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  1. 1. For reprint orders, please contact: PERSPECTIVE Nanomedicine opportunities for cardiovascular disease with perfluorocarbon nanoparticles Gregory M Lanza1†, Nanomedicine promises to enhance the ability of clinicians to address some of the Patrick M Winter1,2, serious challenges responsible for cardiovascular mortality, morbidity and numerous Shelton D Caruthers1,3, Michael S Hughes1,4, societal consequences. Targeted imaging and therapy applications with perfluorocarbon Tillmann Cyrus1,5, nanoparticles are relevant to a broad spectrum of cardiovascular diseases, ranging from Jon N Marsh1,6, asymptomatic atherosclerotic disease to acute myocardial infarction or stroke. As Anne M Neubauer1,7, illustrated in this article, perfluorocarbon nanoparticles offer new tools to recognize Kathy C Partlow1,8 & and characterize pathology, to identify and segment high-risk patients and to treat Samuel A Wickline1,9 chronic and acute disease. †Author for correspondence 1Division of Cardiology, Washington University Medical School, Cortex Since the beginning of the last century, cardio- approximately 100,000 per particle, and greatly Building, Suite 101, vascular disease (CVD) has been the number amplifies the T1-weighted signal [5–7], while the 4320 Forest Park Avenue, one killer in the USA, with nearly 2500 Ameri- PFC core affords concurrent opportunity for 19F St Louis, MO 63108, USA Tel.: +1 314 454 8813; cans dying of CVD each day, an average of imaging and spectroscopy [8–10]. Fax: +1 314 454 5265; 1 death every 35 s [1]. The annual economic Homing ligands (e.g., monoclonal antibodies, E-mail: impact of CVD is estimated to be a staggering peptides or peptidomimetics) are cross-linked to 2E-mail: patrick@ US$403.1 billion, or approximately 3.5% of the the outer surface to afford active targeting to 3Philips Medical Systems, US gross domestic product in 2005 [1]. biomarkers expressed within the vasculature. Cleveland, OH 44143, USA Although no single technology can offer solu- PFC nanoparticles are naturally constrained by E-mail: scaruthers@ tions to all problems, the rapid coevolution of size to the circulation, which minimizes unin- 4E-mail: MSH@ molecular biology, cell biology, genomics, pro- tended binding to extravascular, nontarget tis- teomics, material sciences and bioengineering sues expressing similar epitopes. Moreover, their 5E-mail: tcyrus@ have created a cadre of ‘nanotools’, as exempli- prolonged circulatory half-life of approximately fied by perfluorocarbon (PFC) nanoparticles, 5 h allows saturation of receptors without addi- 6E-mail: JNM@ which offer unique diagnostic and therapeutic tion of polyethylene glycol or lipid surfactant 7E-mail: Aneubauer@ approaches to address CVD issues. polymerization [Hu G et al., Unpublished Data]. Site-targeted nanoparticles offer the oppor- 8E-mail: Kathy@ PFC nanoparticles: a tunity for local drug delivery in combination 9E-mail: Wicklines@ platform technology with molecular imaging, which can provide Perfluorocarbon nanoparticles represent a plat- noninvasive confirmation of targeting, spatial form technology with flexible molecular imag- localization of drug distribution and quantific- ing and local drug delivery potential. They are ation of therapeutic payload accumulated at the lipid-encapsulated emulsions with nominal sizes site. We have proposed that targeted PFC nano- between 200 and 250 nm. The core of the parti- particles deliver chemotherapeutic agents cle (98% volume) comprises perfluoro- through a mechanism we refer to as ‘contact- chemicals, which are chemically stable, facilitated lipid exchange’. Subsequent studies nonmetabolizable and intrinsically nontoxic [2]. utilizing confocal microscopy have illustrated Perfluorochemicals have seen use in varied the exchange of fluorescent-labeled phospholip- human applications, including blood replace- ids from the outer surfactant layer of the parti- ment, liquid breathing, ocular fluid replacement cle to the target cell membrane (Figure 1) [11]. Keywords: atherosclerosis, and medical imaging. The utility of targeted PFC nanoparticles has MRI, nanomedicine, nanoparticles, restenosis, For imaging, the PFC core of the nanoparticle been demonstrated for a variety of applications stroke, ultrasound creates inherent acoustic contrast when bound to in animal models and phantoms, including the tissues owing to its low speed-of-sound, which is diagnosis of ruptured plaque, the quantification a half to a third of that of water [2–4]. In MR, the and antiangiogenic treatment of atherosclerotic increased surface area of the nanoparticles sup- plaque and the localization and delivery of ports high payloads of paramagnetic metals, antirestenotic therapy following angioplasty. 10.2217/17435889.1.3.321 © 2006 Future Medicine Ltd ISSN 1743-5889 Nanomedicine (2006) 1(3), 321–329 321
