scholarly journals ECM-enriched alginate hydrogels for bioartificial pancreas: an ideal niche to improve insulin secretion and diabetic glucose profile

2019 ◽  
Vol 17 (4) ◽  
pp. 228080001984892 ◽  
Author(s):  
Joana Crisóstomo ◽  
Ana M Pereira ◽  
Sílvia J Bidarra ◽  
Ana C Gonçalves ◽  
Pedro L Granja ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cells ◽  
Diabetic Patients ◽  
Bioartificial Pancreas ◽  
Multicellular Spheroids ◽  
Rgd Peptides ◽  
Alginate Hydrogels ◽  
And Function

Introduction: The success of a bioartificial pancreas crucially depends on ameliorating encapsulated beta cells survival and function. By mimicking the cellular in vivo niche, the aim of this study was to develop a novel model for beta cells encapsulation capable of establishing an appropriate microenvironment that supports interactions between cells and extracellular matrix (ECM) components. Methods: ECM components (Arg-Gly-Asp, abbreviated as RGD) were chemically incorporated in alginate hydrogels (alginate-RGD). After encapsulation, INS-1E beta cells outcome was analyzed in vitro and after their implantation in an animal model of diabetes. Results: Our alginate-RGD model demonstrated to be a good in vitro niche for supporting beta cells viability, proliferation, and activity, namely by improving the key feature of insulin secretion. RGD peptides promoted cell–matrix interactions, enhanced endogenous ECM components expression, and favored the assembly of individual cells into multicellular spheroids, an essential configuration for proper beta cell functioning. In vivo, our pivotal model for diabetes treatment exhibited an improved glycemic profile of type 2 diabetic rats, where insulin secreted from encapsulated cells was more efficiently used. Conclusions: We were able to successfully introduce a novel valuable function in an old ally in biomedical applications, the alginate. The proposed alginate-RGD model stands out as a promising approach to improve beta cells survival and function, increasing the success of this therapeutic strategy, which might greatly improve the quality of life of an increasing number of diabetic patients worldwide.

scholarly journals The dynamin-related GTPase Opa1 is required for glucose-stimulated ATP production in pancreatic beta cells

2011 ◽  
Vol 22 (13) ◽  
pp. 2235-2245 ◽  
Author(s):  
Zhongyan Zhang ◽  
Nobunao Wakabayashi ◽  
Junko Wakabayashi ◽  
Yasushi Tamura ◽  
Woo-Jin Song ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Electron Transport ◽  
Beta Cells ◽  
Pancreatic Beta Cells ◽  
Electron Transport Chain ◽  
Chain Complex ◽  
Atp Production ◽  
Transport Chain

Previous studies using in vitro cell culture systems have shown the role of the dynamin-related GTPase Opa1 in apoptosis prevention and mitochondrial DNA (mtDNA) maintenance. However, it remains to be tested whether these functions of Opa1 are physiologically important in vivo in mammals. Here, using the Cre-loxP system, we deleted mouse Opa1 in pancreatic beta cells, in which glucose-stimulated ATP production in mitochondria plays a key role in insulin secretion. Beta cells lacking Opa1 maintained normal copy numbers of mtDNA; however, the amount and activity of electron transport chain complex IV were significantly decreased, leading to impaired glucose-stimulated ATP production and insulin secretion. In addition, in Opa1-null beta cells, cell proliferation was impaired, whereas apoptosis was not promoted. Consequently, mice lacking Opa1 in beta cells develop hyperglycemia. The data suggest that the function of Opa1 in the maintenance of the electron transport chain is physiologically relevant in beta cells.

scholarly journals Recent Advances in Three-Dimensional Multicellular Spheroid Culture and Future Development

Micromachines ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 96
Author(s):  
Honglin Shen ◽  
Shuxiang Cai ◽  
Chuanxiang Wu ◽  
Wenguang Yang ◽  
Haibo Yu ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Multicellular Spheroids ◽  
Three Dimensional Model ◽  
Advantages And Disadvantages ◽  
High Throughput Drug Screening ◽  
Tumor Research ◽  
Basic Biology ◽  
And Function

