Islet organoid as a promising model for diabetes

The efficiency of stem cell differentiation into functional beta cells for treating insulin-requiring diabetes: Recent advances and current challenges

In recent years, the potential of stem cells (SCs) to differentiate into various types of cells, including β-cells, has led to a significant boost in development. The efficiency of this differentiation process and the functionality of the cells post-transplantation are crucial factors for the success of stem cell therapy in diabetes. Herein, this article reviews the current advances and challenges faced by stem cell differentiation into functional β-cells for diabetes treatment. In vitro, researchers have sought to enhance the differentiation efficiency of functional β-cells by mimicking the normal pancreatic development process, using gene manipulation, pharmacological and culture conditions stimulation, three-dimensional (3D) and organoid culture, or sorting for functional β-cells based on mature islet cell markers. Furthermore, in vivo studies have also looked at suitable transplantation sites, the enhancement of the transplantation microenvironment, immune modulation, and vascular function reconstruction to improve the survival rate of functional β-cells, thereby enhancing the treatment of diabetes. Despite these advancements, developing stem cells to produce functional β-cells for efficacious diabetes treatment is a continuous research endeavor requiring significant multidisciplinary collaboration, for the stem-cell-derived beta cells to evolve into an effective cellular therapy.

Recent progress in modeling and treating diabetes using stem cell-derived islets

Stem cell-derived islets (SC-islets) offer the potential to be an unlimited source of cells for disease modeling and the treatment of diabetes. SC-islets can be genetically modified, treated with chemical compounds, or differentiated from patient derived stem cells to model diabetes. These models provide insights into disease pathogenesis and vulnerabilities that may be targeted to provide treatment. SC-islets themselves are also being investigated as a cell therapy for diabetes. However, the transplantation process is imperfect; side effects from immunosuppressant use have reduced SC-islet therapeutic potential. Alternative methods to this include encapsulation, use of immunomodulating molecules, and genetic modification of SC-islets. This review covers recent advances using SC-islets to understand different diabetes pathologies and as a cell therapy.

Brown Adipose Tissue as a Unique Niche for Islet Organoid Transplantation: Insights From In Vivo Imaging

Background

Transplantation of human-induced pluripotent stem cell (hiPSC)-derived islet organoids is a promising cell replacement therapy for type 1 diabetes (T1D). It is important to improve the efficacy of islet organoids transplantation by identifying new transplantation sites with high vascularization and sufficient accommodation to support graft survival with a high capacity for oxygen delivery.

Methods

A human-induced pluripotent stem cell line (hiPSCs-L1) was generated constitutively expressing luciferase. Luciferase-expressing hiPSCs were differentiated into islet organoids. The islet organoids were transplanted into the scapular brown adipose tissue (BAT) of nonobese diabetic/severe combined immunodeficiency disease (NOD/SCID) mice as the BAT group and under the left kidney capsule (KC) of NOD/SCID mice as a control group, respectively. Bioluminescence imaging (BLI) of the organoid grafts was performed on days 1, 7, 14, 28, 35, 42, 49, 56, and 63 posttransplantation.

Results

BLI signals were detected in all recipients, including both the BAT and control groups. The BLI signal gradually decreased in both BAT and KC groups. However, the graft BLI signal intensity under the left KC decreased substantially faster than that of the BAT. Furthermore, our data show that islet organoids transplanted into streptozotocin-induced diabetic mice restored normoglycemia. Positron emission tomography/MRI verified that the islet organoids were transplanted at the intended location in these diabetic mice. Immunofluorescence staining revealed the presence of functional organoid grafts, as confirmed by insulin and glucagon staining.

Conclusions

Our results demonstrate that BAT is a potentially desirable site for islet organoid transplantation for T1D therapy.

