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Insulin-secreting Cells (insulin-secreting + cell)
Selected AbstractsTissue surface tensions guide in vitro self-assembly of rodent pancreatic islet cellsDEVELOPMENTAL DYNAMICS, Issue 8 2007Dongxuan Jia Abstract The organization of endocrine cells in pancreatic islets is established through a series of morphogenetic events involving cell sorting, migration, and re-aggregation processes for which intercellular adhesion is thought to play a central role. In animals, these morphogenetic events result in an islet topology in which insulin-secreting cells form the core, while glucagon, somatostatin, and pancreatic polypeptide-secreting cells segregate to the periphery. Isolated pancreatic islet cells self-assemble in vitro into pseudoislets with the same cell type organization as native islets. It is widely held that differential adhesion between cells of the pancreatic islets generates this specific topology. However, this differential adhesion has never been rigorously quantified. In this manuscript, we use tissue surface tensiometry to measure the cohesivity of spherical aggregates from three immortalized mouse pancreatic islet cell lines. We show that, as predicted by the differential adhesion hypothesis, aggregates of the internally segregating INS-1 and MIN6 beta-cell lines are substantially more cohesive than those of the externally segregating ,-TC line. Furthermore, we show that forced overexpression of P-cadherin by ,-TC cells significantly perturbs the sorting process. Collectively, the data indicate that differential adhesion can drive the in vitro organization of immortalized rodent pancreatic islet cells. Developmental Dynamics 236:2039,2049, 2007. © 2007 Wiley-Liss, Inc. [source] Human islet-derived precursor cells can cycle between epithelial clusters and mesenchymal phenotypesJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 8b 2009Behrous Davani Abstract We showed previously that undifferentiated, proliferating human islet-derived precursor cells (hIPCs) are a type of mesenchymal stem/stromal cell (MSC) that can be induced by serum deprivation to form clusters and ultimately differentiate in vitro to endocrine cells. We also demonstrated that partially differentiated hIPC clusters, when implanted under the kidney capsules of mice, continued to differentiate in vivo into hormone-producing cells. However, we noted that not all hIPC preparations yielded insulin-secreting cells in vivo and that in some animals no hormone-expressing cells were found. This suggested that the implanted cells were not always irreversibly committed to further differentiation and may even de-differentiate to a mesenchymal phenotype. In this study, we show that human cells with a mesenchymal phenotype are indeed found in the grafts of mice implanted with hIPCs in epithelial cell clusters (ECCs), which are obtained after 4-day in vitro culture of hIPCs in serum-free medium (SFM); mesenchymal cells were predominant in some grafts. We could mimic the transition of ECCs to de-differentiated mesenchymal cells in vitro by exposure to foetal bovine serum (FBS) or mouse serums, and to a significantly lesser extent to human serum. In a complementary series of experiments, we show that mouse serum and FBS are more effective stimulants of mesenchymal hIPC migration than is human serum. We found that proliferation was not needed for the transition from ECCs to de-differentiated cells because mitomycin-treated hIPCs that could not proliferate underwent a similar transition. Lastly, we show that cells exhibiting a mesenchymal phenotype can be found in grafts of adult human islets in mice. We conclude that epithelial-to-mesenchymal transition (EMT) of cells in hIPC ECCs can occur following implantation in mice. This potential for EMT of human islets or differentiated precursor cells must be considered in strategies for cell replacement therapy for diabetes. [source] Effects of strong static magnetic fields used in magnetic resonance imaging on insulin-secreting cellsBIOELECTROMAGNETICS, Issue 1 2009Tomonori Sakurai Abstract The magnetic flux density of MRI for clinical diagnosis has been steadily increasing. However, there remains very little biological data regarding the effect of strong static magnetic fields (SMFs) on human health. To evaluate the effects of strong SMFs on biological systems, we cultured insulin-secreting cells under exposure to sham and SMF conditions (3,10 T of magnetic flux density, and 0,41.7 T/m of magnetic field gradient) for 0.5 or 1 h, and analyzed insulin secretion, mRNA expression, glucose-stimulated insulin secretion, insulin content, cell proliferation and cell number. Exposure to SMF with a high magnetic field gradient for 1 h significantly increased insulin secretion and insulin 1 mRNA expression. Exposure to SMF with a high magnetic flux density for 0.5 h significantly enhanced responsiveness to glucose stimulation. Exposure to SMF did not affect the insulin content, cell proliferation or cell number. Our results suggested that MRI systems with a higher magnetic flux density might not cause cell proliferative or functional damages on insulin-secreting cells, and that SMF with a high magnetic field gradient might be used clinically after thorough in vivo investigations are conducted. Bioelectromagnetics 30:1,8, 2009. © 2008 Wiley-Liss, Inc. [source] | ||||||||||