Detection of Vascular Reactive Oxygen Species in Experimental Atherosclerosis by High-Resolution Near-Infrared Fluorescence Imaging Using VCAM-1-Targeted Liposomes Entrapping a Fluorogenic Redox-Sensitive Probe

Abstract

Excessive production of reactive oxygen species (ROS) and the ensuing oxidative stress are instrumental in all phases of atherosclerosis. Despite the major achievements in understanding the regulatory pathways and molecular sources of ROS in the vasculature, the specific detection and quantification of ROS in experimental models of disease remain a challenge. We aimed to develop a reliable and straightforward imaging procedure to interrogate the ROS overproduction in the vasculature and in various organs/tissues in atherosclerosis. To this purpose, the cell-impermeant ROS Brite™ 700 (RB700) probe that produces bright near-infrared fluorescence upon ROS oxidation was encapsulated into VCAM-1-targeted, sterically stabilized liposomes (VLp). Cultured human endothelial cells (EC) and macrophages (Mac) were used for in vitro experiments. C57BL6/J and ApoE-/- mice were randomized to receive normal or high-fat, cholesterol-rich diet for 10 or 32 weeks. The mice received a retroorbital injection with fluorescent tagged VLp incorporating RB700 (VLp-RB700). After two hours, the specific signals of the oxidized RB700 and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl) (NBD-DSPE), inserted into liposome bilayers, were measured ex vivo in the mouse aorta and various organs by high-resolution fluorescent imaging. VLp-RB700 was efficiently taken up by cultured human EC and Mac, as confirmed by fluorescence microscopy and spectrofluorimetry. After systemic administration in atherosclerotic ApoE-/- mice, VLp-RB700 were efficiently concentrated at the sites of aortic lesions, as indicated by the augmented NBD fluorescence. Significant increases in oxidized RB700 signal were detected in the aorta and in the liver and kidney of atherosclerotic ApoE-/- mice. RB700 encapsulation into sterically stabilized VCAM-1-sensitive Lp could be a novel strategy for the qualitative and quantitative detection of ROS in the vasculature and various organs and tissues in animal models of disease. The accurate and precise detection of ROS in experimental models of disease could ease the translation of the results to human pathologies.

Redox-Responsive MRI Probes Based on First-Row Transition-Metal Complexes

“…Also, animal models for diseases that involve inflammatory processes should be pursued in future applications, in preference to artificially induced inflammation such as injection of LPS into mice . Various photoacoustic, fluorescent, or radioisotope probes have been shown to register ROS-derived inflammation in mouse models including tumors, bacterial infections, or atherosclerosis. , A recently reported Gd­(III)-based MRI probe for myeloperoxidase activity showed improved contrast of unstable atherosclerotic plaque in mice …”

Photoluminescence properties of cuprous phosphide prepared through phosphating copper with a native oxide layer

“…[1][2][3][4][5][6][7][8][9] For example, the infrared window of biological tissue is 700-900 nm, and the near-infrared light within this range can be used to detect blood oxygen signals. 10,11 Cuprous phosphide (Cu 3 P) is widely used in catalysts, electrode materials and welding materials. However, as a p-type semiconductor material, its electrical and optical properties and applications have been neglected.…”

Targeting Peptide, Fluorescent Reagent Modified Magnetic Liposomes Coated with Rapamycin Target Early Atherosclerotic Plaque and Therapy

“…There is much evidence of liposome-linked or encapsulated targeting peptides [ 37 ] for the targeting or encapsulation of rapamycin for disease therapy (or that of USPIO), drugs and for early MRI diagnosis and therapy of diseases [ 38 ]. Liposomes of fluorescence imaging are also used in the diagnosis and treatment of atherosclerosis [ 39 , 40 ]. However, so far, there are no reports of such comprehensive nanoparticles that we have synthesized by using DSPE-PEG2000-VHP, DSPE-FITC (targeting peptide VHP (or fluorescent reagent) to modify the phospholipid molecules), Rap and encapsulated USPIOs, which target atherosclerotic plaque and bimodal imaging to achieve diagnostic and therapeutic effects for early atherosclerosis.…”