Engineering the 3D structure of organoids

Organoids form through the sel f-organizing capabilities of stem cells to produce a variety of differentiated cell and tissue types. Most organoid models, however, are limited in terms of the structure and function of the tissues that form, in part because it is difficult to regulate the cell type, arrangement, and cell-cell/cell-matrix interactions within these systems. In this article, we will discuss the engineering approaches to generate more complex organoids with improved function and translational relevance, as well as their advantages and disadvantages. Additionally, we will explore how biofabrication strategies can manipulate the cell composition, 3D organization, and scale-up of organoids, thus improving their utility for disease modeling, drug screening, and regenerative medicine applications.

Development of Novel 3D Spheroids for Discrete Subaortic Stenosis

In this study, we propose a new method for bioprinting 3D Spheroids to study complex congenital heart disease known as discrete subaortic stenosis (DSS). The bioprinter allows us to manipulate the extrusion pressure to change the size of the spheroids, and the alginate porosity increases in size over time. The spheroids are composed of human umbilical vein endothelial cells (HUVECs), and we demonstrated that pressure and time during the bioprinting process can modulate the diameter of the spheroids. In addition, we used Pluronic acid to maintain the shape and position of the spheroids. Characterization of HUVECs in the spheroids confirmed their uniform distribution and we demonstrated cell viability as a function of time. Compared to traditional 2D cell cultures, the 3D spheroids model provides more relevant physiological environments, making it valuable for drug testing and therapeutic applications.

Organoids as Tools for Investigating Skin Aging: Mechanisms, Applications, and Insights

Organoids have emerged as transformative tools in biomedical research, renowned for their ability to replicate the complexity construct of human tissues. Skin aging is a multifaceted biological process, influenced by both intrinsic factors and extrinsic factors. Traditional models for studying skin aging often fall short in capturing the intricate dynamics of human skin. In contrast, skin organoids offer a more physiologically relevant system, reflecting the structural and functional characteristics of native skin. These characteristics make skin organoids highly suitable for studying the mechanisms of skin aging, identifying novel therapeutic targets, and testing anti-aging interventions. Despite their promise, challenges such as limited scalability, reproducibility, and ethical considerations remain. Addressing these hurdles through interdisciplinary research and technological advancements will be essential to maximizing the potential of skin organoids for dermatological research and personalized anti-aging therapies.

Patient-derived induced pluripotent stem cells: Tools to advance the understanding and drug discovery in Major Depressive Disorder

Major Depressive Disorder (MDD) is a pleomorphic disease with substantial patterns of symptoms and severity with mensurable deficits in several associated domains. The broad spectrum of phenotypes observed in patients diagnosed with depressive disorders is the reflection of a very complex disease where clusters of biological and external factors (e.g., response/processing of life events, intrapsychic factors) converge and mediate pathogenesis, clinical presentation/phenotypes and trajectory. Patient-derived induced pluripotent stem cells (iPSCs) enable their differentiation into specialised cell types in the central nervous system to explore the pathophysiological substrates of MDD. These models may complement animal models to advance drug discovery and identify therapeutic approaches, such as cell therapy, drug repurposing, and elucidation of drug metabolism, toxicity, and mechanisms of action at the molecular/cellular level, to pave the way for precision psychiatry. Despite the remarkable scientific and clinical progress made over the last few decades, the disease is still poorly understood, the incidence and prevalence continue to increase, and more research is needed to meet clinical demands. This review aims to summarise and provide a critical overview of the research conducted thus far using patient-derived iPSCs for the modelling of psychiatric disorders, with a particular emphasis on MDD.

Signaling pathways in colorectal cancer implications for the target therapies

Colorectal carcinoma (CRC) stands as a pressing global health issue, marked by the unbridled proliferation of immature cells influenced by multifaceted internal and external factors. Numerous studies have explored the intricate mechanisms of tumorigenesis in CRC, with a primary emphasis on signaling pathways, particularly those associated with growth factors and chemokines. However, the sheer diversity of molecular targets introduces complexity into the selection of targeted therapies, posing a significant challenge in achieving treatment precision. The quest for an effective CRC treatment is further complicated by the absence of pathological insights into the mutations or alterations occurring in tumor cells. This study reveals the transfer of signaling from the cell membrane to the nucleus, unveiling recent advancements in this crucial cellular process. By shedding light on this novel dimension, the research enhances our understanding of the molecular intricacies underlying CRC, providing a potential avenue for breakthroughs in targeted therapeutic strategies. In addition, the study comprehensively outlines the potential immune responses incited by the aberrant activation of signaling pathways, with a specific focus on immune cells, cytokines, and their collective impact on the dynamic landscape of drug development. This research not only contributes significantly to advancing CRC treatment and molecular medicine but also lays the groundwork for future breakthroughs and clinical trials, fostering optimism for improved outcomes and refined approaches in combating colorectal carcinoma.

Application and challenge of pancreatic organoids in therapeutic research

The in-vivo non-human primate animal and in-vitro cell disease models play a crucial part in the study of the mechanisms underlying the occurrence and development of pancreatic diseases, but with increasingly prominent limitations with in-depth research. Organoids derived from human pluripotent and adult stem cells resemble human in-vivo organs in their cellular composition, spatial tissue structure and physiological function, making them as an advantageous research tool. Up until now, numerous human organoids, including pancreas, have been effectively developed, demonstrating significant potential for research in organ development, disease modeling, drug screening, and regenerative medicine. However, different from intestine, liver and other organs, the pancreas is the only special organ in the human body, consisting of an exocrine gland and an endocrine gland. Thus, the development of pancreatic organoid technology faces greater challenges, and how to construct a composite pancreatic organoid with exocrine and endocrine gland is still difficult in current research. By reviewing the fundamental architecture and physiological role of the human pancreas, along with the swiftly developing domain of pancreatic organoids, we summarize the method and characteristics of human pancreatic organoids, and its application in modeling pancreatic diseases, as a platform for individualized drug screening and in regenerative medicine study. As the first comprehensive review that focus on the pharmacological study of human pancreatic organoid, the review hopes to help scholars to have a deeper understanding in the study of pancreatic organoid.

Unravelling microRNA regulation and miRNA-mRNA regulatory networks in osteogenesis driven by 3D nanotopographical cues

Three-dimensional (3D) culturing of cells is being adopted for developing tissues for various applications such as mechanistic studies, drug testing, tissue regeneration, and animal-free meat. These approaches often involve cost-effective differentiation of stem or progenitor cells. One approach is to exploit architectural cues on a 3D substrate to drive cellular differentiation, which has been shown to be effective in various studies. Although extensive gene expression data from such studies have shown that gene expression patterns might differ, the gene regulatory networks controlling the expression of genes are rarely studied. In this study, we profiled genes and microRNAs (miRNAs) via next-generation sequencing (NGS) in human mesenchymal stem cells (hMSCs) driven toward osteogenesis via architectural cues in 3D matrices (3D conditions) and compared with cells in two-dimensional (2D) culture driven toward osteogenesis via soluble osteoinductive factors (OF conditions). The total number of differentially expressed genes was smaller in 3D compared to OF conditions. A distinct set of genes was observed under these conditions that have been shown to control osteogenic differentiation via different pathways. Small RNA sequencing revealed a core set of miRNAs to be differentially expressed under these conditions, similar to those that have been previously implicated in osteogenesis. We also observed a distinct regulation of miRNAs in these samples that can modulate gene expression, suggesting supplementary gene regulatory networks operative under different stimuli. This study provides insights into studying gene regulatory networks for identifying critical nodes to target for enhanced cellular differentiation and reveal the differences in physical and biochemical cues to drive cell fates.