Ameliorating and refining islet organoids to illuminate treatment and pathogenesis of diabetes mellitus

Diabetes mellitus, a significant global public health challenge, severely impacts human health worldwide. The organoid, an innovative in vitro three-dimensional (3D) culture model, closely mimics tissues or organs in vivo. Insulin-secreting islet organoid, derived from stem cells induced in vitro with 3D structures, has emerged as a potential alternative for islet transplantation and as a possible disease model that mirrors the human body's in vivo environment, eliminating species difference. This technology has gained considerable attention for its potential in diabetes treatment. Despite advances, the process of stem cell differentiation into islet organoid and its cultivation demonstrates deficiencies, prompting ongoing efforts to develop more efficient differentiation protocols and 3D biomimetic materials. At present, the constructed islet organoid exhibit limitations in their composition, structure, and functionality when compared to natural islets. Consequently, further research is imperative to achieve a multi-tissue system composition and improved insulin secretion functionality in islet organoid, while addressing transplantation-related safety concerns, such as tumorigenicity, immune rejection, infection, and thrombosis. This review delves into the methodologies and strategies for constructing the islet organoid, its application in diabetes treatment, and the pivotal scientific challenges within organoid research, offering fresh perspectives for a deeper understanding of diabetes pathogenesis and the development of therapeutic interventions.

Cell identity dynamics and insight into insulin secretagogues when employing stem cell-derived islets for disease modeling

Stem cell-derived islets (SC-islets) are not only an unlimited source for cell-based therapy of type 1 diabetes but have also emerged as an attractive material for modeling diabetes and conducting screening for treatment options. Prior to SC-islets becoming the established standard for disease modeling and drug development, it is essential to understand their response to various nutrient sources in vitro. This study demonstrates an enhanced efficiency of pancreatic endocrine cell differentiation through the incorporation of WNT signaling inhibition following the definitive endoderm stage. We have identified a tri-hormonal cell population within SC-islets, which undergoes reduction concurrent with the emergence of elevated numbers of glucagon-positive cells during extended in vitro culture. Over a 6-week period of in vitro culture, the SC-islets consistently demonstrated robust insulin secretion in response to glucose stimulation. Moreover, they manifested diverse reactivity patterns when exposed to distinct nutrient sources and exhibited deviant glycolytic metabolic characteristics in comparison to human primary islets. Although the SC-islets demonstrated an aberrant glucose metabolism trafficking, the evaluation of a potential antidiabetic drug, pyruvate kinase agonist known as TEPP46, significantly improved in vitro insulin secretion of SC-islets. Overall, this study provided cell identity dynamics investigation of SC-islets during prolonged culturing in vitro, and insights into insulin secretagogues. Associated advantages and limitations were discussed when employing SC-islets for disease modeling.

Emerging approaches for the development of artificial islets

The islet of Langerhans, functioning as a "mini organ", plays a vital role in regulating endocrine activities due to its intricate structure. Dysfunction in these islets is closely associated with the development of diabetes mellitus (DM). To offer valuable insights for DM research and treatment, various approaches have been proposed to create artificial islets or islet organoids with high similarity to natural islets, under the collaborative effort of biologists, clinical physicians, and biomedical engineers. This review investigates the design and fabrication of artificial islets considering both biological and tissue engineering aspects. It begins by examining the natural structures and functions of native islets and proceeds to analyze the protocols for generating islets from stem cells. The review also outlines various techniques used in crafting artificial islets, with a specific focus on hydrogel-based ones. Additionally, it provides a concise overview of the materials and devices employed in the clinical applications of artificial islets. Throughout, the primary goal is to develop artificial islets, thereby bridging the realms of developmental biology, clinical medicine, and tissue engineering.

