Using stem cells to study and possibly treat type 1 diabetes

Postnatal maturation of calcium signaling in islets of Langerhans from neonatal mice

Pancreatic islet cells develop mature physiological responses to glucose and other fuels postnatally. In this study, we used fluorescence imaging techniques to measure changes in intracellular calcium ([Ca²⁺]_i) to compare islets isolated from mice on postnatal days 0, 4, and 12 with islets from adult CD-1 mice. In addition, we used publicly available RNA-sequencing data to compare expression levels of key genes in β-cell physiology with [Ca²⁺]_i data across these ages. We show that islets isolated from mice on postnatal day 0 displayed elevated [Ca²⁺]_i in basal glucose (≤4 mM) but lower [Ca²⁺]_i responses to stimulation by 12-20 mM glucose compared to adult. Neonatal islets displayed more adult-like [Ca²⁺]_i in basal glucose by day 4 but continued to show lower [Ca²⁺]_i responses to 16 and 20 mM glucose stimulation up to at least day 12. A right shift in glucose sensing (EC₅₀) correlated with lower fragment-per-kilobase-of-transcript-per-million-reads-mapped (FPKM) of Slc2a2 (glut2) and Actn3 and increased FPKM for Galk1 and Nupr1. Differences in [Ca²⁺]_i responses to additional stimuli were also observed. Calcium levels in the endoplasmic reticulum were elevated on day 0 but became adult-like by day 4, which corresponded with reduced expression in Atp2a2 (SERCA2) and novel K+-channel Ktd17, increased expression of Pml, Wfs1, Thada, and Herpud1, and basal [Ca²⁺]_i maturing to adult levels. Ion-channel activity also matured rapidly, but RNA sequencing data mining did not yield strong leads. In conclusion, the maturation of islet [Ca²⁺]_i signaling is complex and multifaceted; several possible gene targets were identified that may participate in this process.

Protein-engineered molecules carrying GAD65 epitopes and targeting CD35 selectively down-modulate disease-associated human B lymphocytes

Type 1 diabetes mellitus is an autoimmune metabolic disorder characterized by chronic hyperglycemia, the presence of autoreactive T and B cells and autoantibodies against self-antigens. A membrane-bound enzyme on the pancreatic beta-cells, glutamic acid decarboxylase 65 (GAD65), is one of the main autoantigens in type 1 diabetes. Autoantibodies against GAD65 are potentially involved in beta-cell destruction and decline of pancreatic functions. The human complement receptor type 1 (CD35) on B and T lymphocytes has a suppressive activity on these cells. We hypothesized that it may be possible to eliminate GAD65-specific B cells from type 1 diabetes patients by using chimeric molecules, containing an anti-CD35 antibody, coupled to peptides resembling GAD65 B/T epitopes. These molecules are expected to selectively bind the anti-GAD65 specific B cells by the co-cross-linking of the immunoglobulin receptor and CD35 and to deliver a suppressive signal. Two synthetic peptides derived from GAD65 protein (GAD65 epitopes) and anti-CD35 monoclonal antibody were used for the construction of two chimeras. The immunomodulatory activity of the engineered antibodies was tested in vitro using peripheral blood mononuclear cells (PBMCs) from type 1 diabetes patients. A reduction in the number of anti-GAD65 IgG antibody-secreting plasma cells and increased percentage of apoptotic B lymphocytes was observed after treatment of these PBMCs with the engineered antibodies. The constructed chimeric molecules are able to selectively modulate the activity of GAD65-specific B lymphocytes and the production of anti-GAD65 IgG autoantibodies by co-cross-linking of the inhibitory CD35 and the B cell antigen receptor (BCR). This treatment presents a possible way to alter the autoimmune nature of these cells.

