids derived from induced pluripotent stem cells (iPSCs), could serve as promising alternatives. Different iPSC-derived organoids, such as lung, cardiac, brain, intestinal, kidney, liver, nasal, retinal, skin, and pancreatic organoids, have already shown immense potential in COVID-19 modeling. In the present comprehensive review article, we summarize the current knowledge on COVID-19 modeling and drug screening using selected iPSC-derived 3D culture models, including lung, brain, intestinal, cardiac, blood vessels, liver, kidney, and inner ear organoids. Undoubtedly, according to reviewed studies, organoids are the state-of-the-art approach to COVID-19 modeling.

Induced pluripotent stem cells: Generation methods and a new perspective in COVID-19 research

Induced pluripotent stem cells (iPSCs) exhibit an unlimited ability to self-renew and produce various differentiated cell types, thereby creating high hopes for both scientists and patients as a great tool for basic research as well as for regenerative medicine purposes. The availability and safety of iPSCs for therapeutic purposes require safe and highly efficient methods for production of these cells. Different methods have been used to produce iPSCs, each of which has advantages and disadvantages. Studying these methods would be very helpful in developing an easy, safe, and efficient method for the generation of iPSCs. Since iPSCs can be generated from somatic cells, they can be considered as valuable cellular resources available for important research needs and various therapeutic purposes. Coronavirus disease 2019 (COVID-19) is a disease that has endangered numerous human lives worldwide and currently has no definitive cure. Therefore, researchers have been rigorously studying and examining all aspects of COVID-19 and potential treatment modalities and various drugs in order to enable the treatment, control, and prevention of COVID-19. iPSCs have become one of the most attractive and promising tools in this field by providing the ability to study COVID-19 and the effectiveness of drugs on this disease outside the human body. In this study, we discuss the different methods of generation of iPSCs as well as their respective advantages and disadvantages. We also present recent applications of iPSCs in the study and treatment of COVID-19.

Use of mouse primary epidermal organoids for USA300 infection modeling and drug screening

Skin infections caused by drug-resistant Staphylococcus aureus occur at high rates nationwide. Mouse primary epidermal organoids (mPEOs) possess stratified histological and morphological characteristics of epidermis and are highly similar to their derived tissue at the transcriptomic and proteomic levels. Herein, the susceptibility of mPEOs to methicillin-resistant S. aureus USA300 infection was investigated. The results show that mPEOs support USA300 colonization and invasion, exhibiting swollen epithelial squamous cells with nuclear necrosis and secreting inflammatory factors such as IL-1β. Meanwhile mPEOs beneficial to observe the process of USA300 colonization with increasing infection time, and USA300 induces mPEOs to undergo pyroptosis and autophagy. In addition, we performed a drug screen for the mPEO infection model and showed that vancomycin restores cell viability and inhibits bacterial internalization in a concentration-dependent manner. In conclusion, we establish an in vitro skin infection model that contributes to the examination of drug screening strategies and antimicrobial drug mechanisms.

Organoid Technologies for SARS-CoV-2 Research

Purpose of Review

Organoids are an emerging technology utilizing three-dimensional (3D), multi-cellular in vitro models to represent the function and physiological responses of tissues and organs. By using physiologically relevant models, more accurate tissue responses to viral infection can be observed, and effective treatments and preventive strategies can be identified. Animals and two-dimensional (2D) cell culture models occasionally result in inaccurate disease modeling outcomes. Organoids have been developed to better represent human organ and tissue systems, and accurately model tissue function and disease responses. By using organoids to study SARS-Cov-2 infection, researchers have now evaluated the viral effects on different organs and evaluate efficacy of potential treatments. The purpose of this review is to highlight organoid technologies and their ability to model SARS-Cov-2 infection and tissue responses.

Recent Findings

Lung, cardiac, kidney, and small intestine organoids have been examined as potential models of SARS-CoV-2 infection. Lung organoid research has highlighted that SARS-CoV-2 shows preferential infection of club cells and have shown value for the rapid screening and evaluations of multiple anti-viral drugs. Kidney organoid research suggests human recombinant soluble ACE2 as a preventative measure during early-stage infection. Using small intestine organoids, fecal to oral transmission has been evaluated as a transmission route for the virus. Lastly in cardiac organoids drug evaluation studies have found that drugs such as bromodomain, external family inhibitors, BETi, and apabetalone may be effective treatments for SARs-CoV-2 cardiac injury.

Summary

Organoids are an effective tool to study the effects of viral infections and for drug screening and evaluation studies. By using organoids, more accurate disease modeling can be performed, and physiological effects of infection and treatment can be better understood.

Applications of human organoids in the personalized treatment for digestive diseases

Digestive system diseases arise primarily through the interplay of genetic and environmental influences; there is an urgent need in elucidating the pathogenic mechanisms of these diseases and deploy personalized treatments. Traditional and long-established model systems rarely reproduce either tissue complexity or human physiology faithfully; these shortcomings underscore the need for better models. Organoids represent a promising research model, helping us gain a more profound understanding of the digestive organs; this model can also be used to provide patients with precise and individualized treatment and to build rapid in vitro test models for drug screening or gene/cell therapy, linking basic research with clinical treatment. Over the past few decades, the use of organoids has led to an advanced understanding of the composition of each digestive organ and has facilitated disease modeling, chemotherapy dose prediction, CRISPR-Cas9 genetic intervention, high-throughput drug screening, and identification of SARS-CoV-2 targets, pathogenic infection. However, the existing organoids of the digestive system mainly include the epithelial system. In order to reveal the pathogenic mechanism of digestive diseases, it is necessary to establish a completer and more physiological organoid model. Combining organoids and advanced techniques to test individualized treatments of different formulations is a promising approach that requires further exploration. This review highlights the advancements in the field of organoid technology from the perspectives of disease modeling and personalized therapy.