Progress in experimental models to investigate the in vivo and in vitro antidiabetic activity of drugs

Diabetes mellitus is one of the world's most prevalent and complex metabolic disorders, and it is a rapidly growing global public health issue. It is characterized by hyperglycemia, a condition involving a high blood glucose level brought on by deficiencies in insulin secretion, decreased activity of insulin, or both. Prolonged effects of diabetes include cardiovascular problems, retinopathy, neuropathy, nephropathy, and vascular alterations in both macro- and micro-blood vessels. In vivo and in vitro models have always been important for investigating and characterizing disease pathogenesis, identifying targets, and reviewing novel treatment options and medications. Fully understanding these models is crucial for the researchers so this review summarizes the different experimental in vivo and in vitro model options used to study diabetes and its consequences. The most popular in vivo studies involves the small animal models, such as rodent models, chemically induced diabetogens like streptozotocin and alloxan, and the possibility of deleting or overexpressing a specific gene by knockout and transgenic technologies on these animals. Other models include virally induced models, diet/nutrition induced diabetic animals, surgically induced models or pancreatectomy models, and non-obese models. Large animals or non-rodent models like porcine (pig), canine (dog), nonhuman primate, and Zebrafish models are also outlined. The in vitro models discussed are murine and human beta-cell lines and pancreatic islets, human stem cells, and organoid cultures. The other enzymatic in vitro tests to assess diabetes include assay of amylase inhibition and inhibition of α-glucosidase activity.

Bioengineering toolkits for potentiating organoid therapeutics

Organoids are three-dimensional, multicellular constructs that recapitulate the structural and functional features of specific organs. Because of these characteristics, organoids have been widely applied in biomedical research in recent decades. Remarkable advancements in organoid technology have positioned them as promising candidates for regenerative medicine. However, current organoids still have limitations, such as the absence of internal vasculature, limited functionality, and a small size that is not commensurate with that of actual organs. These limitations hinder their survival and regenerative effects after transplantation. Another significant concern is the reliance on mouse tumor-derived matrix in organoid culture, which is unsuitable for clinical translation due to its tumor origin and safety issues. Therefore, our aim is to describe engineering strategies and alternative biocompatible materials that can facilitate the practical applications of organoids in regenerative medicine. Furthermore, we highlight meaningful progress in organoid transplantation, with a particular emphasis on the functional restoration of various organs.

Single-cell sequencing: A promising approach for uncovering the characteristic of pancreatic islet cells in type 2 diabetes

Single-cell sequencing is a novel and rapidly advancing high-throughput technique that can be used to investigating genomics, transcriptomics, and epigenetics at a single-cell level. Currently, single-cell sequencing can not only be used to draw the pancreatic islet cells map and uncover the characteristics of cellular heterogeneity in type 2 diabetes, but can also be used to label and purify functional beta cells in pancreatic stem cells, improving stem cells and islet organoids therapies. In addition, this technology helps to analyze islet cell dedifferentiation and can be applied to the treatment of type 2 diabetes. In this review, we summarize the development and process of single-cell sequencing, describe the potential applications of single-cell sequencing in the field of type 2 diabetes, and discuss the prospects and limitations of single-cell sequencing to provide a new direction for exploring the pathogenesis of type 2 diabetes and finding therapeutic targets.

ECM-derived biomaterials for regulating tissue multicellularity and maturation

Recent breakthroughs in developing human-relevant organotypic models led to the building of highly resemblant tissue constructs that hold immense potential for transplantation, drug screening, and disease modeling. Despite the progress in fine-tuning stem cell multilineage differentiation in highly controlled spatiotemporal conditions and hosting microenvironments, 3D models still experience naive and incomplete morphogenesis. In particular, existing systems and induction protocols fail to maintain stem cell long-term potency, induce high tissue-level multicellularity, or drive the maturity of stem cell-derived 3D models to levels seen in their in vivo counterparts. In this review, we highlight the use of extracellular matrix (ECM)-derived biomaterials in providing stem cell niche-mimicking microenvironment capable of preserving stem cell long-term potency and inducing spatial and region-specific differentiation. We also examine the maturation of different 3D models, including organoids, encapsulated in ECM biomaterials and provide looking-forward perspectives on employing ECM biomaterials in building more innovative, transplantable, and functional organs.

