Ultra-ROS Responsive Polymer For Efficient Gene Delivery

Gene therapy has shown great potentials in the treatment of a number of key diseases.Nevertheless,the lack of efficient and safe gene vectors is a main bottleneck for the development of gene therapy.There are lots of studies on cationic polymer gene carriers for their simple synthesis and low immunogenicity.However,they also have a conflict between gene transfection efficiency and cytotoxicity.Since the level of intracellular reactive oxygen species(ROS)in tumor or inflammation sites is relatively higher than normal tissues,it is necessary to design a ROS responsive carrier which can not only improve the transfection efficiency but also reduce the cytotoxicity.As the ROS level under disease-relevant conditions is low to 100 ?M H2O2,so it is meaningful to design a smart and ultra-ROS responsive gene carrier which could control release of drugs.Myocardial ischemia reperfusion(IR)injury is a common pathological process;cardiac microvascular endothelial cells(CMECs)would express more intracellularadhesion molecule-1(ICAM-1)after IR-stimulation.ICAM-1 is known as a major molecule involved in polymorphonuclear neutrophils(PMNs)infiltration to release a lot of ROS,finally resulted in serious inflammation and deteriorated IR injury.Therefore,the inflammatory responses can be suppressed by selective knockdown of ICAM-1 by RNA interference technique.Based on this,we designed an ultra-ROS responsive gene carrier and investigated the relationship between ROS sensitivity and transfection efficiency.Moreover,we functionalized PEI-TeTe with PEG and cRGD to obtain a smart carrier(RPPT)which was stable in blood and could enhance cellular uptake by cRGD-induced active targeting effect to deliver ICAM-1 siRNA for heart myocardial injury treatment.Part ?.Ultra-ROS responsive polymer for safe and efficient delivery of DNA to cancer cells.PEI-TeTe was successfully synthesized via the Michael addition between ditelluride-containing diacrylate and low molecular weight polyethyleneimine.GPC spectroscopy showed that PEI-TeTe would be degraded into small molecules after H2O2(0.1 mM)treatment,indicating that PEI-TeTe was ultrasensitive to ROS.Agarose gel,ethidium bromide exclusion assay and heparin replacement assay showed that PEI-TeTe/DNA polyplexes could rapidly release DNA after H2O2 treatment intracellular kinetics investigation showed that total cellular uptake of PEI-TeTe/DNA polyplexes was extremely high and a significant amount of free DNA was disassembled from the polyplexes in the ROS-generating HeLa cells.In addition,PEI-TeTe/DNA polyplexes exhibited more excellent gene transfection efficiency and smaller cytotoxicity in cancer cells than in normal cells.PEI-TeTe/DNA polyplexes showed high in vivo transfection effiency than PEI-SeSe/DNA polyplexes and PEI 25k/DNA polyplexes.Part ?-Ultra-ROS responsive polymer for efficient delivery of ICAM-1 siRNA and reduced ischemia reperfusion InjuryWe designed an ultra-ROS responsive gene carrier(RPPT)which was stable in blood and could target to rat cardiac microvascular endothelial cells(RCMECs).RPPT/siRNA polyplexes could rapidly release siRNA after H2O2(0.1 mM)treatment and it was stable under serum.The biodistribution showed that RPPT displayed conspicuously siRNA distribution levels than PPT and PEI 25k in heart tissues;it also could effectively deliver siRNA to RCMECs.In vivo transfection showed that RPPT/siICAM-1 polyplexes markedly attenuated the ICAM-1 expression;moreover,the expression of tumor necrosis factor a(TNF-a)and interleukin-6(IL-6)were dramatically reduced;suggesting that ICAM-1 gene silencing could effectively modulate inflammatory responses.These results showed that RPPT/siICAM-1 polyplexes could suppress the expression of ICAM-1 and inflammation.Finaly,the infarct size,cardiac fibrosis,cardiac tissue necrosis and TUNEL-positive apoptotic cell death were almost diminished and heart function was restored.In summary,PEI-TeTe was ultra-sensitive to ROS and would be degraded under low concentration of ROS.So it could solve the contradiction between transfection efficiency and cytotoxicity.The RPPT which was modified with PEG and cRGD could deliver siICAM-1 to RCMECs by cRGD-induced active targeting effect.The RPPT/siICAM-1 polyplexes could effectively science ICAM-1 expression to suppress inflammation;finally improving heart function.