A Study On Macrophage Membrane-Based Biomimetic Drug Delivery System For Atherosclerosis Treatment

The morbidity and mortality of cardiovascular disease in the world are increasing year by year.The unstable atherosclerotic plaque and plaque rupture are major factors leading to death in patients with cardiovascular disease.Oral drugs are often used to inhibit the development of AS in clinic,but this method often shows some defects such as toxic side effects and low targeting.In recent years,it shows great potential to combine drug molecules with suitable nano-carriers to form drug-loaded nanoparticles,but these synthetic nanoparticles are still difficult to fully replicate the natural complex mechanisms and biological functions in vivo.Therefore,biomimetic nanotechnology has gradually attracted wide attention,showing a great application prospect.In this study,based on the pathological characteristics of AS lesions,nano-drugs(RAPNPs)were prepared by using the anti-AS drug rapamycin(RAP)as the therapeutic drug and the degradable polyethylene glycol-polylactic acid-hydroxyl copolymer(PEG-PLGA)as the drug carrier.On this basis,the cell membrane of macrophages which played a key role in the development of AS was selected as biomimetic materials and coated on the outer surface of RAPNPs to prepare biomimetic drug-loaded nanoparticles(MMNPs)with macrophage membrane coating,in order to cooperate with the immune escape and specific targeting of natural macrophages on the basis of the function of PEG-PLGA nanoparticles,and further improve the therapeutic effect of AS.The specific results are as follows:(A)Stable and uniform nano-sized drug-loaded particles(RAPNPs)were successfully prepared.Through the characterization of its particle size,dispersion characteristics,potential and morphology,it is proved that the particle size is small and the EPR effect can be realized.The dispersion property of the nanoparticles is good,and the potential accords with the normal value of the material used.The overall morphology shows a core-shell structure,which proves that the preparation efficiency of nanoparticles is high.By measuring the drug loading rate and entrapment efficiency,it is proved that the nanoparticles can encapsulate the drug RAP with high efficiency.Through the study of drug release characteristics in vitro,it is verified that the nanoparticles can achieve sustained drug release.(B)The extraction method of cell membrane from RAW264.7 macrophages was optimized.Through the determination of the content of extracted cell membrane protein,it is proved that the membrane extraction method has high efficiency.Macrophage membrane microcapsules(MVs)were prepared by repeatedly extruding the extracted cell membrane by a micro-extruder.Through the characterization of DLS and TEM,it is proved that the MVs obtained by this method has uniform particle size,good dispersion and hollow spherical shape.The surface is negatively charged,which is consistent with the characteristics of the cell membrane.(C)The method of preparing biomimetic nanoparticles(MMNPs)coated with membranes was optimized.Through the characterization of DLS and TEM,it is confirmed that MMNPs has smaller nano-size and better dispersibility.By comparing the average particle size and surface potential of MMNPs and RAPNPs,it was preliminarily confirmed that the macrophage membrane was successfully coated on the surface of nanoparticles.Furthermore,it is found that the overall structure of MMNPs is not only the core-shell structure of internal RAPNPs,but also a circular structure on the outside.Combined with the size,the successful preparation of biomimetic nanoparticles was verified.The stability of the bionic particles was verified by measuring the average particle size and PDI of MMNPs for a long time.Through the study of drug release characteristics,it is found that MMNPs can further control drug release.By detecting the composition of membrane proteins,it was confirmed that MMNPs could completely inherit all the proteins and their biological functions of macrophage membrane.(D)By studying the effect of MMNPs on the viability of different cells,it was found that MMNPs had a strong anti-proliferation effect on macrophages and had no obvious toxicity to other cells.Fluorescently labeled nanoparticles(Di ONPs)and biomimetic nanoparticles(MM-Di ONPs)were prepared,and their particle properties were similar to those of RAPNPs and MMNPs.Through the study of cell targeting and phagocytosis in vitro,compared with Di ONPs,it was found that MM-Di ONPs could escape immune surveillance and actively target rich inflammatory macrophages in the focus of AS.In summary,a biomimetic nano-drug delivery system with good dispersion and uniform nanometer particle size was successfully prepared in this study.The system has good nano-drug properties,can completely inherit the membrane surface function of source macrophages,and has the advantages of biodegradability,drug release,long-term circulation,structural stability,active and passive targeting.This delivery system can effectively inhibit the development of AS plaque,thus achieving a safe,stable and efficient AS treatment effect.