Changes on the Pancreas in Experimental Diabetes and the Effect of Lycopene on These Changes: Pdx-1, Ngn-3, and Nestin Expressions

The aim of the present study was to investigate changes occurring in the number of beta cells, as well as the expressions of Ngn-3, nestin and Pdx-1 of pancreatic progenitor cells in the pancreas of experimentally-induced adult diabetic rats and to determine the effect of orally-administered lycopene on these changes. Following the administration of 50 mg/kg streptozotocin to rats, four groups of animals were established: control + corn oil, control + lycopene, diabetic + corn oil and diabetic + lycopene. The animals in the control + lycopene and diabetic + lycopene groups received 4 mg/kg lycopene for a period of four weeks. The expressions of insulin, Ngn-3, nestin, and Pdx-1 were determined through immunohistochemistry in sections taken from pancreas tissue samples at the end of the experiment. The number of insulin-positive cells was found to be significantly low in the diabetic groups compared to the control groups. In addition, the presence of Ngn-3 and nestin-positive cells within the exocrine pancreas surrounding the islands was noted in the diabetic groups. Lycopene, in general did not have any effect in any of the parameters analyzed in the present study. It is suggested that these cells would function as stem cells to replace the lost beta-cell population. It is also suggested that it is possible to demonstrate the antioxidant effects of lycopene in the pancreas of diabetic rats by increasing the dose and duration of lycopene administration. Anat Rec, 300:2200-2207, 2017. © 2017 Wiley Periodicals, Inc.

Distinct and Shared Determinants of Cardiomyocyte Contractility in Multi-Lineage Competent Ethnically Diverse Human iPSCs

The realization of personalized medicine through human induced pluripotent stem cell (iPSC) technology can be advanced by transcriptomics, epigenomics, and bioinformatics that inform on genetic pathways directing tissue development and function. When possible, population diversity should be included in new studies as resources become available. Previously we derived replicate iPSC lines of African American, Hispanic-Latino and Asian self-designated ethnically diverse (ED) origins with normal karyotype, verified teratoma formation, pluripotency biomarkers, and tri-lineage in vitro commitment. Here we perform bioinformatics of RNA-Seq and ChIP-seq pluripotency data sets for two replicate Asian and Hispanic-Latino ED-iPSC lines that reveal differences in generation of contractile cardiomyocytes but similar and robust differentiation to multiple neural, pancreatic, and smooth muscle cell types. We identify shared and distinct genes and contributing pathways in the replicate ED-iPSC lines to enhance our ability to understand how reprogramming to iPSC impacts genes and pathways contributing to cardiomyocyte contractility potential.

Insulin-secreting β cells require a post-genomic concept

Pancreatic insulin-secreting β cells are essential in maintaining normal glucose homeostasis accomplished by highly specialized transcription of insulin gene, of which occupies up to 40% their transcriptome. Deficiency of these cells causes diabetes mellitus, a global public health problem. Although tremendous endeavors have been made to generate insulin-secreting cells from human pluripotent stem cells (i.e., primitive cells capable of giving rise to all cell types in the body), a regenerative therapy to diabetes has not yet been established. Furthermore, the nomenclature of β cells has become inconsistent, confusing and controversial due to the lack of standardized positive controls of developmental stage-matched in vivo cells. In order to minimize this negative impact and facilitate critical research in this field, a post-genomic concept of pancreatic β cells might be helpful. In this review article, we will briefly describe how β cells were discovered and islet lineage is developed that may help understand the cause of nomenclatural controversy, suggest a post-genomic definition and finally provide a conclusive remark on future research of this pivotal cell.

Polymer microarray technology for stem cell engineering

Stem cells hold remarkable promise for applications in tissue engineering and disease modeling. During the past decade, significant progress has been made in developing soluble factors (e.g., small molecules and growth factors) to direct stem cells into a desired phenotype. However, the current lack of suitable synthetic materials to regulate stem cell activity has limited the realization of the enormous potential of stem cells. This can be attributed to a large number of materials properties (e.g., chemical structures and physical properties of materials) that can affect stem cell fate. This makes it challenging to design biomaterials to direct stem cell behavior. To address this, polymer microarray technology has been developed to rapidly identify materials for a variety of stem cell applications. In this article, we summarize recent developments in polymer array technology and their applications in stem cell engineering.

STATEMENT OF SIGNIFICANCE

Stem cells hold remarkable promise for applications in tissue engineering and disease modeling. In the last decade, significant progress has been made in developing chemically defined media to direct stem cells into a desired phenotype. However, the current lack of the suitable synthetic materials to regulate stem cell activities has been limiting the realization of the potential of stem cells. This can be attributed to the number of variables in material properties (e.g., chemical structures and physical properties) that can affect stem cells. Polymer microarray technology has shown to be a powerful tool to rapidly identify materials for a variety of stem cell applications. Here we summarize recent developments in polymer array technology and their applications in stem cell engineering.

