Generation of functional insulin-producing cells from mouse embryonic stem cells through 804G cell-derived extracellular matrix and protein transduction of transcription factors

Epigenetic modulation of cell fate during pancreas development

Epigenetic modifications to DNA and its associated proteins affect cell plasticity and cell fate restrictions throughout embryonic development. Development of the vertebrate pancreas is characterized by initial is an over-lapping expression of a set of transcriptional regulators in a defined region of the posterior foregut endoderm that collectively promote pancreas progenitor specification and proliferation. As development progresses, these transcription factors segregate into distinct pancreatic lineages, with some being maintained in specific subsets of terminally differentiated pancreas cell types throughout adulthood. Here we describe the progressive stages and cell fate restrictions that occur during pancreas development and the relevant known epigenetic regulatory events that drive the dynamic expression patterns of transcription factors that regulate pancreas development. In addition, we highlight how changes in epigenetic marks can affect susceptibility to pancreas diseases (such as diabetes), adult pancreas cell plasticity, and the ability to derive replacement insulin-producing β cells for the treatment of diabetes.

Endoderm and mesoderm derivatives in embryonic stem cell differentiation and their use in developmental toxicity testing

Embryonic stem cell differentiation models have increasingly been applied in non-animal test systems for developmental toxicity. After the initial focus on cardiac differentiation, attention has also included an array of neuro-ectodermal differentiation routes. Alternative differentiation routes in the mesodermal and endodermal germ lines have received less attention. This review provides an inventory of achievements in the latter areas of embryonic stem cell differentiation, with a view to possibilities for their use in non-animal test systems in developmental toxicology. This includes murine and human stem cell differentiation models, and also gains information from the field of stem cell use in regenerative medicine. Endodermal stem cell derivatives produced in vitro include hepatocytes, pancreatic cells, lung epithelium, and intestinal epithelium, and mesodermal derivatives include cardiac muscle, osteogenic, vascular and hemopoietic cells. This inventory provides an overview of studies on the different cell types together with biomarkers and culture conditions that stimulate these differentiation routes from embryonic stem cells. These models may be used to expand the spectrum of embryonic stem cell based new approach methodologies in non-animal developmental toxicity testing.

Recent Advances in the Generation of β-Cells from Induced Pluripotent Stem Cells as a Potential Cure for Diabetes Mellitus

Diabetes mellitus (DM) is a group of metabolic disorders characterized by high blood glucose levels due to insufficient insulin secretion, insulin action, or both. The present-day solution to diabetes mellitus includes regular administration of insulin, which brings about many medical complications in diabetic patients. Although islet transplantation from cadaveric subjects was proposed to be a permanent cure, the increased risk of infections, the need for immunosuppressive drugs, and their unavailability had restricted its use. To overcome this, the generation of renewable and transplantable β-cells derived from autologous induced pluripotent stem cells (iPSCs) has gained enormous interest as a potential therapeutic strategy to treat diabetes mellitus permanently. To date, extensive research has been undertaken to derive transplantable insulin-producing β-cells (iβ-cells) from iPSCs in vitro by recapitulating the in vivo developmental process of the pancreas. This in vivo developmental process relies on transcription factors, signaling molecules, growth factors, and culture microenvironment. This review highlights the various factors facilitating the generation of mature β-cells from iPSCs. Moreover, this review also describes the generation of pancreatic progenitors and β-cells from diabetic patient-specific iPSCs, exploring the potential of the diabetes disease model and drug discovery. In addition, the applications of genome editing strategies have also been discussed to achieve patient-specific diabetes cell therapy. Last, we have discussed the current challenges and prospects of iPSC-derived β-cells to improve the relative efficacy of the available treatment of diabetes mellitus.

Generation of Functional Insulin-Producing Cells from Mouse Embryonic Stem Cells Through Protein Transduction of Transcription Factors

In this chapter, we describe a simple and unique method for the differentiation of mouse embryonic stem cells into insulin-producing cells. In addition to cytokines and growth factors, key transcription factors for pancreatic development are applied in this method through protein transduction technology. Furthermore, a combination of nanofiber plates and laminin coatings improves the yield of differentiated cells. The insulin-producing cells derived through this method express marker genes of mature β-cells and have an ability to secrete insulin; therefore, these cells are useful for fundamental studies on pancreatic development, drug development, and regenerative medicine for diabetes.

