Synegistic Modification With Anti-inflammatory Polypeptidesand Carbon Monoxide Prodrugfor Creating Multifunctional Vascular Stents

Atherosclerosis（AS）is an inflammatory disease.As a treatment method for atherosclous diseases,vascular stents have been widely used for the advantages of obvious therapeutic effect,less trauma,faster healing,relatively fewer complications and less toxic and side effects.However,the several generations of stents so far have some disadvantages,such as not targeting the implantation process.The plaque rupture caused by the extrusion of the surface of the scaffold facing the lesion site regulates the mechanical damage of the scaffold to the vessel,and these injuries will lead to the release of a large number of inflammatory factors,and induce the monocytes to transform into macrophages and gather in the lesion site.Excess hydrogen peroxide（H₂O₂）produced by the aggregated macrophages not only causes the activated macrophages to release high migration protein and aggravate the inflammatory response;It also induces macrophages to phagocytosis of lipids at the lesions to form foam cells,which turn into necrotic centers and lead to new atherosclerotic lesions.At the same time,when scaffolds are implanted into the human body as foreign bodies,the coagulation system（such as platelet activation）in the human body will be activated,releasing a large number of inflammatory factors,thereby promoting the activity of white blood cells and aggravating local inflammation.Therefore,the ideal drug coating of vascular stents needs to regulate H2O2 and vascular cells in contact with the outer surface of the stent,while the inner surface of the stent needs to be stable in the blood environment and respond to macrophages,platelets and other substances.The synergistic functions of internal and external surfaces in removing free radicals at vascular lesions,inhibiting inflammatory response,anticoagulation,and regulating the growth of smooth muscle cells and endothelial cells are multiple biological functions.Anti-inflammatory polypeptide is an enzymatic anti-inflammatory biomolecule,which can re-encode activated macrophages through chemotropin receptor Chem R23,inhibit the expression of pro-inflammatory mediators in macrophages,induce the expression of anti-inflammatory and wound repair cytokine IL-10,and the macrophages treated by it will release more proenzymes after phagocytosis.Thereby reducing the levels of pro-inflammatory factors（such as IL-6,IL-1,and TNF-α）.In addition,anti-inflammatory peptides can also help maintain vascular homeostasis through specific GPCRs mediated,anti-platelet activation,reduce the activation of vascular smooth muscle cells stimulated by platelet derived growth factor,and stimulate the release of vascular protective molecules（such as prostacyclin and nitric oxide,etc.）from vascular endothelial cells.CO can activate the guanosine cyclase（GC）of platelets and smooth muscle cells,and increase the level of c GMP in vivo,thereby inhibiting platelet activation and smooth muscle cell proliferation.CO can also inhibit human platelet aggregation by arachidonic acid,ADP,collagen,thrombin or prostaglandin peroxide analogs.In addition,CO also promotes endogenous NO production through activation of p38mitogen-activated protein kinase（MAPK）,thereby enhancing the ability of wound surface and endothelial repair.The donor drug selected in this paper,CORM401,is a new water-soluble donor.Through the response of oxidizing substances（such as H₂O₂peroxide）related to the atherosclerotic site,it can eliminate excessive H₂O₂ in the atherosclerotic site and inhibit the inflammatory response,and catalyze the release of CO.So that CO in the lesion site play the function of anticoagulation,selective regulation of cell growth behavior.In this paper,316 L SS,a common medical metal material,was used as the modified object.After the base functional coating was grafted on the surface of the material,the biodegradable polymer coating of CORM401 drug was loaded on the outer surface of the material to realize the design of different functional coatings on the inner and outer surfaces of the scaffold.The aim was to inhibit the expression of pro-inflammatory factors and promote the expression of anti-inflammatory factors in macrophages by using anti-inflammatory polypeptides on the inner surface of scaffolds after implantation in vivo.CORM401 drug on the outer surface responds to oxidizing substances（such as H₂O₂）in the atherosclerotic site,eliminates excessive H₂O₂ in the atherosclerotic site,inhibits inflammatory response,and catalyzes the release of CO,so that CO can play an anticoagulant role in the lesion site and selectively regulate cell growth behavior.The internal and external surface synergism can regulate the inflammatory response at the lesion site,and simultaneously take into account the anticoagulation and selective regulation of the growth behavior and function of vascular cells.In this paper,X-ray photoelectron spectroscopy（XPS）,Fourier transform infrared spectroscopy（FTIR）,quartz microcrystal balance（QCM-D）and other methods were used to characterize the chemical composition and structure of the coating.Meanwhile,the biological functions of the coating were studied by inflammatory factor detection test,cell test and blood test.The experimental results showed that COPEP coating can effectively regulate the inflammatory response and selectively regulate the cell growth behavior with both anticoagulation and selective regulation.This paper provides a new idea for the surface modification of cardiovascular scaffolds.