Distinct accumulation of nanoplastics in human intestinal organoids

Plastic particles, especially nanoplastics, represent an emerging concern of threat to human health, oral uptake is an important pathway for the plastic particles ingestion by human. While their fate and adverse effects in animal gastrointestinal tract are increasingly investigated, knowledge about their uptake and toxicity in human intestine is still limited. Here, by exposing human intestinal organoids to polystyrene nanoplastics (PS-NPs, ~50 nm in size) with concentrations of 10 and 100 μg/mL, we present evidence of their distinct accumulation in various type cells in intestinal organoids, then causing the cell apoptosis and inflammatory response. Our results further revealed that the effective inhibition of PS-NPs accumulation in secretive cells through co-exposure to a clathrin-mediated endocytosis inhibitor (chlorpromazine), and proved the essential role of active endocytosis in the PS-NPs uptaking into enterocyte cells. Our work not only elucidated the potential uptake and toxicity of PS-NPs in human intestinal cells and the underlying mechanism, but also provide a potential therapeutic approach to relieve the toxicity of PS-NPs to human through the endocytosis inhibition.

Organoids in gastrointestinal diseases: from experimental models to clinical translation

We are entering an era of medicine where increasingly sophisticated data will be obtained from patients to determine proper diagnosis, predict outcomes and direct therapies. We predict that the most valuable data will be produced by systems that are highly dynamic in both time and space. Three-dimensional (3D) organoids are poised to be such a highly valuable system for a variety of gastrointestinal (GI) diseases. In the lab, organoids have emerged as powerful systems to model molecular and cellular processes orchestrating natural and pathophysiological human tissue formation in remarkable detail. Preclinical studies have impressively demonstrated that these organs-in-a-dish can be used to model immunological, neoplastic, metabolic or infectious GI disorders by taking advantage of patient-derived material. Technological breakthroughs now allow to study cellular communication and molecular mechanisms of interorgan cross-talk in health and disease including communication along for example, the gut-brain axis or gut-liver axis. Despite considerable success in culturing classical 3D organoids from various parts of the GI tract, some challenges remain to develop these systems to best help patients. Novel platforms such as organ-on-a-chip, engineered biomimetic systems including engineered organoids, micromanufacturing, bioprinting and enhanced rigour and reproducibility will open improved avenues for tissue engineering, as well as regenerative and personalised medicine. This review will highlight some of the established methods and also some exciting novel perspectives on organoids in the fields of gastroenterology. At present, this field is poised to move forward and impact many currently intractable GI diseases in the form of novel diagnostics and therapeutics.

Microbiome as an immune regulator in health, disease, and therapeutics

New discoveries in drugs and drug delivery systems are focused on identifying and delivering a pharmacologically effective agent, potentially targeting a specific molecular component. However, current drug discovery and therapeutic delivery approaches do not necessarily exploit the complex regulatory network of an indispensable microbiota that has been engineered through evolutionary processes in humans or has been altered by environmental exposure or diseases. The human microbiome, in all its complexity, plays an integral role in the maintenance of host functions such as metabolism and immunity. However, dysregulation in this intricate ecosystem has been linked with a variety of diseases, ranging from inflammatory bowel disease to cancer. Therapeutics and bacteria have an undeniable effect on each other and understanding the interplay between microbes and drugs could lead to new therapies, or to changes in how existing drugs are delivered. In addition, targeting the human microbiome using engineered therapeutics has the potential to address global health challenges. Here, we present the challenges and cutting-edge developments in microbiome-immune cell interactions and outline novel targeting strategies to advance drug discovery and therapeutics, which are defining a new era of personalized and precision medicine.

Human milk inhibits some enveloped virus infections, including SARS-CoV-2, in an intestinal model

Human milk is important for antimicrobial defense in infants and has well demonstrated antiviral activity. We evaluated the protective ability of human milk against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in a human fetal intestinal cell culture model. We found that, in this model, human milk blocks SARS-CoV-2 replication, irrespective of the presence of SARS-CoV-2 spike-specific antibodies. Complete inhibition of both enveloped Middle East respiratory syndrome coronavirus and human respiratory syncytial virus infections was also observed, whereas no inhibition of non-enveloped enterovirus A71 infection was seen. Transcriptome analysis after 24 h of the intestinal monolayers treated with human milk showed large transcriptomic changes from human milk treatment, and subsequent analysis suggested that <i>ATP1A1</i> down-regulation by milk might be of importance. Inhibition of ATP1A1 blocked SARS-CoV-2 infection in our intestinal model, whereas no effect on EV-A71 infection was seen. Our data indicate that human milk has potent antiviral activity against particular (enveloped) viruses by potentially blocking the ATP1A1-mediated endocytic process.