An Exploration of Organoid Technology: Present Advancements, Applications, and Obstacles

BACKGROUND

Organoids are in vitro models that exhibit a three-dimensional structure and effectively replicate the structural and physiological features of human organs. The capacity to research complex biological processes and disorders in a controlled setting is laid out by these miniature organ-like structures.

OBJECTIVES

This work examines the potential applications of organoid technology, as well as the challenges and future directions associated with its implementation. It aims to emphasize the pivotal role of organoids in disease modeling, drug discovery, developmental biology, precision medicine, and fundamental research.

METHODS

The manuscript was put together by conducting a comprehensive literature review, which involved an in-depth evaluation of globally renowned scientific research databases.

RESULTS

The field of organoids has generated significant attention due to its potential applications in tissue development and disease modelling, as well as its implications for personalised medicine, drug screening, and cell-based therapies. The utilisation of organoids has proven to be effective in the examination of various conditions, encompassing genetic disorders, cancer, neurodevelopmental disorders, and infectious diseases.

CONCLUSION

The exploration of the wider uses of organoids is still in its early phases. Research shall be conducted to integrate 3D organoid systems as alternatives for current models, potentially improving both fundamental and clinical studies in the future.

Characterization of human pluripotent stem cell differentiation by single-cell dual-omics analyses

In vivo differentiation of human pluripotent stem cells (hPSCs) has unique advantages, such as multilineage differentiation, angiogenesis, and close cell-cell interactions. To systematically investigate multilineage differentiation mechanisms of hPSCs, we constructed the in vivo hPSC differentiation landscape containing 239,670 cells using teratoma models. We identified 43 cell types, inferred 18 cell differentiation trajectories, and characterized common and specific gene regulation patterns during hPSC differentiation at both transcriptional and epigenetic levels. Additionally, we developed the developmental single-cell Basic Local Alignment Search Tool (dscBLAST), an R-based cell identification tool, to simplify the identification processes of developmental cells. Using dscBLAST, we aligned cells in multiple differentiation models to normally developing cells to further understand their differentiation states. Overall, our study offers new insights into stem cell differentiation and human embryonic development; dscBLAST shows favorable cell identification performance, providing a powerful identification tool for developmental cells.

Engineered organoids in oral and maxillofacial regeneration

Oral and maxillofacial organoids, as three-dimensional study models of organs, have attracted increasing attention in tissue regeneration and disease modeling. However, traditional strategies for organoid construction still fail to precisely recapitulate the key characteristics of real organs, due to the difficulty in controlling the self-organization of cells in vitro. This review aims to summarize the recent progress of novel approaches to engineering oral and maxillofacial organoids. First, we introduced the necessary components and their roles in forming oral and maxillofacial organoids. Besides, we discussed cutting-edge technology in advancing the architecture and function of organoids, especially focusing on oral and maxillofacial tissue regeneration via novel strategy with designed cell-signal scaffold compounds. Finally, current limitations and future prospects of oral and maxillofacial organoids were represented to provide guidance for further disciplinary progression and clinical application to achieve organ regeneration.

Advancement of Organoid Technology in Regenerative Medicine

Purpose

Organoids are three-dimensional cultures of stem cells in an environment similar to the body's extracellular matrix. This is also a novel development in the realm of regenerative medicine. Stem cells can begin to develop into 3D structures by modifying signaling pathways. To form organoids, stem cells are transplanted into the extracellular matrix. Organoids have provided the required technologies to reproduce human tissues. As a result, it might be used in place of animal models in scientific study. The key goals of these investigations are research into viral and genetic illnesses, malignancies, and extracellular vesicles, pharmaceutical discovery, and organ transplantation. Organoids can help pave the road for precision medicine through genetic editing, pharmaceutical development, and cell therapy.

Methods

PubMed, Google Scholar, and Scopus were used to search for all relevant papers written in English (1907-2021). The study abstracts were scrutinized. Studies on the use of stem-cell-derived organoids in regenerative medicine, organoids as 3D culture models for EVs analysis, and organoids for precision medicine were included. Articles with other irrelevant aims, meetings, letters, commentaries, congress and conference abstracts, and articles with no available full texts were excluded.

Results

According to the included studies, organoids have various origins, types, and applications in regenerative and precision medicine, as well as an important role in studying extracellular vesicles.

Conclusion

Organoids are considered a bridge that connects preclinical studies to clinical ones. However, the lack of a standardized protocol and other barriers addressed in this review, hinder the vast use of this technology.

Lay Summary

Organoids are 3D stem cell propagations in biological or synthetic scaffolds that mimic ECM to allow intercellular or matrix-cellular crosstalk. Because these structures are similar to organs in the body, they can be used as research models. Organoids are medicine's future hope for organ transplantation, tumor biobank formation, and the development of precision medicine. Organoid models can be used to study cell-to-cell interactions as well as effective factors like inflammation and aging. Bioengineering technologies are also used to define the size, shape, and composition of organoids before transforming them into precise structures. Finally, the importance of organoid applications in regenerative medicine has opened a new window for a better understanding of biological research, as discussed in this study.

Mimicking Tumor Microenvironment by 3D Bioprinting: 3D Cancer Modeling

The tumor microenvironment typically comprises cancer cells, tumor vasculature, stromal components like fibroblasts, and host immune cells that assemble to support tumorigenesis. However, preexisting classic cancer models like 2D cell culture methods, 3D cancer spheroids, and tumor organoids seem to lack essential tumor microenvironment components. 3D bioprinting offers enormous advantages for developing in vitro tumor models by allowing user-controlled deposition of multiple biomaterials, cells, and biomolecules in a predefined architecture. This review highlights the recent developments in 3D cancer modeling using different bioprinting techniques to recreate the TME. 3D bioprinters enable fabrication of high-resolution microstructures to reproduce TME intricacies. Furthermore, 3D bioprinted models can be applied as a preclinical model for versatile research applications in the tumor biology and pharmaceutical industries. These models provide an opportunity to develop high-throughput drug screening platforms and can further be developed to suit individual patient requirements hence giving a boost to the field of personalized anti-cancer therapeutics. We underlined the various ways the existing studies have tried to mimic the TME, mimic the hallmark events of cancer growth and metastasis within the 3D bioprinted models and showcase the 3D drug-tumor interaction and further utilization of such models to develop personalized medicine.

