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Ultrasound in medicine & biology

Ultrasonic imaging of endothelial CD81 expression using CD81-targeted contrast agents in in vitro and in vivo studies.


PMID 22341598

Abstract

This study is designed to investigate the feasibility for molecular imaging of endothelial CD81 expression inxa0vitro and inxa0vivo using the CD81-targeted ultrasound contrast agents (UCA). In the inxa0vitro study, murine bEnd.3 cells were stimulated with phenazine methosulfate (PMS), an oxidative stress inducer. Changes in CD81 expression after stimulation were confirmed by Western blotting, tracked by using the targeted UCA and further imaged under ultrasound imaging system with 5 MHz transmit frequency. In the inxa0vivo study, expression of endothelial CD81 proteins in murine carotid artery vessels was studied using high-frequency ultrasound system with 40xa0MHz transmit frequency. Our results showed that endothelial CD81 expression was gradually up-regulated with the increase of PMS concentration. Correspondingly, the accumulation of targeted UCA was gradually improved and could be inhibited significantly upon addition of free anti-CD81 antibodies. The mean video intensity (grey-level) of stimulated cells and vessels from backscatter of the CD81-targeted UCA was 17.2 (interquartile range [IQR] 15.4-19.8) and 27.2 (IQR 22.4-29.8), significantly greater than that of non-stimulated cells with 9.0xa0(IQR 8.6-10.8) (p < 0.01) and non-stimulated vessels with 11.3 (IQR 10.4-13.2) (p < 0.01), respectively. Inxa0conclusion, CD81-targeted UCA allows noninvasive assessment of the expression levels of CD81 on the vascular endothelium and may provide potential insights into early atherosclerotic plaque detection and treatment monitoring.