Bioengineered Co-culture of organoids to recapitulate host-microbe interactions

The recent spike in the instances of complex physiological host-microbe interactions has raised the demand for developing in vitro models that recapitulate the microbial microenvironment in the human body. Organoids are steadily emerging as an in vitro culture system that closely mimics the structural, functional, and genetic features of complex human organs, particularly for better understanding host-microbe interactions. Recent advances in organoid culture technology have become new avenues for assessing the pathogenesis of symbiotic interactions, pathogen-induced infectious diseases, and various other diseases. The co-cultures of organoids with microbes have shown great promise in simulating host-microbe interactions with a high level of complexity for further advancement in related fields. In this review, we provide an overview of bioengineering approaches for microbe-co-cultured organoids. Latest developments in the applications of microbe-co-cultured organoids to study human physiology and pathophysiology are also highlighted. Further, an outlook on future research on bioengineered organoid co-cultures for various applications is presented.

Biobanking in times of crisis – The COVID-19 Autopsy and Biosample Registry Baden-Wuerttemberg

Biobanking plays a critical role in diagnostics, biomarker research and development of novel treatment approaches for various diseases. In urgent need of understanding, preventing and treating coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the importance of biobanking including data sharing and management further increased. To provide high quality tissue biomaterials and data for research and public health, the COVID-19 Autopsy and Biosample Registry was established in the state of Baden-Wuerttemberg (BW) in Germany, combining expertise and technologies of the Institutes of Pathology of the five university hospitals in BW (Heidelberg, Tübingen, Ulm, Freiburg, Mannheim). The COVID-19 Autopsy and Biosample Registry BW comprises tissue samples from autopsies and associated data of deceased patients in the context of SARS-CoV-2 infection and/or vaccination against SARS-CoV-2. The aim is to collect autopsy biospecimens, associated clinical and diagnostic data in a timely manner, register them, make them accessible for research projects and thus to support especially tissue-related research addressing COVID-19. By now, the BW network holds multiple collaborations and supported numerous publications to increase the understanding of COVID-19 disease. The achievements of the BW network as a landmark biobanking model project represent a potential blueprint for future disease-related biobanking and registry effort.

SARS-CoV-2 induces barrier damage and inflammatory responses in the human iPSC-derived intestinal epithelium

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread and led to global health crises. COVID-19 causes well-known respiratory failure and gastrointestinal symptoms, such as diarrhea, nausea, and vomiting. Thus, human gastrointestinal cell models are urgently needed for COVID-19 research; however, it is difficult to obtain primary human intestinal cells. In this study, we examined whether human induced pluripotent stem cell (iPSC)-derived small intestinal epithelial cells (iPSC-SIECs) could be used as a SARS-CoV-2 infection model. We observed that iPSC-SIECs, such as absorptive and Paneth cells, were infected with SARS-CoV-2, and remdesivir treatment decreased intracellular SARS-CoV-2 replication in iPSC-SIECs. SARS-CoV-2 infection decreased expression levels of tight junction markers, ZO-3 and CLDN1, and transepithelial electrical resistance (TEER), which evaluates the integrity of tight junction dynamics. In addition, SARS-CoV-2 infection increased expression levels of proinflammatory genes, which are elevated in patients with COVID-19. These findings suggest iPSC-SIECs as a useful in vitro model for elucidating COVID-19 pathology and drug development.

3D printed human organoids: High throughput system for drug screening and testing in current COVID-19 pandemic

In the current pandemic, scenario the world is facing a huge shortage of effective drugs and other prophylactic medicine to treat patients which created havoc in several countries with poor resources. With limited demand and supply of effective drugs, researchers rushed to repurpose the existing approved drugs for the treatment of COVID-19. The process of drug screening and testing is very costly and requires several steps for validation and treatment efficacy evaluation ranging from in-vitro to in-vivo setups. After these steps, a clinical trial is mandatory for the evaluation of treatment efficacy and side effects in humans. These processes enhance the overall cost and sometimes the lead molecule show adverse effects in humans and the trial ends up in the final stages. Recently with the advent of 3D organoid culture which mimics the human tissue exactly the process of drug screening and testing can be done in a faster and cost-effective manner. Further 3D organoids prepared from stems cells taken from individuals can be beneficial for personalized drug therapy which could save millions of lives. This review discussed approaches and techniques for the synthesis of 3D-printed human organoids for drug screening. The key findings of the usage of organoids for personalized medicine for the treatment of COVID-19 have been discussed. In the end, the key challenges for the wide applicability of human organoids for drug screening with prospects of future orientation have been included. This article is protected by copyright. All rights reserved.

Human interaction targets of SARS-COV-2 spike protein: A systematic review

Objectives:

The development of effective targeted therapy and drug-design approaches against the SARS-CoV-2 is a universal health priority. Therefore, it is important to assess possible therapeutic strategies against SARS-CoV-2 via its most interaction targets. The present study aimed to perform a systematic review on clinical and experimental investigations regarding SARS-COV-2 interaction targets for human cell entry.

Methods:

A systematic search using relevant MeSH terms and keywords was performed in PubMed, Scopus, Embase, and Web of Science (ISI) databases up to July 2021. Two reviewers independently assessed the eligibility of the studies, extracted the data, and evaluated the methodological quality of the included studies. Additionally, a narrative synthesis was done as a qualitative method for data gathering and synthesis of each outcome measure.