Human iPSC-derived renal organoids engineered to report oxidative stress can predict drug-induced toxicity

Advances in regenerative medicine have led to the construction of many types of organoids, which reproduce important aspects of endogenous organs but may be limited or disorganized in nature. While their usefulness for restoring function remains unclear, they have undoubted usefulness in research, diagnostics, and toxicology. In toxicology, there is an urgent need for better models for human kidneys. We used human iPS-cell (hiPSC)-derived renal organoids to identify HMOX1 as a useful marker of toxic stress via the oxidative stress pathway, and then constructed an HMOX1 reporter in hiPSCs. We used two forms of hiPSC-derived HMOX1-reporter renal organoids to probe their ability to detect nephrotoxicants in a panel of blind-coded compounds. Our results highlight the potential usefulness, and some limitations, of HMOX1-reporter renal organoids as screening tools. The results may guide development of similar stress-reporting organoid assays for other stem-cell-derived organs and tissues.

Microfluidic Organ-on-a-Chip Devices for Liver Disease Modeling In Vitro

Mortality from liver disease conditions continues to be very high. As liver diseases manifest and progress silently, prompt measures after diagnosis are essential in the treatment of these conditions. Microfluidic organs-on-chip platforms have significant potential for the study of the pathophysiology of liver diseases in vitro. Different liver-on-a-chip microphysiological platforms have been reported to study cell-signaling pathways such as those activating stellate cells within liver diseases. Moreover, the drug efficacy for liver conditions might be evaluated on a cellular metabolic level. Here, we present a comprehensive review of microphysiological platforms used for modelling liver diseases. First, we briefly introduce the concept and importance of organs-on-a-chip in studying liver diseases in vitro, reflecting on existing reviews of healthy liver-on-a-chip platforms. Second, the techniques of cell cultures used in the microfluidic devices, including 2D, 3D, and spheroid cells, are explained. Next, the types of liver diseases (NAFLD, ALD, hepatitis infections, and drug injury) on-chip are explained for a further comprehensive overview of the design and methods of developing liver diseases in vitro. Finally, some challenges in design and existing solutions to them are reviewed.

A Cerebral Organoid Connectivity Apparatus to Model Neuronal Tract Circuitry

Mental disorders have high prevalence, but the efficacy of existing therapeutics is limited, in part, because the pathogenic mechanisms remain enigmatic. Current models of neural circuitry include animal models and post-mortem brain tissue, which have allowed enormous progress in understanding the pathophysiology of mental disorders. However, these models limit the ability to assess the functional alterations in short-range and long-range network connectivity between brain regions that are implicated in many mental disorders, e.g., schizophrenia and autism spectrum disorders. This work addresses these limitations by developing an in vitro model of the human brain that models the in vivo cerebral tract environment. In this study, microfabrication and stem cell differentiation techniques were combined to develop an in vitro cerebral tract model that anchors human induced pluripotent stem cell-derived cerebral organoids (COs) and provides a scaffold to promote the formation of a functional connecting neuronal tract. Two designs of a Cerebral Organoid Connectivity Apparatus (COCA) were fabricated using SU-8 photoresist. The first design contains a series of spikes which anchor the CO to the COCA (spiked design), whereas the second design contains flat supporting structures with open holes in a grid pattern to anchor the organoids (grid design); both designs allow effective media exchange. Morphological and functional analyses reveal the expression of key neuronal markers as well as functional activity and signal propagation along cerebral tracts connecting CO pairs. The reported in vitro models enable the investigation of critical neural circuitry involved in neurodevelopmental processes and has the potential to help devise personalized and targeted therapeutic strategies.

Post-translational modifications by SIRT3 de-2-hydroxyisobutyrylase activity regulate glycolysis and enable nephrogenesis

Abnormal kidney development leads to lower nephron number, predisposing to renal diseases in adulthood. In embryonic kidneys, nephron endowment is dictated by the availability of nephron progenitors, whose self-renewal and differentiation require a relatively repressed chromatin state. More recently, NAD⁺-dependent deacetylase sirtuins (SIRTs) have emerged as possible regulators that link epigenetic processes to the metabolism. Here, we discovered a novel role for the NAD⁺-dependent deacylase SIRT3 in kidney development. In the embryonic kidney, SIRT3 was highly expressed only as a short isoform, with nuclear and extra-nuclear localisation. The nuclear SIRT3 did not act as deacetylase but exerted de-2-hydroxyisobutyrylase activity on lysine residues of histone proteins. Extra-nuclear SIRT3 regulated lysine 2-hydroxyisobutyrylation (Khib) levels of phosphofructokinase (PFK) and Sirt3 deficiency increased PFK Khib levels, inducing a glycolysis boost. This altered Khib landscape in Sirt3^−/− metanephroi was associated with decreased nephron progenitors, impaired nephrogenesis and a reduced number of nephrons. These data describe an unprecedented role of SIRT3 in controlling early renal development through the regulation of epigenetics and metabolic processes.

High-dose drug heat map analysis for drug safety and efficacy in multi-spheroid brain normal cells and GBM patient-derived cells

To test the safety and efficacy of drugs via a high does drug heat map, a multi-spheroids array chip was developed by adopting a micropillar and microwell structure. In the chip, patient-derived cells were encapsulated in alginate and grown to maturity for more than 7 days to form cancer multi-spheroids. Multi-spheroids grown in conventional well plates require many cells and are easily damaged as a result of multiple pipetting during maintenance culture or experimental procedures. To address these issues, we applied a micropillar and microwell structure to the multi-spheroids array. Patient-derived cells from patients with Glioblastoma (GBM), the most common and lethal form of central nervous system cancer, were used to validate the array chip performance. After forming multi-spheroids with a diameter greater than 100μm in a 12×36 pillar array chip (25mm × 75mm), we tested 70 drug compounds (6 replicates) using a high-dose to determine safety and efficacy for drug candidates. Comparing the drug response of multi-spheroids derived from normal cells and cancer cells, we found that four compounds (Dacomitinib, Cediranib, LY2835219, BGJ398) did not show toxicity to astrocyte cell and were efficacious to patient-derived GBM cells.

Preclinical tumor organoid models in personalized cancer therapy: Not everyone fits the mold

In contrast to conventional cancer treatment, in personalized cancer medicine each patient receives a specific treatment. The response to therapy, clinical outcomes, and tumor behavior such as metastases, tumor progression, carcinogenesis can be significantly affected by the heterogeneous tumor microenvironment (TME) and interpersonal differences. Therefore, using native tumor microenvironment mimicking models is necessary to improving personalized cancer therapy. Both in vitro 2D cell culture and in vivo animal models poorly recapitulate the heterogeneous tumor (immune) microenvironments of native tumors. The development of 3D culture models, native tumor microenvironment mimicking models, made it possible to evaluate the chemoresistance of tumor tissue and the functionality of drugs in the presence of cell-extracellular matrix and cell-cell interactions in a 3D construction. Various personalized tumor models have been designed to preserving the native tumor microenvironment, including patient-derived tumor xenografts and organoid culture strategies. In this review, we will discuss the patient-derived organoids as a native tumor microenvironment mimicking model in personalized cancer therapy. In addition, we will also review the potential and the limitations of organoid culture systems for predicting patient outcomes and preclinical drug screening. Finally, we will discuss immunotherapy drug screening in tumor organoids by using microfluidic technology.