Derivation of Ethnically Diverse Human Induced Pluripotent Stem Cell Lines

The human genome with all its ethnic variations contributes to differences in human development, aging, disease, repair, and response to medical treatments and is an exciting area of research and clinical study. The availability of well-characterized ethnically diverse stem cell lines is limited and has not kept pace with other advances in stem cell research. Here we derived xenofree ethnically diverse-human induced pluripotent stem cell (ED-iPSC) lines from fibroblasts obtained from individuals of African American, Hispanic-Latino, Asian, and Caucasian ethnic origin and have characterized the lines under a uniform platform for comparative analysis. Derived ED-iPSC lines are low passage number and evaluated in vivo by teratoma formation and in vitro by high throughput microarray analysis of EB formation and early differentiation for tri-lineage commitment to endoderm, ectoderm and mesoderm. These new xenofree ED-iPSC lines represent a well-characterized valuable resource with potential for use in future research in drug discovery or clinical investigations.

A practical guide to induced pluripotent stem cell research using patient samples

Approximately 3 years ago, we assessed how patient induced pluripotent stem cell (iPSC) research could potentially impact human pathobiology studies in the future. Since then, the field has grown considerably with numerous technical developments, and the idea of modeling diseases 'in a dish' is becoming increasingly popular in biomedical research. Likely, it is even acceptable to include patient iPSCs as one of the standard research tools for disease mechanism studies, just like knockout mice. However, as the field matures, we acknowledge there remain many practical limitations and obstacles for their genuine application to understand diseases, and accept that it has not been as straightforward to model disorders as initially proposed. A major practical challenge has been efficient direction of iPSC differentiation into desired lineages and preparation of the large numbers of specific cell types required for study. Another even larger obstacle is the limited value of in vitro outcomes, which often do not closely represent disease conditions. To overcome the latter issue, many new approaches are underway, including three-dimensional organoid cultures from iPSCs, xenotransplantation of human cells to animal models and in vitro interaction of multiple cell types derived from isogenic iPSCs. Here we summarize the areas where patient iPSC studies have provided truly valuable information beyond existing skepticism, discuss the desired technologies to overcome current limitations and include practical guidance for how to utilize the resources. Undoubtedly, these human patient cells are an asset for experimental pathology studies. The future rests on how wisely we use them.

Engineered hair follicle mesenchymal stem cells overexpressing controlled-release insulin reverse hyperglycemia in mice with type L diabetes

Genetically engineered stem cells that overexpress genes encoding therapeutic products can be exploited to correct metabolic disorders by repairing and regenerating diseased organs or restoring their function. Hair follicles are readily accessible and serve as a rich source of autologous stem cells for cell-based gene therapy. Here we isolated mesenchymal stem cells from human hair follicles (HF-MSCs) and engineered them to overexpress the human insulin gene and release human insulin in a time- and dose-dependent manner in response to rapamycin. The engineered HF-MSCs retained their characteristic cell surface markers and retained their potential to differentiate into adipocytes and osteoblasts. When mice with streptozotocin-induced type 1 diabetes were engrafted with these engineered HF-MSCs, these cells expressed and released a dose of human insulin, dramatically reversed hyperglycemia, and significantly reduced death rate. Moreover, the engineered HF-MSCs did not form detectable tumors throughout the 120-day animal tests in our experiment. Our results show that HF-MSCs can be used to safely and efficiently express therapeutic transgenes and therefore show promise for cell-based gene therapy of human disease.

Diagnosis and classification of autoimmune diabetes mellitus

Diabetes mellitus is increasing in prevalence worldwide. The economic costs and burden of the disease are considerable given the cardiovascular complications and co-morbidities that it may entail. Two major groups of diabetes mellitus have been defined, type 1, or immune-based, and type 2. In recent years, other subgroups have been described in-between these major groups. Correct classification of the disease is crucial in order to ascribe the most efficient preventive, diagnostic and treatment strategies for each patient. In the present review, we discuss the epidemiology, etiopathogenesis, diagnostic criteria and clinical classification of what is currently known as autoimmune diabetes. In addition, the other groups of diabetes mellitus will be regarded in relation to their pathogenesis and potential autoimmunity features.

