Changes in gene expression and morphology of mouse embryonic stem cells on differentiation into insulin-producing cells in vitro and in vivo

Differentiation of Human Deceased Donor, Adipose-Derived, Mesenchymal Stem Cells into Functional Beta Cells

There is an emerging need for the rapid generation of functional beta cells that can be used in cell replacement therapy for the treatment of type 1 diabetes (T1D). Differentiation of stem cells into insulin-producing cells provides a promising strategy to restore pancreatic endocrine function. Stem cells can be isolated from various human tissues including adipose tissue (AT). Our study outlines a novel, non-enzymatic process to harvest mesenchymal stem cells (MSC) from research-consented, deceased donor AT. Following their expansion, MSC were characterised morphologically and phenotypically by flow cytometry to establish their use for downstream differentiation studies. MSC were induced to differentiate into insulin-producing beta cells using a step-wise differentiation medium. The differentiation was evaluated by analysing the morphology, dithizone staining, immunocytochemistry, and expression of pancreatic beta cell marker genes. We stimulated the beta cells with different concentrations of glucose and observed a dose-dependent increase in gene expression. In addition, an increase in insulin and c-Peptide secretion as a function of glucose challenge confirmed the functionality of the differentiated beta cells. The differentiation of adipose-derived MSC into beta cells has been well established. However, our data demonstrates, for the first time, that the ready availability and properties of MSC isolated from deceased donor adipose tissue render them well-suited as a source for increased production of functional beta cells. Consequently, these cells can be a promising therapeutic approach for cell replacement therapy to treat patients with T1D.

Developmentally-Inspired Biomimetic Culture Models to Produce Functional Islet-Like Cells From Pluripotent Precursors

Insulin-producing beta cells sourced from pluripotent stem cells hold great potential as a virtually unlimited cell source to treat diabetes. Directed pancreatic differentiation protocols aim to mimic various stimuli present during embryonic development through sequential changes of in vitro culture conditions. This is commonly accomplished by the timed addition of soluble signaling factors, in conjunction with cell-handling steps such as the formation of 3D cell aggregates. Interestingly, when stem cells at the pancreatic progenitor stage are transplanted, they form functional insulin-producing cells, suggesting that in vivo microenvironmental cues promote beta cell specification. Among these cues, biophysical stimuli have only recently emerged in the context of optimizing pancreatic differentiation protocols. This review focuses on studies of cell–microenvironment interactions and their impact on differentiating pancreatic cells when considering cell signaling, cell–cell and cell–ECM interactions. We highlight the development of in vitro cell culture models that allow systematic studies of pancreatic cell mechanobiology in response to extracellular matrix proteins, biomechanical effects, soluble factor modulation of biomechanics, substrate stiffness, fluid flow and topography. Finally, we explore how these new mechanical insights could lead to novel pancreatic differentiation protocols that improve efficiency, maturity, and throughput.

Regenerative Medicine and Diabetes: Targeting the Extracellular Matrix Beyond the Stem Cell Approach and Encapsulation Technology

According to the Juvenile Diabetes Research Foundation (JDRF), almost 1. 25 million people in the United States (US) have type 1 diabetes, which makes them dependent on insulin injections. Nationwide, type 2 diabetes rates have nearly doubled in the past 20 years resulting in more than 29 million American adults with diabetes and another 86 million in a pre-diabetic state. The International Diabetes Ferderation (IDF) has estimated that there will be almost 650 million adult diabetic patients worldwide at the end of the next 20 years (excluding patients over the age of 80). At this time, pancreas transplantation is the only available cure for selected patients, but it is offered only to a small percentage of them due to organ shortage and the risks linked to immunosuppressive regimes. Currently, exogenous insulin therapy is still considered to be the gold standard when managing diabetes, though stem cell biology is recognized as one of the most promising strategies for restoring endocrine pancreatic function. However, many issues remain to be solved, and there are currently no recognized treatments for diabetes based on stem cells. In addition to stem cell resesarch, several β-cell substitutive therapies have been explored in the recent era, including the use of acellular extracellular matrix scaffolding as a template for cellular seeding, thus providing an empty template to be repopulated with β-cells. Although this bioengineering approach still has to overcome important hurdles in regards to clinical application (including the origin of insulin producing cells as well as immune-related limitations), it could theoretically provide an inexhaustible source of bio-engineered pancreases.

Amniotic fluid stem cells prevent β-cell injury

BACKGROUND AIMS

The contribution of amniotic fluid stem cells (AFSC) to tissue protection and regeneration in models of acute and chronic kidney injuries and lung failure has been shown in recent years. In the present study, we used a chemically induced mouse model of type 1 diabetes to determine whether AFSC could play a role in modulating β-cell injury and restoring β-cell function.

