15 results on '"Heimberg, Harry"'
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2. Reprogramming of human exocrine pancreas cells to beta cells.
- Author
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Staels, Willem, Heremans, Yves, and Heimberg, Harry
- Abstract
One of the key promises of regenerative medicine is providing a cure for diabetes. Cell-based therapies are proving their safety and efficiency, but donor beta cell shortages and immunological issues remain major hurdles. Reprogramming of human pancreatic exocrine cells towards beta cells would offer a major advantage by providing an abundant and autologous source of beta cells. Over the past decade our understanding of transdifferentiation processes greatly increased allowing us to design reprogramming protocols that fairly aim for clinical trials. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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3. Purification of Rat Pancreatic ß-Cells by Fluorescence-Activated Cell Sorting.
- Author
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Walker, John M., Özcan, Sabire, Stangé, Geert, Van De Casteele, Mark, and Heimberg, Harry
- Abstract
The β-cell is receptive to intricate hormonal, neuronal and nutrient signaling which is key for normal physiology but complicates the study of specific effects of individual factors on β-cell function. To preserve the microenvironment of the β-cell, most studies of β-cell physiology have been performed on in vitro cultured islets of Langerhans. However, whereas islets in the pancreas are highly vascularized and oxygenated, ischemic conditions cannot be avoided in the center of cultured isolated islets, leading to abnormal islet cell function and viability. Moreover, in the absence of blood flow, intercellular communication in islets is likely to change as well. Furthermore, contamination of islets with anatomically associated acinar cells is inevitable during isolation and may have a major influence on the specificity of experiments. [ABSTRACT FROM AUTHOR]
- Published
- 2003
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4. Clinical Immunosuppressants Inhibit Inflammatory, Proliferative, and Reprogramming Potential, But not Angiogenesis of Human Pancreatic Duct Cells
- Author
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Ding, Lei, Heremans, Yves, Pipeleers, Daniel, Ling, Zhidong, Heimberg, Harry, Gysemans, Conny, and Mathieu, Chantal
- Abstract
The presence of pancreatic duct cells in clinical islet grafts may affect long-term metabolic success. Human pancreatic duct cells express factors that may exert both protective and damaging effects on islet cells in the graft. Here we studied the potential of commonly used immunosuppressive drugs in islet transplantation—sirolimus, tacrolimus, and mycophenolate mofetil (MMF)—to influence the inflammatory and angiogenic capacity of human pancreatic duct cells in addition to their proliferation and reprogramming abilities. Our data show that the expression of specific proinflammatory cytokines by the human pancreatic duct cells was either unaltered or inhibited by the immunosuppressants studied, especially tacrolimus and MMF, whereas expression of chemotactic and angiogenic factors was unaffected. Although none of the immunosuppressants directly led to duct cell death, MMF prevented duct cell proliferation, and sirolimus inhibited neurogenin 3-mediated duct-to-(neuro)endocrine cell reprogramming. Our data indicate that the immunosuppressant tacrolimus was the least aggressive on the angiogenic, proliferative, and reprogramming potential of human pancreatic duct cells, while it was most powerful in inhibiting inflammatory cytokines, which may influence the outcome of islet transplantation.
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- 2015
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5. Reversal of hyperglycemia in diabetic mice by a marginal islet mass together with human blood outgrowth endothelial cells is independent of the delivery technique and blood clot-induced processes
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Coppens, Violette, Heremans, Yves, Leuckx, Gunter, Suenens, Krista, Jacobs-Tulleneers-Thevissen, Daniel, Verdonck, Kristoff, Luttun, Aernout, Heimberg, Harry, and De Leu, Nico
- Abstract
We recently reported that human blood outgrowth endothelial cells (BOEC) are supportive to reverse hyperglycemia in marginal islet mass-transplanted diabetic mice. In this report, we investigated whether the observed effect was evoked by islet packing in a blood clot prior to transplantation or could be mimicked by another method of islet/cell delivery. A marginal islet mass with or without BOEC was grafted underneath the kidney capsule of diabetic recipient mice via a (blood clot-independent) tubing system and compared with previous islet packing in a blood clot. The effect on metabolic outcome of both delivery techniques as well as the additive effect of BOEC was subsequently evaluated. Marginal islet mass transplantation via a tubing system required more islets per recipient than via a blood clot. Using the tubing method, transplantation of a marginal islet mass combined with 5 x 105BOEC resulted in reversal of hyperglycemia, improved glucose tolerance and increased kidney insulin content. The present study provides evidence that (1) previous packing in a blood clot results in more effective islet delivery compared with tubing; (2) BOEC exert a beneficial effect on marginal islet transplantation, independent of grafting technique and potential blood clot-induced processes. These data further support the use of BOEC in (pre-) clinical studies that aim to improve current islet transplantation protocols.