Bioengineering and vascularization strategies for islet organoids: advancing toward diabetes therapy

Diabetes presents a pressing healthcare crisis, necessitating innovative solutions. Organoid technologies have rapidly advanced, leading to the emergence of bioengineering islet organoids as an unlimited source of insulin-producing cells for treating insulin-dependent diabetes. This advancement surpasses the need for cadaveric islet transplantation. However, clinical translation of this approach faces two major limitations: immature endocrine function and the absence of a perfusable vasculature compared to primary human islets. In this review, we summarize the latest developments in bioengineering functional islet organoids in vitro and promoting vascularization of organoid grafts before and after transplantation. We highlight the crucial roles of the vasculature in ensuring long-term survival, maturation, and functionality of islet organoids. Additionally, we discuss key considerations that must be addressed before clinical translation of islet organoid-based therapy, including functional immaturity, undesired heterogeneity, and potential tumorigenic risks.

Induced Pluripotent Stem Cells as a Possible Approach for Exploring the Pathophysiology of Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine condition among women with pleiotropic sequelae possessing reproductive, metabolic, and psychological characteristics. Although the exact origin of PCOS is elusive, it is known to be a complex multigenic disorder with a genetic, epigenetic, and environmental background. However, the pathogenesis of PCOS, and the role of genetic variants in increasing the risk of the condition, are still unknown due to the lack of an appropriate study model. Since the debut of induced pluripotent stem cell (iPSC) technology, the ability of reprogrammed somatic cells to self-renew and their potential for multidirectional differentiation have made them excellent tools to study different disease mechanisms. Recently, researchers have succeeded in establishing human in vitro PCOS disease models utilizing iPSC lines from heterogeneous PCOS patient groups (iPSCPCOS). The current review sets out to summarize, for the first time, our current knowledge of the implications and challenges of iPSC technology in comprehending PCOS pathogenesis and tissue-specific disease mechanisms. Additionally, we suggest that the analysis of polygenic risk prediction based on genome-wide association studies (GWAS) could, theoretically, be utilized when creating iPSC lines as an additional research tool to identify women who are genetically susceptible to PCOS. Taken together, iPSCPCOS may provide a new paradigm for the exploration of PCOS tissue-specific disease mechanisms.

Modeling Liver Development and Disease in a Dish

Historically, biological research has relied primarily on animal models. While this led to the understanding of numerous human biological processes, inherent species-specific differences make it difficult to answer certain liver-related developmental and disease-specific questions. The advent of 3D organoid models that are either derived from pluripotent stem cells or generated from healthy or diseased tissue-derived stem cells have made it possible to recapitulate the biological aspects of human organs. Organoid technology has been instrumental in understanding the disease mechanism and complements animal models. This review underscores the advances in organoid technology and specifically how liver organoids are used to better understand human-specific biological processes in development and disease. We also discuss advances made in the application of organoid models in drug screening and personalized medicine.

Simultaneous LC-MS determination of glucose regulatory peptides secreted by stem cell-derived islet organoids

For studying stem cell-derived islet organoids (SC-islets) in an organ-on-chip (OoC) platform, we have developed a reversed-phase liquid chromatography-tandem mass spectrometry (RPLC-MS/MS) method allowing for simultaneous determination of insulin, somatostatin-14, and glucagon, with improved matrix robustness compared to earlier methodology. Combining phenyl/hexyl-C18 separations using 2.1 mm inner diameter LC columns and triple quadrupole mass spectrometry, identification and quantification were secured with negligible variance in retention time and quantifier/qualifier ratios, negligible levels of carryover (<2%), and sufficient precision (±10% RSD) and accuracy (±15% relative error) with and without use of an internal standard. The obtained lower limits of quantification were 0.2 µg/L for human insulin, 0.1 µg/L for somatostatin-14, and 0.05 µg/L for glucagon. The here-developed RPLC-MS/MS method showed that the SC-islets have an insulin response dependent on glucose concentration, and the SC-islets produce and release somatostatin-14 and glucagon. The RPLC-MS/MS method for these peptide hormones was compatible with an unfiltered offline sample collection from SC-islets cultivated on a pumpless, recirculating OoC (rOoC) platform. The SC-islets background secretion of insulin was not significantly different on the rOoC device compared to a standard cell culture well-plate. Taken together, RPLC-MS/MS method is well suited for multi-hormone measurements of SC-islets on an OoC platform.