A culture substratum with net-like polyamide fibers promotes the differentiation of mouse and human pluripotent stem cells to insulin-producing cells

Insulin-producing and -secreting cells derived from mouse pluripotent stem cells (PSCs) are useful for pancreatic development research and evaluating drugs that may induce insulin secretion. Previously, we have established a differentiation protocol to derive insulin-secreting cells from mouse embryonic stem cells (ESCs) using a combination of growth factors, recombinant proteins, and a culture substratum with net-like fibers. However, it has not been tested which materials and diameters of these fibers are more effective for the differentiation. Therefore, the present study aimed to produce net-like culture substratum formed from polyamide (PA) and polyacrylonitrile (PAN) fibers. Substrata were delineated into PA100, 300, 600, PAN100, 300, and 600 groups based on fiber diameters. The differentiation efficiencies of mouse ESCs cultured on the substrata were then examined by insulin 1 (Ins1) expression. Expression was found to be highest in PA300 differentiated cells, indicating the potential to produce high levels of insulin. To understand any differences in substratum properties, the adsorption capacities of laminin were measured, revealing that PA300 had the highest for it. We next examined the stage of differentiation affected by incubation with PA300. This showed that Sox17- and Pdx1-GFP-positive cells increased during the first step of differentiation. To show the production of insulin without absorption from the medium, we confirmed the expression of insulin C-peptide after differentiation. Finally, we tested the effects of PA300 on the differentiation of human-induced PSC, and found more Sox17-positive cells with the PA300 substratum at the definitive endoderm stage. Furthermore, these cells expressed insulin C-peptide and had glucose-responsive C-peptide secretion. In summary, our study identified and validated a novel substratum which is suitable for pancreatic differentiation of mouse and human PSCs.

Feasibility of Induced Pluripotent Stem Cell Therapies for Treatment of Type 1 Diabetes

IMPACT STATEMENT

This review of iPSCs to treat T1D provides a current assessment of the challenges and potential for this proposed new therapy.

Human Induced Pluripotent Stem Cells in the Curative Treatment of Diabetes and Potential Impediments Ahead

The successful landmark discovery of mouse and human inducible pluripotential stem cells (iPSC's) by Takahashi and Yamanaka in 2006 and 2007 has triggered a revolution in the potential generation of self-compatible cells for regenerative medicine, and further opened up a new avenue for "disease in dish" drug screening of self-target cells (Neofytou et al. 2015). The introduction of four 'Yamanaka' transcription factors through viral or other transfection of mature cells can induce pluripotency and acquired plasticity. These factors include transduction with octamer-binding transcription factor-4 (Oct-4), nanog homeobox (Nanog), sex-determining region Y-box-2 (Sox-2) and MYC protooncogene (cMyc). Such cells become iPSC's (Takahashi and Yamanaka 2006). These reprogrammed cells exhibit increased telomerase activity and have a hypomethylated gene promotor region similar to embryonic stem cells (ESC's). These milestone discoveries have generated immense hope that diseases such as diabetes could be treated and effectively cured by transplantation of self-compatible, personalized autologous stem cell transplantation of β-cells that release physiological insulin under glycemic control (Maehr et al. 2009; Park et al. 2008) (Fig. 1). Diabetes is a profligate disease of disordered glucose metabolism resulting from an absolute or relative deficiency of insulin, the consequences of which lead to immense socio-economic societal burden. While there are many different types of diabetes, the two major types (type 1 diabetes (T1DM) and type 2 diabetes (T2DM) are caused respectively by immune-mediated destruction (T1DM) or malfunctioning (T2DM) insulin-producing β-cells within the endocrine pancreas, the islets of Langerhans (Atkinson et al. 2011; Holman et al. 2015; You and Henneberg 2016). Almost 425 million people are affected by the global burden of diabetes, and this is predicted to increase by 48% (629 million) by 2045 (International Diabetes Federation Atlas 8th Ed 2018). Whole pancreas or islet cell transplantation offer an effective alternative to injected insulin, but both require lifelong potent immunosuppression to control both allo-and autoimmunity. Whole pancreas transplantation involves invasive complex surgery and is associated with greater morbidity and occasional mortality, while islet transplantation involves a minimally invasive intraportal hepatic infusion. Generally, whole pancreas transplantation provides greater metabolic reserve, but this may be matched by cumulative multiple islet infusions to achieve insulin independence. An additional challenge of islet transplantation is progressive loss of complete insulin independence over time, which may be multifactorial, the dominant factor however being ineffective control of autoimmunity. Both whole pancreas and islet transplantation are restricted to patients at risk of severe hypoglycemia that cannot be stabilized by alternate means, or in recipients that are already immunosuppressed in order to sustain a kidney or other solid organ transplant. The risks of chronic immunosuppression and the scarcity of human organ donors mean that both of these transplantation therapies cannot presently be extended to the broader diabetic population (Shapiro 2011; Shapiro et al. 2006). Recent progress in xenotransplantation of multiple knock-out 'humanized' pig islets could offer one potential solution, perhaps aided by clustered regularly interspaced short palindromic repeats/CRISPR associated-9 (CRISPR/Cas-9) gene editing approaches, but this remains to be proven in practice. Human stem cell derived new β-cell products could effectively address the global supply challenge for broad application across all forms of diabetes, but recurrent autoimmunity may still remain an insurmountable challenge. Considerable progress in the generation of human stem cell derived SC-β cells from ESC, iPS and other adult cell sources such as mesenchymal stem cells (MSCs) offer huge hope that a personalized, 'syngeneic' cell could be transplanted without risk of alloimmunity, thereby securing sufficient supply to meet future global demand (Cito et al. 2018).