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- 2013
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6. Pdx1- and Ngn3-Cre-Mediated PLAG1Expression in the Pancreas Leads to Endocrine Hormone Imbalances That Affect Glucose Metabolism
- Author
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Declercq, Jeroen, Kumar, Anujith, Gysemans, Conny, Di Pietro, Caterina, Schraenen, Anica, Chintinne, Marie, Lemaire, Katleen, Van Lommel, Leentje, Van De Casteele, Marc, Heimberg, Harry, Pipeleers, Daniel, Schuit, Frans C., Mathieu, Chantal, Ectors, Nadine, Van De Ven, Wim J. M., and Verfaillie, Catherine M.
- Abstract
Pleomorphic adenoma gene-like 1 (PLAGL1)has been linked to transient neonatal diabetes mellitus. Here, we investigated the role of the related pleomorphic adenoma gene 1 (PLAG1)in glucose homeostasis. PLAG1transgenic mice in which expression of the PLAG1transgene can be targeted to different organs by Cre-mediated modulation were crossed with Pdx1-Creor Ngn3-Cremice, resulting in double transgenic P1-Pdx1Cre or P1-Ngn3Cre mice, respectively. P1-Pdx1Cre and P1-Ngn3Cre mice developed hyperplasia of pancreatic islets due to increased β- and δ- but not α-cell proliferation. In young P1-Pdx1Cre mice (less than 15 weeks) there was a balanced increase in the pancreatic content of insulin and somatostatin, which was associated with normoglycemia. In older P1-Pdx1Cre mice the pancreatic somatostatin content far exceeded that of insulin, leading to the progressive development of severe hypoglycemia beyond 30 weeks. In contrast, in older P1-Ngn3Cre mice the relative increase of the pancreatic insulin content exceeded that of somatostatin and these mice remained normoglycemic. In conclusion, forced expression of PLAG1under the control of the Pdx1or Ngn3promoter in murine pancreas induces different degrees of endocrine hormone imbalances within the pancreas, which is associated with hypoglycemia in P1-Pdx1Cre mice but not P1-Ngn3Cre mice. These results suggest that once stem cell-derived islet transplantations become possible, the appropriate balance between different hormone-producing cells will need to be preserved to prevent deregulated glucose metabolism.
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- 2011
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7. Investigation and Characterization of the Duct Cell-Enriching Process During Serum-Free Suspension and Monolayer Culture Using the Human Exocrine Pancreas Fraction
- Author
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Klein, Tino, Heremans, Yves, Heimberg, Harry, Pipeleers, Daniel, Madsen, Ole D., Serup, Palle, and Heller, R. Scott
- Abstract
We aimed to characterize a serum-free culture system resulting in highly enriched duct cells from human exocrine pancreas. In addition, we tested the effect of vascular endothelial growth factor (VEGF) on endothelial cell proliferation and endocrine differentiation of the duct cells.
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- 2009
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8. Expression of the Notch Signaling Pathway and Effect on Exocrine Cell Proliferation in Adult Rat Pancreas
- Author
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Rooman, Ilse, De Medts, Nele, Baeyens, Luc, Lardon, Jessy, De Breuck, Saskia, Heimberg, Harry, and Bouwens, Luc
- Abstract
When pancreatic tissue is injured after duct obstruction, acinoductal metaplasia is observed. Similar metaplastic changes occur when exocrine pancreatic cells are isolated and cultured. We demonstrate that under these experimental conditions the exocrine acinar cells lose their differentiated characteristics: expression of the acinar transcription factors p48/Ptf1α and Mist1 is decreased or lost, whereas expression of the embryonic transcription factor Pdx1 is increased. The receptors Notch1 and Notch2, members of the DSL family of Notch ligands, and the target genes in the Notch-signaling pathway Hes1, Hey1, and Hey2become strongly up-regulated. We noted also reduced expression of Sel1L, a Notch repressor that is normally highly expressed in exocrine pancreas. Stimulation of Notch by its ligand Jagged1 diminished the proliferation of cultured metaplastic exocrine cells. Chemical inhibition of Notch signaling resulted in increased proliferation and induction of the cell-cycle regulator p21Cip1. This effect seems to be Hes1-independent and mainly coincides with decreased Hey1 and Hey2 mRNA expression. In conclusion, we demonstrate that during acinoductal metaplasia the Notch-signaling pathway is activated concomitantly with changes in transcription factor expression of pancreatic acinar cells. In addition, we show that Notch signaling is implicated in the suppression of proliferation of these metaplastic exocrine cells. The latter may be important in protection from neoplastic transformation.
