Neurogenic differentiation 1 directs differentiation of cytokeratin 19-positive human pancreatic nonendocrine cells into insulin-producing cells

Beneficial impact of Ac3IV, an AVP analogue acting specifically at V1a and V1b receptors, on diabetes islet morphology and transdifferentiation of alpha- and beta-cells

Ac3IV (Ac-CYIQNCPRG-NH2) is an enzymatically stable vasopressin analogue that selectively activates Avpr1a (V1a) and Avpr1b (V1b) receptors. In the current study we have employed streptozotocin (STZ) diabetic transgenic Ins1Cre/+;Rosa26-eYFP and GluCreERT2;Rosa26-eYFP mice, to evaluate the impact of sustained Ac3IV treatment on pancreatic islet cell morphology and transdifferentiation. Twice-daily administration of Ac3IV (25 nmol/kg bw) to STZ-diabetic Ins1Cre/+;Rosa26-eYFP mice for 12 days increased pancreatic insulin (p<0.01) and significantly reversed the detrimental effects of STZ on pancreatic islet morphology. Such benefits were coupled with increased (p<0.01) beta-cell proliferation and decreased (p<0.05) beta-cell apoptosis. In terms of islet cell lineage tracing, induction of diabetes increased (p<0.001) beta- to alpha-cell differentiation in Ins1Cre/+;Rosa26-eYFP mice, with Ac3IV partially reversing (p<0.05) such transition events. Comparable benefits of Ac3IV on pancreatic islet architecture were observed in STZ-diabetic GluCreERT2;ROSA26-eYFP transgenic mice. In this model, Ac3IV provoked improvements in islet morphology which were linked to increased (p<0.05-p<0.01) transition of alpha- to beta-cells. Ac3IV also increased (p<0.05-p<0.01) CK-19 co-expression with insulin in pancreatic ductal and islet cells. Blood glucose levels were unchanged by Ac3IV in both models, reflecting the severity of diabetes induced. Taken together these data indicate that activation of islet receptors for V1a and V1b positively modulates alpha- and beta-cell turnover and endocrine cell lineage transition events to preserve beta-cell identity and islet architecture.

Highly efficient ex vivo lentiviral transduction of primary human pancreatic exocrine cells

The lack of efficient gene transfer methods into primary human pancreatic exocrine cells hampers studies on the plasticity of these cells and their possible role in beta cell regeneration. Therefore, improved gene transfer protocols are needed. Lentiviral vectors are widely used to drive ectopic gene expression in mammalian cells, including primary human islet cells. Here we aimed to optimize gene transfer into primary human exocrine cells using modified lentiviral vectors or transduction conditions. We evaluated different promoters, viral envelopes, medium composition and transduction adjuvants. Transduction efficiency of a reporter vector was evaluated by fluorescence microscopy and flow cytometry. We show that protamine sulfate-assisted transduction of a VSV-G-pseudotyped vector expressing eGFP under the control of a CMV promoter in a serum-free environment resulted in the best transduction efficiency of exocrine cells, reaching up to 90% of GFP-positive cells 5 days after transduction. Our findings will enable further studies on pancreas (patho)physiology that require gene transfer such as gene overexpression, gene knockdown or lineage tracing studies.

Maternal high-fat diet impairs glucose metabolism, β-cell function and proliferation in the second generation of offspring rats

Background

This study aimed to assess the impact of perinatal high-fat (HF) diet in female Sprague-Dawley rats (F0) on glucose metabolism and islet function in their early life of second-generation of offspring (F2).

Methods

F0 rats were fed with a standard chow (SC) or HF diet for 8 weeks before mating, up to termination of lactation for their first-generation of offspring (F1-SC and F1-HF). F1 females were mated with normal males at the age of week 11, and producing F2 offspring (F2-SC, F2-HF). All the offspring were fed SC diet after weaning for 3 weeks. The glucose level and islet function of F2 offspring were assessed at the age of week 3 and 12.

Results

The F2-HF offspring had a high birth weight and maintained a higher body mass at the age of week 3 and 12, along with an impaired glucose tolerance and lower serum insulin levels compared with the F2-SC. β-cell proliferation was also impaired in the islets of F2-HF rats at the age of week 3 and 12. The pancreatic and duodenal homeobox factor-1 (Pdx1) and Neurogenic differentiation 1 (NeuroD1) expressions were decreased in the islet of F2-HF rats at the age of week 12.