Results:

A total of 5610 studies were identified, and 128 articles were included in the systematic review. Based on the results, spike antigen was the only interaction protein from SARS-CoV-2. However, the interaction proteins from humans varied including different spike receptors and several cleavage enzymes. The most common interactions of the spike protein of SARS-CoV-2 for cell entry were ACE2 (entry receptor) and TMPRSS2 (for spike priming). A lot of published studies have mainly focused on the ACE2 receptor followed by the TMPRSS family and furin. Based on the results, ACE2 polymorphisms as well as spike RBD mutations affected the SARS-CoV-2 binding affinity.

Conclusion:

The included studies shed more light on SARS-CoV-2 cellular entry mechanisms and detailed interactions, which could enhance the understanding of SARS-CoV-2 pathogenesis and the development of new and comprehensive therapeutic approaches.

Human organoid models to study SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is one of the deadliest pandemics in history. SARS-CoV-2 not only infects the respiratory tract, but also causes damage to many organs. Organoids, which can self-renew and recapitulate the various physiology of different organs, serve as powerful platforms to model COVID-19. In this Perspective, we overview the current effort to apply both human pluripotent stem cell-derived organoids and adult organoids to study SARS-CoV-2 tropism, host response and immune cell-mediated host damage, and perform drug discovery and vaccine development. We summarize the technologies used in organoid-based COVID-19 research, discuss the remaining challenges and provide future perspectives in the application of organoid models to study SARS-CoV-2 and future emerging viruses.

A Pan-Cancer In Silico Analysis of the COVID-19 Internalization Protease: Transmembrane Proteaseserine-2

The new coronavirus (2019-nCoV) is an emerging pathogen that can cause severe respiratory infections in humans. It is worth noting that many of the affected COVID-19 patients have malignant tumors. In addition, cancer has been identified as a personal risk factor for COVID-19. Transmembrane proteaseserine-2 (TMPRSS2) is a crucial host protease that mediates S protein activation and initially promotes virus entry into host cells. Moreover, it is abnormally expressed in a variety of tumors. However, the systematic analysis of TMPRSS2 aberrations in human cancer remains to be elucidated. Here, we analyzed the genetic changes, RNA expression, and DNA methylation of TMPRSS2 in more than 30 tumors. It has been reported that TMPRSS2 is overexpressed in tumors such as prostate adenocarcinoma (PRAD), and in contrast, the expression of TMPRSS2 is decreased in tumors such as head and neck cancer (HNSC). In addition, TMPRSS2 low DNA methylation was also found in most of these TMPRSS2 high-expressing tumors in this study. Clinical studies have found that there is a significant correlation between the expression of TMPRSS2 and the prognosis of some tumor patients. The expression of TMPRSS2 is also related to the infiltration of cancer-related fibroblasts, and the potential pathways and functional mechanisms were analyzed through KEGG/GO enrichment. In the end, our study planned the genetic and epigenetic variation of TMPRSS2 in human malignant tumors for the first time and provided a relatively comprehensive understanding of the carcinogenic effects of TMPRSS2.

Functional Genomic Screening in Human Pluripotent Stem Cells Reveals New Roadblocks in Early Pancreatic Endoderm Formation

Human pluripotent stem cells, with their ability to proliferate indefinitely and to differentiate into virtually all cell types of the human body, provide a novel resource to study human development and to implement relevant disease models. Here, we employed a human pancreatic differentiation platform complemented with an shRNA screen in human pluripotent stem cells (PSCs) to identify potential drivers of early endoderm and pancreatic development. Deep sequencing followed by abundancy ranking pinpointed six top hit genes potentially associated with either improved or impaired endodermal differentiation, which were selected for functional validation in CRISPR-Cas9 mediated knockout (KO) lines. Upon endoderm differentiation (DE), particularly the loss of SLC22A1 and DSC2 led to impaired differentiation efficiency into CXCR4/KIT-positive DE cells. qPCR analysis also revealed changes in differentiation markers CXCR4, FOXA2, SOX17, and GATA6. Further differentiation of PSCs to the pancreatic progenitor (PP) stage resulted in a decreased proportion of PDX1/NKX6-1-positive cells in SLC22A1 KO lines, and in DSC2 KO lines when differentiated under specific culture conditions. Taken together, our study reveals novel genes with potential roles in early endodermal development.

Three-Dimensional Cell Culture Models to Study Respiratory Virus Infections Including COVID-19

Respiratory viral infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), are among the most common illnesses and a leading cause of morbidity and mortality worldwide. Due to the severe effects on health, the need of new tools to study the pathogenesis of respiratory viruses as well as to test for new antiviral drugs and vaccines is urgent. In vitro culture model systems, such as three-dimensional (3D) cultures, are emerging as a desirable approach to understand the virus host interactions and to identify novel therapeutic agents. In the first part of the article, we address the various scaffold-free and scaffold-based 3D culture models such as hydrogels, bioreactors, spheroids and 3D bioprinting as well as present their properties and advantages over conventional 2D methods. Then, we review the 3D models that have been used to study the most common respiratory viruses including influenza, parainfluenza, respiratory syncytial virus (RSV) and coronaviruses. Herein, we also explain how 3D models have been applied to understand the novel SARS-CoV-2 infectivity and to develop potential therapies.

