Theranostic multifunctional lipid nanoparticles containing curcumin for integrated imaging and stabilizing vulnerable atherosclerotic plaques through an "eat-me" signal

BACKGROUNDCurcumin has emerged as a promising candidate capable of polarization of macrophages, which promote the stability of atherosclerotic plaque. Nevertheless, a notable limitation lies in the non-specific nature of curcumins targeting. The present study endeavors to harness multifunctional lipid nanoparticles (MLNPs), which could both facilitate imaging and achieve targeted delivery of curcumin specifically to inflammatory macrophages, to effectively counteract vulnerable plaque and mitigate the risk of ischemic events. METHODSThe term "MLNPs", for targeted delivery of curcumin using multimodal imaging techniques including single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI), refers to a new type of nanoparticle designed to specifically target and modulate macrophages with phagocytic function. These nanoparticles are cholesteryl-9-carboxynonanoate-(125I-iron oxide nanoparticle/Cur)-lipid-coated nanoparticles [9-CCN-(125I-ION/Cur)-LNPs], which carry hybrid imaging agents. These agents are combinations of 125I-ION and lipids that contain phagocytic "eat-me" signals, which induces macrophages to swallow MLNPs. RESULTSThe accumulation of the devised 9-CCN-(125I-ION/Cur)-LNPs on the unstable plaque of animal models in vivo was accurately reflected and lesions were highlighted by both SPECT and MRI. The intense radioactive signals on SPECT images facilitated the identification and quantification of the target lesion, while MRI based on ION particles facilitated the visualization of the focal localization and volumetry of atherosclerotic plaque. The targeted distribution of the unstable plaque in the rabbit aorta was further confirmed by ex vivo planar images of nuclide and Prussian blue staining for ION. Additionally, 9-CCN-(125I-ION/Cur)-LNPs were found to specifically and effectively bind to the pro-inflammatory M1 macrophages present in the unstable plaque, resulting in the accumulation of radionuclide and hypointensity on T2W images. CONCLUSIONSThe 9-CCN-(125I-ION/Cur)-LNPs demonstrated remarkable capability in the delivery of both 125I-ION and curcumin to macrophages, ultimately resulting in M1-M2 macrophage polarization, which may offer valuable insights into addressing unstable atherosclerotic plaque.