Enhancement of insulin-producing cell differentiation from embryonic stem cells using pax4-nucleofection method

Pax4 in Health and Diabetes

Paired box 4 (Pax4) is a key transcription factor involved in the embryonic development of the pancreatic islets of Langerhans. Consisting of a conserved paired box domain and a homeodomain, this transcription factor plays an essential role in early endocrine progenitor cells, where it is necessary for cell-fate commitment towards the insulin-secreting β cell lineage. Knockout of Pax4 in animal models leads to the absence of β cells, which is accompanied by a significant increase in glucagon-producing α cells, and typically results in lethality within days after birth. Mutations in Pax4 that cause an impaired Pax4 function are associated with diabetes pathogenesis in humans. In adulthood, Pax4 expression is limited to a distinct subset of β cells that possess the ability to proliferate in response to heightened metabolic needs. Upregulation of Pax4 expression is known to promote β cell survival and proliferation. Additionally, ectopic expression of Pax4 in pancreatic islet α cells or δ cells has been found to generate functional β-like cells that can improve blood glucose regulation in experimental diabetes models. Therefore, Pax4 represents a promising therapeutic target for the protection and regeneration of β cells in the treatment of diabetes. The purpose of this review is to provide a thorough and up-to-date overview of the role of Pax4 in pancreatic β cells and its potential as a therapeutic target for diabetes.

An epigenome-wide association study of insulin resistance in African Americans

Background

African Americans have a high risk for type 2 diabetes (T2D) and insulin resistance. Studies among other population groups have identified DNA methylation loci associated with insulin resistance, but data in African Americans are lacking. Using DNA methylation profiles of blood samples obtained from the Illumina Infinium® HumanMethylation450 BeadChip, we performed an epigenome-wide association study to identify DNA methylation loci associated with insulin resistance among 136 non-diabetic, unrelated African American men (mean age 41.6 years) from the Howard University Family Study.

Results

We identified three differentially methylated positions (DMPs) for homeostatic model assessment of insulin resistance (HOMA-IR) at 5% FDR. One DMP (cg14013695, HOXA5) is a known locus among Mexican Americans, while the other two DMPs are novel—cg00456326 (OSR1; beta = 0.027) and cg20259981 (ST18; beta = 0.010). Although the cg00456326 DMP is novel, the OSR1 gene has previously been found associated with both insulin resistance and T2D in Europeans. The genes HOXA5 and ST18 have been implicated in biological processes relevant to insulin resistance. Differential methylation at the significant HOXA5 and OSR1 DMPs is associated with differences in gene expression in the iMETHYL database. Analysis of differentially methylated regions (DMRs) did not identify any epigenome-wide DMRs for HOMA-IR. We tested transferability of HOMA-IR associated DMPs from five previous EWAS in Mexican Americans, Indian Asians, Europeans, and European ancestry Americans. Out of the 730 previously reported HOMA-IR DMPs, 47 (6.4%) were associated with HOMA-IR in this cohort of African Americans.

Conclusions

The findings from our study suggest substantial differences in DNA methylation patterns associated with insulin resistance across populations. Two of the DMPs we identified in African Americans have not been reported in other populations, and we found low transferability of HOMA-IR DMPs reported in other populations in African Americans. More work in African-ancestry populations is needed to confirm our findings as well as functional analyses to understand how such DNA methylation alterations contribute to T2D pathology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01309-4.