Scientific inertia in animal-based research in biomedicine

Despite aspirations to substitute animal experimentation with alternative methods and recent progress in the area of non-animal approaches, such as organoïds and organ(s)-on-a-chip technologies, there is no extensive replacement of animal-based research in biomedicine. In this paper, I will analyse this state of affairs with reference to key institutional and socio-epistemic barriers for the development and use of non-animal approaches in the context of biomedical research in Europe. I will argue that there exist several factors that inhibit change in this context. In particular, there is what I call "scientific inertia", i.e. a certain degree of conservatism in scientific practice regarding the development and use of non-animal approaches to replace animal experimentation. This type of inertia is facilitated by socio-epistemic characteristics of animal-based research in the life sciences and is a key factor in understanding the status quo in biomedical research. The underlying reasons for scientific inertia have not received sufficient attention in the literature to date because the phenomenon transcends traditional disciplinary boundaries in the study of animal experimentation. This paper addresses this issue and seeks to contribute to a better understanding of scientific inertia by using a methodology that looks at the interplay of institutional, epistemic, and regulatory aspects of animal-based research.

MS imaging of multicellular tumor spheroids and organoids as an emerging tool for personalized medicine and drug discovery

MS imaging (MSI) is a powerful tool in drug discovery because of its ability to interrogate a wide range of endogenous and exogenous molecules in a broad variety of samples. The impressive versatility of the approach, where almost any ionizable biomolecule can be analyzed, including peptides, proteins, lipids, carbohydrates, and nucleic acids, has been applied to numerous types of complex biological samples. While originally demonstrated with harvested organs from animal models and biopsies from humans, these models are time consuming and expensive, which makes it necessary to extend the approach to 3D cell culture systems. These systems, which include spheroid models, prepared from immortalized cell lines, and organoid cultures, grown from patient biopsies, can provide insight on the intersection of molecular information on a spatial scale. In particular, the investigation of drug compounds, their metabolism, and the subsequent distribution of their metabolites in 3D cell culture systems by MSI has been a promising area of study. This review summarizes the different ionization methods, sample preparation steps, and data analysis methods of MSI and focuses on several of the latest applications of MALDI-MSI for drug studies in spheroids and organoids. Finally, the application of this approach in patient-derived organoids to evaluate personalized medicine options is discussed.

The Horse as a Model for the Study of Cutaneous Wound Healing

Significance: Cutaneous wounds are a major problem in both human and equine medicine. The economic cost of treating skin wounds and related complications in humans and horses is high, and in both species, particular types of chronic wounds do not respond well to current therapies, leading to suffering and morbidity. Recent Advances: Conventional methods for the treatment of cutaneous wounds are generic and have not changed significantly in decades. However, as more is learned about the mechanisms involved in normal skin wound healing, and how failure of these processes leads to chronic nonhealing wounds, novel therapies targeting the specific pathologies of hard-to-heal wounds are being developed and evaluated. Critical Issues: Physiologically relevant animal models are needed to (1) study the mechanisms involved in normal and impaired skin wound healing and (2) test newly developed therapies. Future Directions: Similarities in normal wound healing in humans and horses, and the natural development of distinct types of hard-to-heal chronic wounds in both species, make the horse a physiologically relevant model for the study of mechanisms involved in wound repair. Horses are also well-suited models to test novel therapies. In addition, studies in horses have the potential to benefit veterinary, as well as human medicine.

Flavonoids and cellular stress: a complex interplay affecting human health

Flavonoid consumption has beneficial effects on human health, however, clinical evidence remains often inconclusive due to high interindividual variability. Although this high interindividual variability has been consistently observed in flavonoid research, the potential underlying reasons are still poorly studied. Especially the knowledge on the impact of health status on flavonoid responsiveness is limited and merits more investigation. Here, we aim to highlight the bidirectional interplay between flavonoids and cellular stress. First, the state-of-the-art concerning inflammatory stress and mitochondrial dysfunction is reviewed and a comprehensive overview of recent in vitro studies investigating the impact of flavonoids on cellular stress, induced by tumor necrosis factor α, lipopolysaccharide and mitochondrial stressors, is given. Second, we critically discuss the influence of cellular stress on flavonoid uptake, accumulation, metabolism and cell responses, which has, to our knowledge, never been extensively reviewed before. Next, we advocate the innovative insight that stratification of the general population based on health status can reveal subpopulations that benefit more from flavonoid consumption. Finally, suggestions are given for the development of future cell models that simulate the physiological micro-environment, including interindividual variability, since more mechanistic research is needed to establish scientific-based personalized food recommendations for specific subpopulations.

Organoid Technology: Current Standing and Future Perspectives

Organoids are powerful systems to facilitate the study of individuals' disorders and personalized treatments. Likewise, emerging this technology has improved the chance of translatability of drugs for pre-clinical therapies and mimicking the complexity of organs, while it proposes numerous approaches for human disease modeling, tissue engineering, drug development, diagnosis, and regenerative medicine. In this review, we outline the past/present organoid technology and summarize its faithful applications, then, we discuss the challenges and limitations encountered by 3D organoids. In the end, we offer the human organoids as basic mechanistic infrastructure for "human modelling" systems to prescribe personalized medicines. © AlphaMed Press 2021 SIGNIFICANCE STATEMENT: This concise review concerns about organoids, available methods for in vitro organoid formation and different types of human organoid models. We, then, summarize biological approaches to improve 3D organoids complexity and therapeutic potentials of organoids. Despite the existing incomprehensive review articles in literature that examine partial aspects of the organoid technology, the present review article comprehensively and critically presents this technology from different aspects. It effectively provides a systematic overview on the past and current applications of organoids and discusses the future perspectives and suggestions to improve this technology and its applications.

Biosynthetic, biomimetic, and self-assembled vascularized Organ-on-a-Chip systems

Organ-on-a-Chip (OOC) devices have seen major advances in the last years with respect to biological complexity, physiological composition and biomedical relevance. In this context, integration of vasculature has proven to be a crucial element for long-term culture of thick tissue samples as well as for realistic pharmacokinetic, toxicity and metabolic modelling. With the emergence of digital production technologies and the reinvention of existing tools, a multitude of design approaches for guided angio- and vasculogenesis is available today. The underlying production methods can be categorized into biosynthetic, biomimetic and self-assembled vasculature formation. The diversity and importance of production approaches, vascularization strategies as well as biomaterials and cell sourcing are illustrated in this work. A comprehensive technological review with a strong focus on the challenge of producing physiologically relevant vascular structures is given. Finally, the remaining obstacles and opportunities in the development of vascularized Organ-on-a-Chip platforms for advancing drug development and predictive disease modelling are noted.