Three-dimensional multicellular spheroids (MCSs) have received extensive attention in the field of biomedicine due to their ability to simulate the structure and function of tissues in vivo more accurately than traditional in vitro two-dimensional models and to simulate cell–cell and cell extracellular matrix (ECM) interactions. It has become an important in vitro three-dimensional model for tumor research, high-throughput drug screening, tissue engineering, and basic biology research. In the review, we first summarize methods for MCSs generation and their respective advantages and disadvantages and highlight the advances of hydrogel and microfluidic systems in the generation of spheroids. Then, we look at the application of MCSs in cancer research and other aspects. Finally, we discuss the development direction and prospects of MCSs

scholarly journals Hyperglycemia downregulates Connexin36 in pancreatic islets via the upregulation of ICER-1/ICER-1γ

2013 ◽  
Vol 51 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Jacques-Antoine Haefliger ◽  
Françoise Rohner-Jeanrenaud ◽  
Dorothée Caille ◽  
Anne Charollais ◽  
Paolo Meda ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Pancreatic Islets ◽  
Chronic Exposure ◽  
Prolonged Exposure ◽  
Mrna Levels ◽  
Adult Rats ◽  
Junction Protein ◽  
And Function

Channels formed by the gap junction protein Connexin36 (CX36) contribute to the proper control of insulin secretion. We previously demonstrated that chronic exposure to glucose decreases Cx36 levels in insulin-secreting cells in vitro. Here, we investigated whether hyperglycemia also regulates Cx36 in vivo. Using a model of continuous glucose infusion in adult rats, we showed that prolonged (24–48 h) hyperglycemia reduced the Cx36 gene Gjd2 mRNA levels in pancreatic islets. Accordingly, prolonged exposure to high glucose concentrations also reduced the expression and function of Cx36 in the rat insulin-producing INS-1E cell line. The glucose effect was blocked after inhibition of the cAMP/PKA pathway and was associated with an overexpression of the inducible cAMP early repressor ICER-1/ICER-1γ, which binds to a functional cAMP-response element in the promoter of the Cx36 gene Gjd2. The involvement of this repressor was further demonstrated using an antisense strategy of ICER-1 inhibition, which prevented glucose-induced downregulation of Cx36. The data indicate that chronic exposure to glucose alters the in vivo expression of Cx36 by the insulin-producing β-cells through ICER-1/ICER-1γ overexpression. This mechanism may contribute to the reduced glucose sensitivity and altered insulin secretion, which contribute to the pathophysiology of diabetes.

scholarly journals Small Islets Transplantation Superiority to Large Ones: Implications from Islet Microcirculation and Revascularization

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Wenjuan Li ◽  
Ruxing Zhao ◽  
Jidong Liu ◽  
Meng Tian ◽  
Yiran Lu ◽  
...  
Keyword(s):  
Cell Mass ◽  
Diabetic Patients ◽  
Vascular Endothelial ◽  
Pancreatic Islet Transplantation ◽  
Histological Phenotype ◽  
And Function ◽  
Endothelial Growth Factor ◽  
Selection Of

Pancreatic islet transplantation is a promising therapy to regain glycemic control in diabetic patients. The selection of ideal grafts is the basis to guarantee short-term effectivity and longevity of the transplanted islets. Contradictory to the traditional notion, recent findings implied the superiority of small islets for better transplantation outcomes rather than the large and intact ones. However, the mechanisms remain to be elucidated. Recent evidences emphasized the major impact of microcirculation on isletβ-cell mass and function. And potentials in islet graft revascularization are crucial for their survival and preserved function in the recipient. In this study, we verified the distinct histological phenotype and functionality of small islets versus large ones both in vitro and in vivo. With efforts to exploring the differences in microcirculation and revascularization of islet grafts, we further evaluated local expressions of angiotensin and vascular endothelial growth factor A (VEGF-A) at different levels. Our findings reveal that, apart from the higher density of insulin-producingβ-cells, small islets express less angiotensin and more angiotrophic VEGF-A. We therefore hypothesized a logical explanation of the small islet superiority for transplantation outcome from the aspects of facilitated microcirculation and revascularization intrinsically in small islets.

scholarly journals The Tetracycline-Controlled Transactivator (Tet-On/Off) System in Beta Cells Reduces Insulin Expression and Secretion in Mice

2021 ◽  
Author(s):  
Nathalie Jouvet ◽  
Khalil Bouyakdan ◽  
Scott A. Campbell ◽  
Cindy Baldwin ◽  
Shannon E. Townsend ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cells ◽  
Cell Biology ◽  
Genetic Manipulation ◽  
Ectopic Expression ◽  
Whole Body ◽  
Specific Gene

