The aim of this study was to observe the therapeutic effect of insulin-loaded linear poly(ethylene glycol)-brush-like poly(
l
-lysine) block copolymer poly(ethylene glycol)-
b
-(poly(ethylenediamine
l
-glutamate)-
g
-poly(
l
-lysine)) (PEG-
b
-(PELG-
g
-PLL) on renal ischemia/reperfusion-induced lung injury through downregulating hypoxia-inducible factor (HIF) as compared to free insulin. Sprague Dawley rats were pretreated with 30 U/kg insulin or insulin/PEG-
b
-(PELG-
g
-PLL) complex, and then subjected to 45 minutes of ischemia and 24 hours of reperfusion. The blood and lungs were collected, the level of serum creatinine and blood urea nitrogen were measured, and the dry/wet lung ratios, the activity of superoxide dismutase and myeloperoxidase, the content of methane dicarboxylic aldehyde and tumor necrosis factor-α, and the expression of HIF-1α and vascular endothelial growth factor (VEGF) were measured in pulmonary tissues. Both insulin and insulin/PEG-
b
-(PELG-
g
-PLL) preconditioning improved the recovery of renal function, reduced pulmonary oxidative stress injury, restrained inflammatory damage, and downregulated the expression of HIF-1α and VEGF as compared to ischemia/reperfusion group, while insulin/PEG-
b
-(PELG-
g
-PLL) significantly improved this effect.
BackgroundHepatic ischemia/reperfusion-induced pancreatic islet injury (HI/RIPII) was an important pathophysiological phenomenon in clinics. In the present study, we observed the effects of phycocyanin on HI/RIPII. However, the half-life of phycocyanin was extremely short and limited its use in vivo.Materials and methodsIn order to overcome this shortcoming, poly(ethylene glycol)-b-(poly(l-glutamic acid)-g-polyethylenimine) (PEG-b-(PG-g-PEI)) was synthesized and estimated as a nanocarrier for lengthening delivery of phycocyanin through the abdominal subcutaneous injection in rats. Phycocyanin (isoelectric point=4.3) was encapsulated with PEG-b-(PG-g-PEI) via electrostatic interactions at pH 7.4.ResultsIn vitro phycocyanin was fast and efficiently encapsulated and showing efficient loading and sustained release. In vivo the anti-HI/RIPII function of phycocyanin/PEG-b-(PG-g-PEI) complex was surveyed in rats using free phycocyanin as the controls, and the results showed that phycocyanin/PEG-b-(PG-g-PEI) complex reduced HI/RIPII property and enlarged islet functionality.ConclusionThese results suggested that PEG-b-(PG-g-PEI) might be treated as a potential phycocyanin nanocarrier.
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