Organoids and organ chips in ophthalmology

Recent advances have driven the development of stem cell-derived, self-organizing, three-dimensional miniature organs, termed organoids, which mimic different eye tissues including the retina, cornea, and lens. Organoids and engineered microfluidic organ-on-chips (organ chips) are transformative technologies that show promise in simulating the architectural and functional complexity of native organs. Accordingly, they enable exploration of facets of human disease and development not accurately recapitulated by animal models. Together, these technologies will increase our understanding of the basic physiology of different eye structures, enable us to interrogate unknown aspects of ophthalmic disease pathogenesis, and serve as clinically-relevant surrogates for the evaluation of ocular therapeutics. Both the burden and prevalence of monogenic and multifactorial ophthalmic diseases, which can cause visual impairment or blindness, in the human population warrants a paradigm shift towards organoids and organ chips that can provide sensitive, quantitative, and scalable phenotypic assays. In this article, we review the current situation of organoids and organ chips in ophthalmology and discuss how they can be leveraged for translational applications.

Tissue-engineered parathyroid gland and its regulatory secretion of parathyroid hormone

Parathyroid glands (PTGs) are important endocrine organs being mainly responsible for the secretion of parathyroid hormone (PTH) to regulate the balance of calcium (Ca) /phosphorus (P) ions in the body. Once PTGs get injured or removed, their resulting defect or loss of PTH secretion should disturb the level of Ca/P in blood, thus damaging other related organs (bone, kidney, etc.) and even causing death. Recently, tissue-engineered PTGs (TE-PTGs) have attracted lots of attention as a potential treatment for the related diseases of PTGs caused by hypoparathyroidism and hyperparathyroidism, including tetany, muscle cramp, nephrolithiasis, nephrocalcinosis, and osteoporosis. Although great progress has been made in the establishment of TE-PTGs with an effective strategy to integrate the key factors of cells and biomaterials, its regulatory secretion of PTH to mimic its natural rhythms in the body remains a huge challenge. This review comprehensively describes an overview of PTGs from physiology and pathology to cytobiology and tissue engineering. The state of the arts in TE-PTGs and the feasible strategies to regulate PTH secretion behaviors are highlighted to provide an important foundation for further investigation.

Biomaterials and Culture Systems for Development of Organoid and Organ-on-a-Chip Models

The development of novel 3D tissue culture systems has enabled the in vitro study of in vivo processes, thereby overcoming many of the limitations of previous 2D tissue culture systems. Advances in biomaterials, including the discovery of novel synthetic polymers has allowed for the generation of physiologically relevant in vitro 3D culture models. A large number of 3D culture systems, aided by novel organ-on-a-chip and bioreactor technologies have been developed to improve reproducibility and scalability of in vitro organ models. The discovery of induced pluripotent stem cells (iPSCs) and the increasing number of protocols to generate iPSC-derived cell types has allowed for the generation of novel 3D models with minimal ethical limitations. The production of iPSC-derived 3D cultures has revolutionized the field of developmental biology and in particular, the study of fetal brain development. Furthermore, physiologically relevant 3D cultures generated from PSCs or adult stem cells (ASCs) have greatly advanced in vitro disease modelling and drug discovery. This review focuses on advances in 3D culture systems over the past years to model fetal development, disease pathology and support drug discovery in vitro, with a specific focus on the enabling role of biomaterials.

Organoids for replacement therapy: expectations, limitations and reality

PURPOSE OF REVIEW

To discuss existing expectations from organoids and how they can affect biomedical research and society, and to analyse the current limitations and how they can potentially be overcome.

RECENT FINDINGS

Recent success with engineering human organoids has created great enthusiasm and expectations, especially for their potential as tissue substitutes. The most feasible applications for organoid technologies at the moment are: drug testing, disease modelling and studying of human development.

SUMMARY

Being able to engineer transplantable tissues in a dish would fundamentally change the way we conduct biomedical research and clinical practice, and impact important aspects of science and society - from animal experimentation to personalized medicine, bioethics, transplantation and gene therapy. However, whether organoids will soon be able to fulfil these expectations is still unclear, because of significant existing limitations. By answering a set of questions, here I will examine the expectations on the future of organoids and how they can affect the field and the society, I will analyse the most important limitations that still prevent the production of transplantable human tissues in a dish, and discuss possible solution strategies.

Use of l-pNIPAM hydrogel as a 3D-scaffold for intestinal crypts and stem cell tissue engineering

Intestinal stem cells hold great potential in tissue regeneration of the intestine, however, there are key limitations in their culture in vitro. We previously reported a novel synthetic non-biodegradable hydrogel as a 3D culture model for intestinal epithelium using Caco2 and HT29-MTX cells. Here, we investigated the potential of this system as a 3D scaffold for crypts and single intestinal stem cells to support long-term culture and differentiation. Intestinal crypts were extracted from murine small intestines and Lgr5+ stem cells isolated by magnetic activated cell sorting. Crypts and stem cells were suspended within Matrigel or l-pNIPAM for 14 days or suspended within Matrigel for 7 days then released, dissociated, and suspended within, or on l-pNIPAM hydrogel for 28 days. Cellular behaviour and phenotype were determined by histology and immunohistochemistry for stem cell and differentiation markers: Lgr5, E-cadherin MUC2 chromograninA and lysozymes. Isolated crypts and Lgr5+ intestinal stem cells formed enteroids with a central lumen surrounded by multiple crypt-like buds when cultured in Matrigel. In contrast, when crypts and stem cells were directly suspended within, or layered on l-pNIPAM hydrogel under dynamic culture conditions they formed spherical balls of cells, with no central lumen. When enteroids were initially formed in Matrigel from crypts or single Lgr5+ intestinal stem cells and dissociated into small fragments or single cells and transferred to l-pNIPAM hydrogel they formed new larger enteroids with numerous crypt-like buds. These crypt-like buds showed the presence of mucin-producing cells, which resembled goblet cells, scattered throughout their structures. Immunohistochemistry staining also showed the expression of Lgr5 and differentiation markers of all the main intestinal cell types including: enterocytes, goblet cells, enteroendocrine and Paneth cells. This demonstrated that l-pNIPAM hydrogel supported long-term culture of crypts and Lgr5+ stem cells and promoted intestinal cell differentiation.

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

BACKGROUND & AIMS

The development of hepatic models capable of long-term expansion with competent liver functionality is technically challenging in a personalized setting. Stem cell-based organoid technologies can provide an alternative source of patient-derived primary hepatocytes. However, self-renewing and functionally competent human pluripotent stem cell (PSC)-derived hepatic organoids have not been developed.