Stalling SARS-CoV2 infection with stem cells: can regenerating perinatal tissue mesenchymal stem cells offer a multi-tiered therapeutic approach to COVID-19?

The emergence of COVID-19 has created a major health crisis across the globe. Invasion of SARS-CoV-2 into the lungs causes acute respiratory distress syndrome (ARDS) that result in the damage of lung alveolar epithelial cells. Currently, there is no standard treatment available to treat the disease and the resultant lung scarring is irreversible even after recovery. This has prompted researchers across the globe to focus on developing new therapeutics and vaccines for the treatment and prevention of COVID-19. Mesenchymal stem cells (MSCs) have emerged as an efficient drug screening platform and MSC-derived organoids has found applications in disease modeling and drug discovery. Perinatal tissue derived MSC based cell therapies have been explored in the treatment of various disease conditions including ARDS because of their enhanced regenerative and immunomodulatory properties. The multi-utility properties of MSCs have been described in this review wherein we discuss the potential use of MSC-derived lung organoids in screening of novel therapeutic compounds for COVID-19 and also in disease modeling to better understand the pathogenesis of the disease. This article also summarizes the rationale behind the development of MSC-based cell- and cell-free therapies and vaccines for COVID-19 with a focus on the current progress in this area. With the pandemic raging, an important necessity is to develop novel treatment strategies which will not only alleviate the disease symptoms but also avoid any off-target effects which could further increase post infection sequelae. Naturally occurring mesenchymal stem cells could be the magic bullet which fulfil these criteria.

Spike residue 403 affects binding of coronavirus spikes to human ACE2

The bat sarbecovirus RaTG13 is a close relative of SARS-CoV-2, the cause of the COVID-19 pandemic. However, this bat virus was most likely unable to directly infect humans since its Spike (S) protein does not interact efficiently with the human ACE2 receptor. Here, we show that a single T403R mutation increases binding of RaTG13 S to human ACE2 and allows VSV pseudoparticle infection of human lung cells and intestinal organoids. Conversely, mutation of R403T in the SARS-CoV-2 S reduces pseudoparticle infection and viral replication. The T403R RaTG13 S is neutralized by sera from individuals vaccinated against COVID-19 indicating that vaccination might protect against future zoonoses. Our data suggest that a positively charged amino acid at position 403 in the S protein is critical for efficient utilization of human ACE2 by S proteins of bat coronaviruses. This finding could help to better predict the zoonotic potential of animal coronaviruses.

Transcriptional changes and the role of ONECUT1 in hPSC pancreatic differentiation

Cell type specification during pancreatic development is tightly controlled by a transcriptional and epigenetic network. The precise role of most transcription factors, however, has been only described in mice. To convey such concepts to human pancreatic development, alternative model systems such as pancreatic in vitro differentiation of human pluripotent stem cells can be employed. Here, we analyzed stage-specific RNA-, ChIP-, and ATAC-sequencing data to dissect transcriptional and regulatory mechanisms during pancreatic development. Transcriptome and open chromatin maps of pancreatic differentiation from human pluripotent stem cells provide a stage-specific pattern of known pancreatic transcription factors and indicate ONECUT1 as a crucial fate regulator in pancreas progenitors. Moreover, our data suggest that ONECUT1 is also involved in preparing pancreatic progenitors for later endocrine specification. The dissection of the transcriptional and regulatory circuitry revealed an important role for ONECUT1 within such network and will serve as resource to study human development and disease.

Microbiome Profiling Using Shotgun Metagenomic Sequencing Identified Unique Microorganisms in COVID-19 Patients With Altered Gut Microbiota

COVID-19 is mainly associated with respiratory distress syndrome, but a subset of patients often present gastrointestinal (GI) symptoms. Imbalances of gut microbiota have been previously linked to respiratory virus infection. Understanding how the gut–lung axis affects the progression of COVID-19 can provide a novel framework for therapies and management. In this study, we examined the gut microbiota of patients with COVID-19 (n = 47) and compared it to healthy controls (n = 19). Using shotgun metagenomic sequencing, we have identified four microorganisms unique in COVID-19 patients, namely Streptococcus thermophilus, Bacteroides oleiciplenus, Fusobacterium ulcerans, and Prevotella bivia. The abundances of Bacteroides stercoris, B. vulgatus, B. massiliensis, Bifidobacterium longum, Streptococcus thermophilus, Lachnospiraceae bacterium 5163FAA, Prevotella bivia, Erysipelotrichaceae bacterium 6145, and Erysipelotrichaceae bacterium 2244A were enriched in COVID-19 patients, whereas the abundances of Clostridium nexile, Streptococcus salivarius, Coprococcus catus, Eubacterium hallii, Enterobacter aerogenes, and Adlercreutzia equolifaciens were decreased (p < 0.05). The relative abundance of butyrate-producing Roseburia inulinivorans is evidently depleted in COVID-19 patients, while the relative abundances of Paraprevotella sp. and the probiotic Streptococcus thermophilus were increased. We further identified 30 KEGG orthology (KO) modules overrepresented, with 7 increasing and 23 decreasing modules. Notably, 15 optimal microbial markers were identified using the random forest model to have strong diagnostic potential in distinguishing COVID-19. Based on Spearman’s correlation, eight species were associated with eight clinical indices. Moreover, the increased abundance of Bacteroidetes and decreased abundance of Firmicutes were also found across clinical types of COVID-19. Our findings suggest that the alterations of gut microbiota in patients with COVID-19 may influence disease severity. Our COVID-19 classifier, which was cross-regionally verified, provides a proof of concept that a set of microbial species markers can distinguish the presence of COVID-19.

