Pancreatic islet differentiation of human embryonic stem cells by microRNA overexpression

Machine learning workflows identify a microRNA signature of insulin transcription in human tissues

Dicer knockout mouse models demonstrated a key role for microRNAs in pancreatic β-cell function. Studies to identify specific microRNA(s) associated with human (pro-)endocrine gene expression are needed. We profiled microRNAs and key pancreatic genes in 353 human tissue samples. Machine learning workflows identified microRNAs associated with (pro-)insulin transcripts in a discovery set of islets (n = 30) and insulin-negative tissues (n = 62). This microRNA signature was validated in remaining 261 tissues that include nine islet samples from individuals with type 2 diabetes. Top eight microRNAs (miR-183-5p, -375-3p, 216b-5p, 183-3p, -7-5p, -217-5p, -7-2-3p, and -429-3p) were confirmed to be associated with and predictive of (pro-)insulin transcript levels. Use of doxycycline-inducible microRNA-overexpressing human pancreatic duct cell lines confirmed the regulatory roles of these microRNAs in (pro-)endocrine gene expression. Knockdown of these microRNAs in human islet cells reduced (pro-)insulin transcript abundance. Our data provide specific microRNAs to further study microRNA-mRNA interactions in regulating insulin transcription.

miR-375 Promotes Pancreatic Differentiation In Vitro by Affecting Different Target Genes at Different Stages

Human embryonic stem cells (hESCs) possess the ability to differentiate into insulin-producing cells (IPCs), which can be used to treat type I diabetes. miR-375 is an essential transcriptional regulator in the development and maturation of the pancreas. In this study, we optimized a protocol to differentiate hESCs into IPCs and successfully obtained IPCs. Then, we performed overexpression and inhibition experiments of miR-375 on cells at different stages of differentiation and performed RNA-seq. The results showed that the expression of miR-375 fluctuated during hESC differentiation and was affected by miR-375 mimics and inhibitors. miR-375 influences global gene expression and the target genes of miR-375. The overexpression of miR-375 can cause changes in multiple signaling pathways during pancreatic development. miR-375 is a major participant in the differentiation of pancreatic β-cells through different target genes at different stages. This study provides new ideas for further investigation of how microRNAs affect cell fate and gene transcription.

Generation of high yield insulin-producing cells (IPCs) from various sources of stem cells

Type 1 diabetes mellitus occurs when beta cell mass is reduced to less than 20% of the normal level due to immune system destruction of beta cell resulting in an inability to secrete enough insulin. The prevalence of diabetes is expanding according to the American Diabetes Association and the World Health Organization (WHO), foretold to exceed 350 million by 2030. The current treatment does not cure many of the serious complications associated with the disease such as neuropathy, nephropathy, dyslipidemia, retinopathy and cardiovascular disease. Whole pancreas or isolated pancreatic islet transplantation as an alternative therapy can prevent or reduce some of the complications of diabetes. However, the shortage of matched organ or islets cells donor and alloimmune responses limit this therapeutic strategy. Recently, several reports have raised extremely promising results to use different sources of stem cells to differentiate insulin-producing cells and focus on the expansion of these alternative sources. Stem cells, due to their potential for multiple differentiation and self-renewal can differentiate into all cell types, including insulin-producing cells (IPCs). Generation of new beta cells can be achieved from various stem cell sources, including embryonic stem cells (ESCs), adult stem cells, such as mesenchymal stem cells (MSCs) and induced pluripotent stem cells (iPSCs). Thus, this chapter discusses on the assistance of cellular reprogramming of various stem cells as candidates for the generation of IPCs using transcription factors/miRNA, cytokines/small molecules and tissue engineering.

The Role of MicroRNAs in the Induction of Pancreatic Differentiation

Stem cell-based therapy is one of the therapeutic options with promising results in the treatment of diabetes. Stem cells from various sources are expanded and induced to generate the cells capable of secreting insulin. These insulin-producing cells [IPCs] could be used as an alternative to islets in the treatment of patients with diabetes. Soluble growth factors, small molecules, geneencoding transcription factors, and microRNAs [miRNAs] are commonly used for the induction of stem cell differentiation. MiRNAs are small non-coding RNAs with 21-23 nucleotides that are involved in the regulation of gene expression by targeting multiple mRNA targets. Studies have shown the dynamic expression of miRNAs during pancreatic development and stem cell differentiation. MiR- 7 and miR-375 are the most abundant miRNAs in pancreatic islet cells and play key roles in pancreatic development as well as islet cell functions. Some studies have tried to use these small RNAs for the induction of pancreatic differentiation. This review focuses on the miRNAs used in the induction of stem cells into IPCs and discusses their functions in pancreatic β-cells.