METHODS

We developed a novel method to efficiently and reproducibly generate functionally mature human hepatic organoids derived from PSCs, including human embryonic stem cells and induced PSCs. The maturity of the organoids was validated by a detailed transcriptome analysis and functional performance assays. The organoids were applied to screening platforms for the prediction of toxicity and the evaluation of drugs that target hepatic steatosis through real-time monitoring of cellular bioenergetics and high-content analyses.

RESULTS

Our organoids were morphologically indistinguishable from adult liver tissue-derived epithelial organoids and exhibited self-renewal. With further maturation, their molecular features approximated those of liver tissue, although these features were lacking in 2D differentiated hepatocytes. Our organoids preserved mature liver properties, including serum protein production, drug metabolism and detoxifying functions, active mitochondrial bioenergetics, and regenerative and inflammatory responses. The organoids exhibited significant toxic responses to clinically relevant concentrations of drugs that had been withdrawn from the market due to hepatotoxicity and recapitulated human disease phenotypes such as hepatic steatosis.

CONCLUSIONS

Our organoids exhibit self-renewal (expandable and further able to differentiate) while maintaining their mature hepatic characteristics over long-term culture. These organoids may provide a versatile and valuable platform for physiologically and pathologically relevant hepatic models in the context of personalized medicine.

LAY SUMMARY

A functionally mature, human cell-based liver model exhibiting human responses in toxicity prediction and drug evaluation is urgently needed for pre-clinical drug development. Here, we develop a novel human pluripotent stem cell-derived hepatocyte-like liver organoid that is critically advanced in terms of its generation method, functional performance, and application technologies. Our organoids can contribute to the better understanding of liver development and regeneration, and provide insights for metabolic studies and disease modeling, as well as toxicity assessments and drug screening for personalized medicine.

A Cancer Spheroid Array Chip for Selecting Effective Drug

A cancer spheroid array chip was developed by modifying a micropillar and microwell structure to improve the evaluation of drugs targeting specific mutations such as phosphor-epidermal growth factor receptor (p-EGFR). The chip encapsulated cells in alginate and allowed cancer cells to grow for over seven days to form cancer spheroids. However, reagents or media used to screen drugs in a high-density spheroid array had to be replaced very carefully, and this was a tedious task. Particularly, the immunostaining of cancer spheroids required numerous steps to replace many of the reagents used for drug evaluation. To solve this problem, we adapted a micropillar and microwell structure to a spheroid array. Thus, culturing cancer spheroids in alginate spots attached to the micropillar allowed us to replace the reagents in the microwell chip with a single fill of fresh medium, without damaging the cancer spheroids. In this study, a cancer spheroid array was made from a p-EGFR-overexpressing cell line (A549 lung cancer cell line). In a 12 by 36 column array chip (25 mm by 75 mm), the spheroid over 100 µm in diameter started to form at day seven and p-EGFR was also considerably overexpressed. The array was used for p-EGFR inhibition and cell viability measurement against seventy drugs, including ten EGFR-targeting drugs. By comparing drug response in the spheroid array (spheroid model) with that in the single-cell model, we demonstrated that the two models showed different responses and that the spheroid model might be more resistant to some drugs, thus narrowing the choice of drug candidates.

An Air Bubble-Isolating Rotating Wall Vessel Bioreactor for Improved Spheroid/Organoid Formation

IMPACT STATEMENT

The rotating wall vessel (RWV) bioreactor is a powerful tool for the generation of sizeable, faster-growing organoids. However, the ideal, low-shear, modeled microgravity environment in the RWV is frequently disrupted by the formation of bubbles, a critical but understated failure mode. To address this, we have designed and fabricated a novel, modified RWV bioreactor capable of continuously removing bubbles while providing optimal fluid dynamics. We validated the capacity of this device with computational and empirical studies. We anticipate that our novel bioreactor will be more consistent and easier to use and may fill a unique and unmet niche in the burgeoning field of organoids.

Three-Dimensional Organoids in Cancer Research: The Search for the Holy Grail of Preclinical Cancer Modeling

Most solid tumors become therapy resistant and will relapse, with no durable treatment option available. One major impediment to our understanding of cancer biology and finding innovative approaches to cancer treatment stems from the lack of better preclinical tumor models that address and explain tumor heterogeneity and person-to-person differences in therapeutic and toxic responses. Past cancer research has been driven by inadequate in vitro assays utilizing two-dimensional monolayers of cancer cells and animal models. Additionally, animal models do not truly mimic the original human tumor, are time consuming, and usually costly. New preclinical models are needed for innovation in cancer translational research. Hence, it is time to welcome the three-dimensional (3D) organoids: self-organizing cells grown in 3D culture systems mimicking the parent tissues from which the primary cells originate. The 3D organoids offer deeper insights into the crucial cellular processes in tissue and organ formation and pathological processes. Generation of near-perfect physiological microenvironments allow 3D organoids to couple with gene editing tools, such as the clustered regularly interspersed short palindromic repeat (CRISPR)/CRISPR-associated 9 and the transcription activator-like effector nucleases to model human diseases, offering distinct advantages over current models. We explain in this expert review that through recapitulating patients' normal and tumor tissues, organoid technology can markedly advance personalized medicine and help reveal once hidden aspects of cancers. The use of defined tissue- or organ-specific matrices, among other factors, will likely allow organoid technology to realize its potential in innovating many fields of life sciences.

Disturbed redox homeostasis and oxidative stress: Potential players in the developmental regression in Rett syndrome

Rett syndrome (RTT) is a neurodevelopmental disorder affecting mostly girls. A seemingly normal initial development is followed by developmental stagnation and regression, leading to severe mental impairment with autistic features, motor dysfunction, irregular breathing and epilepsy. Currently, a cure does not exist. Due to the close association of RTT with mitochondrial alterations, cellular redox-impairment and oxidative stress, compounds stabilizing mitochondrial function, cellular redox-homeostasis, and oxidant detoxification are increasingly considered as treatment concepts. Indeed, antioxidants and free-radical scavengers ameliorate certain aspects of the complex and severe clinical presentation of RTT. To further evaluate these strategies, reliable biosensors are needed to quantify redox-conditions in brain and peripheral organs of mouse models or in patient-derived cells. Genetically-encoded redox-sensors meet these requirements. Expressed in transgenic mouse-models such as our unique Rett-redox indicator mice, they will report for any cell type desired the severity of oxidant stress throughout the various disease stages of RTT. Furthermore, these sensors will be crucial to evaluate in vitro and in vivo the outcome of mitochondria- and redox-balance targeted treatments.