Combined KIT and FGFR2b signaling regulates epithelial progenitor expansion during organogenesis

Organ formation and regeneration require epithelial progenitor expansion to engineer, maintain, and repair the branched tissue architecture. Identifying the mechanisms that control progenitor expansion will inform therapeutic organ (re)generation. Here, we discover that combined KIT and fibroblast growth factor receptor 2b (FGFR2b) signaling specifically increases distal progenitor expansion during salivary gland organogenesis. FGFR2b signaling upregulates the epithelial KIT pathway so that combined KIT/FGFR2b signaling, via separate AKT and mitogen-activated protein kinase (MAPK) pathways, amplifies FGFR2b-dependent transcription. Combined KIT/FGFR2b signaling selectively expands the number of KIT+K14+SOX10+ distal progenitors, and a genetic loss of KIT signaling depletes the distal progenitors but also unexpectedly depletes the K5+ proximal progenitors. This occurs because the distal progenitors produce neurotrophic factors that support gland innervation, which maintains the proximal progenitors. Furthermore, a rare population of KIT+FGFR2b+ cells is present in adult glands, in which KIT signaling also regulates epithelial-neuronal communication during homeostasis. Our findings provide a framework to direct regeneration of branched epithelial organs.

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Combined KIT and FGFR2b signaling amplifies FGFR2b-dependent transcription

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KIT/FGFR2b signaling during organogenesis expands distal KIT+ epithelial progenitors

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Distal progenitors communicate with proximal progenitors via the neuronal niche

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KIT+ progenitors maintain epithelial-neuronal communication during adult homeostasis

Type 1 diabetes: translating mechanistic observations into effective clinical outcomes

Type 1 diabetes (T1D) remains an important health problem, particularly in western countries, where the incidence has been increasing in younger children. In 1986, Eisenbarth described T1D as a chronic autoimmune disease. Work over the past three-and-a-half decades has identified many of the genetic, immunological and environmental factors that are involved in the disease and have led to hypotheses concerning its pathogenesis. Clinical trials have been conducted to test these hypotheses but have had mixed results. Here, we discuss the findings that have led to our current concepts of the disease mechanisms involved in T1D and the clinical studies promoted by these studies. The findings from preclinical and clinical studies support the original proposed model for how T1D develops but have also suggested that this disease is more complex than was originally thought and will require broader treatment approaches.

Proteins and small molecules for cellular regenerative medicine

Regenerative medicine seeks to understand tissue development and homeostasis and build on that knowledge to enhance regeneration of injured tissues. By replenishing lost functional tissues and cells, regenerative medicine could change the treatment paradigm for a broad range of degenerative and ischemic diseases. Multipotent cells hold promise as potential building blocks for regenerating lost tissues, but successful tissue regeneration will depend on comprehensive control of multipotent cells-differentiation into a target cell type, delivery to a desired tissue, and integration into a durable functional structure. At each step of this process, proteins and small molecules provide essential signals and, in some cases, may themselves act as effective therapies. Identifying these signals is thus a fundamental goal of regenerative medicine. In this review we discuss current progress using proteins and small molecules to regulate tissue regeneration, both in combination with cellular therapies and as monotherapy.

Treatment options for diabetes: potential role of stem cells

There are diseases and injuries in which a patient's cells or tissues are destroyed that can only be adequately corrected by tissue or organ transplants. Stem cells may be able to generate new tissue and even cure diseases for which there is no adequate therapy. Type 1 diabetes (T1DM), an insulin-dependent diabetes, is a chronic disease affecting genetically predisposed individuals, in which insulin-secreting beta (β)-cells within pancreatic islets of Langerhans are selectively and irreversibly destroyed by autoimmune assault. Type 2 diabetes (T2DM) is characterized by a gradual decrease in insulin sensitivity in peripheral tissues and the liver (insulin resistance), followed by a gradual decline in β-cell function and insulin secretion. Successful replacing of damaged β-cells has shown considerable potential in treating T1DM, but lack of adequate donors is a barrier. The literature suggests that embryonic and adult stem cells are promising alternatives in long-term treatment of diabetes. However, any successful strategy should address both the need for β-cell replacement and controlling the autoimmune response to cells that express insulin. This review summarizes the current knowledge of options and the potential of stem cell transplantation in diabetes treatment.

Microarrayed Materials for Stem Cells

Stem cells hold remarkable promise for applications in disease modeling, cancer therapy and regenerative medicine. Despite the significant progress made during the last decade, designing materials to control stem cell fate remains challenging. As an alternative, materials microarray technology has received great attention because it allows for high throughput materials synthesis and screening at a reasonable cost. Here, we discuss recent developments in materials microarray technology and their applications in stem cell engineering. Future opportunities in the field will also be reviewed.