Gastrin producing syngeneic mesenchymal stem cells protect non-obese diabetic mice from type 1 diabetes

Progressive destruction of pancreatic islet β-cells by immune cells is a primary feature of type 1 diabetes (T1D) and therapies that can restore the functional β-cell mass are needed to alleviate disease progression. Here, we report the use of mesenchymal stromal/stem cells (MSCs) for the production and delivery of Gastrin, a peptide hormone that is produced by intestinal cells and foetal islets and can increase β-Cell mass, to promote protection from T1D. A single injection of syngeneic MSCs that were engineered to express Gastrin (Gastrin-MSCs) caused a significant delay in hyperglycaemia in non-obese diabetic (NOD) mice compared to engineered control-MSCs. Similar treatment of early-hyperglycaemic mice caused the restoration of euglycemia for a considerable duration, and these therapeutic effects were associated with the protection of, and/or higher frequencies of, insulin-producing islets and less severe insulitis. While the overall immune cell phenotype was not affected profoundly upon treatment using Gastrin-MSCs or upon in vitro culture, pancreatic lymph node cells from Gastrin-MSC treated mice, upon ex vivo challenge with self-antigen, showed a Th2 and Th17 bias, and diminished the diabetogenic property in NOD-Rag1 deficient mice suggesting a disease protective immune modulation under Gastrin-MSC treatment associated protection from hyperglycaemia. Overall, this study shows the potential of production and delivery of Gastrin in vivo, by MSCs, in protecting insulin-producing β-cells and ameliorating the disease progression in T1D.

Directed Differentiation of Pluripotent Stem Cells by Transcription Factors

Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs) have been used as promising tools for regenerative medicine, disease modeling, and drug screening. Traditional and common strategies for pluripotent stem cell (PSC) differentiation toward disease-relevant cell types depend on sequential treatment of signaling molecules identified based on knowledge of developmental biology. However, these strategies suffer from low purity, inefficiency, and time-consuming culture conditions. A growing body of recent research has shown efficient cell fate reprogramming by forced expression of single or multiple transcription factors. Here, we review transcription factor-directed differentiation methods of PSCs toward neural, muscle, liver, and pancreatic endocrine cells. Potential applications and limitations are also discussed in order to establish future directions of this technique for therapeutic purposes.

The Diabetes-Linked Transcription Factor PAX4: From Gene to Functional Consequences

Paired box 4 (PAX4) is a key factor in the generation of insulin producing β-cells during embryonic development. In adult islets, PAX4 expression is sequestered to a subset of β-cells that are prone to proliferation and more resistant to stress-induced apoptosis. The importance of this transcription factor for adequate pancreatic islets functionality has been manifested by the association of mutations in PAX4 with the development of diabetes, independently of its etiology. Overexpression of this factor in adult islets stimulates β-cell proliferation and increases their resistance to apoptosis. Additionally, in an experimental model of autoimmune diabetes, a novel immunomodulatory function for this factor has been suggested. Altogether these data pinpoint at PAX4 as an important target for novel regenerative therapies for diabetes treatment, aiming at the preservation of the remaining β-cells in parallel to the stimulation of their proliferation to replenish the β-cell mass lost during the progression of the disease. However, the adequate development of such therapies requires the knowledge of the molecular mechanisms controlling the expression of PAX4 as well as the downstream effectors that could account for PAX4 action.

Differentiation of stem cells into insulin-producing cells: current status and challenges. Arch Immunol Ther Exp (Warsz). 2013;61:149-158. [PMID: 23283518 DOI: 10.1007/s00005-012-0213-y]

Diabetes mellitus is one of the most serious public health challenges of the twenty-first century. Allogenic islet transplantation is an efficient therapy for type 1 diabetes. However, immune rejection, side effects of immunosuppressive treatment as well as lack of sufficient donor organs limits its potential. In recent years, several promising approaches for generation of new pancreatic β cells have been developed. This review provides an overview of current status of pancreatic and extra-pancreatic stem cells differentiation into insulin-producing cells and the possible application of these cells for diabetes treatment. The PubMed database was searched for English language articles published between 2001 and 2012, using the keyword combinations: diabetes mellitus, differentiation, insulin-producing cells, stem cells.