The Predominant microRNAs in β-cell Clusters for Insulin Regulation and Diabetic Control

micro (mi)-RNAs are vital regulators of multiple processes including insulin signaling pathways and glucose metabolism. Pancreatic β-cells function is dependent on some miRNAs and their target mRNA, which together form a complex regulative network. Several miRNAs are known to be directly involved in β-cells functions such as insulin expression and secretion. These small RNAs may also play significant roles in the fate of β-cells such as proliferation, differentiation, survival and apoptosis. Among the miRNAs, miR-7, miR-9, miR-375, miR-130 and miR-124 are of particular interest due to being highly expressed in these cells. Under diabetic conditions, although no specific miRNA profile has been noticed, the expression of some miRNAs and their target mRNAs are altered by posttranscriptional mechanisms, exerting diverse signs in the pathobiology of various diabetic complications. The aim of this review article is to discuss miRNAs involved in the process of stem cells differentiation into β-cells, resulting in enhanced β-cell functions with respect to diabetic disorders. This paper will also look into the impact of miRNA expression patterns on in vitro proliferation and differentiation of β-cells. The efficacy of the computational genomics and biochemical analysis to link the changes in miRNA expression profiles of stem cell-derived β-cells to therapeutically relevant outputs will be discussed as well.

Directed differentiation into insulin-producing cells using microRNA manipulation

Our commentary is focused on three studies that used microRNA overexpression methods for directed differentiation of stem cells into insulin-producing cells. Islet transplantation is the only cell-based therapy used to treat type 1 diabetes mellitus. However, due to the scarcity of cadaveric donors and limited availability of good quality and quantity of islets for transplant, alternate sources of insulin-producing cells are being studied and used by researchers. This commentary provides an overview of distinct studies focused on manipulating microRNA expression to optimize differentiation of embryonic stem cells or induced pluripotent stem cells into insulin-producing cells. These studies have used different approaches to overexpress microRNAs that are highly abundant in human islets (such as miR-375 and miR-7) in their differentiation protocol to achieve better differentiation into functional islet beta (β)-cells.

Overexpression of microRNA-375 and microRNA-122 promotes the differentiation of human induced pluripotent stem cells into hepatocyte-like cells

MicroRNAs (miRNAs) are involved in the regulation of gene expression. In this study, we evaluated the use of overexpression of microRNA-375 (miR-375) and miR-122 in differentiating the Human Induced Pluripotent Stem Cells (hiPSCs) into functional hepatocyte-like cells (HLCs) without growth factors. We also compared the differentiation by miRNAs versus growth factors. HiPSCs were divided into two main groups: 1- HiPSCs were induced using lentiviral overexpression of miR-375 to differentiate into definitive endoderm (DE) cells in seven days. Then lentiviral overexpression of miR-122 was applied to differentiate DE cells into HLCs in additional 14 days. 2- HiPSCs were differentiated into HLCs using growth factors in 21 days. DE and hepatocyte markers were investigated by qRT-PCR, immunofluorescence, secretion analysis and LDL uptake assay. In the produced cells of both groups: the expression levels of DE markers (FOXA2 and SOX17) and hepatocyte markers (albumin, CK18, and HNF4a) in comparison with the undifferentiated hiPSCs increased significantly in seven and 21 days respectively. The albumin and urea secretion and LDL uptake were also detected. These results weren't significantly different between two groups. Therefore, we demonstrated that the over expression of miR-375 and then miR-122 could differentiate hiPSCs into functional HLCs without growth factors for developing cell-based therapies.