Recent Advances of COVID-19 Modeling Based on Regenerative Medicine

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) has caused a pandemic since December 2019 that originated in Wuhan, China. Soon after that, the world health organization declared Coronavirus disease-2019 a global health concern. SARS-CoV-2 is responsible for a lethal respiratory infection as well as the involvement of other organs due to its large tropism spectrum such as neurologic, cardiovascular, endocrine, gastrointestinal, and renal systems. Since the behavior of the virus is not fully understood, a new manifestation of the infection is revealed every day. In order to be able to design more efficient drugs and vaccines to treat the infection, finding out the exact mechanism of pathogenicity would be necessary. Although there have been some big steps toward understanding the relevant process, there are still some deficiencies in this field. Accordingly, regenerative medicine (RM), can offer promising opportunities in discovering the exact mechanisms and specific treatments. For instance, since it is not always possible to catch the pathophysiology mechanisms in human beings, several modeling methods have been introduced in this field that can be studied in three main groups: stem cell-based models, organoids, and animal models. Regarding stem cell-based models, induced pluripotent stem cells are the major study subjects, which are generated by reprogramming the somatic stem cells and then directing them into different adult cell populations to study their behavior toward the infection. In organoid models, different cell lines can be guided to produce a 3D structure including liver, heart, and brain-like platforms. Among animal models, mice are the most common species in this field. However, in order for mice models to be permissive to the virus, angiotensin-converting enzyme 2 receptors, the main receptor involved in the pathogenicity of the virus, should be introduced to the host cells through different methods. Here, the current known mechanism of SARS-CoV-2 infection, different suggested models, the specific response toward different manipulation as well as challenges and shortcomings in each case have been reviewed. Finally, we have tried to provide a quick summary of the present available RM-based models for SARS-CoV-2 infection, as an essential part of developing drugs, for future therapeutic goals.

[Model systems in gastroenterological research : From animal models to human organoids to the clinic]

Over the last few decades, various models have been established within gastroenterological research that have significantly contributed to a better understanding of the (patho)physiological processes of various gastrointestinal (GI) diseases (inflammation, organ injuries, carcinomas). This review will focus on such models including genetically engineered mouse models (GEMMs), xenografts, and organoid-based culture systems. GEMMs laid the foundation for successful modeling of such diseases. These have the decisive advantage that diseases can be assessed in their physiological environment and thus allow the examination of cell-cell communications of various cell types (epithelium, fibroblast, immune cells). However, the discrepancy between the genetic background of mice and humans reflected a pivotal disadvantage that could at least partially be circumvented by transplanting human cells into immunocompromised host animals. The time-consuming and labor-intensive generation of such xenograft models, however, considerably limits their usefulness for timely preclinical drug screenings. Thus, novel organoid-based human cell culture systems from adult stem cells or pluripotent stem cells are a promising human tool for modeling GI diseases. The first results already show their usefulness in the regulation of adult tissue homeostasis, regeneration, and tumor development. In addition, this system can be easily established in clinical diagnostics and thus enables real-time ex vivo pharmacotyping to develop personalized therapy strategies, particularly for cancer patients.

Endocytosis and Transcytosis of SARS-CoV-2 Across the Intestinal Epithelium and Other Tissue Barriers

Since 2003, the world has been confronted with three new betacoronaviruses that cause human respiratory infections: SARS-CoV, which causes severe acute respiratory syndrome (SARS), MERS-CoV, which causes Middle East respiratory syndrome (MERS), and SARS-CoV-2, which causes Coronavirus Disease 2019 (COVID-19). The mechanisms of coronavirus transmission and dissemination in the human body determine the diagnostic and therapeutic strategies. An important problem is the possibility that viral particles overcome tissue barriers such as the intestine, respiratory tract, blood-brain barrier, and placenta. In this work, we will 1) consider the issue of endocytosis and the possibility of transcytosis and paracellular trafficking of coronaviruses across tissue barriers with an emphasis on the intestinal epithelium; 2) discuss the possibility of antibody-mediated transcytosis of opsonized viruses due to complexes of immunoglobulins with their receptors; 3) assess the possibility of the virus transfer into extracellular vesicles during intracellular transport; and 4) describe the clinical significance of these processes. Models of the intestinal epithelium and other barrier tissues for in vitro transcytosis studies will also be briefly characterized.

Application of Human Induced Pluripotent Stem Cell-Derived Cellular and Organoid Models for COVID-19 Research

The outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid international spread has caused the coronavirus disease 2019 (COVID-19) pandemics, which is a global public health crisis. Thus, there is an urgent need to establish biological models to study the pathology of SARS-CoV-2 infection, which not only involves respiratory failure, but also includes dysregulation of other organs and systems, including the brain, heart, liver, intestines, pancreas, kidneys, eyes, and so on. Cellular and organoid models derived from human induced pluripotent stem cells (iPSCs) are ideal tools for in vitro simulation of viral life cycles and drug screening to prevent the reemergence of coronavirus. These iPSC-derived models could recapitulate the functions and physiology of various human cell types and assemble the complex microenvironments similar with those in the human organs; therefore, they can improve the study efficiency of viral infection mechanisms, mimic the natural host-virus interaction, and be suited for long-term experiments. In this review, we focus on the application of in vitro iPSC-derived cellular and organoid models in COVID-19 studies.