Erythropoietin facilitates definitive endodermal differentiation of mouse embryonic stem cells via activation of ERK signaling

Artificially generated pancreatic β-cells from pluripotent stem cells are expected for cell replacement therapy for type 1 diabetes. Several strategies are adopted to direct pluripotent stem cells toward pancreatic differentiation. However, a standard differentiation method for clinical application has not been established. It is important to develop more effective and safer methods for generating pancreatic β-cells without toxic or mutagenic chemicals. In the present study, we screened several endogenous factors involved in organ development to identify the factor, which induced the efficiency of pancreatic differentiation and found that treatment with erythropoietin (EPO) facilitated the differentiation of mouse embryonic stem cells (ESCs) into definitive endoderm. At an early stage of differentiation, EPO treatment significantly increased Sox17 gene expression, as a marker of the definitive endoderm. Contrary to the canonical function of EPO, it did not affect the levels of phosphorylated JAK2 and STAT5, but stimulated the phosphorylation of ERK1/2 and Akt. The MEK inhibitor U0126 significantly inhibited EPO-induced Sox17 expression. The differentiation of ESCs into definitive endoderm is an important step for the differentiation into pancreatic and other endodermal lineages. This study suggests a possible role of EPO in embryonic endodermal development and a new agent for directing the differentiation into endodermal lineages like pancreatic β-cells.

Bioencapsulation technologies in tissue engineering

Bioencapsulation technologies have played an important role in the developing successes of tissue engineering. Besides offering immunoisolation, they also show promise for cell/tissue banking and the directed differentiation of stem cells, by providing a unique microenvironment. This review describes bioencapsulation technologies and summarizes their recent progress in research into tissue engineering. The review concludes with a brief outlook regarding future research directions in this field.

The role of microRNAs in islet β-cell development

Cell-based therapies suggest novel treatments to overcome the complication of the current therapeutic approaches in diabetes mellitus type 1. Replacement of the destroyed pancreatic islet β-cells by appropriate alternative cells needs an efficient approach to differentiate the cells into viable and functional insulin producing cells. Small non-coding RNA molecules, microRNAs (miRNA), have critical roles in post-transcriptional regulation of gene expression. Therefore, they can direct the cells toward β-cell like cells and control islet β-cell development. Previous reports showed the manipulation of the miRNA expression on islet β-cell differentiation and regeneration. Likewise, the regulation of epithelial to mesenchymal transi-tion by the miR-30 family and the miR-200 family may be a useful approach to conduct islet β-cell development. Investigation of stem cells differentiation showed that the dynamic expression patterns of miR-375 and miR-7 are similar to developing human fetal pancreas while dynamic expression of miR-146a and miR-34a occurred during the differentiation. Moreover, miR-342 and its both targets, FOXA2 and MAFB, are found in β-cell differentiation and maturation. Because miRNAs can target specific transcription factors during islet β-cell development and differentiation, they could be offerred as alternative regenerative treatment for diabetes mellitus. Considering that the application of these non-coding RNAs remains limited in the literature, in this review article, we present an overview of the roles of miRNAs in the islet β-cell development, focusing on the application of different miRNAs in the experimental protocols.