Identification, Prediction and Data Analysis of Noncoding RNAs: A Review

BACKGROUND

Noncoding RNAs (ncRNAs) which play an important role in various cellular processes are important in medicine as well as in drug design strategies. Different studies have shown that ncRNAs are dis-regulated in cancer cells and play an important role in human tumorigenesis. Therefore, it is important to identify and predict such molecules by experimental and computational methods, respectively. However, to avoid expensive experimental methods, computational algorithms have been developed for accurately and fast prediction of ncRNAs.

OBJECTIVE

The aim of this review was to introduce the experimental and computational methods to identify and predict ncRNAs structure. Also, we explained the ncRNA's roles in cellular processes and drugs design, briefly.

METHOD

In this survey, we will introduce ncRNAs and their roles in biological and medicinal processes. Then, some important laboratory techniques will be studied to identify ncRNAs. Finally, the state-of-the-art models and algorithms will be introduced along with important tools and databases.

RESULTS

The results showed that the integration of experimental and computational approaches improves to identify ncRNAs. Moreover, the high accurate databases, algorithms and tools were compared to predict the ncRNAs.

CONCLUSION

ncRNAs prediction is an exciting research field, but there are different difficulties. It requires accurate and reliable algorithms and tools. Also, it should be mentioned that computational costs of such algorithm including running time and usage memory are very important. Finally, some suggestions were presented to improve computational methods of ncRNAs gene and structural prediction.

miR‑6835‑3p regulates the function of pancreatic islet cells by modulating the expression of AdipoR1

Effective drugs and strategies for treating type 2 diabetes mellitus (2‑DM) are urgently required. The aim of the present study was to elucidate the mechanism underlying microRNA (miR)‑6835‑3p regulation of adiponectin receptor 1 (AdipoR1) expression and the miR‑6835‑3p/AdipoR1 signaling pathway in pancreatic islet cells. In addition, the potential anti‑diabetes effect of miR‑6835‑3p on insulin secretion was investigated. Luciferase activity analysis was performed to evaluate how miR‑6835‑3p targets the 3'‑untranslated region of AdipoR1. The SU.86.86 and MIN‑6 cell lines were co‑cultured with or without miR‑6835‑3p inhibitors or mimics, and the insulin secretory functions of these cell lines were then determined. Luciferase reporter analysis revealed that AdipoR1 was a direct target of miR‑6835‑3p. In addition, miR‑6835‑3p overexpression suppressed the mRNA and protein expression levels of AdipoR1 in the SU.86.86 and MIN‑6 cell lines. Furthermore, miR‑6835‑3p exerted negative effects on insulin secretion in SU.86.86 and MIN‑6 cells, which were mediated by regulating AdipoR1 expression. AdipoR1 was a direct target of miR‑6835‑3p; therefore, inhibition of AdiopR1 expression may reduce insulin secretion and may be considered a key regulator of insulin secretion. The results of the present study suggested that targeting AdipoR1 with miR‑6835‑3p inhibitors may be a potential strategy for promoting glucose‑stimulated insulin secretion, and thereby, may be an effective treatment for type 2‑DM.

miR-7 Modulates hESC Differentiation into Insulin-Producing Beta-like Cells and Contributes to Cell Maturation

Human pluripotent stem cells retain the extraordinary capacity to differentiate into pancreatic beta cells. For this particular lineage, more effort is still required to stress the importance of developing an efficient, reproducible, easy, and cost-effective differentiation protocol to obtain more mature, homogeneous, and functional insulin-secreting cells. In addition, microRNAs (miRNAs) have emerged as a class of small non-coding RNAs that regulate many cellular processes, including pancreatic differentiation. Some miRNAs are known to be preferentially expressed in islets. Of note, miR-375 and miR-7 are two of the most abundant pancreatic miRNAs, and they are necessary for proper pancreatic islet development. Here we provide new insight into specific miRNAs involved in pancreatic differentiation. We found that miR-7 is differentially expressed during the differentiation of human embryonic stem cells (hESCs) into a beta cell-like phenotype and that its modulation plays an important role in generating mature pancreatic beta cells. This strategy may be exploited to optimize the potential for in vitro differentiation of hESCs into insulin-producing beta-like cells for use in preclinical studies and future clinical applications as well as the prospective uses of miRNAs to improve this process.

