scholarly journals Amyloid-Targeting PET Tracer [18F]Flutemetamol Accumulates in Atherosclerotic Plaques

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1072 ◽  
Author(s):  
Sanna Hellberg ◽  
Johanna Silvola ◽  
Heidi Liljenbäck ◽  
Max Kiugel ◽  
Olli Eskola ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Mouse Strains ◽  
Aortic Tissue ◽  
Atherosclerotic Plaques ◽  
Carotid Artery Plaque ◽  
Pet Tracer ◽  
Pet Ct ◽  
Human Carotid

Atherosclerosis is characterized by the accumulation of oxidized lipids in the artery wall, which triggers an inflammatory response. Oxidized low-density lipoprotein (ox-LDL) presents amyloid-like structural properties, and different amyloid species have recently been recognized in atherosclerotic plaques. Therefore, we studied the uptake of the amyloid imaging agent [18F]Flutemetamol in atherosclerotic plaques. The binding of [18F]Flutemetamol to human carotid artery plaque was studied in vitro. In vivo uptake of the tracer was studied in hypercholesterolemic IGF-II/LDLR−/−ApoB100/100 mice and C57BL/6N controls. Tracer biodistribution was studied in vivo with PET/CT, and ex vivo by gamma counter and digital ex vivo autoradiography. The presence of amyloid, ox-LDL, and macrophages in the plaques was examined by immunohistochemistry. [18F]Flutemetamol showed specific accumulation in human carotid plaque, especially in areas positive for amyloid beta. The aortas of IGF-II/LDLR−/−ApoB100/100 mice showed large thioflavin-S-positive atherosclerotic plaques containing ox-LDL and macrophages. Autoradiography revealed 1.7-fold higher uptake in the plaques than in a lesion-free vessel wall, but no difference in aortic tissue uptake between mouse strains were observed in the in vivo PET/CT. In conclusion, [18F]Flutemetamol binds to amyloid-positive areas in human atherosclerotic plaques. Further studies are warranted to clarify the uptake mechanisms, and the potential of the tracer for in vivo imaging of atherosclerosis in patients.

Abstract 18873: Al 18 F-NOTA-folate Accumulates in Atherosclerotic Plaques and Can be Detected by PET/CT

Circulation ◽  
2015 ◽  
Vol 132 (suppl_3) ◽  
Author(s):  
Johanna M Silvola ◽  
Xiang-Guo Li ◽  
Jenni Virta ◽  
Guru Prasad Padmasola ◽  
Päivi Marjamäki ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Folate Receptor ◽  
Specific Radioactivity ◽  
Experimental Models ◽  
Atherosclerotic Plaques ◽  
Pet Tracer ◽  
Contrast Enhanced Ct ◽  
Pet Ct ◽  
Atheromatous Plaques

Introduction:Macrophages are a major cell type in inflamed atherosclerotic plaques. Since folate receptor β (FR-β) is highly expressed in activated macrophages, we hypothesized that it might serve as a new marker for inflamed atherosclerotic plaques. Hypothesis: We aimed at evaluating a FR-β targeted PET tracer, Al 18 F NOTA-Folate, for the detection of inflamed atherosclerotic plaques. Methods:Atherosclerotic mice deficient for low density lipoprotein receptor (LDLR -/- ApoB 100/100 , n=12), C57BL control mice (n=9), and Watanabe rabbits (n=4) with endothelial denudation-induced atherosclerosis in the aorta were used. Biodistribution of Al 18 F-NOTA-Folate (specific radioactivity 130 GMq/μmol) was investigated in vivo by PET/contrast enhanced CT and ex vivo by gamma counting and autoradiography of aortic sections. In addition, prior to Al 18 F-NOTA-Folate study, the Watanabe rabbits were PET/CT imaged with 18 F-FDG. Results:Atherosclerotic mice demonstrated large and macrophage-rich atheromatous plaques in the aorta. The in vivo PET/CT revealed significantly higher uptake of Al 18 F-NOTA-Folate in the aortic arch of atherosclerotic mice compared to controls (aorta-to-blood ratio 1.5±0.3 vs. 0.7±0.2, P <0.0001), which were verified by ex vivo measurements. Autoradiography confirmed focally increased uptake of Al 18 F-NOTA-Folate in the atherosclerotic plaques (plaque-to-normal vessel wall ratio 2.6±0.7, P <0.0001). Competitive study with excess of unlabelled folate reduced Al 18 F-NOTA-Folate uptake in the aorta by app. 80% and thus verified the specificity of its binding. In the rabbit aorta, the PET/CT showed a strong focal in vivo uptake of Al 18 F-NOTA-Folate co-localizing with an atherosclerotic abdominal aorta with highest aorta-to-blood ratio of 6.0. For comparison, with 18 F-FDG the ratio was 2.4 in the same area. Conclusions: Al 18 F-NOTA-Folate, targeting FR-β, accumulates in macrophage-rich atherosclerotic plaques, which can be detected in vivo by PET/CT in experimental models of atherosclerosis. Further development of the tracer for imaging of patients with atherosclerosis is warranted.

