Imaging of carotid artery inflammatory plaques with superparamagnetic nanoparticles and an external magnet collar

LIFU-responsive nanomedicine enables acoustic droplet vaporization-induced apoptosis of macrophages for stabilizing vulnerable atherosclerotic plaques

Due to the high risk of tearing and rupture, vulnerable atherosclerotic plaques would induce serious cardiovascular and cerebrovascular diseases. Despite the available clinical methods can evaluate the vulnerability of plaques and specifically treat vulnerable plaques before a cardiovascular event, but the efficiency is still low and undesirable. Herein, we rationally design and engineer the low-intensity focused ultrasound (LIFU)-responsive FPD@CD nanomedicine for the highly efficient treatment of vulnerable plaques by facilely loading phase transition agent perfluorohexane (PFH) into biocompatible PLGA-PEG-PLGA nanoparticles (PPP NPs) and then attaching dextran sulphate (DS) onto the surface of PPP NPs for targeting delivery. DS, as a typical macrophages-targeted molecule, can achieve the precise vaporization of NPs and subsequently controllable apoptosis of RAW 264.7 macrophages as induced by acoustic droplet vaporization (ADV) effect. In addition, the introduction of DiR and Fe₃O₄ endows nanomedicine with near-infrared fluorescence (NIRF) and magnetic resonance (MR) imaging capabilities. The engineered FPD@CD nanomedicine that uses macrophages as therapeutic targets achieve the conspicuous therapeutic effect of shrinking vulnerable plaques based on in vivo and in vitro evaluation outcomes. A reduction of 49.4% of vascular stenosis degree in gross pathology specimens were achieved throughout the treatment period. This specific, efficient and biosafe treatment modality potentiates the biomedical application in patients with cardiovascular and cerebrovascular diseases based on the relief of the plaque rupture concerns.

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A new nanomedicine-enabled treatment strategy has been developed for treating vulnerable plaques by employing ADV.

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The optimal treatment conditions for ADV have been explored, including LIFU irradiation power intensity and plaque stability.

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The underlying mechanism of nanomedicine-enabled ADV in the treatment of vulnerable plaques has been studied systematically.

In vivo MRI detection of intraplaque macrophages with biocompatible silica-coated iron oxide nanoparticles in murine atherosclerosis

Identification of a vulnerable atherosclerotic plaque before rupture is an unmet clinical need. Integrating nanomedicine with multimodal imaging has the potential to precisely detect biological processes in atherosclerosis. We synthesized silica-coated iron oxide nanoparticles (SIONs) coated with rhodamine B isothiocyanate and polyethylene glycol and investigated their feasibility in the detection of macrophages in inflamed atherosclerotic plaques of apolipoprotein E-deficient (ApoE^-/-) mice via magnetic resonance (MR) and fluorescence reflectance (FR) imaging. In vitro cellular uptake of SIONs was assessed in macrophages using confocal laser scanning microscopy (CLSM). In vivo MR imaging was performed 24 h after SION injection via the tail vein in 26-week-old ApoE^-/- mice fed a high-cholesterol diet (HCD). We also performed FR imaging of the extracted aortas from four different mice: two normal-diet-fed C57BL/6 mice injected with saline or 10 mg/kg SIONs and two HCD-fed ApoE^-/- mice injected with 5 or 10 mg/kg SIONs. The harvested aortas were cryosectioned and stained with immunohistochemical staining. The CLSM images at 24 h after incubation showed efficient uptake of SIONs by macrophages, with no evidence of cytotoxicity. The in vivo and ex vivo MR and FR images demonstrated SION deposition in the atheroma. Upon immunohistochemical staining of the aorta, CLSM images revealed colocalization of macrophages and SIONs in the atherosclerotic plaque. These results demonstrate that polyethylene glycosylated SIONs could be a highly effective method to identify macrophage activity in atherosclerotic plaques as a multimodal imaging agent.

Iron Oxide Nanoparticles in Regenerative Medicine and Tissue Engineering

In recent years, many promising nanotechnological approaches to biomedical research have been developed in order to increase implementation of regenerative medicine and tissue engineering in clinical practice. In the meantime, the use of nanomaterials for the regeneration of diseased or injured tissues is considered advantageous in most areas of medicine. In particular, for the treatment of cardiovascular, osteochondral and neurological defects, but also for the recovery of functions of other organs such as kidney, liver, pancreas, bladder, urethra and for wound healing, nanomaterials are increasingly being developed that serve as scaffolds, mimic the extracellular matrix and promote adhesion or differentiation of cells. This review focuses on the latest developments in regenerative medicine, in which iron oxide nanoparticles (IONPs) play a crucial role for tissue engineering and cell therapy. IONPs are not only enabling the use of non-invasive observation methods to monitor the therapy, but can also accelerate and enhance regeneration, either thanks to their inherent magnetic properties or by functionalization with bioactive or therapeutic compounds, such as drugs, enzymes and growth factors. In addition, the presence of magnetic fields can direct IONP-labeled cells specifically to the site of action or induce cell differentiation into a specific cell type through mechanotransduction.