Adiponectin receptor 1-mediated micro RNA-323-3p regulates functions of the MIN6 cell line via the AMP-activated protein kinase/sirtuin-1 pathway

Background

The development of an effective treatment for type 2 diabetes mellitus is urgently needed. This study aimed to investigate the role of micro RNA (miR)-323-3p in regulating the expression of adiponectin receptor 1 (AdipoR1), as well as the insulin secretion and cell function of pancreatic MIN6 β-cells.

Methods

MIN6 cells were treated with miR-323-3p mimics or inhibitors, and the effects on cell growth, proliferation, mitosis, and insulin secretion were studied. The expression levels of sirtuin-1 (SIRT-1) and AMP-activated protein kinase (AMPK) genes were also assessed.

Results

miR-323-3p directly targeted AdipoR1, and suppressed its expression at mRNA and protein levels. It also regulated the protein expression of SIRT-1 and AMPK, which are downstream target genes of the AdipoR1 signaling pathway. miR-323-3p suppressed cell growth, proliferation, mitosis, and insulin secretion of MIN6 cells.

Conclusions

miR-323-3p appears to be a crucial diabetes factor that mediates its functions by inhibiting the AdipoR1/AMPK/SIRT-1 signaling pathway. Our findings suggest that targeting AdipoR1 with inhibitors of miR-323-3p is a potential approach to improve the function of islet cells.

Embryonic Stem Cells in Development and Regenerative Medicine

After progressive improvement in embryonic stem (ES) cell field, several studies have been conducted to explore the usage of ES cells in regenerative medicine. Unlimited self renewal and pluripoteny properties, combined with encouraging preclinical trials, remark that ES cell technology might be promising for clinical practice. ES cells, which can form three germ layers in vitro, are potential candidates to study development at the cellular and molecular level. Understanding the cell fate decision and differentiation processes during development might enable generating functional progenitor cells for tissue restoration. Progression in gene modifications and tissue engineering technology has facilitated the derivation of desired cells for therapy. Success in differentiation protocols and identification the regulatory pathways simplify the research for clinical applications. Although there are established protocols for cell differentiation in vitro and promising preclinical studies in vivo, many challenges need to be adressed before clinical translation. In this review, ES cells are discussed as a model of development in vitro and as a potential candidate for regenerative medicine. This review also dissusses current challenges for ES cell based therapy.

Modeling spatial distribution of oxygen in 3d culture of islet beta-cells

Three-dimensional (3D) scaffold culture of pancreatic β-cell has been proven to be able to better mimic physiological conditions in the body. However, one critical issue with culturing pancreatic β-cells is that β-cells consume large amounts of oxygen, and hence insufficient oxygen supply in the culture leads to loss of β-cell mass and functions. This becomes more significant when cells are cultured in a 3D scaffold. In this study, in order to understand the effect of oxygen tension inside a cell-laden collagen culture on β-cell proliferation, a culture model with encapsulation of an oxygen-generator was established. The oxygen-generator was made by embedding hydrogen peroxide into nontoxic polydimethylsiloxane to avoid the toxicity of a chemical reaction in the β-cell culture. To examine the effectiveness of the oxygenation enabled 3D culture, the spatial-temporal distribution of oxygen tension inside a scaffold was evaluated by a mathematical modeling approach. Our simulation results indicated that an oxygenation-aided 3D culture would augment the oxygen supply required for the β-cells. Furthermore, we identified that cell seeding density and the capacity of the oxygenator are two critical parameters in the optimization of the culture. Notably, cell-laden scaffold cultures with an in situ oxygen supply significantly improved the β-cells' biological function. These β-cells possess high insulin secretion capacity. The results obtained in this work would provide valuable information for optimizing and encouraging functional β-cell cultures. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 33:221-228, 2017.

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.

The expression and functional roles of microRNAs in stem cell differentiation

microRNAs (miRNAs) are key regulators of cell state transition and retention during stem cell proliferation and differentiation by post-transcriptionally downregulating hundreds of conserved target genes via seed-pairing in their 3' untranslated region. In embryonic and adult stem cells, dozens of miRNAs that elaborately control stem cell processes by modulating the transcriptomic context therein have been identified. Some miRNAs accelerate the change of cell state into progenitor cell lineages-such as myoblast, myeloid or lymphoid progenitors, and neuro precursor stem cells-and other miRNAs decelerate the change but induce proliferative activity, resulting in cell state retention. This cell state choice can be controlled by endogenously or exogenously changing miRNA levels or by including or excluding target sites. This control of miRNA-mediated gene regulation could improve our understanding of stem cell biology and facilitate their development as therapeutic tools.

