Publications (2)3.61 Total impact
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ABSTRACT: Objective: To investigate the protective effects of a pentadecapeptide of islet neogenesis-associated protein (INGAP-PP) on transplanted islets function. Methods: Islets were cultured in RPMI 1640 with or without INGAP-PP (10 μg/mL). After 24 h, the viability of the islets and glucose-stimulated insulin secretion (GSIS) were measured. The expression of genes B cell lymphoma/lewkmia2 (Bcl2) and protein kinase B (Akt) were detected by RT-PCR assay. Healthy rats transplanted with islets under the renal capsule were injected with INGAP-PP or saline in in the abdominal cavity. One week later, the expression of insulin nestin pancreatic (nestin) and duodenal homeobox 1 (Pdx1) and proliferating cell nuclear antigen (PCNA) in the transplanted islets were observed by immunohistochemistry. After that they were transplanted to the renal capsule of diabetic rats. Results: 1. The amount of insulin released was increased in co-cultured group in concentration of 16.7 mmol/L glucose, which was (185.00±20.01 μU/mL) vs. (58.67±17.03 μU/mL). Gene expression of Bcl2 (0.61±0.22 vs. 0.50±0.21) and Akt (1.12±0.19 vs. 0.94±0.16) in the co-cultured group were increased compared with that of the control group. Islets viability in the co-cultured group (683.9±7.08) was higher than that of control group (547.9±8.02). The stimulating index (SI) of the co-cultured group was also higher than that of the control group. 2. The group of islets under the renal capsule which were co-cultured and injected with INGAP-PP had the more nestin expression in the islets. Conclusions: The function of islet can be protected by the INGAP-PP, which will promote the viability, differentiation and regeneration of islet before transplantation. And it will be beneficial for the function of allograft after islets transplantation.
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ABSTRACT: The differentiation of pancreatic ductal epithelial cells into beta-cells has been considered as an alternative method for increasing the number of islets for transplantation. Critical factors have been introduced into the in vitro differentiation protocol for pancreatic duct cells in order to enhance the production of beta-cells. Islet neogenesis-associated protein (INGAP) is an initiator of islet neogenesis and the peptide sequence 104-118 of INGAP has been shown to stimulate an increase in beta-cell mass in animals and also found in human pathological states involving islet neogenesis. To establish a novel method for the differentiation of beta-cells from human pancreatic duct cells with INGAP-related pentadecapeptide (INGAP-PP), the pancreatic duct cells were isolated, purified and expanded in vitro and differentiated using a four-step protocol that included nicotinamide, exendin-4, transforming growth factor beta(1) and INGAP-PP/Scrambled peptide (Scrambled-P). The production of islet-like clusters (ILCs) in the INGAP-PP group was significantly higher than that in the Scrambled-P control group after differentiation from an equal number of duct cells. The duct cells showed positive staining and expression for cytokeratin 19, pancreatic duodenal homeobox-1, nestin, and were negative for insulin and glucagon, as detected by both immunofluorescence and RT-PCR. Following differentiation the cells became insulin and glucagon positive. In addition, the ILCs from the INGAP-PP group secreted higher levels of insulin and C-peptide than the Scrambled-P group under a high glucose challenge. We conclude that INGAP peptide enhances the in vitro differentiation of pancreatic duct cells into islet-like clusters.
Nanjing Medical University
Nan-ching, Jiangsu Sheng, China
- Department of Endocrinology