Organoid: Bridging the gap between basic research and clinical practice

Nowadays, the diagnosis and treatment system of malignant tumors has increasingly tended to be more precise and personalized while the existing tumor models are still unable to fully meet the needs of clinical practice. Notably, the emerging organoid platform has been proven to have huge potential in the field of basic-translational medicine, which is expected to promote a paradigm shift in personalized medicine. Here, given the unique advantages of organoid platform, we mainly explore the prominent role of organoid models in basic research and clinical practice from perspectives of tumor biology, tumorigenic microbes-host interaction, clinical decision-making, and regenerative strategy. In addition, we also put forward some practical suggestions on how to construct a new generation of organoid platform, which is destined to vigorously promote the reform of basic-translational medicine.

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.

Bidirectional Relationship between Glycemic Control and COVID-19 and Perspectives of Islet Organoid Models of SARS-CoV-2 Infection

Infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) leads to morbidity and mortality, with several clinical manifestations, and has caused a widespread pandemic. It has been found that type 2 diabetes is a risk factor for severe coronavirus disease 2019 (COVID-19) illness. Moreover, accumulating evidence has shown that SARS-CoV-2 infection can increase the risk of hyperglycemia and diabetes, though the underlying mechanism remains unclear because of a lack of authentic disease models to recapitulate the abnormalities involved in the development, regeneration, and function of human pancreatic islets under SARS-CoV-2 infection. Stem-cell-derived islet organoids have been valued as a model to study islets’ development and function, and thus provide a promising model for unraveling the mechanisms underlying the onset of diabetes under SARS-CoV-2 infection. This review summarized the latest results from clinical and basic research on SARS-CoV-2-induced pancreatic islet damage and impaired glycemic control. Furthermore, we discuss the potential and perspectives of using human ES/iPS cell-derived islet organoids to unravel the bidirectional relationship between glycemic control and SARS-CoV-2 infection.

Pancreatic Organoids: A Frontier Method for Investigating Pancreatic-Related Diseases

The pancreas represents an important organ that has not been comprehensively studied in many fields. To fill this gap, many models have been generated, and traditional models have shown good performance in addressing pancreatic-related diseases, but are increasingly struggling to keep up with the need for further research due to ethical issues, genetic heterogeneity and difficult clinical translation. The new era calls for new and more reliable research models. Therefore, organoids have been proposed as a novel model for the evaluation of pancreatic-related diseases such as pancreatic malignancy, diabetes, and pancreatic cystic fibrosis. Compared with common traditional models, including 2D cell culture and gene editing mice, organoids derived from living humans or mice cause minimal harm to the donor, raise fewer ethical concerns, and reasonably address the claims of heterogeneity, which allows for the further development of pathogenesis studies and clinical trial analysis. In this review, we analyse studies on the use of pancreatic organoids in research on pancreatic-related diseases, discuss the advantages and disadvantages, and hypothesize future trends.

Research Progress on Mesenchymal Stem Cells for the Treatment of Diabetes and Its Complications

Diabetes mellitus (DM) is a chronic disease that threatens human health. Although many drugs are available to treat DM, various complications caused by DM are unavoidable. As an emerging treatment for DM, mesenchymal stem cells (MSCs) have shown many advantages and are gradually gaining public attention. This review summarizes the clinical studies on the use of MSCs to treat DM and the potential mechanisms of complications such as pancreatic dysfunction, cardiovascular lesions, renal lesions, neurological lesions, and trauma repair. This review focuses on the research progress on MSC-mediated secretion of cytokines, improvements in the microenvironment, repair of tissue morphology, and related signaling pathways. At present, the sample sizes in clinical studies of MSCs in treating DM are small, and there is a lack of standardized quality control systems in the preparation, transportation, and infusion methods, so we need to conduct more in-depth studies. In conclusion, MSCs have shown superior potential for use in the treatment of DM and its complications and will hopefully become a novel therapeutic approach in the future.