Brain Organoids: A New, Transformative Investigational Tool for Neuroscience Research

Brain organoids are self-assembled, three-dimensionally structured tissues that are typically derived from pluripotent stem cells. They are multicellular aggregates that more accurately recapitulate the tissue microenvironment compared to the other cell culture systems and can also reproduce organ function. They are promising models for evaluating drug leads, particularly those that target neurodegeneration, since they are genetically and phenotypically stable over prolonged durations of culturing and they reasonably reproduce critical physiological phenomena such as biochemical gradients and responses by the native tissue to stimuli. Beyond drug discovery, the use of brain organoids could also be extended to investigating early brain development and identifying the mechanisms that elicit neurodegeneration. Herein, the current state of the fabrication and use of brain organoids in drug development and medical research is summarized. Although the use of brain organoids represents a quantum leap over existing investigational tools used by the pharmaceutical industry, they are nonetheless imperfect systems that could be greatly improved through bioengineering. To this end, some key scientific challenges that would need to be addressed in order to enhance the relevance of brain organoids as model tissue are listed. Potential solutions to these challenges, including the use of bioprinting, are highlighted thereafter.

Vincristine Impairs Microtubules and Causes Neurotoxicity in Cerebral Organoids

The advance of nanotechnology in drug delivery systems has allowed central nervous system (CNS) accumulation of several anti-tumor agents with poor brain penetration but also lead to concerns about central neurotoxicity. Vincristine is commonly administered as an effective anti-brain tumor drug. It is known to act by interfering with microtubule dynamics, but models for detailed elucidation of its mechanism of neurotoxicity are limited. Here we generated cerebral organoids using human-induced pluripotent stem cells (iPSCs) for evaluation of neurotoxic mechanisms. Cerebral organoids were treated with different concentrations of vincristine for 48 h and their expansion was measured. We also assayed various cell markers, microtubule associated proteins, and matrix metalloproteinases (MMP) in cerebral organoids. After treatment for 48 h, we observed dose-dependent neurotoxicity, including reduced neuron and astrocyte numbers at high concentration. Vincristine treatment also impaired the microtubule-associated protein tubulin, and fibronectin, and downregulated MMP10 activity. Further analysis using the STRING database found that, both MMP10 and fibronectin bind with MMP9 experimentally, and text-mining indicated an interaction between MMP10 and fibronectin. Our organoid model system allowed quantitative investigation of the effects of vincristine treatment. Our findings indicated vincristine exhibited dose-dependent neurotoxicity, inhibited fibronectin, tubulin, and MMP10 expression in cerebral organoids.

Pluripotent Stem Cells for Retinal Tissue Engineering: Current Status and Future Prospects

The retina is a very fine and layered neural tissue, which vitally depends on the preservation of cells, structure, connectivity and vasculature to maintain vision. There is an urgent need to find technical and biological solutions to major challenges associated with functional replacement of retinal cells. The major unmet challenges include generating sufficient numbers of specific cell types, achieving functional integration of transplanted cells, especially photoreceptors, and surgical delivery of retinal cells or tissue without triggering immune responses, inflammation and/or remodeling. The advances of regenerative medicine enabled generation of three-dimensional tissues (organoids), partially recreating the anatomical structure, biological complexity and physiology of several tissues, which are important targets for stem cell replacement therapies. Derivation of retinal tissue in a dish creates new opportunities for cell replacement therapies of blindness and addresses the need to preserve retinal architecture to restore vision. Retinal cell therapies aimed at preserving and improving vision have achieved many improvements in the past ten years. Retinal organoid technologies provide a number of solutions to technical and biological challenges associated with functional replacement of retinal cells to achieve long-term vision restoration. Our review summarizes the progress in cell therapies of retina, with focus on human pluripotent stem cell-derived retinal tissue, and critically evaluates the potential of retinal organoid approaches to solve a major unmet clinical need—retinal repair and vision restoration in conditions caused by retinal degeneration and traumatic ocular injuries. We also analyze obstacles in commercialization of retinal organoid technology for clinical application.

Human breast cancer decellularized scaffolds promote epithelial-to-mesenchymal transitions and stemness of breast cancer cells in vitro

Breast cancer, with unsatisfactory survival rates, is the leading cause of cancer-related death in women worldwide. Recent advances in the genetic basis of breast cancer have benefitted the development of gene-based medicines and therapies. Tissue engineering technologies, including tissue decellularizations and reconstructions, are potential therapeutic alternatives for cancer research and tissue regeneration. In our study, human breast cancer biopsies were decellularized by a detergent technique, with sodium lauryl ether sulfate (SLES) solution, for the first time. And the decellularization process was optimized to maximally maintain tissue microarchitectures and extracellular matrix (ECM) components with minimal DNA compounds preserved. Histology analysis and DNA quantification results confirmed the decellularization effect with maximal genetic compounds removal. Quantification, immunofluorescence, and histology analyses demonstrated better preservation of ECM components in 0.5% SLES-treated scaffolds. Scaffolds seeded with MCF-7 cells demonstrated the process of cell recellularization in vitro, with increased cell migration, proliferation, and epithelial-to-mesenchymal transition (EMT) process. When treated with 5-fluorouracil, the expressions of stem cell markers, including Oct4, Sox2, and CD49F, were maximally maintained in the recellularized scaffold with decreased apoptosis rates compared with monolayer cells. These results showed that the decellularized breast scaffold model with SLES treatments would help to simulate the pathogenesis of breast cancer in vitro. And we hope that this model could further accelerate the development of effective therapies for breast cancer and benefit drug screenings.

Oxygen Regulation in Development: Lessons from Embryogenesis towards Tissue Engineering

Oxygen is a vital source of energy necessary to sustain and complete embryonic development. Not only is oxygen the driving force for many cellular functions and metabolism, but it is also involved in regulating stem cell fate, morphogenesis, and organogenesis. Low oxygen levels are the naturally preferred microenvironment for most processes during early development and mainly drive proliferation. Later on, more oxygen and also nutrients are needed for organogenesis and morphogenesis. Therefore, it is critical to maintain oxygen levels within a narrow range as required during development. Modulating oxygen tensions is performed via oxygen homeostasis mainly through the function of hypoxia-inducible factors. Through the function of these factors, oxygen levels are sensed and regulated in different tissues, starting from their embryonic state to adult development. To be able to mimic this process in a tissue engineering setting, it is important to understand the role and levels of oxygen in each developmental stage, from embryonic stem cell differentiation to organogenesis and morphogenesis. Taking lessons from native tissue microenvironments, researchers have explored approaches to control oxygen tensions such as hemoglobin-based, perfluorocarbon-based, and oxygen-generating biomaterials, within synthetic tissue engineering scaffolds and organoids, with the aim of overcoming insufficient or nonuniform oxygen levels and nutrient supply.