Histopathological features of SARS-CoV-2 infection and relationships with organoid technology

Coronavirus disease 2019 (COVID-19) following infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has caused a global pandemic that is still having serious effects worldwide. This virus, which targets the lungs in particular, can also damage other tissues. Angiotensin converting enzyme 2 (ACE-2) plays a key role in viral entry into host cells. The presence of ACE-2 in various tissues may permit viral infection. Studies of COVID-19 often make use of postmortem tissues. Although this information provides various useful results, it is also necessary to conduct in vitro studies to understand optimal treatment approaches. Because the virus may show species-specific differences, in vitro technologies using human cells are particularly important. Organoid technologies, three-dimensional structures that can be obtained from human cells, are playing increasingly important roles in studies of SARS-CoV-2. This technology offers a significant advantage in terms of mimicking in vivo tissue structures and testing antiviral compounds. In this mini-review, we summarize studies of SARS-CoV-2 using both histopathological and organoid technology approaches.

Organoids in modelling infectious diseases

Approaches based on animal and two-dimensional (2D) cell culture models cannot ensure reliable results in modeling novel pathogens or in drug testing in the short term; therefore, there is rising interest in platforms such as organoids. To develop a toolbox that can be used successfully to overcome current issues in modeling various infections, it is essential to provide a framework of recent achievements in applying organoids. Organoids have been used to study viruses, bacteria, and protists that cause, for example, respiratory, gastrointestinal, and liver diseases. Their future as models of infection will be associated with improvements in system complexity, including abilities to model tissue structure, a dynamic microenvironment, and coinfection. Teaser. Organoids are a flexible tool for modelling viral, bacterial and protist infections. They can provide fast and reliable information on the biology of pathogens and in drug screening, and thus have become essential in combatting emerging infectious diseases.

Comparison of anti-SARS-CoV-2 activity and intracellular metabolism of remdesivir and its parent nucleoside

Remdesivir, a monophosphate prodrug of nucleoside analog GS-441524, is widely used for the treatment of moderate to severe COVID-19. It has been suggested to use GS-441524 instead of remdesivir in the clinic and in new inhalation formulations. Thus, we compared the anti-SARS-CoV-2 activity of remdesivir and GS-441524 in Vero E6, Vero CCL-81, Calu-3, Caco-2 ​cells, and anti-HCoV-OC43 activity in Huh-7 ​cells. We also compared the cellular pharmacology of these two compounds in Vero E6, Vero CCL-81, Calu-3, Caco-2, Huh-7, 293T, BHK-21, 3T3 and human airway epithelial (HAE) cells. Overall, remdesivir exhibited greater potency and superior intracellular metabolism than GS-441524 except in Vero E6 and Vero CCL-81 ​cells.

IFITM proteins promote SARS-CoV-2 infection and are targets for virus inhibition in vitro

Interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) can restrict viral pathogens, but pro- and anti-viral activities have been reported for coronaviruses. Here, we show that artificial overexpression of IFITMs blocks SARS-CoV-2 infection. However, endogenous IFITM expression supports efficient infection of SARS-CoV-2 in human lung cells. Our results indicate that the SARS-CoV-2 Spike protein interacts with IFITMs and hijacks them for efficient viral infection. IFITM proteins were expressed and further induced by interferons in human lung, gut, heart and brain cells. IFITM-derived peptides and targeting antibodies inhibit SARS-CoV-2 entry and replication in human lung cells, cardiomyocytes and gut organoids. Our results show that IFITM proteins are cofactors for efficient SARS-CoV-2 infection of human cell types representing in vivo targets for viral transmission, dissemination and pathogenesis and are potential targets for therapeutic approaches.

IFITM proteins can inhibit several viruses, but effects on SARS-CoV-2 infection are not well understood. Here, the authors show that endogenous IFITMs support SARS-CoV-2 infection in different in vitro models by binding spike and enhancing virus entry.

[SARS-CoV-2 and the digestive tract - Organoids to model gastrointestinal infection]

SARS-CoV-2 is a novel human pathogenic coronavirus whose predilection for the respiratory tract has given rise to a rapid pandemic spread via airborne particles. Organ-specific susceptibility is substantially determined by the density of cell surface expression of ACE2, which is exploited by viral spike protein as a receptor molecule to mediate adhesion and, thus, to permit internalization of the viral genome into the host cell. Based on an ample data set derived from clinical studies and case reports, evidence suggests that distinct cell populations of the digestive and olfactory-gustatory system are equally equipped with membrane-bound ACE2, rendering them "vulnerable" to SARS-CoV-2. Numerous reports on concomitant gastrointestinal complaints and laboratory abnormalities are thought to reflect a relevant degree of organ dysfunction and underscore the tropism of SARS-CoV-2 for the digestive tract. Organoids are three-dimensional in vitro replicas of organ tissue which, owing to their organotypic complex cellular composition and functional resemblance to primary cells, are particularly appreciated for basic research in the field of infectious diseases. This review specifically addresses the involvement of digestive organs by SARS-CoV-2 and outlines the significant contribution of organoid- and primary-cell culture-based models to gaining a deeper understanding of the underlying pathophysiological processes.