Modelling metabolic diseases and drug response using stem cells and organoids

Metabolic diseases, including obesity, diabetes mellitus and cardiovascular disease, are a major threat to health in the modern world, but efforts to understand the underlying mechanisms and develop rational treatments are limited by the lack of appropriate human model systems. Notably, advances in stem cell and organoid technology allow the generation of cellular models that replicate the histological, molecular and physiological properties of human organs. Combined with marked improvements in gene editing tools, human stem cells and organoids provide unprecedented systems for studying mechanisms of metabolic diseases. Here, we review progress made over the past decade in the generation and use of stem cell-derived metabolic cell types and organoids in metabolic disease research, especially obesity and liver diseases. In particular, we discuss the limitations of animal models and the advantages of stem cells and organoids, including their application to metabolic diseases. We also discuss mechanisms of drug action, understanding the efficacy and toxicity of existing therapies, screening for new treatments and pursuing personalized therapies. We highlight the potential of combining stem cell-derived organoids with gene editing and functional genomics to revolutionize the approach to finding treatments for metabolic diseases.

Importance of multiple endocrine cell types in islet organoids for type 1 diabetes treatment

Almost 50 years ago, scientists developed the bi-hormonal abnormality hypothesis, stating that diabetes is not caused merely by the impaired insulin signaling. Instead, the presence of inappropriate level of glucagon is a prerequisite for the development of type 1 diabetes (T1D). It is widely understood that the hormones insulin and glucagon, secreted by healthy β and α cells respectively, operate in a negative feedback loop to maintain the body's blood sugar levels. Despite this fact, traditional T1D treatments rely solely on exogenous insulin injections. Furthermore, research on cell-based therapies and stem-cell derived tissues tends to focus on the replacement of β cells alone. In vivo, the pancreas is made up of 4 major endocrine cell types, that is, insulin-producing β cells, glucagon-producing α cells, somatostatin-producing δ cells, and pancreatic polypeptide-producing γ cells. These distinct cell types are involved synergistically in regulating islet functions. Therefore, it is necessary to produce a pancreatic islet organoid in vitro consisting of all these cell types that adequately replaces the function of the native islets. In this review, we describe the unique function of each pancreatic endocrine cell type and their interactions contributing to the maintenance of normoglycemia. Furthermore, we detail current sources of whole islets and techniques for their long-term expansion and culture. In addition, we highlight a vast potential of the pancreatic islet organoids for transplantation and diabetes research along with updated new approaches for successful transplantation using stem cell-derived islet organoids.

Challenges with Cell-based Therapies for Type 1 Diabetes Mellitus

Type 1 diabetes (T1D) is a chronic, lifelong metabolic disease. It is characterised by the autoimmune-mediated loss of insulin-producing pancreatic β cells in the islets of Langerhans (β-islets), resulting in disrupted glucose homeostasis. Administration of exogenous insulin is the most common management method for T1D, but this requires lifelong reliance on insulin injections and invasive blood glucose monitoring. Replacement therapies with beta cells are being developed as an advanced curative treatment for T1D. Unfortunately, this approach is limited by the lack of donated pancreatic tissue, the difficulties in beta cell isolation and viability maintenance, the longevity of the transplanted cells in vivo, and consequently high costs. Emerging approaches to address these limitations are under intensive investigations, including the production of insulin-producing beta cells from various stem cells, and the development of bioengineered devices including nanotechnologies for improving islet transplantation efficacy without the need for recipients taking toxic anti-rejection drugs. These emerging approaches present promising prospects, while the challenges with the new techniques need to be tackled for ultimately clinical treatment of T1D. This review discussed the benefits and limitations of the cell-based therapies for beta cell replacement as potential curative treatment for T1D, and the applications of bioengineered devices including nanotechnology to overcome the challenges associated with beta cell transplantation.