  2. 2. PERSPECTIVE – Lanza, Winter, Caruthers et al. Figure 1. ‘Lipid streaming’ into the acute coronary syndromes and strokes, which plasma membrane. often occur in asymptomatic vascular segments with modest disease. Until recently, the dogma has been that a single complex lesion was respon- sible for the clinical event. However, the diffuse nature of arterial tree inflammation renders many lesions within a vascular bed equally susceptible to fissuring of thinning fibrous cap. Although multiple sites of rupture are uncommon as a cause of sudden coronary death, luminal fibrin from multiple ruptures are frequent and associ- ated with plaque hemorrhage and superficial macrophages [12–14]. These sites of intimal tears, demarcated by accumulated surface fibrin, are suggested to be responsible for the rapid progres- sion of vascular stenosis in patients [15]. In fact, accumulated surface fibrin may be the critical hallmark of lesion instability. We have previously reported and demon- A high-power image of a bound phospholipid- strated the use of fibrin-specific paramagnetic rhodamine-labeled nanoparticle with adjacent lipid nanoparticles for detecting fibrin with MRI [6], mixing into the plasma membrane of a C-32 while others have used small paramagnetic pep- melanoma cell transiently expressing a green tides [16,17]. Fibrin-targeted nanoparticles densely endocytic cytoplasmic marker. and specifically adhere to fibrin fibrils along the Reproduced with permission from [11]. clot surface, delivering enormous payloads of gadolinium atoms with each bound particle. In Nanoparticle diagnosis of dogs, gradient echo images of thrombus targeted unstable plaque with antifibrin paramagnetic nanoparticles dis- Atherosclerosis is a progressive inflammatory dis- play high signal intensity (1780 ± 327), whereas ease, which evolves from early ‘fatty streak’ contralateral control clot had a lower signal lesions present at childhood into mature, patho- intensity (815 ± 41), similar to that of the adja- logically complicated plaques. Thrombosis sec- cent muscle (768 ± 47) (Figure 2A). The contrast- ondary to plaque rupture is the principal cause of to-noise ratio (CNR) between the targeted clot and blood measured with this sequence was Figure 2. Molecular imaging of fibrin in thrombi in vivo and approximately 118 ± 21; whereas, the CNR ex vivo. between the targeted clot and the control clot B was 131 ± 37. The concept of detecting human A α-fibrin NP ruptured plaque was illustrated in vitro using carotid artery endarterectomy specimens from a T Lumen Plasma symptomatic patient in which microscopic fibrin deposits within the ruptured ‘shoulders’ of the plaque were readily apparent in contradistinction compared with control specimens (Figure 2B). Although the recognition of intraluminal Calcium fibrin within diseased vascular segments repre- sents a potential major step forward in the pre- Targeted Control vention of infarction or stroke, there is a need to differentiate minimal cap fissuring, which is (A) Thrombi in the external jugular vein targeted with fibrin-specific paramagnetic nanoparticles demonstrating dramatic T1-weighted contrast likely to heal, from plaque ruptures that lead to enhancement in the gradient echo image (arrow). (B) Color-enhanced MRI thrombo-occlusive or -embolic sequellae. The images of fibrin-targeted and control carotid endarterectomy specimens high fluorine content of fibrin-targeted nano- revealing contrast enhancement (white) of a small fibrin deposit on a particles affords a unique opportunity to quan- symptomatic ruptured plaque. Calcium deposit (black). (3D, fat-suppressed, tify the extent of luminal surface thrombus, T1-weighted fast gradient echo). which we hypothesize will correlate with the risk Reprinted with permission from [6]. of clinically significant disease progression. 322 Nanomedicine (2006) 1(3)
