Multimodal positron emission tomography imaging ... - ACS Publications

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Multimodal positron emission tomography imaging to quantify uptake of 89Zr-labeled liposomes in the atherosclerotic vessel wall Mark E. Lobatto, Tina Binderup, Philip M. Robson, Luuk F.P. Giesen, Claudia Calcagno, Julia Witjes, Francois Fay, Samantha Baxter, Chang Ho Wessel, Mootaz Eldib, Jason Bini, Sean D. Carlin, Erik S.G. Stroes, Gert Storm, Andreas Kjær, Jason S. Lewis, Thomas Reiner, Zahi A. Fayad, Willem J. M. Mulder, and Carlos Perez-Medina Bioconjugate Chem., Just Accepted Manuscript • DOI: 10.1021/acs.bioconjchem.9b00256 • Publication Date (Web): 16 May 2019 Downloaded from http://pubs.acs.org on May 18, 2019

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Bioconjugate Chemistry

ACS Paragon Plus Environment

Bioconjugate Chemistry 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Multimodal positron emission tomography imaging to quantify uptake of 89Zr-labeled liposomes in the atherosclerotic vessel wall Mark E. Lobatto1,2,=, Tina Binderup1,3,=, Philip M. Robson1, Luuk F.P. Giesen1, Claudia Calcagno1, Julia Witjes1, Francois Fay1, Samantha Baxter1, Chang-Ho Wessel1, Mootaz Eldib1, Jason Bini1, Sean D. Carlin4, Erik S.G. Stroes5, Gert Storm6,7, Andreas Kjaer8, Jason S. Lewis4,9, Thomas Reiner4, Zahi A. Fayad1, Willem J.M. Mulder1,10,* and Carlos Pérez-Medina1,11,* 1Translational

and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, New York, United States. 2Department of Radiology, Spaarne Gasthuis, Haarlem, The Netherlands. 3Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet & University of Copenhagen, Copenhagen, Denmark. 4Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, United States. 5Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands. 6Department of Targeted Therapeutics, MIRA Institute, University of Twente, Enschede, The Netherlands. 7Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, The Netherlands. 8Clinical Physiology, Nuclear Medicine and PET, University of Copenhagen, Copenhagen, Denmark 9Program in Molecular Pharmacology, Memorial Sloan Kettering Cancer Center, New York, United States. 10Laboratory of Chemical Biology, Department of Biomedical Engineering and Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands 11Centro Nacional de Investigaciones Cardiovasculares Carlos III, Madrid, Spain =Shared first author

*Corresponding authors Willem J.M. Mulder, PhD, [email protected] Carlos Pérez-Medina, PhD, [email protected] Translational and Molecular Imaging Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, Box 1234, New York City, NY, 10029, USA. Phone: 212-824-8910 | Fax: 240-368-8096


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Table of contents graphic

" Atherosclerosis

89Zr-Liposome

Vessel wall

In vivo


Autoradiography

Whole body

PET/MRI

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Ex vivo

2


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Abstract Nanotherapy has recently emerged as an experimental treatment option for atherosclerosis. To fulfill its promise, robust noninvasive imaging approaches for subject selection and treatment evaluation are warranted. To that end, we here present a positron emission tomography (PET)-based method for quantification of liposomal nanoparticle uptake in the atherosclerotic vessel wall. We evaluated a modular procedure to label liposomal nanoparticles with the radioisotope zirconium-89 (89Zr). Their biodistribution and vessel wall targeting in a rabbit atherosclerosis model was evaluated up to 15 days after intravenous injection by PET/computed tomography (CT) and PET/magnetic resonance imaging (PET/MRI). Vascular permeability was assessed in vivo using 3-dimensional dynamic contrast-enhanced MRI (3D DCE-MRI) and ex vivo using near infrared fluorescence (NIRF) imaging. The

89Zr-radiolabeled

liposomes displayed a

biodistribution pattern typical of long circulating nanoparticles. Importantly, they markedly accumulated in atherosclerotic lesions in the abdominal aorta, as evident on PET/MRI and confirmed by autoradiography, and this uptake moderately correlated with vascular permeability. The method presented herein facilitates the development of nanotherapy for atherosclerotic disease as it provides a tool to screen for nanoparticle targeting in individual subjects’ plaques.