- Published
- 2006
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9. A Comprehensive Analysis of Cytokine-induced and Nuclear Factor-κB-dependent Genes in Primary Rat Pancreatic β-Cells*
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Cardozo, Alessandra K., Heimberg, Harry, Heremans, Yves, Leeman, Ruth, Kutlu, Burak, Kruhøffer, Mogens, Ørntoft, Torben, and Eizirik, Décio L.
- Abstract
Type 1 diabetes mellitus results from an autoimmune destruction of pancreatic β-cells. Cytokines, such as interleukin-1β and interferon-γ, are putative mediators of immune-induced β-cell death and, under in vitroconditions, cause β-cell apoptosis. We have recently shown that interleukin-1β + interferon-γ modifies the expression of >200 genes in β-cells. Several of these genes are putative targets for the transcription factor nuclear factor-κB (NF-κB), and in subsequent experiments we showed that NF-κB activation is mostly pro-apoptotic in β-cells. To identify cytokine-induced and NF-κB-regulated genes in primary rat β-cells, we presently combined two experimental approaches: 1) blocking of NF-κB activation in cytokine-exposed β-cells by a recombinant adenovirus (AdIκB(SA)2) containing an inhibitor of NF-κB α (IκBac) super-repressor (S32A/S36A) and 2) study of gene expression by microarray analysis. We identified 66 cytokine-modified and NF-κB-regulated genes in β-cells. Cytokine-induced NF-κB activation decreased Pdx-1 and increased c-Myc expression. This, together with NF-κB-dependent inhibition of Glut-2, pro-hormone convertase-1, and Isl-1 expression, probably contributes to the loss of differentiated β-cell functions. NF-κB also regulates several genes encoding for chemokines and cytokines in β-cells. The present data suggest that NF-κB is a key “switch regulator” of transcription factors and gene networks controlling cytokine-induced β-cell dysfunction and death.
- Published
- 2001
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10. Cellular Origin of Hexokinase in Pancreatic Islets*
- Author
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Schuit, Frans, Moens, Karen, Heimberg, Harry, and Pipeleers, Daniel
- Abstract
Transgenic or tumoral pancreatic islet beta cells with enhanced expression of low Kmhexokinases (HK) exhibit a leftward shift of the normal dose-response curve for glucose-induced insulin release. Furthermore, HK catalyzes roughly 50% of total glucose phosphorylation measured in extracts from freshly isolated rodent islets, suggesting that HK participates in the process of glucose sensing in beta cells. We previously observed that HK activity represents 20% of total glucose phosphorylation in purified rat beta cell preparations and that HK is not homogenously distributed over these cells. The present study provides several arguments for the idea that HK detected in freshly isolated rat islets or islet cell preparations originates mainly from contaminating exocrine cells. First, reverse transcriptase-polymerase chain reaction using isoform-specific primers allowed detection of hexokinase I and IV mRNA in rat beta cells, whereas the messenger levels encoding the hexokinase II and III isoforms were undetectably low. However, immunoblots indicated that hexokinase I protein was 10-fold more abundant in freshly isolated islets and flow-sorted exocrine cells than in purified rat beta cell preparations. Second, comparison of HK activity in the different pancreatic cell types resulted in 15–25-fold higher values in exocrine than in endocrine cells (acinar cells: 21 ± 3 pmol of glucose 6-phosphate formed/h/ng of DNA; duct cells: 30 ± 8 pmol/h/ng of DNA; islet beta cells: 1.2 ± 0.2 pmol/h/ng DNA; alpha cells: 0.9 ± 0.4 pmol/h/ng of DNA). Since freshly purified beta cell preparations contain 3 ± 1% exocrine cells, at least 50% of their HK activity can be accounted for by exocrine contamination. Third, after 5 days of culture of purified islet beta cells, both HK activity and the proportion of exocrine cells decreased by more than 1 order of magnitude, while the ratio of glucokinase over hexokinase activity increased more than 10-fold. Finally, preincubating the cells with 50 mmol/liter 2-deoxyglucose did not affect glucose stimulation of insulin biosynthesis and release. In conclusion, the observation that pancreatic exocrine cells are responsible for a major part of HK activity in islet cell preparations cautions against the use of HK measurements in islet extracts in the study of these enzymes in glucose sensing by pancreatic beta cells.
