Responsive-EGCG-Cy-CD-Pi Nano Drug Delivery System For Atherosclerotic Microenvironment

Cardiovascular disease（CVD）is the leading cause of death worldwide,which seriously endangering human health and causing a huge economic burden.Atherosclerosis is a chronic inflammatory disease of blood vessels,which is also the common pathological basis of coronary artery disease,stroke and other cardiovascular diseases.It is still an urgent problem that finding effective means to treat atherosclerosis for human beings.In recent years,nanomedicine has made great progress in the diagnosis and treatment of inflammation-related diseases,including cardiovascular diseases.The intelligent nano drug delivery system designs structural components based on the biochemical signals that have abnormal changes in the inflammatory site of blood vessels.Because of the characteristics of targeted delivery for therapeutic drugs,specific drug release and high drug utilization rate,it has been designed and applied in the treatment of atherosclerotic diseases.In the atherosclerosis site,the vascular endothelial layer is damaged and uncontrolled production of（ROS）damage the balance between vascular microenvironment oxidation and antioxidation.This will resulte in oxidative stress,which able to oxidative low density lipoprotein（LDL）and promote local inflammation.According to the inflammatory site oxidative,this paper constructs a ROS-responsive nano drug delivery system.After reaching the vascular lesion,the nano drug delivery system has a structural change to crack under the stimulation of ROS,so as to achieve the specific control effect of releasing drugs.In this paper,the cystamine（Cy）,which containing disulfide bond is introduced as an active oxygen-sensitive component,and synthesized Cy-CD by grafting Cy to carboxymethyl-β-cyclodextrin（CM-β-CD）through amide reaction.Through phenolamine crosslinking reaction between Cy-CD and EGCG,the ROS-responsive nano drug delivery system EGCG-Cy-CD with three-dimensional network structure was synthesized.Pivastatin（Pi）that has the anti-inflammatory effects,inhibition of vascular smooth muscle cell proliferation and reduction of oxidized low-density lipoprotein（ox LDL）concentration was selected as the model drug.After interaction of host-guest,Pi was loaded into the hydrophobic cavity of cyclodextrin to obtain Cy-CD-Pi.ROS responsive drug delivery nanoparticles EGCG-Cy-CD-Pi were further prepared by cross-linking with Cy-CD-Pi and EGCG,which disintegrate to release Pi at the site of vascular inflammation（ROS environment）.At the same time,EGCG-Cy-CD-Pi nanoparticles can also respond to release loaded drugs in the GSH environment due to the REDOX sensitivity of disulfide bonds.It was observed by particle size analyzer,scanning electron microscope and transmission electron microscope that EGCG-Cy-CD NPs and EGCG-Cy-CD-Pi NPs were regular spheres with particle size of about 200 nm.The drug loading rate of EGCG-Cy-CD-Pi nanoparticles calculated by UV-Vis spectrophotometer was about 8%.In vitro drug release results showed that the drug release rate of EGCG-Cy-CD-Pi NPs in H₂O₂ and GSH solutions was faster than that in PBS solution.XPS results show that the response behavior of nanoparticles is caused by the rupture of disulfide bonds in Cy.The culture experiments of endothelial cells,smooth muscle cells and macrophages showed that under the synergistic effect of EGCG-Cy-CD nanoparticles and Pi,EGCG-Cy-CD-Pi nanoparticles could significantly promote the proliferation and activity of endothelial cells,inhibit the proliferation of smooth muscle cells and the release of proinflammatory factors by macrophages.It can also promote the outflow of lipid uptake by macrophages.Experimental results of hemocompatibility and acute toxicity in animals showed that EGCG-Cy-CD and EGCG-Cy-CD-Pi nanoparticles had good biosafety.In vivo targeting experiments showed that EGCG-Cy-CD-Pi nanoparticles had the ability to target arterial injury sites.In summary,EGCG-Cy-CD ROS-responsive nano drug delivery system provides a new idea for the in vivo delivery of hydrophobic drugs.The EGCG-Cy-CD-Pi ROS-responsive drug loading nanoparticles loaded with Pi is expected to be a new method for the treatment of atherosclerotic diseases.