The Effects Of Sand PM2.5 On Rat Aortic Subendothelial Matrix And Bone Marrow-derived Endothelial Progenitor Cells

Objective:Investigating the effect of sand PM2.5 on the rat aortic subendothelial matrix and viability of bone marrow-derived endothelial progenitor cells.Methods:Sixty Wistar rats were randomly selected,numbered and labeled,and randomly divided into high,medium and low concentration groups as well as the control group by PM2.5 contamination concentration,and each group was contaminated with 16 mg/m L(high),4 mg/m L(medium),1 mg/m L(low)sand PM2.5 suspension and saline(control)at a volume of 0.15 m L/100 g by intratracheal drip.that lasted for 7 days.During the period,their health status was observed,and their body mass were weighed,and the hearts and thoracic aorta were removed after execution,and the heart mass indexes of different groups were compared.Immunohistochemical staining was performed to observe the expression of collagen I,collagen II,collagen III,matrix metalloproteinase 2(MMP2)and matrix metalloproteinase 9(MMP9),and the image integral optical density(IOD)values were measured and quantitatively analyzed.Rat bone marrow-derived endothelial progenitor cells(BMEPCs)were expanded in passaged culture and stained with medium containing different concentrations of histone PM2.5.The cell optical density(OD)values were measured by CCK-8 after 24 hours.And the cell activity was calculated based on the OD value.,typan blue dye was performed,smears were observed,cells were counted,and cell mortality was calculated.Results: The CMI was calculated after PM2.5 contamination of rats and showed a positive correlation between the elevation and PM2.5 concentration in the low(2.62±2.28)< medium(3.06±1.14)< high(3.60±1.00)dose groups(P<0.05).IOD of collagen I: high dose group(0.19±0.02)< medium dose group(0.65±0.05) medium dose group(3.87±0.30)> low dose group(2.64±0.27)> control group(1.00±0.17)(P<0.05).IOD of collagen III: high-dose group(0.20 ± 0.03)< medium-dose group(0.51 ± 0.06)< control group(1.00 ± 0.07)(P<0.05).IOD of MMP2: high dose group(3.23±0.26)> medium dose group(2.34±0.17)> low dose group(1.52±0.93)> control group(1.00±0.33)(P<0.05).IOD of MMP9: high-dose group(2.99±0.22)> medium-dose group(1.88±0.09)>control group(1.00±0.19)(P<0.05).The viability of the 400?g/m L group(120.7±9.2)and 500 ?g/m L group(116.8±15.2)was higher(P<0.05)on day 3 after BMEPCs infection compared to the control group.The cellular activity of each experimental group decreased on day 4 and 5 compared to the control group(P<0.05).There was no significant difference between the experimental groups with different PM2.5concentrations.Conclusions:1.Short-term exposure to sand PM2.5 can cause changes in the content of collagen I,II,and III by altering the content of MMP2,MMP9,resulting in myocardial and aortic fibrosis.The degree of fibrosis was positively correlated with PM2.5 concentration.2.High concentrations of sand PM2.5 can reduce the activity of BMEPCs,increase the death rate of BMEPCs and affect endothelial damage repair function.