Tissue-Specific Stem Cells Obtained by Reprogramming of Non-Obese Diabetic (NOD) Mouse-Derived Pancreatic Cells Confer Insulin Production in Response to Glucose

Type 1 diabetes occurs due to the autoimmune destruction of pancreatic β-cells in islets. Transplantation of islets is a promising option for the treatment of patients with type 1 diabetes that experience hypoglycemic unawareness despite maximal care, but the present shortage of donor islets hampers such transplantation. Transplantation of insulin-producing cells derived from the patients themselves would be one of the most promising approaches to cure type 1 diabetes. Previously, we demonstrated that insulin-producing cells could be produced by transfecting murine pancreatic cells with Yamanaka’s reprogramming factors. Non-obese diabetic (NOD) mice are naturally occurring mutant mice defective in insulin production due to autoimmune ablation of pancreatic β-cells. In this study, we showed that glucose-sensitive insulin-producing cells are successfully generated by transfecting primary pancreatic cells from NOD mice (aged 6 months old) with a plasmid harboring the cDNAs for Oct-3/4, Sox2, Klf4, and c-Myc. Transfection was repeated 4 times in a 2 day-interval. Sixty-five days after final transfection, cobblestone-like colonies appeared. They proliferated in vitro and expressed pluripotency-related genes as well as Pdx1, a transcription factor specific to tissue-specific stem cells for the β-cell lineage. Transplantation of these cells into nude mice failed to produce teratoma unlike induced pluripotent stem cells (iPSCs). Induction of these cells to the pancreatic β-cell lineage demonstrated their capability to produce insulin in response to glucose. These findings suggest that functional pancreatic β-cells can be produced from patients with type 1 diabetes. We call these resultant cells as “induced tissue-specific stem cells from the pancreas” (iTS-P) that could be valuable sources of safe and effective materials for cell-based therapy in type 1 diabetes.

Genome Editing of the CYP1A1 Locus in iPSCs as a Platform to Map AHR Expression throughout Human Development

The aryl hydrocarbon receptor (AHR) is a ligand activated transcription factor that increases the expression of detoxifying enzymes upon ligand stimulation. Recent studies now suggest that novel endogenous roles of the AHR exist throughout development. In an effort to create an optimized model system for the study of AHR signaling in several cellular lineages, we have employed a CRISPR/CAS9 genome editing strategy in induced pluripotent stem cells (iPSCs) to incorporate a reporter cassette at the transcription start site of one of its canonical targets, cytochrome P450 1A1 (CYP1A1). This cell line faithfully reports on CYP1A1 expression, with luciferase levels as its functional readout, when treated with an endogenous AHR ligand (FICZ) at escalating doses. iPSC-derived fibroblast-like cells respond to acute exposure to environmental and endogenous AHR ligands, and iPSC-derived hepatocytes increase CYP1A1 in a similar manner to primary hepatocytes. This cell line is an important innovation that can be used to map AHR activity in discrete cellular subsets throughout developmental ontogeny. As further endogenous ligands are proposed, this line can be used to screen for safety and efficacy and can report on the ability of small molecules to regulate critical cellular processes by modulating the activity of the AHR.

Human induced pluripotent stem cells differentiate into insulin-producing cells able to engraft in vivo

AIMS

New sources of insulin-secreting cells are strongly required for the cure of diabetes. Recent successes in differentiating embryonic stem cells, in combination with the discovery that it is possible to derive human induced pluripotent stem cells (iPSCs) from somatic cells, have raised the possibility that patient-specific beta cells might be derived from patients through cell reprogramming and differentiation. In this study, we aimed to obtain insulin-producing cells from human iPSCs and test their ability to secrete insulin in vivo.

METHODS

Human iPSCs, derived from both fetal and adult fibroblasts, were differentiated in vitro into pancreas-committed cells and then transplanted into immunodeficient mice at two different stages of differentiation (posterior foregut and endocrine cells).