Pluripotent stem cell-derived pancreatic β-cells: potential for regenerative medicine in diabetes

Diabetes mellitus, which affects 346 million people, is one of the leading causes of death worldwide. Pancreatic β-cells, existing in the islets of Langerhans, play central roles in the progression of diabetes. An efficient strategy to produce functional pancreatic β-cells is important for both transplantation therapy and disease modeling of diabetes. Human pluripotent stem cells, including human embryonic stem cells and induced pluripotent stem cells, provide unlimited starting materials to generate differentiated cells for regenerative studies. Significant progress has been made in human embryonic/induced pluripotent stem cell differentiation in the last several years. However, efficient generation of mature pancreatic β-cells with complete functional capabilities has not yet been accomplished. Here, we review recent successes as well as the technical and theoretical challenges in the use of pluripotent stem cell-derived pancreatic β-cells for disease modeling and replacement therapy of diabetes.

Regulation of mesenchymal stem cell differentiation and insulin secretion by differential expression of Pdx-1

In recent years, major effort has been made to differentiate embryonic stem cells, pancreatic ductal epithelial multipotent progenitor cells, and bone marrow stem cells into insulin secreting cells. Our previous work has also demonstrated the feasibility of inducing mesenchymal stem cells (MSC) to insulin secreting cells through overexpression of Pdx-1, a pancreas and islet-specific transcription factor that plays a major role in differentiation of islet β-cells during development (Yuan et al. in Mol Biol Rep 37:4023-4031, 2010). However, the levels of insulin secretion among these differentiated MSC were quite variable. The purpose of this study is to address the issue whether the insulin secretion level from the differentiated MSC lines are determined by the expression level of the Pdx-1 transgene. To do so, we have generated several differentiated MSC lines with stable transfection of the Pdx-1 gene. Using RT-PCR analysis and insulin secretion assay, we have analyzed Pdx-1 mRNA levels and insulin secretion from these stable MSC lines. Our results showed that Pdx-1 expression is absolutely required for the differentiation of MSC lines to insulin secreting cell lines. Furthermore, we demonstrated that the level of Pdx-1 expression is closely correlated with level of insulin mRNA and insulin secretion level in differentiated MSC stable cell lines. These findings suggest that the level of Pdx-1 expression plays a key role in induction of MSCs to insulin secreting cells.

Induced pluripotent stem cell modeling of complex genetic diseases

The study of complex disease genetics by genome-wide association studies (GWAS) has led to hundreds of genomic loci associated with disease traits in humans. However, the functional consequences of most loci are largely undefined. We discuss here the potential for human induced pluripotent stem (iPS) cells to bridge the gap between genetic variant and mechanisms of complex disease. We also highlight specific diseases and the roadblocks that must be overcome before iPS cell technology can be widely adopted for complex disease modeling.

The evolving biology of cell reprogramming

Modern stem cell biology has achieved a transformation that was thought by many to be every bit as unattainable as the ancient alchemists' dream of transforming base metals into gold. Exciting opportunities arise from the process known as 'cellular reprogramming' in which cells can be reliably changed from one tissue type to another. This is enabling novel approaches to more deeply investigate the fundamental basis of cell identity. In addition, new opportunities have also been created to study (perhaps even to treat) human genetic and degenerative diseases. Specific cell types that are affected in inherited disease can now be generated from easily accessible cells from the patient and compared with equivalent cells from healthy donors. The differences in cellular phenotype between the two may then be identified, and assays developed to establish therapies that prevent the development or progression of disease symptoms. Cellular reprogramming also has the potential to create new cells to replace those whose death or dysfunction causes disease symptoms. For patients suffering from inherited cases of degenerative diseases like Parkinson's disease or amyotrophic lateral sclerosis (also known as motor neuron disease), the future realization of such cell-based therapies would truly be worth its weight in gold. However, before this enormous potential can become a reality, several significant biological and technical challenges must be overcome. Furthermore, to maintain the credibility of the scientific community with the general public, it is important that hope-inspiring advances are not over-hyped. The papers in this issue of the Philosophical Transactions of the Royal Society B: Biological Sciences cover many areas relevant to this topic. In this Introduction, we provide an overall context in which to consider these individual papers.