Imaging atherosclerosis model rabbits with 99Tcm-single chain antibody fragment against vascular cell adhesion molecule-1 / 中华核医学与分子影像杂志

ABSTRACT

Objective To investigate the imaging performance and feasibility of 99Tcm labeled scFv against VCAM-1(99Tcm-scFv-VCAM-1) on atherosclerosis model rabbits.Methods HYNIC was used as a chelator for 99Tcm labeling.The labeling efficiency and radiochemical purity of 99Tcm-scFv-VCAM-1 were measured by instant thin layer chromatography after PD-10 purification.New Zealand white rabbits were employed for establishing atherosclerotic animal models by endothelia immunity injury and high fat diet, and plaques at aorta lesions were examined by HE staining.Model rabbits were sacrificed after administration of 99Tcm-scFv-VCAM-1 at 1 or 2 h respectively, and tissue samples were measured with gamma counter and weighted to obtain in vivo biodistribution data.Planar imaging was performed 1 and 2 h after the injection of 99Tcm-scFv-VCAM-1 to investigate radioactivity of abdominal aorta.After imaging study, atherosclerosis plaque and VCAM-1 expression at aortas were confirmed by the immunohistochemistry (IHC) study.Two-sample t test was used to analyze data.Results 99Tcm-scFv-VCAM-1 was successfully synthesized.Its labeling efficiency was 75%-83%, radiochemistry purity was (98.54±1.03)% and specific activity was 216 MBq/nmol.Atherosclerosis plaque was confirmed at the aortas of experimental rabbits by HE staining, while no plaque was observed in controls.Biodistribution data indicated that the tracer was cleared mainly through the kidneys.Planar imaging showed that the tracer uptake in abdominal aorta of model rabbits was higher than that of control rabbits, the T/B ratios at 2 h of the model group and control group were statistically different (3.68±0.73 vs 2.42±0.39;t=2.950, P<0.05;n=5).Atherosclerosis plaque and high level of VCAM-1 expression were observed at aortas of model rabbits by IHC study.Conclusions It is feasible and effective to detect vulnerable plaques using 99Tcm-scFv-VCAM-1.It may provide a promising way for early diagnosis and accurate evaluation of atherosclerosis.