Objective-Angiogenic expansion of the vasa vasorum is a well-known feature of progressive atherosclerosis, suggesting that antiangiogenic therapies may stabilize or regress plaques. ␣ ␤ 3 Integrin-targeted paramagnetic nanoparticles were prepared for noninvasive assessment of angiogenesis in early atherosclerosis, for site-specific delivery of antiangiogenic drug, and for quantitative follow-up of response. Methods and Results-Expression of ␣ ␤ 3 integrin by vasa vasorum was imaged at 1.5 T in cholesterol-fed rabbit aortas using integrin-targeted paramagnetic nanoparticles that incorporated fumagillin at 0 g/kg or 30 g/kg. Both formulations produced similar MRI signal enhancement (16.7%Ϯ1.1%) when integrated across all aortic slices from the renal arteries to the diaphragm. Seven days after this single treatment, integrin-targeted paramagnetic nanoparticles were readministered and showed decreased MRI enhancement among fumagillin-treated rabbits (2.9%Ϯ1.6%) but not in untreated rabbits (18.1%Ϯ2.1%). In a third group of rabbits, nontargeted fumagillin nanoparticles did not alter vascular ␣ ␤ 3 -integrin expression (12.4%Ϯ0.9%; PϾ0.05) versus the no-drug control. In a second study focused on microscopic changes, fewer microvessels in the fumagillin-treated rabbit aorta were counted compared with control rabbits. Conclusions-This study illustrates the potential of combined molecular imaging and drug delivery with targeted nanoparticles to noninvasively define atherosclerotic burden, to deliver effective targeted drug at a fraction of previous levels, and to quantify local response to treatment. Key Words: magnetic resonance imaging Ⅲ atherosclerosis Ⅲ molecular imaging Ⅲ angiogenesis Ⅲ nanoparticles Ⅲ fumagillin A key feature of the atherosclerotic process is the angiogenic expansion of the vasa vasorum in the adventitia, which extends into the thickening intimal layer of the atheroma in concert with other neovessels originating from the primary arterial lumen. 1 Extensive neovascular proliferation within atherosclerotic plaques is prominent within "culprit" lesions clinically associated with unstable angina, myocardial infarction, and stroke. [2][3][4] Plaque angiogenesis has been suggested to promote plaque growth, intraplaque hemorrhage, 5 and lesion instability.Magnetic resonance (MR) molecular imaging of focal angiogenesis in vivo with integrin-targeted paramagnetic contrast agents was reported with perfluorocarbon nanoparticles 6 -8 and liposomes. 9 Subsequently, we have developed MRI and postprocessing techniques to permit molecular imaging of the diffuse proliferating neovasculature associated with atherosclerotic plaque development. 10,11 The widespread expression of ␣ ␤ 3 integrins observed by MR agreed with the diffuse nature of angiogenesis microscopically observed in the early atherosclerotic aortas of cholesterol-fed rabbits.The importance of angiogenesis in the progression of atherosclerotic plaque combined with the antiangiogenic impact of 3-hydroxy-3-methylglutaryl (HMG)-coenzyme A (CoA) reductase ...

The in vivo application of cytolytic peptides for cancer therapeutics is hampered by toxicity, nonspecificity, and degradation. We previously developed a specific strategy to synthesize a nanoscale delivery vehicle for cytolytic peptides by incorporating the nonspecific amphipathic cytolytic peptide melittin into the outer lipid monolayer of a perfluorocarbon nanoparticle. Here, we have demonstrated that the favorable pharmacokinetics of this nanocarrier allows accumulation of melittin in murine tumors in vivo and a dramatic reduction in tumor growth without any apparent signs of toxicity. Furthermore, direct assays demonstrated that molecularly targeted nanocarriers selectively delivered melittin to multiple tumor targets, including endothelial and cancer cells, through a hemifusion mechanism. In cells, this hemifusion and transfer process did not disrupt the surface membrane but did trigger apoptosis and in animals caused regression of precancerous dysplastic lesions. Collectively, these data suggest that the ability to restrain the wide-spectrum lytic potential of a potent cytolytic peptide in a nanovehicle, combined with the flexibility of passive or active molecular targeting, represents an innovative molecular design for chemotherapy with broad-spectrum cytolytic peptides for the treatment of cancer at multiple stages.

Neovascularization is a critical component in the progression of malignant melanoma. The objective of this study was to determine whether ␣ ␤ 3 -targeted paramagnetic nanoparticles can detect and characterize sparse ␣ ␤ integrin expression on neovasculature induced by nascent melanoma xenografts (ϳ30 mm

Noninvasive magnetic resonance (MR) molecular imaging and targeted drug delivery systems, often referred to as theranostic agents, are being developed to enable improved detection, patient risk stratification, site-specific treatment, and longitudinal monitoring. 1 One example of these agents, a gadolinium-based perfluoro-carbon nanoparticle, has been used to detect, characterize, treat, and follow angiogenesis in preclinical models of cancer and atherosclerosis. Despite the preclinical success of this and related nanotechnology platforms, the recent discovery of nephrogenic systemic fibrosis (NSF), a serious and unexpected side effect of gadolinium blood pool agents observed in some patients with renal disease or following liver transplant, has cast a shadow on currently approved MR contrast agents. 2 Patients with NSF develop thickening of the skin and connective tissues that can inhibit arm and leg movements and even lead to bone fractures. Approximately 5% of patients experience a rapidly progressive course, which may result in death due to widespread fibrosis. The cause of NSF is unknown and there is no effective treatment of this condition. Although gadolinium has been the dominant paramagnetic metal for MR contrast agents, the issue of NSF has induced consideration of alternative approaches.Manganese was one of the first reported examples 3,4 of paramagnetic contrast material studied in cardiac and hepatic MRI because of its efficient R 1 enhancement. Similar to Ca 2+ and unlike the lanthanides, manganese is a natural cellular constituent, and often a cofactor for enzymes and receptors. Manganese blood pool agents, such as mangafodipir trisodium, have been approved as a hepatocyte-specific contrast agent with transient side-effects due to dechelation of manganese from the linear chelate. Nontargeted liposomal agents have included MnSO 4 3c or Mn-DTPA. 3d Release of Mn caused by disruption of the vesicles allowed MR detection of sites where the vesicles were non-specifically entrapped.Manganese(III)-labeled nanobialys (1) are a potential targeted MR theranostic nanoparticle produced by molecular self-assembly of amphiphilic branched polyethylenimine, which has a toroidal shape, tunable particle size, and low polydispersity. The "bialy" shape affords increased stability and presents kinetically stable, porphyrin coupled Mn(III) complexes directly to the surrounding water. In a typical synthesis, commercially available branched polyethylenimines (MW = 10 kDa) are hydrophobically modified (nominal 55% conjugation of the 1° amine) with linoleic acid by activating the carboxylic acid groups with 1-(3′-dimethylaminopropyl)-3-ethylcarbodiimide methiodide (1.2 equiv) and allowing the reaction overnight at ambient temperature. Supramolecular self-assembly of the amphiphilic polymer in anhydrous chloroform, assumes inverted micellar 5 structures (2) that are able to transfer a water soluble new candidate contrast agent Mn(III)-protoporphyrin chloride (Mn-PPC, 4) into chloroform. Synergistic self-assembly of the ag...