METHODS

Streptozotocin-induced diabetic mice were given intracardial injection of AFSC; morphological and physiological parameters and gene expression profile for the insulin pathway were evaluated after cell transplantation.

RESULTS

AFSC injection resulted in protection from β-cell damage and increased β-cell regeneration in a subset of mice as indicated by glucose and insulin levels, increased islet mass and preservation of islet structure. Moreover, β-cell preservation/regeneration correlated with activation of the insulin receptor/Pi3K/Akt signaling pathway and vascular endothelial growth factor-A expression involved in maintaining β-cell mass and function.

CONCLUSIONS

Our results suggest a therapeutic role for AFSC in preserving and promoting endogenous β-cell functionality and proliferation. The protective role of AFSC is evident when stem cell transplantation is performed before severe hyperglycemia occurs, which suggests the importance of early intervention. The present study demonstrates the possible benefits of the application of a non-genetically engineered stem cell population derived from amniotic fluid for the treatment of type 1 diabetes mellitus and gives new insight on the mechanism by which the beneficial effect is achieved.

Deletion of retinoic acid receptor β (RARβ) impairs pancreatic endocrine differentiation

All-trans retinoic acid (RA) signals via binding to retinoic acid receptors (RARs α, β, and γ). RA directly influences expression of Pdx1, a transcription factor essential for pancreatic development and beta-cell (β-cell) maturation. In this study we follow the differentiation of cultured wild-type (WT) vs. RARβ knockout (KO) embryonic stem (ES) cells into pancreatic islet cells. We found that RARβ KO ES cells show greatly reduced expression of some important endocrine markers of differentiated islet cells, such as glucagon, islet amyloid polypeptide (Iapp), and insulin 1 (Ins1) relative to WT. We conclude that RARβ activity is essential for proper differentiation of ES cells to pancreatic endocrine cells.

Combined transfection of the three transcriptional factors, PDX-1, NeuroD1, and MafA, causes differentiation of bone marrow mesenchymal stem cells into insulin-producing cells

Aims. The goal of cell transcription for treatment of diabetes is to generate surrogate β-cells from an appropriate cell line. However, the induced replacement cells have showed less physiological function in producing insulin compared with normal β-cells. Methods. Here, we report a procedure for induction of insulin-producing cells (IPCs) from bone marrow murine mesenchymal stem cells (BM-mMSCs). These BM-mMSCs have the potential to differentiate into insulin-producing cells when a combination of PDX-1 (pancreatic and duodenal homeobox-1), NeuroD1 (neurogenic differentiation-1), and MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homolog A) genes are transfected into them and expressed in these cells. Results. Insulin biosynthesis and secretion were induced in mMSCs into which these three genes have been transfected and expressed. The amount of induced insulin in the mMSCs which have been transfected with the three genes together is significantly higher than in those mMSCs that were only transfected with one or two of these three genes. Transplantation of the transfected cells into mice with streptozotocin-induced diabetes results in insulin expression and the reversal of the glucose challenge. Conclusions. These findings suggest major implications for cell replacement strategies in generation of surrogate β-cells for the treatment of diabetes.

Fourier transform infrared spectrochemical imaging: review of design and applications with a focal plane array and multiple beam synchrotron radiation source

The beamline design, microscope specifications, and initial results from the new mid-infrared beamline (IRENI) are reviewed. Synchrotron-based spectrochemical imaging, as recently implemented at the Synchrotron Radiation Center in Stoughton, Wisconsin, demonstrates the new capability to achieve diffraction limited chemical imaging across the entire mid-infrared region, simultaneously, with high signal-to-noise ratio. IRENI extracts a large swath of radiation (320 hor. × 25 vert. mrads(2)) to homogeneously illuminate a commercial infrared (IR) microscope equipped with an IR focal plane array (FPA) detector. Wide-field images are collected, in contrast to single-pixel imaging from the confocal geometry with raster scanning, commonly used at most synchrotron beamlines. IRENI rapidly generates high quality, high spatial resolution data. The relevant advantages (spatial oversampling, speed, sensitivity, and signal-to-noise ratio) are discussed in detail and demonstrated with examples from a variety of disciplines, including formalin-fixed and flash-frozen tissue samples, live cells, fixed cells, paint cross-sections, polymer fibers, and novel nanomaterials. The impact of Mie scattering corrections on this high quality data is shown, and first results with a grazing angle objective are presented, along with future enhancements and plans for implementation of similar, small-scale instruments.

