Cyclodextrin-loaded nanobubbles reduce cholesterol and atherosclerosis in vivo

Abstract Background Ischemic heart disease (IHD) is the leading cause of mortality and morbidity worldwide. Atherosclerosis, a chronic inflammatory disease, is the main contributor to IHD. However, atherosclerosis is commonly left undiagnosed and untreated. Our study aims to create a theranostic nanobubbles (NBs), with ultrasonic properties for diagnostic imaging and at the same time for the delivery of 2-Hydroxypropyl-beta-cyclodextrin (CD), an FDA-approved drug to dissolve cholesterol crystals. Methods and Results Using polybutlycyanoacrylate, we created polymeric NBs. The incorporation of near-infrared dye (IR780) resulted in a multimodal contrast NB, which allows in vitro and in vivo visualization on both ultrasound and optical imaging. Furthermore, these NBs can be triggered by ultrasonic bursts to release their dye/drug payload. The safety profile of the NBs, post-incorporation of CD (CDNBs), demonstrated excellent biocompatibility in vitro using cell culture and in human blood. Cellular uptake of CP increased by 2.4x when using CPNBs compared to free CD (p<0.00001). In vivo biodistribution demonstrated that the NBs circulate in blood plasma for 48 hours, with a peak at 1-hour post-injection. In a mouse model of atherosclerosis, ApoE-/- mice on high-fat diet, we intravenously injected CDNBs, free CD or NBs only fortnightly for 8 weeks. En face Oil Red O-staining showed a significant reduction in total plaque area in the CDNB-treated group, as compared to the control animals treated with free CD and with NBs only (p>0.01). There was also a significant reduction in blood plasma cholesterol for the CDNBs-treated mice as compared to the control mice (p>0.01). Conclusion We demonstrated the ability to load CDs into NBs. These CDNBs are taken up by immune cells. The passive accumulation of CDNPs in the atherosclerotic lesions, resulted in the release of CD and the reduction of total plaque area in the entire aorta. These CDNBs treated mice also have a reduced cholesterol level in their plasma. CDNBs represent a novel theranostic nanocarrier with a high potential of clinical translation and ultimately major benefits to patients with atherosclerosis.