Cardiovascular molecular imaging as a tool to study biology

Ultrasound Molecular Imaging of Atherosclerosis for Early Diagnosis and Therapeutic Evaluation through Leucocyte-like Multiple Targeted Microbubbles

Cardiovascular diseases resulting from atherosclerosis have become a serious threat to human health. It is well-known that an ongoing inflammatory response is involved during atherosclerosis progression that ultimately results in the accumulation of lipids and formation of plaques. Monitoring the pathological changes during the inflammatory response will be of great significance for early diagnosis and therapeutic evaluation of atherosclerosis. Targeted contrast-enhanced ultrasonography has been shown to be a promising noninvasive imaging technique for evaluating the degree of atherosclerosis and may potentially be translated to clinical imaging in the future. However, inadequate cell adhesion of targeted microbubbles (MBs) in large arterial vessels still remains a great challenge. Methods: By mimicking the leucocytes that are recruited to the vessel wall during the initiation of atherosclerosis through selectin-dependent arrest and cell adhesion molecule-mediated firm cell adhesion, we developed VCAM-1/ICAM-1/P-selectin-targeted MB_VIS by integrating VCAM-1 and ICAM-1 antibodies and synthetic polymeric sialyl Lewis X (sLe^x) onto the MB surface. Results: The resulting MB_VIS had a high affinity to inflammatory bEnd.3 cells in both static and dynamic flow conditions. Significantly enhanced ultrasound imaging signals were achieved by MB_VIS in detecting the atherosclerosis progress when compared with the single- or dual-targeted MBs. Taking advantage of the artificial MB_VIS, less ultrasound imaging signals were found in the atorvastatin-treated, but not placebo-treated, ApoE-deficient mice with atherosclerosis, revealing a potential therapeutic efficacy of atorvastatin for early stage atherosclerosis. This was further confirmed by histologic staining examination. Conclusions: Our study provides a promising ultrasound molecular imaging probe for early-stage diagnosis and therapeutic evaluation of atherosclerosis.