Immunological applications of stem cells in type 1 diabetes

Current approaches aiming to cure type 1 diabetes (T1D) have made a negligible number of patients insulin-independent. In this review, we revisit the role of stem cell (SC)-based applications in curing T1D. The optimal therapeutic approach for T1D should ideally preserve the remaining β-cells, restore β-cell function, and protect the replaced insulin-producing cells from autoimmunity. SCs possess immunological and regenerative properties that could be harnessed to improve the treatment of T1D; indeed, SCs may reestablish peripheral tolerance toward β-cells through reshaping of the immune response and inhibition of autoreactive T-cell function. Furthermore, SC-derived insulin-producing cells are capable of engrafting and reversing hyperglycemia in mice. Bone marrow mesenchymal SCs display a hypoimmunogenic phenotype as well as a broad range of immunomodulatory capabilities, they have been shown to cure newly diabetic nonobese diabetic (NOD) mice, and they are currently undergoing evaluation in two clinical trials. Cord blood SCs have been shown to facilitate the generation of regulatory T cells, thereby reverting hyperglycemia in NOD mice. T1D patients treated with cord blood SCs also did not show any adverse reaction in the absence of major effects on glycometabolic control. Although hematopoietic SCs rarely revert hyperglycemia in NOD mice, they exhibit profound immunomodulatory properties in humans; newly hyperglycemic T1D patients have been successfully reverted to normoglycemia with autologous nonmyeloablative hematopoietic SC transplantation. Finally, embryonic SCs also offer exciting prospects because they are able to generate glucose-responsive insulin-producing cells. Easy enthusiasm should be mitigated mainly because of the potential oncogenicity of SCs.

Insulin-producing surrogate β-cells from embryonic stem cells: are we there yet?

Embryonic stem cells (ESCs) harbor the potential to generate every cell type of the body by differentiation. The use of hESCs holds great promise for potential cell replacement therapies for degenerative diseases including diabetes mellitus. The recently discovered induced pluripotent stem cells (iPSCs) exhibit immense potential for regenerative medicine as they allow the generation of autologous cells tailored to the patients' immune system. Research for insulin-producing surrogate cells from ESCs has yielded highly controversial results, because many steps and factors in the differentiation process are currently still unknown. Thus, there is no consensus on common standard protocols. The protocols presently used established the differentiation from pluripotent cells toward pancreatic progenitor cells. However, none of the differentiation protocols reported to date have generated by exclusive in vitro differentiation sufficient numbers of insulin-producing cells meeting all essential criteria of a β-cell. The cells often lack the crucial function of regulated insulin secretion upon glucose stimulation. This review focuses on past and current approaches to the generation of insulin-producing cells from pluripotent sources, such as ESCs and iPSCs, and critically discusses the hurdles to be taken before insulin-secreting surrogate cells derived from these stem cells will be of clinical use in humans.

Differentiation of intestinal absorptive cells derived from mouse embryonic bodies can be promoted by inducing the differentiation of definitive endoderm in vivo

AIM: To investigate the effect of inducing the differentiation of definitive endoderm derived from mouse embryonic bodies (EBs) cultured by the hanging drop method in promoting the differentiation of intestinal absorptive cells in vivo.

METHODS: The differentiation of definitive endoderm during EBs formation derived from mouse ES-E14TG2a embryonic stem cells (ESC) and the role of Activin A in promoting its differentiation were monitored by detecting its markers by RT-PCR and fluorescence-activated cell sorting. Subsequently, the EBs with high proportion of definitive endoderm were hypodermically engrafted into the back of NOD/SCID mice to form grafts. The markers for small intestinal absorptive cells, including SI, LPH, and Fabp2, were detected in these grafts by quantitative RT-PCR and immunohistochemistry.

RESULTS: The marker genes for definitive endoderm were more highly expressed in the 5-day EBs than in other stages of EBs (Gsc: 0.9809 ± 0.1001 vs 0.5435 ± 0.0821, 0.5525 ± 0.0786, 0.2234 ± 0.0425; Tm4sf2: 0.9231 ± 0.1121 vs 0.0017 ± 0.0007, 0.0176 ± 0.0058, 0.6542 ± 0.0742; Gpc1: 0.8639 ± 0.1098 vs 0.5882 ± 0.1027, 0.7112 ± 0.0956, 0.4239 ± 0.0874, all P < 0.05). The percentage of definitive endoderm cells in the 5-day EBs induced with 50 μg/L Activin A (SF-A group) was significantly higher than that in controls (all P < 0.05). SI and LPH mRNA expression in the grafts from the SF-A group was significantly higher than that in control groups (all P < 0.05). Immunohistochemical analysis revealed that Fabp2 was expressed in some immature cells without specific structure or adenoid structures in the grafts from the SF-A group.