Restoring insulin production for type 1 diabetes

Current therapies for the treatment of type 1 diabetes include daily administration of exogenous insulin and, less frequently, whole-pancreas or islet transplantation. Insulin injections often result in inaccurate insulin doses, exposing the patient to hypo- and/or hyperglycemic episodes that lead to long-term complications. Islet transplantation is also limited by lack of high-quality islet donors, early graft failure, and chronic post-transplant immunosuppressive treatment. These barriers could be circumvented by designing a safe and efficient strategy to restore insulin production within the patient's body. Porcine islets have been considered as a possible alternative source of transplantable insulin-producing cells to replace human cadaveric islets. More recently, embryonic or induced pluripotent stem cells have also been examined for their ability to differentiate in vitro into pancreatic endocrine cells. Alternatively, it may be feasible to generate new β-cells by ectopic expression of key transcription factors in endogenous non-β-cells. Finally, engineering surrogate β-cells by in vivo delivery of the insulin gene to specific tissues is also being studied as a possible therapy for type 1 diabetes. In the present review, we discuss these different approaches to restore insulin production.

α-cell role in β-cell generation and regeneration

This review considers the role of α-cells in β-cell generation and regeneration. We present recent evidence obtained from lineage-tracing studies showing that α-cells can serve as progenitors of β-cells and present a hypothetical model how injured β-cells might activate α-cells in adult islets to promote β-cell regeneration. β-cells appear to arise by way of their trans-differentiation from undifferentiated α progenitor cells, pro-α-cells, both during embryonic development of the islets and in the adult pancreas in response to β-cell injuries. Plasticity of α-cells is endowed by the expression of the gene encoding proglucagon, a prohormone that can give rise to glucagon and glucagon-like peptides (GLPs). The production of glucagon from proglucagon is characteristic of fully-differentiated α-cells whereas GLP-1 is a product of undifferentiated α-cells. GLP-1, a cell growth and survival factor, is proposed to promote the expansion of neurogenin3-expressing, undifferentiated pro-α-cells during development. β-cells arise from pro-α-cells by a change in the relative amounts of the transcription factors Arx and Pax4, master regulators of the α- and β-cell lineages, respectively. A paracrine/autocrine model is proposed whereby injuries of β-cells in adult islets induce the production and release of factors, such as stromal cell-derived factor-1, that cause the de-differentiation of adjacent α-cells into pro-α-cells. Pro-α-cells produce GLP-1 and its receptor that renders them competent to trans-differentiate into β-cells. The trans-differentiation of pro-α-cells into β-cells provides a potentially exploitable mechanism for the regeneration of β-cells in individuals with type 1 diabetes.

Enhanced differentiation of three-gene-reprogrammed induced pluripotent stem cells into adipocytes via adenoviral-mediated PGC-1α overexpression

Induced pluripotent stem cells formed by the introduction of only three factors, Oct4/Sox2/Klf4 (3-gene iPSCs), may provide a safer option for stem cell-based therapy than iPSCs conventionally introduced with four-gene iPSCs. Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) plays an important role during brown fat development. However, the potential roles of PGC-1α in regulating mitochondrial biogenesis and the differentiation of iPSCs are still unclear. Here, we investigated the effects of adenovirus-mediated PGC-1α overexpression in 3-gene iPSCs. PGC-1α overexpression resulted in increased mitochondrial mass, reactive oxygen species production, and oxygen consumption. Microarray-based bioinformatics showed that the gene expression pattern of PGC-1α-overexpressing 3-gene iPSCs resembled the expression pattern observed in adipocytes. Furthermore, PGC-1α overexpression enhanced adipogenic differentiation and the expression of several brown fat markers, including uncoupling protein-1, cytochrome C, and nuclear respiratory factor-1, whereas it inhibited the expression of the white fat marker uncoupling protein-2. Furthermore, PGC-1α overexpression significantly suppressed osteogenic differentiation. These data demonstrate that PGC-1α directs the differentiation of 3-gene iPSCs into adipocyte-like cells with features of brown fat cells. This may provide a therapeutic strategy for the treatment of mitochondrial disorders and obesity.