Controllable genetic manipulation is an indispensable tool in research, greatly advancing our understanding of cell biology and physiology. However in beta cells, transgene silencing, low inducibility, ectopic expression and off-targets effects are persistent challenges. In this study, we investigated whether an inducible, Tet-Off system with beta-cell specific MIP-itTA driven expression of TetO-Cre<sup>Jaw/J </sup>could circumvent previous issues of specificity and efficacy. Following assessment of tissue-specific gene recombination; beta cell architecture; <i>in vitro</i> and <i>in vivo</i> glucose-stimulated insulin secretion; and whole-body glucose homeostasis, we discovered that expression of any tetracycline-controlled transactivator (e.g. itTA, rtTA or tTA) in beta cells significantly reduced <i>Insulin</i> gene expression and decreased insulin content. This translated into lower pancreatic insulin levels and reduced insulin secretion in mice carrying any tTA transgene, independent of Cre recombinase expression or doxycycline exposure. Our study echoes ongoing challenges faced by fundamental researchers working with beta cells and highlights the need for consistent and comprehensive controls when using the Tet-On or Tet-Off systems for genome editing.

scholarly journals The Tetracycline-Controlled Transactivator (Tet-On/Off) System in Beta Cells Reduces Insulin Expression and Secretion in Mice

2021 ◽  
Author(s):  
Nathalie Jouvet ◽  
Khalil Bouyakdan ◽  
Scott A. Campbell ◽  
Cindy Baldwin ◽  
Shannon E. Townsend ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Beta Cells ◽  
Cell Biology ◽  
Genetic Manipulation ◽  
Ectopic Expression ◽  
Whole Body ◽  
Specific Gene

Controllable genetic manipulation is an indispensable tool in research, greatly advancing our understanding of cell biology and physiology. However in beta cells, transgene silencing, low inducibility, ectopic expression and off-targets effects are persistent challenges. In this study, we investigated whether an inducible, Tet-Off system with beta-cell specific MIP-itTA driven expression of TetO-Cre<sup>Jaw/J </sup>could circumvent previous issues of specificity and efficacy. Following assessment of tissue-specific gene recombination; beta cell architecture; <i>in vitro</i> and <i>in vivo</i> glucose-stimulated insulin secretion; and whole-body glucose homeostasis, we discovered that expression of any tetracycline-controlled transactivator (e.g. itTA, rtTA or tTA) in beta cells significantly reduced <i>Insulin</i> gene expression and decreased insulin content. This translated into lower pancreatic insulin levels and reduced insulin secretion in mice carrying any tTA transgene, independent of Cre recombinase expression or doxycycline exposure. Our study echoes ongoing challenges faced by fundamental researchers working with beta cells and highlights the need for consistent and comprehensive controls when using the Tet-On or Tet-Off systems for genome editing.

Increasing levels of insulin secretion in bioartificial pancreas technology: co-encapsulation of beta cells and nanoparticles containing GLP-1 in alginate hydrogels

2020 ◽  
Vol 10 (4) ◽  
pp. 885-890 ◽  
Author(s):  
Joana Crisóstomo ◽  
Francisca Araújo ◽  
Pedro Granja ◽  
Cristina Barrias ◽  
Bruno Sarmento ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Beta Cells ◽  
Bioartificial Pancreas ◽  
Alginate Hydrogels

Functional and Immunohistochemical Evaluation of Porcine Neonatal Islet-Like Cell Clusters

2003 ◽  
Vol 12 (1) ◽  
pp. 13-25 ◽  
Author(s):  
T. B. Nielsen ◽  
K. B. Yderstraede ◽  
H. D. Schrøder ◽  
Jens Juul Holst ◽  
Klaus Brusgaard ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Nude Mice ◽  
Cell Mass ◽  
Diabetic Patients ◽  
Type I ◽  
Fourfold Increase ◽  
Cell Clusters ◽  
Glucose Challenge