SARS-CoV-2 research using human pluripotent stem cells and organoids

Experimental cell models are indispensable for clarifying the pathophysiology of coronavirus disease 2019 (COVID‐19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection, and for developing therapeutic agents. To recapitulate the symptoms and drug response of COVID‐19 patients in vitro, SARS‐CoV‐2 studies using physiologically relevant human embryonic stem (ES)/induced pluripotent stem (iPS) cell‐derived somatic cells and organoids are ongoing. These cells and organoids have been used to show that SARS‐CoV‐2 can infect and damage various organs including the lung, heart, brain, intestinal tract, kidney, and pancreas. They are also being used to develop COVID‐19 therapeutic agents, including evaluation of their antiviral efficacy and safety. The relationship between COVID‐19 aggravation and human genetic backgrounds has been investigated using genetically modified ES/iPS cells and patient‐derived iPS cells. This review summarizes the latest results and issues of SARS‐CoV‐2 research using human ES/iPS cell‐derived somatic cells and organoids.

Defense of COVID-19 by Human Organoids

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has created an immense menace to public health worldwide, exerting huge effects on global economic and political conditions. Understanding the biology and pathogenesis mechanisms of this novel virus, in large parts, relies on optimal physiological models that allow replication and propagation of SARS-CoV-2. Human organoids, derived from stem cells, are three-dimensional cell cultures that recapitulate the cellular organization, transcriptional and epigenetic signatures of their counterpart organs. Recent studies have indicated their great values as experimental virology platforms, making human organoid an ideal tool for investigating host-pathogen interactions. Here, we summarize research developments for SARS-CoV-2 infection of various human organoids involved in multiple systems, including lung, liver, brain, intestine, kidney and blood vessel organoids. These studies help us reveal the pathogenesis mechanism of COVID-19, and facilitate the development of effective vaccines and drugs as well as other therapeutic regimes.

Advancing lung organoids for COVID-19 research

The COVID-19 pandemic has emphasised the need to develop effective treatments to combat emerging viruses. Model systems that poorly represent a virus' cellular environment, however, may impede research and waste resources. Collaborations between cell biologists and virologists have led to the rapid development of representative organoid model systems to study severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We believe that lung organoids, in particular, have advanced our understanding of SARS-CoV-2 pathogenesis, and have laid a foundation to study future pandemic viruses and develop effective treatments.

Organoids: A New Model for SARS-CoV-2 Translational Research

The 2019-novel coronavirus (SARS-CoV-2) pneumonia epidemic is a thorny public health problem faced by health officials and a major cause of concern for health professionals. However, the currently used immortalized cell lines and animal models, though easy to manipulate, can not thoroughly simulate real viral activity due to a lack of target cells, species isolation, and insufficient adequate tissues and organs for clinical research. Organoid that emerges as an effective model and time-saving approach can simulate the viral life cycle in vitro and explore a therapeutic target for antiviral drug development. The 3D tissue cultures contain patient-specific stem cells in vitro to mimic the complexity of real tissue within the 3D microstructure that has the same functionality as the tissue of interest. It avoids the problems such as the distortion of genetic markers and animal ethics of using 2D cultures for animal testing and can be employed in studies of specific-organ viral infections to fully understand the physiopathological mechanism of SARS-CoV-2 infection for vaccine research and development.

3D Cell Culture Models in COVID-19 Times: A Review of 3D Technologies to Understand and Accelerate Therapeutic Drug Discovery

In the last decades, emerging viruses have become a worldwide concern. The fast and extensive spread of the disease caused by SARS-CoV-2 (COVID-19) has impacted the economy and human activity worldwide, highlighting the human vulnerability to infectious diseases and the need to develop and optimize technologies to tackle them. The three-dimensional (3D) cell culture models emulate major tissue characteristics such as the in vivo virus-host interactions. These systems may help to generate a quick response to confront new viruses, establish a reliable evaluation of the pathophysiology, and contribute to therapeutic drug evaluation in pandemic situations such as the one that humanity is living through today. This review describes different types of 3D cell culture models, such as spheroids, scaffolds, organoids, and organs-on-a-chip, that are used in virus research, including those used to understand the new severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2).

Could Histamine H1 Receptor Antagonists Be Used for Treating COVID-19?

COVID-19 has rapidly become a pandemic worldwide, causing extensive and long-term health issues. There is an urgent need to identify therapies that limit SARS-CoV-2 infection and improve the outcome of COVID-19 patients. Unbalanced lung inflammation is a common feature in severe COVID-19 patients; therefore, reducing lung inflammation can undoubtedly benefit the clinical manifestations. Histamine H1 receptor (H1 receptor) antagonists are widely prescribed medications to treat allergic diseases, while recently it has emerged that they show significant promise as anti-SARS-CoV-2 agents. Here, we briefly summarize the novel use of H1 receptor antagonists in combating SARS-CoV-2 infection. We also describe the potential antiviral mechanisms of H1 receptor antagonists on SARS-CoV-2. Finally, the opportunities and challenges of the use of H1 receptor antagonists in managing COVID-19 are discussed.