  3. 3. Cardiovascular disease and perfluorocarbon nanoparticles – PERSPECTIVE Figure 3. Dual 1H/19F imaging of thrombus in human carotid PFC nanoparticle approach to early endarterectomy specimen. atherosclerotic disease A key feature of the atherosclerotic process is the A B C 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 [20–22]. Extensive neovascular pro- liferation within atherosclerotic plaques is promi- nent within ‘culprit’ lesions associated clinically with unstable angina, myocardial infarction and stroke [23–25], and has been suggested to promote D plaque growth, intraplaque hemorrhage and Concentration of lesion instability [12]. Moulton and colleagues nanoparticles (nM) >1.5 have reported that reduction in plaque angio- genesis can diminish atheroma growth despite 1.0 persistent elevation of total cholesterol levels in apolipoprotein (Apo)E-/- mice treated with TNP- 0.5 470 [26], a direct inhibitor of endothelial cell pro- liferation through methionine aminopeptidase 2 0 blockade [27–29]. Unfortunately, chronic, high doses of TNP-470 administered systemically (A) Optical image of a cross-section of a human carotid endarterectomy with have neurocognitive side effects in humans [30,31]. moderate lumenal narrowing, several atherosclerotic lesions and areas of MR molecular imaging of focal angiogenesis calcification. (B) A 1H image acquired at 4.7 T at the same location reveals signal with integrin-targeted paramagnetic contrast agents enhancement due to the presence of antifibrin paramagnetic nanoparticle. has been reported with PFC nanoparticles [32–34] (C) A 19F projection image acquired at 4.7 T through the entire carotid artery and liposomes [35–37]. ανβ3-targeted PFC nano- sample shows high signal in the same areas due to nanoparticles bound to particles were demonstrated to detect the expan- fibrin. (D) 1H image in (B) with a false color overlay of the quantified sion of the aortic neovasculature in nanoparticle concentration in the carotid as derived from the 19F image. Reproduced with permission from [18]. hyperlipidemic New Zealand White rabbits [38]. Administration of ανβ3-targeted paramagnetic To illustrate this concept, human carotid endar- nanoparticles intravenously, followed by dynamic terectomy specimens were exposed to fibrin-tar- T1-weighted MR images of the aorta over the fol- geted PFC nanoparticles and produced high levels lowing 2 h, illustrated the heterogeneous neovas- of T1-weighted signal enhancement along the culature development associated with early lumenal surface (Figure 3) [18]. 19F projection images atherosclerotic disease. Aortic wall contrast of the same artery corroborated the asymmetric enhancement occured variably along the circum- distribution of fibrin-targeted nanoparticles ference and length of the aorta with greater signal around the vessel wall. Spectroscopic quantifica- enhancement relative to controls observed in vir- tion of nanoparticle binding allowed a quantitative tually every aortic slice of the cholesterol-fed/tar- 19F map of signal intensity that is coregistered with geted rabbits. Among cholesterol-fed rabbits the 1H image and provides visualization of ana- receiving ανβ3-targeted paramagnetic nanoparti- tomical and pathological information in a single cles, aortic wall contrast increased 26 ± 4% and 47 image. Indeed, combination of the 1H and 19F sig- ± 5% over baseline at 15 and 120 min, respec- nals in ‘real time’ synergistically increases informa- tively (Figure 4). In cholesterol-fed rabbits receiving tion content. These data alone, or in combination nontargeted nanoparticles, the aortic wall with contrast-directed, high resolution MRI imag- enhanced by 19 ± 1% within 15 min and ing of identified segments [19], may support the remained at 26 ± 1% from 60 to 120 min, reflect- development of rational guidelines to support stra- ing delayed-washout of the paramagnetic nano- tegic decisions regarding acute mechanical inter- particles from the dysmorphic vasculature. vention versus medical therapy for plaque Competitive blockade of angiogenic stabilization. However, plaque rupture is a late ανβ3-integrins with targeted nonparamagnetic manifestation of atherosclerotic plaque progression nanoparticles reduced the signal enhancement of and further techniques are required to assess and ανβ3-targeted paramagnetic nanoparticles by at treat the disease earlier in its natural progression. least 50%, to approximately the level of the 323
  4. 4. PERSPECTIVE – Lanza, Winter, Caruthers et al. Figure 4. Percent enhancement maps (false-colored from blue cells [39], effective antiangiogenic drug delivery to red). with ανβ3-targeted nanoparticles laden with fumagillin (the lipophilic parent compound of TNP-470) was demonstrated in hyperlipidemic 100 New Zealand White rabbits using a single-dose 80 treatment [40], which delivered far less drug than 60 previously used in the ApoE model studies [26]. 40 In one experiment, hyperlipidemic rabbits 20 (∼80 days on diet) were administered ανβ3-tar- geted fumagillin nanoparticles, ανβ3-targeted From individual aortic segments at the renal artery (A), mid-aorta (B) and nanoparticles without fumagillin or nontargeted diaphragm (C) 2 h after treatment in a cholesterol-fed rabbit given fumagillin nanoparticles and were imaged before αvβ3-targeted nanoparticles. and 4 h after treatment to assess the magnitude Reproduced with permission from [38]. and distribution of signal enhancement [40]. 