CONCLUSION: The differentiation of definitive endoderm derived from mouse ESC could be induced with 50 ng/ml Activin A in EBs cultured by the hanging drop method. Increasing the proportion of definitive endoderm in EBs promotes the differentiation of intestinal absorptive cells in vivo.

Nkx6.2 synergizes with Cdx-2 in stimulating proglucagon gene expression

AIM: To investigate whether the transactivator of the proglucagon gene (Gcg), Cdx-2, synergizes with other transcription factors in stimulating Gcg expression and the trans-differentiation of Gcg-expressing cells.

METHODS: We conducted affinity chromatography to identify proteins that interact with Cdx-2, using GST-tagged Cdx-2 against cell lysates from pancreatic InR1-G9 and intestinal GLUTag cell lines. This was followed by a mass-spectrometry analysis. From a potential Cdx-2 interaction protein identified, we examined its expression in pancreatic and gut endocrine cells, confirmed its interaction with Cdx-2 by GST-pull down and determined its effect in provoking Gcg expression in cell lines that do not express endogenous Gcg.

RESULTS: We identified 18 potential Cdx-2 interacting proteins. One of them is Nkx6.2. This homeodomain (HD) protein is expressed in pancreatic α and intestinal endocrine L cells but not in insulin producing cell lines, including In111. Nkx6.2, but not Nkx6.1, was shown to interact with Cdx-2, detected by GST-pull down. Furthermore, Nkx6.2 was found to synergize with Cdx-2 in provoking Gcg expression when they were ectopically expressed in the In111 cell line. Finally, when Cdx-2 and Nkx6.2 were co-transfected into the undifferentiated rat intestinal IEC-6 cell line, it produced detectable amount of Gcg mRNA.

CONCLUSION: Cdx-2 recruits Nkx6.2 in exerting its effect in stimulating Gcg expression. Our observations further support the notion that multiple HD proteins, including Cdx-2 and Nkx6.2, are involved in the regulation of Gcg expression and the genesis of Gcg-producing cells.

Stem cell-based strategies for the treatment of type 1 diabetes mellitus

IMPORTANCE OF THE FIELD

β-Cell regeneration and β-cell preservation are two promising therapeutic approaches for the management of patients with type 1 diabetes (T1D). Stem cell-based strategies to address the problems of shortage in β cells, autoimmune and alloimmune responses have become an area of intense study.

AREAS COVERED IN THIS REVIEW

This review focuses on the progress that has been made in obtaining functional, insulin-producing cells from various types of stem/progenitor cells, including the current knowledge on the immunomodulatory roles of hematopoietic stem cell and multipotent stromal cell in the therapies for T1D.

WHAT THE READER WILL GAIN

A broad overview of recent advancements in this field is provided. The hurdles that remain in the path of using stem cell-based strategies for the treatment of T1D and possible approaches to overcome these challenges are discussed.

TAKE HOME MESSAGE

Stem cell-based strategies hold great promise for the treatment of T1D. In spite of the progress that has been made over the last decade, a number of obstacles and concerns need to be cleared before widespread clinical application is possible. In particular, the mechanism of ESC and iPSC-derived β-cell maturation in vivo is poorly understood.

Stem cell therapy for type 1 diabetes mellitus

The use of stem cells in regenerative medicine holds great promise for the cure of many diseases, including type 1 diabetes mellitus (T1DM). Any potential stem-cell-based cure for T1DM should address the need for beta-cell replacement, as well as control of the autoimmune response to cells which express insulin. The ex vivo generation of beta cells suitable for transplantation to reconstitute a functional beta-cell mass has used pluripotent cells from diverse sources, as well as organ-specific facultative progenitor cells from the liver and the pancreas. The most effective protocols to date have produced cells that express insulin and have molecular characteristics that closely resemble bona fide insulin-secreting cells; however, these cells are often unresponsive to glucose, a characteristic that should be addressed in future protocols. The use of mesenchymal stromal cells or umbilical cord blood to modulate the immune response is already in clinical trials; however, definitive results are still pending. This Review focuses on current strategies to obtain cells which express insulin from different progenitor sources and highlights the main pathways and genes involved, as well as the different approaches for the modulation of the immune response in patients with T1DM.