Treatment Of Atherosclerosis By Black Phosphorus Quantum Dots And Its Mechanism

Objective: The purpose of this study is to try to treat the mouse model of atherosclerotic disease by using black phosphorus quantum dots,evaluate the model establishment and therapeutic effect through various methods,and explore its mechanism.Methods: Mouse aortic endothelial cells(MAEC)were used to evaluate the cytotoxicity of black phosphorus quantum dots.Healthy male Apo E-/-mice(C57BL/6 series)were randomly divided into normal diet group(18 mice)and high fat diet group(36 mice).The former group was fed with normal diet and the latter was fed with high fat diet for 12 weeks consecutively.Imaging aortic tree of mice noninvasively by ultrasound and monitoring the total cholesterol content at 0th,4th,8th,12th week.Four weeks,eight weeks and twelve weeks after feeding normal diet/ high fat diet,the mice were killed 5/3respectively and inferior vena venous blood were taken to measure lipid levels,stripping the aorta trees line and perform Sudan IV staining to further evaluate the degree of atherosclerosis.The heart,liver,kidney were taken for HE staining to observe the histopathological characteristics.At the end of the 12 th week,the remaining mice were divided into control group(9 mice),model group(9 mice)and black phosphorus treatment group(12 mice).The control group and model group were respectively injected with normal saline 0.1 ml at a time,and the black phosphorus treatment group was injected with black phosphorus quantum dot solution 0.1 ml at a time(0.1mg/ m L).The caudal vein was used to administer the drug every other day for 3 weeks consecutively.Three weeks later,the degree of atherosclerosis in mouse aortic trees was monitored by ultrasound again.At the end of the experiment,all mice were killed,and the whole blood of mice and the whole blood vessels of aortic trees were collected,and the pathological tissues of mice were retained.The therapeutic effect of black phosphorus quantum dots on atherosclerotic diseases was compared and evaluated,and the possible mechanism of action was explored by using RAW264.7 cells in vitro cell experiment.Results: The concentration of BPQDs at 40μg/ m L had no obvious toxic effect on mouse MAEC cells.Ultrasound monitoring showed that plaque formation was observed in the blood vessels of mice in the high-fat diet group at 8 weeks after feeding.With the prolongation of feeding cycle,PSV of all segments of aorta,RI of abdominal main artery and innominate artery showed an upward trend,while vascular tension showed a downward trend.After 3 weeks of administration,the PSV of the innominate artery of mice in the black-phosphorus treatment group was higher than that in the control group and the model group,and the vascular tension of the abdominal aorta and innominate artery in the model group and the black-phosphorus treatment group was lower than that in the control group.With the increase of feeding weeks,the content of total cholesterol in the blood of tail tip of mice in different diet groups showed an increasing trend.At the end of 12 weeks,the contents of TC,TG and LDL in serum of mice in high fat diet group were higher than those in normal diet group.After 3 weeks of administration,the total cholesterol content in the tail tip blood of mice in the model group and the black phosphorus treatment group was still higher than that in the control group,and the serum TC and LDL were also higher than that in the control group,while the HDL content was lower than that in the control group.The red stained area of aortic tree blood vessels in mice stained with Sudan IV increased with modeling time,and the red stained area in high fat diet group was significantly higher than that in normal diet group.After 3 weeks of administration,the red stained area of mice in the model group increased compared with before,while the red stained area of mice in the BP treatment group decreased.HE staining of pathological tissue showed foam cells and lipid deposition in the aortic root of mice in the high-fat diet group,fat cavitation formation in the liver tissue,and no abnormal pathological changes in kidney and heart tissue.After 3 weeks of treatment,no significant changes were observed in liver tissue of mice in the BP treatment group compared with the model group,and no significant abnormal pathological changes were observed in kidney and heart tissue between the three groups.RAW264.7 cells were used to simulate macrophage polarization in vitro,and the expression of M1-type markers in macrophages treated with BPQDs was significantly decreased,while the expression of M2-type markers was significantly increased.Under fluorescence observation,BPQDs promoted the differentiation of macrophages to M2-type spindle.It is suggested that black phosphorus can induce RAW264.7 cells to polarization towards M2-type.Conclusion: 1.Apo E-/-mice were fed with high-fat diet for 12 weeks under ultrasonic monitoring,and the animal model of AS could be successfully established,and the disease progression could be monitored dynamically and noninvasively by ultrasound.2.The injection of black phosphorus quantum dot solution through caudal vein can effectively reduce the plaque area of the blood vessel wall,reduce the level of blood lipid,and delay the progression of AS disease to a certain extent.3.Black phosphorus can induce RAW264.7 cells to polarization toward M2-type and change the M1 /M2 ratio,suggesting that macrophage polarization is one of the possible mechanisms of plaque clearance.