Keywords: PET/MRI, liposomes, atherosclerosis, 89Zr, multimodality imaging


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Introduction Atherosclerosis, the leading cause of cardiovascular disease complications such as myocardial infarction and stroke, is a chronic inflammatory disease affecting the major arteries1. Its progression is driven by the infiltration of lipids and immune cells into the vessel wall2. Nanomedicine has recently emerged as a potential therapeutic option for atherosclerosis3,4, with the first clinical trials recently conducted by our group5. Unlike cancer, atherosclerosis is a slowly progressing – initially mild– disease process, which complicates the implementation of nanotherapeutics, as the therapeutic window might be unclear. Nanomedicine’s integration in atherosclerosis management can greatly benefit from companion imaging, allowing the identification of amenable subjects and providing feedback on atherosclerotic burden6. For example, imaging may assist the development of novel nanotherapies by noninvasively examining biodistribution, the extent of disease, and finally, therapeutic outcomes4. In previous studies we have shown that intravenously injected long-circulating nanoparticles accumulate in atherosclerotic lesions in areas of enhanced permeability in animal models, as well as in atherosclerotic lesions in patients with cardiovascular disease5,7,8. Primarily, these nanotherapeutics were co-localized with macrophages, main contributors to atherosclerotic plaque inflammation and concurrent destabilization. Hence, the inclusion of therapeutics into nanoparticles can facilitate local enrichment of anti-inflammatory compounds, potentially increasing efficacy and decreasing adverse effects9.


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Radiolabeling

of

nanoparticles

is

a

valuable

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approach

to

determine

pharmacokinetics and biodistribution by ex vivo radioactivity quantification methods10. The technique’s sensitivity requires minimal modification to nanoparticles and therefore does not –or marginally at most- compromise their function11. More recently, PET or single-photon emission computed tomography (SPECT) imaging of radiolabeled nanoparticles has allowed the quantitative assessment of biodistribution in vivo, albeit a limitation of nuclear imaging is its low spatial resolution and dearth of anatomical information12,13. This is especially the case in the context of atherosclerosis, where small plaques can occur in multiple regions of the arterial tree, necessitating anatomical reference. The latest advancement in clinical imaging techniques, i.e. PET/MRI in a single hybrid system, has the capability to greatly diversify acquired information. The addition of MRI allows the thorough characterization of atherosclerotic burden and the vessel wall in high resolution, a feature that is more difficult to achieve with CT due to its reduced ability to always distinguish plaque components14. New MRI protocols that, in addition to anatomical information, can concomitantly acquire functional information, such as the quantification of arterial wall microvascular permeability through dynamic contrast enhanced (DCE) imaging, can be of great value15. Moreover, by increasing the length of PET acquisition to match that of the MR scan, simultaneous PET/MRI allows a significant radiation dose reduction while preserving quantification and image quality16. In this study, liposomes were labeled with 89Zr, a positron emitter with a relatively long half-life (78.41 hours) and a favorable positron range. Clinical PET/CT and


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PET/MRI systems were used to improve our understanding of the nanoparticles’ in vivo behavior, and the relation of their accumulation with plaque permeability, in a rabbit model of atherosclerosis.


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Results Radiolabeling of liposomal nanoparticles with 89Zr. Long circulating liposomes, previously applied in experimental atherosclerosis and human studies5,7,17, were prepared by lipid-film hydration and subsequently labeled with

89Zr

in a modular

fashion18. The polyethylene glycol (PEG) coating ensures long circulating properties, due to initial avoidance of capture by the mononuclear phagocyte system (MPS), mainly the liver, spleen and bone marrow, thereby avoiding rapid in vivo clearance19. A schematic representation of the nanoparticle is depicted in Figure 1A. The radiochemical yield was 72 ± 16 % (n = 6) with a radiochemical purity of > 99 %. Radiolabeled liposomes had a mean effective diameter of 106.0 ± 5.2 nm and a dispersity index of 0.14 ± 0.01 (n=6). Liposome composition and size exclusion chromatograms are shown in Supplementary figure 1. MR imaging-based characterization of the rabbit atherosclerosis model. We performed MRI characterization of the vessel wall of New Zealand white rabbits that received double balloon injuries of the abdominal aorta and a high-cholesterol diet, a well-established animal model of atherosclerosis20. The animal model is of interest as it can be scanned on clinical systems and has heterogeneous atherosclerotic plaque formation along the abdominal aorta. First, T2-weighted MR images were acquired to characterize vessel wall morphology, in which rabbits subjected to the above protocol had a markedly thicker vessel wall than healthy control rabbits fed a regular chow-diet, where the vessel wall was barely discernible (0.145 vs 0.083 mm2; P

Multimodal positron emission tomography imaging ... - ACS Publications

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