- Published
- 1999
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11. Glucosamine-induced Insulin Resistance in 3T3-L1 Adipocytes Is Caused by Depletion of Intracellular ATP*
- Author
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Hresko, Richard C., Heimberg, Harry, Chi, Maggie M.-Y., and Mueckler, Mike
- Abstract
Glucosamine, which enters the hexosamine pathway downstream of the rate-limiting step, has been routinely used to mimic the insulin resistance caused by high glucose and insulin. We investigated the effect of glucosamine on insulin-stimulated glucose transport in 3T3-L1 adipocytes. The Δ-insulin (insulin-stimulated minus basal) value for 2-deoxyglucose uptake was dramatically inhibited with increasing concentrations of glucosamine with an ED50of 1.95 mm. Subcellular fractionation experiments demonstrated that reduction in insulin-stimulated 2-deoxyglucose uptake by glucosamine was due to an inhibition of translocation of both Glut 1 and Glut 4 from the low density microsomes (LDM) to the plasma membrane. Analysis of the insulin signaling cascade revealed that glucosamine impaired insulin receptor autophosphorylation, insulin receptor substrate (IRS-1) phosphorylation, IRS-1-associated PI 3-kinase activity in the LDM, and AKT-1 activation by insulin. Measurement of intracellular ATP demonstrated that the effects of glucosamine were highly correlated with its ability to reduce ATP levels. Reduction of intracellular ATP using azide inhibited Glut 1 and Glut 4 translocation from the LDM to the plasma membrane, insulin receptor autophosphorylation, and IRS-1 tyrosine phosphorylation. Additionally, both the reduction in intracellular ATP and the effects on insulin action caused by glucosamine could be prevented by the addition of inosine, which served as an alternative energy source in the medium. We conclude that direct administration of glucosamine can rapidly lower cellular ATP levels and affect insulin action in fat cells by mechanisms independent of increased intracellular UDP-N-acetylhexosamines and that increased metabolism of glucose via the hexosamine pathway may not represent the mechanism of glucose toxicity in fat cells.
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- 1998
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12. Differences in Glucose Transporter Gene Expression between Rat Pancreatic α- and β-Cells Are Correlated to Differences in Glucose Transport but Not in Glucose Utilization *
- Author
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Heimberg, Harry, De Vos, Anick, Pipeleers, Daniel, Thorens, Bernard, and Schuit, Frans
- Abstract
Glucose exerts inverse effects upon the secretory function of islet α- and β-cells, suppressing glucagon release and increasing insulin release. This diverse action may result from differences in glucose transport and metabolism between the two cell types. The present study compares glucose transport in rat α- and β-cells. β-Cells transcribed GLUT2 and, to a lesser extent, GLUT 1; α-cells contained GLUT1 but no GLUT2 mRNA. No other GLUT-like sequences were found among cDNAs from α- or β-cells. Both cell types expressed 43-kDa GLUT1 protein which was enhanced by culture. The 62-kDa β-cell GLUT2 protein was converted to a 58-kDa protein after trypsin treatment of the cells without detectable consequences upon glucose transport kinetics. In β-cells, the rates of glucose transport were 10-fold higher than in α-cells. In both cell types, glucose uptake exceeded the rates of glucose utilization by a factor of 10 or more. Glycolytic flux, measured as D-[53H]glucose utilization, was comparable in α- and β-cells between 1 and 10 mmol/liter substrate. In conclusion, differences in glucose transporter gene expression between α- and β-cells can be correlated with differences in glucose transport kinetics but not with different glucose utilization rates.
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- 1995
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13. Ductal Ngn3-expressing progenitors contribute to adult β cell neogenesis in the pancreas
- Author
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Gribben, Christopher, Lambert, Christopher, Messal, Hendrik A., Hubber, Ella-Louise, Rackham, Chloe, Evans, Ian, Heimberg, Harry, Jones, Peter, Sancho, Rocio, and Behrens, Axel
- Abstract
Ductal cells have been proposed as a source of adult β cell neogenesis, but this has remained controversial. By combining lineage tracing, 3D imaging, and single-cell RNA sequencing (scRNA-seq) approaches, we show that ductal cells contribute to the β cell population over time. Lineage tracing using the Neurogenin3 (Ngn3)-CreERT line identified ductal cells expressing the endocrine master transcription factor Ngn3 that were positive for the δ cell marker somatostatin and occasionally co-expressed insulin. The number of hormone-expressing ductal cells was increased in Akita+/−diabetic mice, and ngn3heterozygosity accelerated diabetes onset. scRNA-seq of Ngn3 lineage-traced islet cells indicated that duct-derived somatostatin-expressing cells, some of which retained expression of ductal markers, gave rise to β cells. This study identified Ngn3-expressing ductal cells as a source of adult β cell neogenesis in homeostasis and diabetes, suggesting that this mechanism, in addition to β cell proliferation, maintains the adult islet β cell population.