Isolation of genes involved in pancreas regeneration by subtractive hybridization

The deterioration of β cells in the pancreas is a crucial factor in the progression of diabetes mellitus; therefore, the recovery of β cells is of vital importance for effective diabetic therapeutic strategies. Partially pancreatectomized rats have been used for the investigation of pancreatic regeneration. Because it was determined that tissue extract from the partially-dissected pancreas induces pancreatic differentiation in embryonic stem cells, paracrine factors were thought to be involved in the regeneration. In this study, we screened for genes that had higher mRNA levels 2 days after 60%-pancreatectomy. The genes were isolated using subtractive hybridization and DNA sequencing. Twelve genes (adipsin, Aplp2, Clu, Col1a2, Glul, Krt8, Lgmn, LOC299907, LOC502894, Pla2g1b, Reg3α and Xbp1) were identified, and RT-PCR and real-time PCR analyses were performed to validate their expression levels. Among the genes identified, three genes (Glul, Lgmn and Reg3a) were selected for further analyses. Assays revealed that Glul and Reg3α enhance cell growth. Glul, Lgmn and Reg3α change the expression level of islet marker genes, where NEUROD, NKX2.2, PAX4 and PAX6 are up-regulated and somatostatin is down-regulated. Thus, we believe that Glul, Lgmn and Reg3a can serve as novel targets in diabetes mellitus genetic therapy.

Functional characterization and expression profiling of human induced pluripotent stem cell- and embryonic stem cell-derived endothelial cells

With regard to human induced pluripotent stem cells (hiPSCs), in which adult cells are reprogrammed into embryonic-like cells using defined factors, their functional and transcriptional expression pattern during endothelial differentiation has yet to be characterized. In this study, hiPSCs and human embryonic stem cells (hESCs) were differentiated using the embryoid body method, and CD31(+) cells were sorted. Fluorescence activated cell sorting analysis of hiPSC-derived endothelial cells (hiPSC-ECs) and hESC-derived endothelial cells (hESC-ECs) demonstrated similar endothelial gene expression patterns. We showed functional vascular formation by hiPSC-ECs in a mouse Matrigel plug model. We compared the gene profiles of hiPSCs, hESCs, hiPSC-ECs, hESC-ECs, and human umbilical vein endothelial cells (HUVECs) using whole genome microarray. Our analysis demonstrates that gene expression variation of hiPSC-ECs and hESC-ECs contributes significantly to biological differences between hiPSC-ECs and hESC-ECs as well as to the "distances" among hiPSCs, hESCs, hiPSC-ECs, hESC-ECs, and HUVECs. We further conclude that hiPSCs can differentiate into functional endothelial cells, but with limited expansion potential compared with hESC-ECs; thus, extensive studies should be performed to explore the cause and extent of such differences before clinical application of hiPSC-ECs can begin.

Induction of insulin-producing cells derived from endometrial mesenchymal stem-like cells

Studies have demonstrated that mesenchymal stem-like cells can be isolated from endometrium. However, the potential of endometrial-derived stem cells to differentiate into insulin-positive cells and functionally secrete insulin remains undetermined. We isolated endometrial mesenchymal stem-like cells (EMSCs) from human endometrial tissue from six donors. The insulin-secreting function of EMSCs was further analyzed in vitro and in transplanted grafts in vivo. We successfully isolated EMSCs from human endometrium, and our results showed that EMSCs expressed high levels of stemness genes (Nanog, Oct-4, Nestin). Under specific induction conditions for 2 weeks, EMSCs formed three-dimensional spheroid bodies (SBs) and secreted C-peptide. The high insulin content of SB-EMSCs was confirmed by enzyme-linked immunosorbent assay, and glucose responsiveness was demonstrated by measuring glucose-dependent insulin secretion. Using cDNA microarrays, we found that the expression profiles of SB-EMSCs are related to those of islet tissues. Insulin and C-peptide production in response to glucose was significantly higher in SB-EMSCs than in undifferentiated EMSC controls. Furthermore, upon differentiation, SB-EMSCs displayed increased mRNA expression levels of NKx2.2, Glut2, insulin, glucagon, and somatostatin. Our results also showed that SB-EMSCs were more resistant to oxidative damage and oxidative damage-induced apoptosis than fibroblasts from the same patient. It is noteworthy that SB-EMSCs xenotransplanted into immunocompromised mice with streptozotocin-induced diabetes restored blood insulin levels to control values and greatly prolonged the survival of graft cells. These data suggest that EMSCs not only play a novel role in the differentiation of pancreatic progenitors, but also can functionally enhance insulin production to restore the regulation of blood glucose levels in an in vivo transplantation model.

