ABSTRACT
Type 2 diabetes mellitus (T2DM) therapy is facing the challenges of long-term medication and gradual destruction of pancreatic islet β-cells. Therefore, it is timely to develop oral prolonged action formulations to improve compliance, while restoring β-cells survival and function. Herein, we designed a simple nanoparticle with enhanced oral absorption and pancreas accumulation property, which combined apical sodium-dependent bile acid transporter-mediated intestinal uptake and lymphatic transportation. In this system, taurocholic acid (TCA) modified poly(lactic-co-glycolic acid) (PLGA) was employed to achieve pancreas location, hydroxychloroquine (HCQ) was loaded to execute therapeutic efficacy, and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) was introduced as stabilizer together with synergist (PLGA-TCA/DLPC/HCQ). In vitro and in vivo results have proven that PLGA-TCA/DLPC/HCQ reversed the pancreatic islets damage and dysfunction, thus impeding hyperglycemia progression and restoring systemic glucose homeostasis via only once administration every day. In terms of mechanism PLGA-TCA/DLPC/HCQ ameliorated oxidative stress, remodeled the inflammatory pancreas microenvironment, and activated PI3K/AKT signaling pathway without obvious toxicity. This strategy not only provides an oral delivery platform for increasing absorption and pancreas targetability but also opens a new avenue for thorough T2DM treatment.
ABSTRACT
Objective:To investigate the influence of α cells and glucagon-like peptide l (GLP-1) in the function of β cells (INS-1 cells) in the rats,and to elucidate the possible mechanism of α cells and INS-1 cells transplantation in influencing hypoglycemia.Methods:The proliferation abilities of INS-1 cells after treated with 10％,20％ and 30％ islet α-cell conditioned medium and 0.03,0.30,3.00,30.0 mg · L-1 of GLP-1 were analyzed by MTT assay.The levels of insulin secretion of INS-1 cells after treated with 10％,20％,30％ α cells,α-cell conditioned medium and different concentrations of GLP-1 were analyzed by enzyme linked immunosorbent assay (ELISA).The concentrations of Ca2+ in INS-1 cells after treated with high glucose and GLP-1 were analyzed by laser confocal microscope.The expression levels of insulin protein after treated with different concentrations of islet α-cell conditioned medium and different concentrations of GLP-1 were detected by Western blotting methed.After the INS-1 cells,the mixture of INS-1 cells and α cells were transplanted into the left renal capsule of the nude mice,the blood glucose levels and the kidney morphology were observed.The levels of insulin/glucagon in the transplanted cells were detected by immunohistochemistry.Results:Compared with control group,both of α-cell conditioned media and GLP-1 promoted the INS-1 cell proliferation and insulin secretion (P ＜ 0.05).The laser confocal microscope results revealed that GLP-1 stimulated the increased intracellular Ca2+ concentration in INS-1 cells (P＜ 0.05).Compared with control group,there was no significant difference in the expression levels of insulin protein in the insulin-1 cells after treated with islet α cell conditioned medium and GLP-1 (P＞0.05).Compared with pre transplantation,the blood glucose level in the transplanted INS-1 cells was significantly decreased at 35 d after renal capsul trasplantation (P＜0.05),and even hypoglycemia presented renal capsular in the diabetic nude mice;the transplantation site was obviously swollen.However,the levels of blood glucose had no change of the diabetic rats after transplated with the mixture of INS-1 and α cells (P＜0.05).The expression of insulin and glucagon in the INS-1 transplanted cells were found by immunohistochemistry staining.Conclusion:Pancreatic islet α cells and their secretions can promote the INS-1 cell proliferation and insulin secretion,and the mixture of INS-1 cells and α cells transplanted under the renal capsule of the diabetic nude mice can reduce the hypoglycemic effect of INS-1 cell transplantation which might be related to the INS-1 cells that can express both of insulin and glucagon genes.
ABSTRACT
Objective:To investigate the influence of α cells and glucagon-like peptide l (GLP-1) in the function of β cells (INS-1 cells) in the rats,and to elucidate the possible mechanism of α cells and INS-1 cells transplantation in influencing hypoglycemia.Methods:The proliferation abilities of INS-1 cells after treated with 10％,20％ and 30％ islet α-cell conditioned medium and 0.03,0.30,3.00,30.0 mg · L-1 of GLP-1 were analyzed by MTT assay.The levels of insulin secretion of INS-1 cells after treated with 10％,20％,30％ α cells,α-cell conditioned medium and different concentrations of GLP-1 were analyzed by enzyme linked immunosorbent assay (ELISA).The concentrations of Ca2+ in INS-1 cells after treated with high glucose and GLP-1 were analyzed by laser confocal microscope.The expression levels of insulin protein after treated with different concentrations of islet α-cell conditioned medium and different concentrations of GLP-1 were detected by Western blotting methed.After the INS-1 cells,the mixture of INS-1 cells and α cells were transplanted into the left renal capsule of the nude mice,the blood glucose levels and the kidney morphology were observed.The levels of insulin/glucagon in the transplanted cells were detected by immunohistochemistry.Results:Compared with control group,both of α-cell conditioned media and GLP-1 promoted the INS-1 cell proliferation and insulin secretion (P ＜ 0.05).The laser confocal microscope results revealed that GLP-1 stimulated the increased intracellular Ca2+ concentration in INS-1 cells (P＜ 0.05).Compared with control group,there was no significant difference in the expression levels of insulin protein in the insulin-1 cells after treated with islet α cell conditioned medium and GLP-1 (P＞0.05).Compared with pre transplantation,the blood glucose level in the transplanted INS-1 cells was significantly decreased at 35 d after renal capsul trasplantation (P＜0.05),and even hypoglycemia presented renal capsular in the diabetic nude mice;the transplantation site was obviously swollen.However,the levels of blood glucose had no change of the diabetic rats after transplated with the mixture of INS-1 and α cells (P＜0.05).The expression of insulin and glucagon in the INS-1 transplanted cells were found by immunohistochemistry staining.Conclusion:Pancreatic islet α cells and their secretions can promote the INS-1 cell proliferation and insulin secretion,and the mixture of INS-1 cells and α cells transplanted under the renal capsule of the diabetic nude mice can reduce the hypoglycemic effect of INS-1 cell transplantation which might be related to the INS-1 cells that can express both of insulin and glucagon genes.