Abstract

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.

• Keywords: Dexamethasone;Porcine neonatal pancreas cell clusters (NPCCs);Transdifferentiation;beta-cell