1 week later, the extent of ανβ3-integrin expres- nontargeted group. In control-diet rabbits, aortic sion in each animal was reassessed with integrin- contrast from ανβ3-targeted paramagnetic nano- targeted paramagnetic nanoparticles (i.e., no particles paralleled the effects noted among cho- drug). Consistent with the early stage of athero- lesterol-fed animals receiving the nontargeted sclerosis in this animal model, T1-weighted agent. The signal enhancement in adjacent skele- black-blood images demonstrated no gross evi- tal muscle produced by ανβ3-targeted and nontar- dence of plaque development in terms of luminal geted paramagnetic nanoparticles was negligible. narrowing or wall thickening when compared MR images were consistent with immunohisto- with previous experiments using age-matched, chemistry observations that showed expansion of nonatherosclerotic rabbits [38]. ανβ3-targeted the aortic vasa vasorum (platelet-endothelial cell nanoparticle enhancement exhibited a patchy adhesion molecule [PECAM]-positive) among distribution within the aortic wall with higher atherosclerotic rabbits in comparison with the levels of angiogenesis noted near the diaphragm. controls (Figure 5). The average MRI signal enhancement measured Site-targeted PFC nanoparticles also offer the at 4 h for each slice and integrated across the opportunity for local drug delivery in combina- entire aortic wall was identical for ανβ3-targeted tion with molecular imaging. After initially dem- nanoparticles with (16.7 ± 1.1%) and without onstrating this mechanism in vitro using (16.7 ± 1.6%) fumagillin. At 1 week later, MRI doxorubicin and paclitaxel nanoparticles to inhibit aortic wall signal enhancement following ανβ3- the proliferation of vascular smooth muscle targeted fumagillin nanoparticle treatment was markedly reduced (2.9 ± 1.6%; p < 0.05) in Figure 5. Microscopic images of aorta from control and both spatial distribution and intensity, while sig- hyperlipidemic rabbits depicting an increase in neovascularity nal from rabbits given ανβ3-targeted nano- stained for ανβ3-integrin expression (LM-609) along the particles lacking fumagillin was undiminished media–adventia border. (18.1 ± 2.1%) (Figure 6). Treatment with non- targeted fumagillin nanoparticles did not signifi- cantly diminish ανβ3-integrin levels, although a Cholesterol fed Control diet numerical decrease was observed (12.4 ± 0.9%). In a separate cohort of rabbits, abdominal aorta sections obtained 1 week after nanoparti- cle treatment revealed mild, heterogeneously distributed intimal thickening [40]. The vast majority of neovessels within the aortic wall were located in the adventitia opposite regions of thickening intimal plaque (Figure 7A), with very few vessels observed in the media or plaque in these animals. The total number of PECAM-positive microvessels per section when Increased angiogenesis averaged across all aortic slices was greater in Reproduced with permission from [38]. untreated rabbits receiving ανβ3-targeted parti- cles without drug (65 ± 28) than in those given 324 Nanomedicine (2006) 1(3)
  5. 5. Cardiovascular disease and perfluorocarbon nanoparticles – PERSPECTIVE Figure 6. MRI aortic wall signal enhancement with heparin-coated stents, to the more recent, new ανβ3-targeted paramagnetic nanoparticle (no drug) 1 week class of drug-eluting stents (DESs), have following treatment with ανβ3-targeted fumagillin or control expanded our armamentarium for reopening (no drug) nanoparticles. stenotic vessels while preventing vascular re- occlusion. Within the last few years, the use of conventional balloon angioplasty and bare- Before After metal stent implantation, which were associated with clinical restenosis rates of 32–42% and Targeted 19–30%, respectively [41–43], have been nanoparticles improved with the local deposition of a phar- with drug macological agent to suppress neointimal pro- (30 µg fumagillin/kg) liferation. Current DESs have reduced the rate of angiographic restenosis to below 9% and diminished the frequency for repeat revasculari- zation to under 5% [44,45]. Unfortunately, DESs cannot be used routinely for all lesions. In some Targeted nanoparticles situations, vessel tortuosity or the distal loca- without drug tion of lesions prevents manipulation of the rel- atively inflexible DES. In other cases, the vessel diameter at the culprit lesion is too small for stent placement. As a result, many lesions, in Reproduced with permission from [40]. whole or part, do not receive the benefit of local antirestenotic therapy after revascularization. Moreover, despite the clear success of DESs, ανβ-targeted fumagillin nanoparticles (32 ± 11), the