Resveratrol promotes osteogenic differentiation and protects against dexamethasone damage in murine induced pluripotent stem cells

Resveratrol is a natural polyphenol antioxidant that has been shown to facilitate osteogenic differentiation. A recent breakthrough has demonstrated that ectopic expression of four genes is sufficient to reprogram murine and human fibroblasts into induced pluripotent stem (iPS) cells. However, the roles of resveratrol in the differentiation and cytoprotection of iPS cells have never been studied. In this study, we showed that, in addition to cardiac cells, neuron-like cells, and adipocytes, mouse iPS cells could differentiate into osteocyte-like cells. Using atomic force microscopy that provided nanoscale resolution, we monitored mechanical properties of living iPS cells during osteogenic differentiation. The intensity of mineralization and stiffness in differentiating iPS significantly increased after 14 days of osteogenic induction. Furthermore, resveratrol was found to facilitate osteogenic differentiation in both iPS and embryonic stem cells, as shown by increased mineralization, up-regulation of osteogenic markers, and decreased elastic modulus. Dexamethasone-induced apoptosis in iPS cell-derived osteocyte-like cells was effectively prevented by pretreatment with resveratrol. Furthermore, resveratrol significantly increased manganese superoxide dismutase expression and intracellular glutathione level, thereby efficiently decreasing dexamethasone-induced reactive oxygen species (ROS) production and cytotoxicity. Transplantation experiments using iPS cell-derived osteocyte-like cells further demonstrated that oral intake of resveratrol could up-regulate osteopontin expression and inhibit teratoma formation in vivo. In sum, resveratrol can facilitate differentiation of iPS cells into osteocyte-like cells, protect these iPS cell-derived osteocyte-like cells from glucocorticoid-induced oxidative damage, and decrease tumorigenicity of iPS cells. These findings implicate roles of resveratrol and iPS cells in the stem cell therapy of orthopedic diseases.

Effects of intrahepatic bone-derived mesenchymal stem cells autotransplantation on the diabetic Beagle dogs

BACKGROUND

To assess the effects of intrahepatic autotransplantation of bone-derived Beagle canine mesenchymal stem cells (BcMSCs) containing human insulin and EGFP in diabetic Beagle dogs.

MATERIALS AND METHODS

BcMSCs were isolated from Beagle canine bone marrow, expanded, and transfected with a recombinant retrovirus MSCV carrying human insulin and EGFP. Animals were made diabetic by an intravenous administration of streptozotocin (STZ, 30 mg/kg) and alloxan (50 mg/kg), followed by intrahepatic autotransplantation of transfected BcMSCs. The variations of body weight, blood glucose, serum insulin levels, and plasma C-peptide were determined after autotransplantation. BcMSCs' survival and human insulin expression in liver and serum were examined by fluorescent microscopy, radioimmunoassay (RIA), and immunohistochemistry (IHC).

RESULTS

The body weight of diabetic Beagle dogs received BcMSCs transplantation increased by 11.09% within 16 wk after treatment, and the average blood glucose levels were 19.80±3.13 mmol/L (d 7) and 9.78±3.11 mmol/L (d 112), while in untreated animals, the average values were 21.20±3.26 mmol/L (d 7) and 22.5±3.22 mmol/L (d 112), showing a significant difference (P<0.05). The detection of C-peptide excluded the possible function of regenerative β cells. However, glucose tolerance test revealed BcMSCs group response was not as efficient as that of normal islets, although they could respond to the glucose challenge.