- Published
- 2021
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14. Lineage Tracing Evidence for Transdifferentiation of Acinar to Duct Cells and Plasticity of Human Pancreas.
- Author
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Houbracken, Isabelle, de Waele, Evelien, Lardon, Jessy, Ling, Zhidong, Heimberg, Harry, Rooman, Ilse, and Bouwens, Luc
- Subjects
CELL differentiation ,PANCREATIC acinar cells ,NEUROPLASTICITY ,DUCTAL carcinoma ,CELL culture ,IMMUNOCYTOCHEMISTRY ,MITOGEN-activated protein kinases ,DEVELOPMENTAL cytology - Abstract
Background & Aims: Animal studies have indicated that pancreatic exocrine acinar cells have phenotypic plasticity. In rodents, acinar cells can differentiate into ductal precursors that can be converted to pancreatic ductal adenocarcinoma or insulin-producing endocrine cells. However, little is known about human acinar cell plasticity. We developed nongenetic and genetic lineage tracing methods to study the fate of human acinar cells in culture. Methods: Human exocrine tissue was obtained from organ donors, dissociated, and cultured. Cell proliferation and survival were measured, and cell phenotypes were analyzed by immunocytochemistry. Nongenetic tracing methods were developed based on selective binding and uptake by acinar cells of a labeled lectin (Ulex europaeus agglutinin 1). Genetic tracing methods were developed based on adenoviral introduction of a Cre-lox reporter system, controlled by the amylase promoter. Results: Both tracing methods showed that human acinar cells can transdifferentiate into cells that express specific ductal markers, such as cytokeratin 19, hepatocyte nuclear factor 1β, SOX9, CD133, carbonic anhydrase II, and cystic fibrosis transmembrane conductance regulator. Within 1 week of culture, all surviving acinar cells had acquired a ductal phenotype. This transdifferentiation was decreased by inhibiting mitogen-activated protein kinase signaling. Conclusions: Human acinar cells have plasticity similar to that described in rodent cells. These results might be used to develop therapeutic strategies for patients with diabetes or pancreatic cancer. [ABSTRACT FROM AUTHOR]
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- 2011
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15. Notch Signaling as Gatekeeper of Rat Acinar-to-β-Cell Conversion in Vitro.
- Author
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Baeyens, Luc, Bonné, Stefan, Bos, Tomas, Rooman, Ilse, Peleman, Cindy, Lahoutte, Tony, German, Michael, Heimberg, Harry, and Bouwens, Luc
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NOTCH genes ,CELLULAR signal transduction ,PANCREATIC acinar cells ,PANCREATIC beta cells ,LABORATORY rats ,EPIDERMAL growth factor ,CELLULAR therapy - Abstract
Background & Aims: Exocrine acinar cells in the pancreas are highly differentiated cells that retain a remarkable degree of plasticity. After isolation and an initial phase of dedifferentiation in vitro, rodent acinar cells can convert to endocrine β-cells when cultured in the presence of appropriate factors. The mechanisms regulating this phenotypic conversion are largely unknown. Methods: Using rat acinar cell cultures, we studied the role of Notch signaling in a model of acinar-to-β-cell conversion. Results: We report a novel lectin-based cell labeling method to demonstrate the acinar origin of newly formed insulin-expressing β-cells. This method allows for specific tracing of the acinar cells. We demonstrate that growth factor-induced conversion of adult acinar cells to β-cells is negatively regulated by Notch1 signaling. Activated Notch1 signaling prevents the reexpression of the proendocrine transcription factor Neurogenin-3, the key regulator of endocrine development in the embryonic pancreas. Interfering with Notch1 signaling allows modulating the acinar cell susceptibility to the differentiation-inducing factors. Its inhibition significantly improves β-cell neoformation with approximately 30% of acinar cells that convert to β-cells. The newly formed β-cells mature when transplanted ectopically and are capable of restoring normal blood glycemia in diabetic recipients. Conclusions: We report for the first time an efficient way to reprogram one third of the acinar cells to β-cells by adult cell type conversion. This could find application in cell replacement therapy of type 1 diabetes, provided that it can be translated from rodent to human models. [Copyright &y& Elsevier]
- Published
- 2009
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