RESULTS

IPSCs were shown to differentiate in insulin-producing cells in vitro, following the stages of pancreatic organogenesis. At the end of the differentiation, the production of INSULIN mRNA was highly increased and 5 ± 2.9 % of the cell population became insulin-positive. Terminally differentiated cells also produced C-peptide in vitro in both basal and stimulated conditions. In vivo, mice transplanted with pancreatic cells secreted human C-peptide in response to glucose stimulus, but transplanted cells were observed to lose insulin secretion capacity during the time. At histological evaluation, the grafts resulted to be composed of a mixed population of cells containing mature pancreatic cells, but also pluripotent and some neuronal cells.

CONCLUSION

These data overall suggest that human iPSCs have the potential to generate insulin-producing cells and that these differentiated cells can engraft and secrete insulin in vivo.

Cell-Penetrating Peptide as a Means of Directing the Differentiation of Induced-Pluripotent Stem Cells

Protein transduction using cell-penetrating peptides (CPPs) is useful for the delivery of large protein molecules, including some transcription factors. This method is safer than gene transfection methods with a viral vector because there is no risk of genomic integration of the exogenous DNA. Recently, this method was reported as a means for the induction of induced pluripotent stem (iPS) cells, directing the differentiation into specific cell types and supporting gene editing/correction. Furthermore, we developed a direct differentiation method to obtain a pancreatic lineage from mouse and human pluripotent stem cells via the protein transduction of three transcription factors, Pdx1, NeuroD, and MafA. Here, we discuss the possibility of using CPPs as a means of directing the differentiation of iPS cells and other stem cell technologies.

Insulin-producing cells from embryonic stem cells rescues hyperglycemia via intra-spleen migration

Implantation of embryonic stem cells (ESC)-derived insulin-producing cells has been extensively investigated for treatment of diabetes in animal models. However, the in vivo behavior and migration of transplanted cells in diabetic models remains unclear. Here we investigated the location and migration of insulin-producing cells labeled with superparamagnetic iron oxide (SPIO) using a dynamic MRI tracking method. SPIO labeled cells showed hypointense signal under the kidney subcapsules of diabetic mice on MRI, and faded gradually over the visiting time. However, new hypointense signal appeared in the spleen 1 week after transplantation, and became obvious with the time prolongation. Further histological examination proved the immigrated cells were insulin and C-peptide positive cells which were evenly distributed throughout the spleen. These intra-spleen insulin-producing cells maintained their protective effects against hyperglycemia in vivo, and these effects were reversed upon spleen removal. Transplantation of insulin-producing cells through spleen acquired an earlier blood glucose control as compared with that through kidney subcapsules. In summary, our data demonstrate that insulin-producing cells transplanted through kidney subcapsules were not located in situ but migrated into spleen, and rescues hyperglycemia in diabetic models. MRI may provide a novel tracking method for preclinical cell transplantation therapy of diabetes continuously and non-invasively.

High oxygen condition facilitates the differentiation of mouse and human pluripotent stem cells into pancreatic progenitors and insulin-producing cells

Pluripotent stem cells have potential applications in regenerative medicine for diabetes. Differentiation of stem cells into insulin-producing cells has been achieved using various protocols. However, both the efficiency of the method and potency of differentiated cells are insufficient. Oxygen tension, the partial pressure of oxygen, has been shown to regulate the embryonic development of several organs, including pancreatic β-cells. In this study, we tried to establish an effective method for the differentiation of induced pluripotent stem cells (iPSCs) into insulin-producing cells by culturing under high oxygen (O2) conditions. Treatment with a high O2 condition in the early stage of differentiation increased insulin-positive cells at the terminus of differentiation. We found that a high O2 condition repressed Notch-dependent gene Hes1 expression and increased Ngn3 expression at the stage of pancreatic progenitors. This effect was caused by inhibition of hypoxia-inducible factor-1α protein level. Moreover, a high O2 condition activated Wnt signaling. Optimal stage-specific treatment with a high O2 condition resulted in a significant increase in insulin production in both mouse embryonic stem cells and human iPSCs and yielded populations containing up to 10% C-peptide-positive cells in human iPSCs. These results suggest that culturing in a high O2 condition at a specific stage is useful for the efficient generation of insulin-producing cells.