- The Effects of Dexamethasone on the Expansion and Transdifferentiation of Transplanted Porcine Neonatal Pancreas Cell Clusters into beta-cells in Normal Nude Mice.
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Ji Hun Yang, Sun Hee Suh, Sung Yoon Jeon, Oak Kee Hong, Kun Ho Yoon
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Korean Diabetes J. 2004;28(5):356-366. Published online October 1, 2004
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 Abstract
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- BACKGROUND
Several studies have suggested that glucocorticoid has an influence on the development and function of the -cells. Thus, we undertook this study to determine whether exposure to dexamethasone (Dx) has an influence on the expansion or transdifferentiation of transplanted porcine NPCCs. METHODS: After transplantation (Tx) of 4,000 islet equivalents (IEQs) of porcine NPCCs into normal nude mice, Dx (1mg/kg) or the control vehicle were injected daily for 10 weeks. To clarify the effects of timing and duration of the Dx, one group was treated by Dx at the first 2 weeks (n=10) and the other group was treated later 8 weeks (n=10) during the 10 weeks treatment period. Thr total graft and beta-cell masses were determined by morphometric analysis. We preformed semi-quantitative RT-PCR for evaluating the pancreas transcription factors. RESULTS: The relative volume and absolute mass of the beta-cells and the total graft were significantly decreased by 10 weeks Dx treatment. Moreover, Dx treatment at thr first 2 weeks (n=10) also significantly decreased the total graft mass and absolute mass of the beta-cells. The relative volume of the beta-cells was negatively correlated and the area of the duct cysts was positively correlated with the duration of the Dx treatment. Pancreas transcription factors including PDX1, Ngn 3, ISL1 and NKx6.1 were decreased in the graft by 2 days treatment of Dx. CONCLUSION: These results suggest that Dx treatment suppresses the expansion and transdifferentiation of transplanted pancreas precursor cells into beta-cell.
- The Effects of High Glucose, Insulin and TGF-beta 1 on Proliferation and Differentiation of the Pancreatic Stellate Cells.
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Oak Kee Hong, Hyuk Sang Kwon, Kyu Hyun Yeom, Marie Lee, Ji Hun Yang, Seung Hyeon Ko, Soon Jib Yoo, Hyun Sik Son, Kun Ho Yoon, Bong Yeon Cha, Kwang Woo Lee, Ho Yong Son, Sung Koo Kang
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Korean Diabetes J. 2003;27(3):228-240. Published online June 1, 2003
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Abstract
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- BACKGROUND
Although chronic pancreatitis gives rise to fibrosis of pancreatic exocrine tissue, and type 2 diabetes is accompanied by pancreatic fibrosis, the mechanisms of fibrogenesis in the pancreas have been insufficiently studied. The activated Pancreatic stellate cells (PSC) have recently been identified in human and experimental fibrotic areas from chronic panceatitis tissues. As PSC are similar in their morphology and biochemistry to hepatic stellate cells, they are suspected to play the same role in pancreatic fibrogenesis as the hepatic stellate cells in liver fibrosis. The PSC were isolated from the rat pancreata, and mediators stimulating the proliferation and differentiation identified. METHODS: The pancreatic stellate shaped cells were isolated by a minor modification to the method described by Apte et al (ref), using a Nycodenz gradient. The isolated PSCs were confirmed by phase-contrast and by the immunofluorescence of vimentin, desmin and smooth muscle a-actin (a-SMA). The level of alpha-SMA was quantified by Western blot in the PSCs in the culture, over time, and the cell proliferation was measured by 3[H]-Thymidine incorporation. The effect of the proliferation and differentiation of the PSC were assessed in relation to D-glucose (500 mg/dL), Insulin (10 IU/mL) and TGF-beta (10 ng/mL) treatment of the culture medium. RESULTS: The stellate shaped cells from the rat pancreata grew readily in the culture. Unactivated PSCs, cultured for 3 days, had an angular appearance, contained lipid droplets, manifesting positive vitamin A autofliuorescence, and stained positively for vimentin and desmin, but negatively for alpha-SMA. Within 4~8 days of primary culturing, the PSCs were activated, the sizes and numbers of the fat droplets decreased, the cells flattened, developed long cytoplasmic extensions and expressed alpha-SMA. After 3 passages, almost 100% of the cells were positive for alpha-SMA expression, indicating a myofibroblast type of differentiation in vitro. The addition of high-glucose concentrations and insulin to the activated PSCs significantly stimulated cell proliferation (194.4+/-8.3, 175.0+/-31.0 vs. control), and when the combination of high- glucose and insulin was applied, the cell proliferation was increased to an even greater extent (247.0+/-21.8 vs. control). CONCLUSIONS: Pancreata stellate cells can be isolated, and cultured in vitro, from normal SD rats. High concentrations of glucose and insulin in culture medium activated the PSC proliferation.
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