Stepwise differentiation of functional pancreatic β cells from human pluripotent stem cells

Pancreatic β cells differentiated from stem cells provide promise for cell replacement therapy of diabetes. Human pluripotent stem cells could be differentiated into definitive endoderm, followed by pancreatic progenitors, and then subjected to endocrinal differentiation and maturation in a stepwise fashion. Many achievements have been made in making pancreatic β cells from human pluripotent stem cells in last two decades, and a couple of phase I/II clinical trials have just been initiated. Here, we overview the major progresses in differentiating pancreatic β cells from human pluripotent stem cells with the focus on recent technical advances in each differentiation stage, and briefly discuss the current limitations as well.

Development of scaffold-free vascularized pancreatic beta-islets in vitro models by the anchoring of cell lines to a bioligand-functionalized gelatine substrate

Bioengineered pancreatic β-islets have been widely advocated for the research and treatment of diabetes by offering both suitable cell culture models for the study of the pathology and the testing of new drugs and a therapy in those patients no longer responding to insulin administration and as an alternative to the shortage of donors for organ and islet transplantation. Unlike most of the studies published so far where pancreatic islets of pancreatic β-cells are encapsulated in hydrogels, this study demonstrate the formation of bioengineered pancreatic islets through cell anchoring to a gelatine-based biomaterial, PhenoDrive-Y, able to mimic the basement membrane of tissues. Through simple culture conditions, PhenoDrive-Y led human pancreatic β-cell lines and human umbilical endothelial cell lines to form organized structures closely resembling the natural vascularized pancreatic islets. When compared to gelatine, the cultures in presence of PhenoDrive-Y show higher degree of organization in tissue-like structures, a more pronounced endothelial sprouting and higher expression of typical cell markers. Noticeably, when challenged by hyperglycaemic conditions, the cells embedded in the PhenoDrive-Y assembled spheroids responded with higher levels of insulin production. In conclusion, the present work demonstrates the potential of PhenoDrive-Y as substrate for the development of bioengineered vascularized pancreatic islets and to be particularly suitable as a model for in vitro studies and testing of new therapeutics. Graphical abstract.

In Vitro Disease Models of the Endocrine Pancreas

The ethical constraints and shortcomings of animal models, combined with the demand to study disease pathogenesis under controlled conditions, are giving rise to a new field at the interface of tissue engineering and pathophysiology, which focuses on the development of in vitro models of disease. In vitro models are defined as synthetic experimental systems that contain living human cells and mimic tissue- and organ-level physiology in vitro by taking advantage of recent advances in tissue engineering and microfabrication. This review provides an overview of in vitro models and focuses specifically on in vitro disease models of the endocrine pancreas and diabetes. First, we briefly review the anatomy, physiology, and pathophysiology of the human pancreas, with an emphasis on islets of Langerhans and beta cell dysfunction. We then discuss different types of in vitro models and fundamental elements that should be considered when developing an in vitro disease model. Finally, we review the current state and breakthroughs in the field of pancreatic in vitro models and conclude with some challenges that need to be addressed in the future development of in vitro models.

Maturity Onset Diabetes of the Young-New Approaches for Disease Modelling

Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous group of monogenic endocrine disorders that is characterised by autosomal dominant inheritance and pancreatic β-cell dysfunction. These patients are commonly misdiagnosed with type 1 or type 2 diabetes, as the clinical symptoms largely overlap. Even though several biomarkers have been tested none of which could be used as single clinical discriminator. The correct diagnosis for individuals with MODY is of utmost importance, as the applied treatment depends on the gene mutation or is subtype-specific. Moreover, in patients with HNF1A-MODY, additional clinical monitoring can be included due to the high incidence of vascular complications observed in these patients. Finally, stratification of MODY patients will enable better and newer treatment options for MODY patients, once the disease pathology for each patient group is better understood. In the current review the clinical characteristics and the known disease-related abnormalities of the most common MODY subtypes are discussed, together with the up-to-date applied diagnostic criteria and treatment options. Additionally, the usage of pluripotent stem cells together with CRISPR/Cas9 gene editing for disease modelling with the possibility to reveal new pathophysiological mechanisms in MODY is discussed.