| Myocardial ischemia reperfusion(IR)injury,which often occurs during the treatment of myocardial infarction,could causes irreversible damage to myocardial tissue.During the process of IR injury,adhesion molecules such as vascular cell adhesion molecule(VCAM)and intracellular adhesion molecule(ICAM)are overexpressed,mediating polymorphonuclear neutrophils(PMNs)infiltration,which results in severe inflammation and reactive oxygen species(ROS)generating,leading to serious IR injury.The use of molecule inhibitors is currently an effective method for clinical IR anti-inflammatory treatment.However,the high cost of treatment and side effects are the main limiting factors for anti-inflammatory treatment.Gene therapy has the advantages of good specificity,high efficiency and long duration.Down-regulation of adhesion molecule expression by siRNA delivery could block neutrophil recruitment,inhibit inflammatory response,and ultimately achieve the purpose of treating IR injury.Efficient vectors are necessary for gene delivery.Cationic polymers are one of the most important non-viral vectors,which could condense negatively charged nucleic acid molecules through electrostatic interaction,facilitating cell uptake and gene transfection.However,the application of cationic polymers is limited due to the inconsistencies between transfection efficiency and cytotoxicity.Therefore,degradable stimulus-responsive polymers emerged.Motivated by these understandings,we herein designed and reported two stimuli-responsive gene delivery systems for anti-inflammatory therapy against myocardial ischemia-reperfusion injury as follows:1 Bioreducible,branched poly(?-amino ester)s mediate anti-inflammation ICAM-1 siRNA delivery against myocardial ischemia-reperfusion injuryDisulfide bonds containing bioreducible branched poly(?-amino ester)(BPAE-SS)was designed and synthesized for ICAM-1 siRNA delivery and inhibition of inflammatory response towards the treatment of myocardial IR injury.Nanocomplexes(?150 nm)could be formed by branched BPAE-SS and siRNA.Compared with linear polymers,BPAE had stronger siRNA condensation capacity and higher cellular uptake levels.BPAE-SS/siICAM-1 nanocomplexes were taken up by cells via endocytosis,which could escape from the endosome via proton sponge effect.BPAE-SS degradation and ICAM-1 siRNA release was caused by rapidly disulfide bonds break down under the stimulation of high concentration of glutathione(GSH)in the cytoplasm.In the LPS-induced RCMECs cells,ICAM-1 mRNA expression was reduced by 75%after BPAE-SS/siICAM-1 complex treatment.In the rat myocardial IR model,the expression of ICAM-1 mRNA of injured tissue was reduced by 79%treated with i.v.injected BPAE-SS/siICAM-1 complex.Pro-inflammatory factors such as tumor necrosis factor(TNF-?)and interleukin 6(IL-6)were significantly reduced,demonstrating that the inflammatory response was effectively inhibited.After BPAE-SS/siICAM-1 treatment,the myocardial infarct size was reduced to 6%,cardiac fibrosis was reduced to 8%,cardiac necrosis was significantly improved,myocardial cell apoptosis rate was reduced to 9%,and left ventricular systolic function was basically restored investigated by echocardiography.2 Targetable ROS-responsive cross-linked polymer co-delivery ICAM-1 and VCAM-1 siRNA for myocardial ischemia-reperfusion injury therapyThioketal bonds containing ROS degradable crosslinked polyamidoamine(RP)was designed and synthesized.RPPR was obtained after PEG and cRGD modification and used for ICAM-1 and VCAM-1 siRNA co-delivery for myocardial IR injury therapy.ROS responsive RPPR has good serum stability,which could condense siRNA into complex with stable particle size(150-180 nm)in serum.In LPS-induced RCMECs cells,RPPR silenced 76%of ICAM-1 mRNA expression.Complexes co-delivering siICAM-1 and siVCAM-1(RPPR/siCAM2)silenced>70%of TNF-?mRNA expression,which had greater silencing efficiency than RPPR/siICAM-1(40%)and RPPR/siVCAM-1(41%),with synergistic anti-inflammatory effects.In the rat IR model,RPPR could be efficiently enriched in cardiac tissue and be taken up by vascular endothelial cells actively targeted by cRGD at the site of injury.RPPR/siCAM2 complexes could dissociate and release ICAM-1 siRNA and VCAM-1 siRNA due to the cleavage of thioketal bonds under the high concentration of intracellular ROS,thereby silencing the expression of ICAM-1 and VCAM-1 simultaneously.The silencing efficiency of TNF-? mRNA(77%)was significantly higher than that of RPPR/siICAM-1 complex(54%)and RPPR/siVCAM-1 complex(57%).After RPPR/siCAM2 treatment,the myocardial infarct size was reduced to 7%,the degree of fibrosis in the heart tissue was reduced to 9%,cardiac necrosis was significantly improved,the cardiomyocyte apoptosis rate was reduced to 8%,and left ventricular systolic function was basically restored investigated by echocardiography. |
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