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@#To further evaluate the effect of miR-217 in the proliferation of mouse adult pancreatic stem cells, we firstly transfected adult pancreatic stem cells with miR-217 mimics and studied the effect of miR-217 on proliferation through Western blot and immunofluorescence. Results showed that during the proliferation of adult pancreatic stem cells, miR-217 inhibited the protein expression of Ki-67 and Cyclin D1, which are related to cell propagation. As well as that, to investigate the target genes of miR-217 and their conserved sites bound by the seed region of miR-217, we used bioinformatic algorithms to find a potential target of miR-217 and verified by dual-luciferase activity assay. Surprisingly, dual-luciferase activity assay revealed that miR-217 could decrease PMIR-REPORT-Sirt1-3′UTR luciferase activity and Sirt1 is a direct target of miR-217. Finally, we verified the function of Sirt1 in the proliferation of pancreatic stem cells. Overexpression of miR-217 in pancreatic stem cells inhibited the level of Sirt1 in protein level but not in mRNA level. Furthermore, activator of Sirt1 played positive effect on colony formation ability and cell proliferation and inhibitor of Sirt1 showed the opposite function. In conclusion, miR-217 inhibits the proliferation of mouse adult pancreatic stem cells through Sirt1 and decreased expression of miR-217 to contribute to the pancreatic stem cells development.
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As a new biotechnology, protein transduction connects the target fragment with biology active and protein transduction domain, and transducer it in to cells, exert its biological effects. Protein transduc-tion domain is a small molecule peptide, not only the protein transduction domain can penetrate through cell membrane, but could maintain the activity of its fusion protein. Protein transduction is an emerging biology technology, it has been applied into all aspects of cell gene regulation since its invention. In this article, we take Tat, Pdx-1 and Beta/NeuroD for instance and review the application of transduction protein in the dif-ferentiation of pancreatic stem cell.
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La diabetes mellitus tipo 1 es una enfermedad metabólica multifactorial en la que los mecanismos inmunológicos juegan un papel fundamental. Una vez desarrollada la enfermedad, los pacientes son dependientes de la administración exógena de insulina. Actualmente, el campo de la investigación experimental ha identificado una población pancreática con características de células madre. Esta población de células positivas a nestina, se expresa bajo ciertas condiciones especiales y abre la posibilidad de desarrollar técnicas para la obtención de nuevas células β que pudieran regenerar el tejido dañado. Este trabajo es una revisión acerca del desarrollo embrionario del páncreas, las células madre pancreáticas embrionarias, los modelos actuales de lesión para la inducción de la expresión de células madre en páncreas adultos, el papel de los radicales libres sobre la expresión de nuevas células madre y las terapias experimentales actuales para mejorar la expresión de estas células.
Diabetes mellitus type 1 is a multifactorial metabolic disease in which immunological mechanisms play an essential role. Once the disease is fully established, affected individuals are dependent upon exogenous insulin administration. Current research has identified a pancreatic population resembling stem cells features. This population of nestin-positive cells is activated under specific circumstances and opens the possibility of developing procedures for obtaining new β cells for the regeneration of the pancreatic islets. In this work we review the embryonic development of pancreas, pancreatic stem cells, the current models for the induction of stem cells in adult pancreas, the role of free radicals on the induction of new stem cells, and the current therapeutic procedures to improve the expression of these cells.
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Objective Compare the reproductive activity of pancreatic stem cells isolated from diabetic rat with that of normal rat to assess the effect of microenvirement on stem cells'proliferation.Methods Diabetic rat model were prepared by peritoneal injecting 60mg/kg streptozotocin.Pancreata from 10 diabetic rats and 10 normal rats were trimmed and digested into single cells which were then inoculated onto the culture plate respectively.After passaging 3 generation the cells were identified by nestin immunostaining.During culturing the cell growth curve was observed and the cell cycle of the third and seventh generation cultured cells was evaluated by flow cytometry.Results After passaging pancreatic stem cells was purified and identified by nestin immunostaining.The reproductive activity of diabetic rat was much better[ratio of s stage:(20.7?2.7)% vs(14.1?2.5)%,P0.05].Conclusions The stem cells are stimulated to proliferate after islet injure.The reproductive activity of cells can be provoked by the microenvironment.
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Objective To isolate and identify pancreatic stem cells of Kunming mouse and to observe the differentiation potency of those cells. Methods Pancreas of postnatal Kunming mice were digested by enzymes to isolate pancreatic stem cells. The potency of the cell differentiation was then identified with special marker of cytokeratin 19(CK 19), insulin and glucagons by immunocytochemical staining. Results Few epithelioid cells could be found to survive at the beginning of isolation, but when medium was replaced by that with growth factor, the cells proliferated quickly in fusiform shape and formed colony gradually. The cells were CK 19 immunoreactive positive after transfer of culture. After differentiation induced by high glucose, the cells formed the pancreatic islet like structures. Immunocytochemical staining showed that part of the cells of pancreatic islet like structures were insulin immunoreactive positive and few of the cells were glucagon immunoreactive positive. Conclusion Pancreatic stem cells of Kumming mouse can proliferate when cultured in vitro and have the potency of differentiation into ? and? cells of pancreatic islet.