Porcine neonatal islet-like cell clusters (NICCs) may be an attractive source of insulin-producing tissue for xenotransplantation in type I diabetic patients. We examined the functional and immunohistochemical outcome of the islet grafts in vitro during long-term culture and in vivo after transplantation to athymic nude mice. On average we obtained 29,000 NICCs from each pancreas. In a perifusion system, NICCs responded poorly to a glucose challenge alone, but 10 mmol/L arginine elicited a fourfold increase in insulin secretion and 16.7 mmol/L glucose + 10 mmol/L arginine caused a sevenfold increase in insulin secretion, indicating some sensitivity towards glucose. Hormone content as well as the number of hormone-containing cells increased for the first 14 days of culture. When NICCs were stained for hormones, proliferation (Ki67), and duct cells (CK7), some insulin- and glucagon-positive cells co-stained for proliferation. However no co-staining was observed between insulin- and glucagon-positive cells or between hormone- and CK7-positive cells. Following transplantation of 2000 NICCs under the renal capsule of diabetic nude mice, BG levels were normalized within an average of 13 weeks. Oral and IP glucose tolerance tests revealed a normal or even faster clearance of a glucose load compared with normal controls. Immunohistochemical examination of the grafts revealed primarily insulin-positive cells. In summary, in vitro, NICCs responded to a challenge including glucose and arginine. There was a potential for expansion of the β-cell mass of NICCs in vitro as well as in vivo where NICCs eventually may normalize blood glucose of diabetic mice.

scholarly journals Pancreatic beta cell selective deletion of mitofusins 1 and 2 (Mfn1 and Mfn2) disrupts mitochondrial architecture and abrogates glucose-stimulated insulin secretion in vivo

2020 ◽  
Author(s):  
Eleni Georgiadou ◽  
Charanya Muralidharan ◽  
Michelle Martinez ◽  
Pauline Chabosseau ◽  
Alejandra Tomas ◽  
...  
Keyword(s):  
Insulin Secretion ◽  
Membrane Potential ◽  
Beta Cell ◽  
Beta Cells ◽  
Glucose Sensing ◽  
Mitochondrial Fusion ◽  
Intravital Imaging ◽  
Mouse Islets

AbstractBackground and aimsMitochondria are highly dynamic organelles, fundamental to cellular energy homeostasis. Mitochondrial metabolism of glucose is essential for the initiation of insulin release from pancreatic beta cells. Whether mitochondrial ultra-structure, and the proteins controlling fission and fusion, are important for glucose recognition are unclear. Mitochondrial fusion is supported by proteins including mitofusin 1 (MFN1), mitofusin 2 (MFN2) and optic atrophy (OPA1), and fission by dynamin-related protein 1 (DRP1). Here, we generated mice with beta cell-selective, adult-restricted deletion of Mfn1 and Mfn2 (βMfn1/2-KO), and explored the impact on insulin secretion and glucose homeostasis in vivo and in vitro.Materials and methodsC57BL/6J mice bearing Mfn1 and Mfn2 alleles with loxP sites, were crossed to animals carrying an inducible Cre recombinase at the Pdx1 locus (PdxCreERT). Isolated islets were used for live beta cell fluorescence imaging of cytosolic (Cal-520) or mitochondrial (Pericam) free Ca2+ concentration and membrane potential (TMRE). Mitochondrial network characteristics were quantified using super resolution fluorescence and transmission electron microscopy. Beta cell-beta cell connectivity was assessed using the Pearson (R) analysis and Monte Carlo simulation in intact mouse islets. Intravital imaging was performed in mice injected with an adeno-associated virus to express the cytosolic Ca2+ sensor GCaMP6s selectively in beta cells and TMRM to visualise mitochondria using multiphoton microscopy.ResultsβMfn1/2-KO mice displayed higher fasting glycaemia than control littermates at 14 weeks (8.6 vs 6.4 mmol/L, p>0.05) and a >five-fold decrease in plasma insulin post-intraperitoneal glucose injection (5-15 min, p<0.0001). Mitochondrial length, and glucose-induced Ca2+ accumulation, mitochondrial hyperpolarisation and beta cell connectivity were all significantly reduced in βMfn1/2-KO mouse islets. Examined by intravital imaging of the exteriorised pancreas, antiparallel changes in cytosolic Ca2+ and mitochondrial membrane potential, observed in control animals in vivo, were suppressed after Mfn1/2 deletion.ConclusionMitochondrial fusion and fission cycles are essential in the beta cell to maintain normal mitochondrial bioenergetics and glucose sensing both in vitro and in the living mouse. Such cycles may be disrupted in some forms of diabetes to impair mitochondrial function and, consequently, insulin secretion.

Sign in / Sign up

Export Citation Format

Share Document