incidence of late in-stent thrombosis has particularly in the upper half of the aorta, which arisen as an infrequent but serious complication typically displayed more prominent disease of delayed endothelial healing [46]. To avoid (Figure 7B) between untreated and treated animals acute thrombosis, aggressive dual (and occa- (73 ± 28 vs 24 ± 5, respectively; p = 0.05) and sionally triple) antiplatelet therapy is employed paralleled the overall distribution of MR signal for 6 months to 1 year. We now recognize that enhancement changes observed. The total dose of some patients are nonresponders to one or fumagillin administered as a single injection in more of the drugs [47–49]. In other instances, ανβ3-targeted nanoparticles was more than thrombosis presents when antithrombotic 10,000-times lower than the cumulative oral dose drugs are withheld secondary to bleeding com- of TNP-470 reported by Moulton and col- plications or the need for emergent surgery. leagues. Uniquely, incorporation of fumagillin Late in-stent thrombosis has been linked to into paramagnetic nanoparticles allowed local fatal outcomes [46] and the risk can persist up to drug delivery to be confirmed, assessed and quan- 30 months after DES implantation [48,49]. Tar- tified noninvasively. From a clinical perspective, geted local delivery of antirestenotic drugs, these studies illustrate how nanomedicine tech- such as paclitaxel or rapamycin, into the niques allow the severity and distribution of stretch-injured arterial wall rather than the inti- atherosclerosis to be quantified directly. In indi- mal surface could permit better healing and viduals requiring early, aggressive intervention, recovery of the endothelium. More rapid targeted PFC nanoparticles may provide a vehicle endothelial repair of the injured wall should to treat rapidly progressing plaque locally with substantially diminish the incidence of throm- direct, noninvasive longitudinal follow-up. bosis and reduce the long-term requirement for aggressive antiplatelet therapy. Nanomedicine approaches to Nanomedicine offers techniques to address antirestenotic therapy restenosis in lesions not amenable to current following angioplasty DES technology. Ligand-directed PFC nano- Far too often, the progression of atherosclerosis particles can penetrate balloon-injured vessel to acute coronary syndromes presents the need walls and target intramural biomarkers, includ- for acute revascularization. Fortunately, contin- ing tissue factor [50], collagen III and integrins uous advances from balloon-angioplasty, bare- (Figure 8) [51]. Using intramural targeting and metal stents and drug-covered stents, such as anchoring of rapamycin nanoparticles to 325
  6. 6. PERSPECTIVE – Lanza, Winter, Caruthers et al. Figure 7. Angiogenesis associated rapamycin were administered to one artery while with neointima formation is the contralateral vessel received targeted nano- diminished with integrin-targeted particles without drug or saline. At 2 weeks after fumagillin nanoparticles. nanoparticle treatment, plaque development was determined by MR angiography and microscopic morphometric quantification. Routine MR angi- A ograms were indistinguishable between control and targeted-vessel segments. Microscopic analy- sis of serial vascular sections 2 weeks after injury revealed that the intimal plaque:lumen area ratio of vessels treated with ανβ3-targeted rapamycin nanoparticles was significantly less (∼50%; p < 0.05) than arteries receiving targeted nano- particles without drug or saline. Although pre- liminary, these data suggest that ανβ3-integrin- targeted nanoparticles can provide effective local, intramural therapy and may be a tool to extend B the use of antirestenotic drugs to revascularized 100 sites with or without adjunctive stent placement. Neovessels/section 75 Conclusion Nanomedicine is a new evolving field referred to 50 by many names, which promises to significantly * enhance the tools available to clinicians to address 25 some of the serious challenges responsible for 0 profound mortality, morbidity and numerous Targeted, Targeted, with drug no drug societal consequences. Unlike the simple pharma- ceutics of the past, nanomedicine agents are typi- (A) Platelet-endothelial cell adhesion molecule cally 3D, multicomponent systems that require (PECAM)-stained section (4x) of abdominal aorta from a hyperlipidemic rabbit displaying adventitia, interdisciplinary expertise to produce and use. In media and plaque. Higher magnification inset (20x) this article, we have briefly introduced the oppor- shows microvessels were located predominantly in tunities associated with targeted PFC nanoparti- the adventitia, associated with thickening cles in