Conclusions

Maternal HF diet during pre-gestation, gestation, and lactation in rats could result in the increased body weight and glucose intolerance in their early life of F2 offspring due to impaired β-cell function and proliferation.

Differentiation of iPSCs into insulin-producing cells via adenoviral transfection of PDX-1, NeuroD1 and MafA

AIMS

The aim of this study was to evaluate the effect of PDX-1 (pancreatic and duodenal homeobox-1), NeuroD1 (neurogenic differentiation-1) and MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homolog A) in the differentiation of induced pluripotent stem cells (iPSCs) into insulin-producing cells and to explore this new approach of cell transplantation therapy for type 1 diabetes in mice.

METHODS

iPSCs were infected with adenovirus (Ad-Mouse PDX-1-IRES-GFP, Ad-Mouse NeuroD1-IRES-GFP and Ad-Mouse Mafa-IRES-GFP) and then differentiated into insulin-producing cells in vitro. RT-PCR was applied to detect insulin gene expression, immunofluorescence to identify insulin protein, and mouse insulin enzyme-linked immunosorbent assay (ELISA) was used to evaluate the amount of insulin at different concentration of glucose. Insulin-producing cells were transplanted into the liver parenchyma of diabetic mice. Immunohistochemistry, intraperitoneal glucose tolerance test (IPGTT) and fasting blood glucose (FBG) were performed to assess the function of insulin-producing cells.

RESULTS

Insulin biosynthesis and secretion were induced in iPSCs and insulin-producing cells were responsive to glucose in a dose-dependent manner. Gene expression of the three-gene-modified embryoid bodies (EBs) was similar to the mouse pancreatic β cell line MIN6. Transplantation of insulin-producing cells into type I diabetic mice resulted in hyperglycemia reversal.

CONCLUSIONS

The insulin-producing cells we obtained from three-gene-modified EBs may be used as seed cells for tissue engineering and may represent a cell replacement strategy for the production of β cells for the treatment of type 1 diabetes.

A new method for generating insulin-secreting cells from human pancreatic epithelial cells after islet isolation transformed by NeuroD1

The generation of insulin-secreting cells from nonendocrine pancreatic epithelial cells (NEPEC) has been demonstrated for potential clinical use in the treatment of diabetes. However, previous methods either had limited efficacy or required viral vectors, which hinder clinical application. In this study, we aimed to establish an efficient method of insulin-secreting cell generation from NEPEC without viral vectors. We used nonislet fractions from both research-grade human pancreata from brain-dead donors and clinical pancreata after total pancreatectomy with autologous islet transplantation to treat chronic pancreatitis. It is of note that a few islets could be mingled in the nonislet fractions, but their influence could be limited. The NeuroD1 gene was induced into NEPEC using an effective triple lipofection method without viral vectors to generate insulin-secreting cells. The differentiation was promoted by adding a growth factor cocktail into the culture medium. Using the research-grade human pancreata, the effective method showed high efficacy in the differentiation of NEPEC into insulin-positive cells that secreted insulin in response to a glucose challenge and improved diabetes after being transplanted into diabetic athymic mice. Using the clinical pancreata, similar efficacy was obtained, even though those pancreata suffered chronic pancreatitis. In conclusion, our effective differentiation protocol with triple lipofection method enabled us to achieve very efficient insulin-secreting cell generation from human NEPEC without viral vectors. This method offers the potential for supplemental insulin-secreting cell transplantation for both allogeneic and autologous islet transplantation.

Islet organogenesis, angiogenesis and innervation

The pancreas is characterized by a major component, an exocrine and ductal system involved in digestion, and a minor component, the endocrine islets represented by islet micro-organs that tightly regulate glucose homoeostasis. Pancreatic organogenesis is strictly co-ordinated by transcription factors that are expressed sequentially to yield functional islets capable of maintaining glucose homoeostasis. Angiogenesis and innervation complete islet development, equipping islets to respond to metabolic demands. Proper regulation of this triad of processes during development is critical for establishing functional islets.