Beta cell neogenesis from ducts and phenotypic conversion of residual islet cells in the adult pancreas of glucose intolerant mice induced by selective alloxan perfusion.
ABSTRACT The aim of this study was to clarify the pattern of beta cell neogenesis in the alloxan-perfused, beta cells-depleted segment of glucose intolerant mice induced by selective alloxan perfusion. First, duct cells proliferated in the perfused segment, then cells co-expressing multiple islet hormones and transcription factors such as PDX-1, Nkx2.2, Isl1, and Pax6 were observed in duct cells, and newly formed islet-like cell clusters (ICCs) containing beta cells were recognized. In residual beta cell-depleted islets, glucagon or somatostatin and PDX-1 double-positive immature endocrine cells were recognized. Glucagon or somatostatin, insulin and PDX-1 triple-positive cells then appeared and these cells appeared to undergo terminal differentiation into beta cells. In conclusion, we demonstrated at least two different processes of beta cell neogenesis, i.e., formation of new ICCs from ductal epithelium and redifferentiation of residual non-beta islet cells in this model. In addition, transcription factors that appear in the processes of endocrine cell development may also play essential roles during beta cell neogenesis from duct cells.
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ABSTRACT: We previously demonstrated the development of beta-cells in the native pancreas after syngeneic pancreas transplantation (PTx) in a model of type 2 diabetes, namely the Spontaneously Diabetic Torii (SDT; RT1 a) rat. In this study, we evaluated the effect of fully allogeneic PTx (allo-PTx) under immunosuppression on the native pancreases in the recipients. Diabetic 25-week-old SDT rats were divided into two groups: untreated controls and PTx-treated recipients. Dark Agouti (RT1 a) pancreases were then transplanted into the SDT rats. FK506 was administered daily postoperatively. Each group was examined for 15 weeks. Control SDT rats showed a disappearance of the pancreatic and duodenal homeobox-1 (PDX-1) expression of the pancreases with the development of diabetes. In addition, the islets were gradually replaced by fibrosis, thus resulting in a marked decrease in the beta-cell mass at 40 weeks of age. On the other hand, in PTx recipients, islet-like cell clusters were found in the native pancreases. The beta-cell mass significantly increased in the native pancreases in the recipients at 10 and 15 weeks posttransplantation in comparison to the age-matched controls. Moreover, we observed the re-expression of PDX-1 in the islet-like cell clusters. Interestingly, insulin and glucagon double-positive stained cells in the mesenchyme and insulin single-positive cells in the ductal epithelium were also observed. Our results indicated that the benefits of avoiding glucose toxicity by allo-PTx under immunosuppression could therefore induce the PDX-1 expression in the native pancreases, thus potentially resulting in the development of beta-cells in type 2 diabetic recipients.Journal of Surgical Research 05/2008; 145(2):229-37. · 2.02 Impact Factor
Conference Paper: A PC environment for discrete component digital design[Show abstract] [Hide abstract]
ABSTRACT: A description is given of the implementation, operational experience and ongoing refinement of a computer-aided design tool for discrete component digital design in the department of electrical and computer engineering at the Air Force Institution of Technology. Specifically, a graphical user interface, simulation, and artificial intelligence technology are used to aid in the design of digital logic circuits. This is being incorporated into a first-quarter course to provide students with exposure to modern design techniques. The implementation and enhancements of a prototype design for an engineering workstation are described in detailFrontiers in Education Conference, 1988., Proceedings; 11/1988
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ABSTRACT: Type 1 diabetes is inhibited in diabetes-prone BioBreeding (BBdp) rats fed a low-antigen hydrolyzed casein (HC) diet. In cereal-fed BBdp rats, islet expansion is defective accompanied by a futile upregulation of islet neogenesis without increased islet mass, due to a subtle blockage in islet cell cycle. We hypothesized that islet growth is enhanced before insulitis in HC-fed young BBdp rats and that islet neogenesis could be stimulated by a trophic factor, islet neogenesis-associated protein (INGAP). beta-Cell homeostasis was analyzed using immunohistochemistry, morphometry, laser capture microdissection and RT-PCR in BBdp rats fed HC or cereal diets. beta-cell proliferation in small and medium islets, and the number and area fraction of medium and large islets were increased in HC-fed animals. In situ islet cell cycle analysis revealed an increased proportion of proliferating S + G2 cells in medium and large islets of 25-45 day HC-fed rats. Expression of the cell cycle inhibitor, p16(INK4a) correlated with islet size and the percentage of p16(INK4a+) beta-cells increased in HC-fed BBdp rats, likely reflecting an increase in large islet area fraction. In HC-fed rats, extra-islet insulin(+) clusters (EIC), insulin(+) duct cells, large islet area fraction, and beta-cell mass were increased. Neurogenin-3 and Pdx-1, markers of beta-cell progenitors, were increased in EIC of weanling HC-fed rats. Daily injection of INGAP (30-45 days) increased the number of small islets, total islets, and insulin(+) cells in small ducts. Thus, in BBdp rats fed a protective HC diet, beta-cell expansion is enhanced through increased beta-cell proliferation and stimulation of islet neogenesis.Journal of Cellular Physiology 08/2010; 224(2):501-8. · 4.22 Impact Factor