Changes in microRNA expression during differentiation of embryonic and induced pluripotent stem cells to definitive endoderm

Pluripotent stem cells, including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have the potential to treat type 1 diabetes through cell replacement therapy. However, the protocols used to generate insulin-expressing cells in vitro frequently result in cells which have an immature phenotype and are functionally restricted. MicroRNAs (miRNAs) are now known to be important in cell fate specification, and a unique miRNA signature characterises pancreatic development at the definitive endoderm stage. Several studies have described differences in miRNA expression between ESCs and iPSCs. Here we have used microarray analysis both to identify miRNAs up- or down-regulated upon endoderm formation, and also miRNAs differentially expressed between ESCs and iPSCs. Several miRNAs fulfilling both these criteria were identified, suggesting that differences in the expression of these miRNAs may affect the ability of pluripotent stem cells to differentiate into definitive endoderm. The expression of these miRNAs was validated by qRT-PCR, and the relationship between one of these miRNAs, miR-151a-5p, and its predicted target gene, SOX17, was investigated by luciferase assay, and suggested an interaction between miR-151a-5p and this key transcription factor. In conclusion, these findings demonstrate a unique miRNA expression pattern for definitive endoderm derived from both embryonic and induced pluripotent stem cells.

Proliferation and odontogenic differentiation of BMP2 gene‑transfected stem cells from human tooth apical papilla: an in vitro study

Stem cells from the apical papilla (SCAP) have odontogenic potential, which plays a pivotal role in the root dentin development of permanent teeth. Human bone morphogenetic protein 2 (BMP2) is a well-known gene that participates in regulating the odontogenic differentiation of dental tissue-derived stem cells. However, little is known regarding the effects of the BMP2 gene on the proliferation and odontogenic differentiation of SCAP. This study aimed to evaluate the odontogenic differentiation potential of lentiviral-mediated BMP2 gene-transfected human SCAP (SCAP/BMP2) in vitro. SCAP were isolated by enzymatic dissociation of human teeth apical papillae. The multipotential of SCAP was verified by their osteogenic and adipogenic differentiation characteristics. The phenotype of SCAP was evaluated by flow cytometry (FCM). The proliferation status of the blank vector-transfected SCAP (SCAP/Vector) and SCAP/BMP2 was analyzed by a cell counting kit-8 (CCK-8). Odontogenic genes, including alkaline phosphatase (ALP), osteocalcin (OCN), dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP1) of the two groups of cells were evaluated by quantitative polymerase chain reaction (qPCR). ALP staining and alizarin red (AR) staining of the cells was performed on the 16th day after transfection. In vitro results of CCK-8, qPCR, ALP and AR staining demonstrated that: i) SCAP/BMP2 had a comparable proliferation rate to SCAP/Vector; ii) SCAP/BMP2 presented significantly better potential to differentiate into odontoblasts compared to SCAP/Vector by upregulating ALP, OCN, DSPP and DMP1 genes; iii) more ALP granules and mineralized deposits were formed by SCAP/BMP2 as compared to SCAP/Vector. The results suggested that lentiviral-mediated BMP2 gene transfection enhances the odontogenic differentiation capacity of human SCAP in vitro.

The potential of cell-based therapy for diabetes and diabetes-related vascular complications

Cell therapy has enormous potential for the treatment of conditions of unmet medical need. Cell therapy may be applied to diabetes mellitus in the context of beta cell replacement or for the treatment of diabetic complications. A large number of cell types including hematopoietic stem cells, mesenchymal stem cells, umbilical cord blood, conditioned lymphocytes, mononuclear cells, or a combination of these cells have been shown to be safe and feasible for the treatment of patients with diabetes mellitus. The first part of this review article will focus on the current perspective of the role of embryonic stem cells and inducible pluripotent stem cells for beta cell replacement and the current clinical data on cell-based therapy for the restoration of normoglycemia. The second part of this review will highlight the therapeutic role of MSCs in islet cells cotransplantation and the management of diabetes related vascular complications.