CONCLUSION

Experimental diabetes could be relieved effectively for up to 16 wk by intrahepatic autotransplantation of BcMSCs expressing human insulin, which implies a novel approach of gene therapy for type I diabetes.

Establishment of endoderm progenitors by SOX transcription factor expression in human embryonic stem cells

In this study, we explore endoderm cell fate regulation through the expression of lineage-determining transcription factors. We demonstrate that stable endoderm progenitors can be established from human ES cells by constitutive expression of SOX7 or SOX17, producing extraembryonic endoderm and definitive endoderm progenitors, respectively. In teratoma assays and growth factor-mediated differentiation, SOX7 cells appear restricted to the extraembryonic endoderm, and SOX17 cells demonstrate a mesendodermal phenotype in teratomas and the ability to undergo endoderm maturation in vitro in the absence of cytokine-mediated endoderm induction. These endoderm progenitor cells maintain a stable phenotype through many passages in culture, thereby providing new tools to explore the pathways of endoderm differentiation.

Reduced serum concentration is permissive for increased in vitro endocrine differentiation from murine embryonic stem cells

Embryonic stem cells (ESCs) have been shown to be capable of differentiating into pancreatic progenitors and insulin-producing cells in vitro. However, before ESC derivatives can be used in clinical settings, efficient selective differentiation needs to be achieved. Essential to improving ESC differentiation to islet endocrine cells is an understanding of the influences of extrinsic signals and transcription factors on cell specification. Herein, we investigate the influence of serum-supplemented growth conditions on the differentiation of murine ESCs to endocrine lineages in the context of over-expression of two pancreatic transcription factors, Pdx1 and Ngn3. To study the effect of different serum formulations and concentrations on the ability of murine ESCs to differentiate into endocrine cells in vitro, cells were grown into embryoid bodies and then differentiated in various serum replacement (SR), fetal calf serum (FCS) and serum-free conditions. Using immunohistochemistry and quantitative real-time RT-PCR (QPCR), we found that, of the conditions tested, 1% SR differentiation medium resulted in the highest levels of insulin-1 mRNA and significantly increased the total number of insulin-expressing cells. Applying this knowledge to cell lines in which Pdx1 or Ngn3 transgene expression could be induced by exposure to doxycycline we differentiated TetPDX1 and TetNgn3 ESCs under conditions of either 10% FCS or 1% SR medium. In the presence of 10% serum, induced expression of either Pdx1 or Ngn3 in differentiating ESCs resulted in modest increases in hormone transcripts and cell counts. However, changing the serum formulation from 10% FCS to 1% SR significantly enhanced the number of insulin+/C-peptide+ cells in parallel with increased insulin-1 transcript levels in both inducible cell lines. In summary, these data demonstrate that induced expression of key pancreatic transcription factors in combination with low serum/SR concentrations increases endocrine cell differentiation from murine ESCs.

Pax genes in embryogenesis and oncogenesis

The paired box genes are a family of nine developmental control genes, which in human beings (PAX) and mice (Pax) encode nuclear transcription factors. The temporal and spatial expressions of these highly conserved genes are tightly regulated during foetal development including organogenesis. PAY/Paxgenes are switched off during the terminal differentiation of most structures. Specific mutations within a number of PAX/Pax genes lead to developmental abnormalities in both human beings and mice. Mutation in PAX3 causes Waardenburg syndrome, and craniofacial-deafness-hand syndrome. The Splotch phenotype in mouse exhibits defects in neural crest derivatives such as, pigment cells, sympathetic ganglia and cardiac neural crest-derived structures. The PAX family also plays key roles in several human malignancies. In particular, PAX3 is involved in rhabdomyosarcoma and tumours of neural crest origin, including melanoma and neuroblastoma. This review critically evaluates the roles of PAX/Pax in oncogenesis. It especially highlights recent advances in knowledge of how their genetic alterations directly interfere in the transcriptional networks that regulate cell differentiation, proliferation, migration and survival and may contribute to oncogenesis.