Quantitative Assessment Of Synovial Neovascularization In Rheumatoid Arthritis By RGD Microbubbles-mediated High Frequency Contrast-enhanced Ultrasound

Objective RGD(arginine-glycine-aspartic acid,Arg-Gly-Asp)microbubbles were prepared,and their targeting to synovial neovascularization in the ankle joint of rats with rheumatoid arthritis was observed by contrast-enhanced ultrasound,and verified by histopathology.Methods RGD microbubbles were prepared and their general characteristics were detected.Rat model of rheumatoid arthritis was established by collagen-induced method,and the rats in the control group were immunized twice with the same dose of normal saline.The imaging of RGD microbubbles and naked microbubbles in the synovial tissue of collagen-induced arthritis(CIA)rats was detected by ultrasound contrast-enhanced technology,and the contrast intensity difference between RGD microbubbles and naked microbubbles before and after target tissue explosion was compared to verify the targeting of RGD microbubbles.Finally,rat ankle joints were taken for hematoxylin-eosin(HE)andαvβ3,CD31immunohistochemical staining to confirm collagen-induced arthritis(CIA)rat ankle joint synovial thickening and angiogenesis.Results Compared with naked microbubbles,the particle size of the prepared RGD microbubbles was 0.82±0.25μm vs 0.80±0.19μm,and the potential was-1.63±3.52m V vs-1.65±3.51m V,with no statistical significance(ALL P>0.05).microbubbles concentration was all 10~8particles/m L.Microbubbles loading rate of RGD:92.28%.CIA rat model was successfully established,and molding rate up to 70%.Contrast-enhanced ultrasound showed that the contrast intensity difference of RGD microbubbles before and after ankle synovial tissue explosion in CIA rats was significantly higher than that of naked microbubbles group,with statistical significance(P<0.05).Histopathology showed that the synovium of CIA rats was significantly thickened andαvβ3,CD31 were highly expressed compared with control rats.Conclusion The RGD microbubbles prepared in this study have uniform particle size and good dispersion.Ultrasound contrast-enhanced technique detected that RGD microbubbles had good targeting ability to neovascularization in the ankle synovial tissue of CIA rats,which was confirmed by histopathology.This study can be used for the early diagnosis of RA and providing a theoretical basis for the subsequent accurate and effective evaluation of its activity and drug efficacy.