Macrophage Membrane-coated Nanoparticles Disguised As Macrophages For Preventing And Treating T2DM

High-fat diet,obesity and chronic inflammation can induce type 2 diabetes.For obese patients,the LPS released by the intestinal flora is absorbed into the blood circulatory system because of the alteration of intestinal flora and increased intestinal permeability.Besides,a high-fat diet leads to increased levels of FFA and glucose in plasma.Stimulants,such as LPS and FFA,activate macrophages to produce reactive oxygen species and pro-inflammatory cytokines which induce the inflammatory cascade.The inflammatory response accelerates the damage of insulin receptors and induces insulin resistance,thereby leading to insulin resistance and T2 DM.At the same time,insulin resistance can induce increased levels of triglycerides,low-density lipoproteins,and decreased levels of high-density lipoproteins,leading to dyslipidemia,which is the main pathogenic factor in inducing cardiovascular complications of diabetes.Considering that the macrophage membrane could specifically recognize stimuli and neutralize inflammatory factors,we prepared a core-shell structured cell membrane biomimetic nanoparticle by extracting macrophage cell membrane and encapsulating BSA nanoparticles(BSA@MMs).The prepared BSA@MMs nanoparticles retain the biological properties of the macrophage membrane.They can capture LPS and neutralize inflammatory cytokines to block the inflammatory response and thereby improve insulin sensitivity.Finally,we evaluated the regulatory effect of BSA@MMs on dyslipidemia caused by insulin resistance and its protective effect on the heart.The content of this topic is as follows:The second chapter described the construction and characterization of BSA@MMs nanoparticles.The positively charged BSA NPs were prepared by desolvation technique.The macrophage membrane vesicles were obtained by ultrasonic disruption,differential centrifugation and extrusion.The electrostatic effect was used to promote the fusion of BSA NPs and cell membrane vesicles.Finally,BSA@MMs NPs were prepared by the methods of ultrasonic fusion,shaking incubation and co-extrusion.TEM,particle size and Zeta potential characterizations showed that the macrophage membrane-coated BSA NPs were successfully constructed.The BSA@MMs NPs dispersed well and exhibited an obvious core-shell structure,with diameters of 100～180 nm.The potential of BSA@MMs NPs is similar to that of membrane vesicles,both of them are negative and stable.In the third chapter,we evaluated the safety of BSA@MMs,and in vitro effects of BSA@MMs.The results of cytotoxicity experiments and in vivo toxicity experiments showed that BSA@MMs NPs have good biocompatibility.The results of cell uptake and in vivo distribution experiments revealed that BSA@MMs NPs can avoid the phagocytosis of macrophages and have good long-term circulation characteristics.In vitro adsorption experiments showed that BSA@MMs NPs can adsorb and reduce the level of inflammatory cytokines in the system.Cellular ROS assay verified the detoxification effect of BSA@MMs on LPS in vitro.BSA@MMs NPs can reduce the production of ROS in macrophages and inhibit their conversion to pro-inflammatory phenotypes.In the fourth chapter,we measured the therapeutic effect of BSA@MMs in vivo.To evaluate the therapeutic effect of BSA@MMs,we established the T2 DM mice models.In vivo results showed that BSA@MMs can significantly reduce the concentration of pro-inflammatory cytokine in the serum of mice,such as TNF-α,IL-1,and IL-6,inhibiting the inflammatory response in the body.Also,they could reduce blood glucose and improve insulin sensitivity in vivo to achieve the purpose of prevention and treatment of T2 DM.The histological examination showed that BSA@MMs NPs have the function of protecting lung and islets of Langerhans.The blood lipid-related indicators,including LDL-c,HDL-c,TG,TC,were measured to verify the blood lipid-regulating effect of BSA@MMs.Finally,the myocardial enzymes,including AST,CK and LDH,were measured to verify the protective effect of BSA@MMs on cardiomyocytes.