atherosclerosis-related diseases. The neointima. Neovessels were generally not found in potential impact of these few concepts is enor- regions where plaque progression was minimal or mous, but pales in comparison with the advance- nonexistant in this cohort of rabbits. Note that ments likely to evolve in this field over the larger, mature vessels stained positively for PECAM were not included in the estimates. (B) The coming decades. number of neovascular vessels within the adventitia was reduced (*p = 0.05) in fumagillin- Future perspective treated rabbits over the proximal half of the aorta Developments in nanotechnology are proceed- (i.e., renal artery to diaphragm), which correlated ing at breakneck speeds, particularly in the mate- with the region of greatest MR signal and rials science arena, although biomedical fumagillin response in the imaging studies. applications of these techniques have lagged. In Reproduced with permission from [40]. general, ‘nanoceuticals’, involving targeted diag- nostic and/or drug delivery, are considerably ανβ3-integrin expressed on smooth muscle cells more complex to develop than traditional drug and other plaque components (e.g., macrophages candidates, since they often incorporate multiple or T cells), the inhibition of vascular stenosis fol- active pharmaceutical ingredients and present lowing balloon overstretch injury in rabbit mod- complex process, stability and safety challenges. els was demonstrated [52]. In those studies, Yet, the opportunity for these technologies to femoral arteries of 12 rabbits on atherogenic diets reach the clinic has never been better. for 3 weeks were subjected to balloon stretch Only 10 years ago, the concept of ligand- injury via a catheter approach from the left com- directed targeted imaging for MRI and ultra- mon carotid artery. Using a double-balloon tech- sonography was the scientific equivalent of the nique, paramagnetic ανβ3-nanoparticles with search for the ‘holy grail’. Today, these tools are 326 Nanomedicine (2006) 1(3)
  7. 7. Cardiovascular disease and perfluorocarbon nanoparticles – PERSPECTIVE Figure 8. Volume-rendered image consisting of a 3D MR more commonplace. Platform technologies, angiogram coregistered with T1 enhancement in the wall of such as PFC nanoparticles, are emerging with carotid arteries of a domestic pig following angioplasty and the ability to detect, treat and monitor nascent exposure to ανβ3-targeted paramagnetic nanoparticles. disease, and will soon enter clinical trials, prob- ably in 2007. Conservatively speaking, nano- Carotid arteries medicine has turned the feasibility corner and R L L R demonstrated opportunity in numerous animal model studies by several independent investiga- tors. The question is no longer whether bio- αvβ3- medical nanotechnology is destined for the targeted clinic, but only when such tools will be contrast approved and available in the marketplace. Disclosures Depiction of ανβ3-targeted contrast (golden; arrows) in the vascular wall. Frames Equipment support from Philips Medical Systems, Cleve- at different angles detailing the asymmetry and morphology of balloon land, OH, USA. Financial Support: overstretch injury pattern. NHLBI/NCI/NIBIB. Co-founders (GL, SW): Kereos, Reproduced with permission from [51]. Inc., St. Louis, MO, USA. Executive summary Nanomedicine promises to enhance the ability of clinicians to address some of the serious challenges responsible for cardiovascular mortality, morbidity and numerous societal consequences. In cardiology, new nanotechnologies offer the following possibilities: • Ligand-directed perfluorocarbon nanoparticles provide a platform for use with all clinically relevant imaging modalities. • Perfluorocarbon nanoparticles may be used alone or in combination with imaging to deliver drugs locally and treat pathology early in its natural progression. • Fibrin-specific perfluorocarbon nanoparticles may allow the detection and quantification of unstable plaque in susceptible patients, which may be an important feature of future strategies to prevent heart attacks or stroke. • Integrin-targeted perfluorocarbon nanoparticles may allow direct and serial assessments of angiogenesis in atherosclerosis as a biosignature and catalyst of plaque progression. • Integrin-targeted perfluorocarbon nanoparticles could deliver anti-angiogenic therapy locally at markedly lower dosages than could be used systemically to modify and stabilize plaque progression. • Targeted perfluorocarbon nanoparticles could locally deliver antirestenotic drugs, with or without adjunctive bare-metal stent placement, to extend the benefits of antiproliferative drugs post-angioplasty. 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