Engineered Kidney Tubules for Modeling Patient-Specific Diseases and Drug Discovery

The lack of engineering systems able to faithfully reproduce complex kidney structures in vitro has made it difficult to efficiently model kidney diseases and development. Using polydimethylsiloxane (PDMS) scaffolds and a kidney-derived cell line we developed a system to rapidly engineer custom-made 3D tubules with typical renal epithelial properties. This system was successfully employed to engineer patient-specific tubules, to model polycystic kidney disease (PKD) and test drug efficacy, and to identify a potential new pharmacological treatment. By optimizing our system we constructed functional ureteric bud (UB)-like tubules from human induced pluripotent stem cells (iPSCs), and identified a combination of growth factors that induces budding morphogenesis like embryonic kidneys do. Finally, we applied this assay to investigate budding defects in UB-like tubules derived from a patient with a PAX2 mutation. Our system enables the modeling of human kidney disease and development, drug testing and discovery, and lays the groundwork for engineering anatomically correct kidney tissues in vitro and developing personalized medicine applications.

The Use of Ex Vivo Organ Cultures in Tick-Borne Virus Research

Each year there are more than 15 000 cases of human disease caused by infections with tick-borne viruses (TBVs). These illnesses occur worldwide and can range from very mild illness to severe encephalitis and hemorrhagic fever. Although TBVs are currently identified as neglected vector-borne pathogens and receive less attention than mosquito-borne viruses, TBVs are expanding into new regions, and infection rates are increasing. Furthermore, effective vaccines, diagnostic tools, and other countermeasures are limited. The application of contemporary technologies to TBV infections presents an excellent opportunity to develop improved, effective countermeasures. Experimental tick and mammal models of infection can be used to characterize determinants of infection, transmission, and virulence and to test candidate countermeasures. The use of ex vivo tick cultures in TBV research provides a unique way to look at infection in specific tick organs. Mammal ex vivo organ slice and, more recently, organoid cultures are additional models that can be used to elucidate direct tissue-specific responses to infection. These ex vivo model systems are convenient for testing methods involving transcript knockdown and small molecules under tightly controlled conditions. They can also be combined with in vitro and in vivo studies to tease out possible host factors and potential vaccine or therapeutic candidates. In this brief perspective, we describe how ex vivo cultures can be combined with modern technologies to advance research on TBV infections.

Personalized Cancer Medicine: An Organoid Approach

Personalized cancer therapy applies specific treatments to each patient. Using personalized tumor models with similar characteristics to the original tumors may result in more accurate predictions of drug responses in patients. Tumor organoid models have several advantages over pre-existing models, including conserving the molecular and cellular composition of the original tumor. These advantages highlight the tremendous potential of tumor organoids in personalized cancer therapy, particularly preclinical drug screening and predicting patient responses to selected treatment regimens. Here, we highlight the advantages, challenges, and translational potential of tumor organoids in personalized cancer therapy and focus on gene-drug associations, drug response prediction, and treatment selection. Finally, we discuss how microfluidic technology can contribute to immunotherapy drug screening in tumor organoids.

Tranylcypromine Causes Neurotoxicity and Represses BHC110/LSD1 in Human-Induced Pluripotent Stem Cell-Derived Cerebral Organoids Model

Recent breakthroughs in human pluripotent stem cell-derived cerebral organoids provide a valuable platform for investigating the human brain after different drugs treatments and for understanding the complex genetic background to human pathology. Here, we identified tranylcypromine, which is used to treat refractory depression, caused human-induced pluripotent stem cell-derived brain organoids neurotoxicity, leading to decreased proliferation activity and apoptosis induction. Moreover, tranylcypromine treatment affects neurons and astrocytes, which impairs cell density and arrangement. Finally, staining of histone demethylation-related genes revealed that tranylcypromine suppresses the transcriptional activity of BHC110/LSD1-targeted genes and increases the expression of histone di-methylated K4. These results show that human brain organoids can be applied as an in vitro model for CNS drug screening to evaluate structural, cellular, and molecular changes in the normal brains or brains of patients with neuropsychiatric disorders after drug treatments.

Chronic kidney disease

Chronic kidney disease (CKD) is defined by persistent urine abnormalities, structural abnormalities or impaired excretory renal function suggestive of a loss of functional nephrons. The majority of patients with CKD are at risk of accelerated cardiovascular disease and death. For those who progress to end-stage renal disease, the limited accessibility to renal replacement therapy is a problem in many parts of the world. Risk factors for the development and progression of CKD include low nephron number at birth, nephron loss due to increasing age and acute or chronic kidney injuries caused by toxic exposures or diseases (for example, obesity and type 2 diabetes mellitus). The management of patients with CKD is focused on early detection or prevention, treatment of the underlying cause (if possible) to curb progression and attention to secondary processes that contribute to ongoing nephron loss. Blood pressure control, inhibition of the renin-angiotensin system and disease-specific interventions are the cornerstones of therapy. CKD complications such as anaemia, metabolic acidosis and secondary hyperparathyroidism affect cardiovascular health and quality of life, and require diagnosis and treatment.

A liver-specific gene expression panel predicts the differentiation status of in vitro hepatocyte models

Alternative cell sources, such as three-dimensional organoids and induced pluripotent stem cell-derived cells, might provide a potentially effective approach for both drug development applications and clinical transplantation. For example, the development of cell sources for liver cell-based therapy has been increasingly needed, and liver transplantation is performed for the treatment for patients with severe end-stage liver disease. Differentiated liver cells and three-dimensional organoids are expected to provide new cell sources for tissue models and revolutionary clinical therapies. However, conventional experimental methods confirming the expression levels of liver-specific lineage markers cannot provide complete information regarding the differentiation status or degree of similarity between liver and differentiated cell sources. Therefore, in this study, to overcome several issues associated with the assessment of differentiated liver cells and organoids, we developed a liver-specific gene expression panel (LiGEP) algorithm that presents the degree of liver similarity as a "percentage." We demonstrated that the percentage calculated using the LiGEP algorithm was correlated with the developmental stages of in vivo liver tissues in mice, suggesting that LiGEP can correctly predict developmental stages. Moreover, three-dimensional cultured HepaRG cells and human pluripotent stem cell-derived hepatocyte-like cells showed liver similarity scores of 59.14% and 32%, respectively, although general liver-specific markers were detected.

CONCLUSION

Our study describes a quantitative and predictive model for differentiated samples, particularly liver-specific cells or organoids; and this model can be further expanded to various tissue-specific organoids; our LiGEP can provide useful information and insights regarding the differentiation status of in vitro liver models. (Hepatology 2017;66:1662-1674).

Laser-Induced Focused Ultrasound for Cavitation Treatment: Toward High-Precision Invisible Sonic Scalpel

Beyond the implementation of the photoacoustic effect to photoacoustic imaging and laser ultrasonics, this study demonstrates a novel application of the photoacoustic effect for high-precision cavitation treatment of tissue using laser-induced focused ultrasound. The focused ultrasound is generated by pulsed optical excitation of an efficient photoacoustic film coated on a concave surface, and its amplitude is high enough to produce controllable microcavitation within the focal region (lateral focus <100 µm). Such microcavitation is used to cut or ablate soft tissue in a highly precise manner. This work demonstrates precise cutting of tissue-mimicking gels as well as accurate ablation of gels and animal eye tissues.