scholarly journals Improved Detection of Molecular Markers of Atherosclerotic Plaques Using Sub-Millimeter PET Imaging

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1838 ◽  
Author(s):  
Jessica Bridoux ◽  
Sara Neyt ◽  
Pieterjan Debie ◽  
Benedicte Descamps ◽  
Nick Devoogdt ◽  
...  
Keyword(s):  
Pet Imaging ◽  
Ex Vivo ◽  
High Sensitivity ◽  
Radiochemical Yield ◽  
Control Group ◽  
Complexing Agent ◽  
Atherosclerotic Plaques ◽  
Atherosclerotic Lesions ◽  
Pet Ct

Since atherosclerotic plaques are small and sparse, their non-invasive detection via PET imaging requires both highly specific radiotracers as well as imaging systems with high sensitivity and resolution. This study aimed to assess the targeting and biodistribution of a novel fluorine-18 anti-VCAM-1 Nanobody (Nb), and to investigate whether sub-millimetre resolution PET imaging could improve detectability of plaques in mice. The anti-VCAM-1 Nb functionalised with the novel restrained complexing agent (RESCA) chelator was labelled with [18F]AlF with a high radiochemical yield (>75%) and radiochemical purity (>99%). Subsequently, [18F]AlF(RESCA)-cAbVCAM1-5 was injected in ApoE−/− mice, or co-injected with excess of unlabelled Nb (control group). Mice were imaged sequentially using a cross-over design on two different commercially available PET/CT systems and finally sacrificed for ex vivo analysis. Both the PET/CT images and ex vivo data showed specific uptake of [18F]AlF(RESCA)-cAbVCAM1-5 in atherosclerotic lesions. Non-specific bone uptake was also noticeable, most probably due to in vivo defluorination. Image analysis yielded higher target-to-heart and target-to-brain ratios with the β-CUBE (MOLECUBES) PET scanner, demonstrating that preclinical detection of atherosclerotic lesions could be improved using the latest PET technology.

scholarly journals Biodistribution of Nanostructured Lipid Carriers in Mice Atherosclerotic Model

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3499 ◽  
Author(s):  
Devel ◽  
Almer ◽  
Cabella ◽  
Beau ◽  
Bernes ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Ex Vivo ◽  
Particle Diameter ◽  
Nanostructured Lipid Carriers ◽  
Atherosclerotic Plaques ◽  
Particle Uptake ◽  
Atherosclerotic Lesions ◽  
Physico Chemical

Atherosclerosis is a major cardiovascular disease worldwide, that could benefit from innovative nanomedicine imaging tools and treatments. In this perspective, we here studied, by fluorescence imaging in ApoE-/- mice, the biodistribution of non-functionalized and RXP470.1-targeted nanostructured lipid carriers (NLC) loaded with DiD dye. RXP470.1 specifically binds to MMP12, a metalloprotease that is over-expressed by macrophages residing in atherosclerotic plaques. Physico-chemical characterizations showed that RXP-NLC (about 105 RXP470.1 moieties/particle) displayed similar features as non-functionalized NLC in terms of particle diameter (about 60-65 nm), surface charge (about −5 — −10 mV), and colloidal stability. In vitro inhibition assays demonstrated that RXP-NLC conserved a selectivity and affinity profile, which favored MMP-12. In vivo data indicated that NLC and RXP-NLC presented prolonged blood circulation and accumulation in atherosclerotic lesions in a few hours. Twenty-four hours after injection, particle uptake in atherosclerotic plaques of the brachiocephalic artery was similar for both nanoparticles, as assessed by ex vivo imaging. This suggests that the RXP470.1 coating did not significantly induce an active targeting of the nanoparticles within the plaques. Overall, NLCs appeared to be very promising nanovectors to efficiently and specifically deliver imaging agents or drugs in atherosclerotic lesions, opening avenues for new nanomedicine strategies for cardiovascular diseases.

scholarly journals YKL-40 Aggravates Early-Stage Atherosclerosis by Inhibiting Macrophage Apoptosis in an Aven-dependent Way

2021 ◽  
Vol 9 ◽  
Author(s):  
Wei Huan ◽  
Liu Yandong ◽  
Wang Chao ◽  
Zou Sili ◽  
Bai Jun ◽  
...  
Keyword(s):  
Early Stage ◽  
Expression Level ◽  
Atherosclerotic Plaques ◽  
Caspase 9 ◽  
Apoptosis Rate ◽  
Macrophage Apoptosis ◽  
Apoptosis Inhibitor ◽  
Human Carotid

Objective: programmed cell removal in atherosclerotic plaques plays a crucial role in retarding lesion progression. Macrophage apoptosis has a critical role in PrCR, especially in early-stage lesions. YKL-40 has been shown to be elevated as lesions develop and is closely related to macrophages. This study aimed to determine the effect of YKL-40 on regulating macrophage apoptosis and early-stage atherosclerosis progression.Research design and Methods: The correlations among the expression level of YKL-40, the area of early-stage plaque, and the macrophage apoptosis rate in plaques have been shown in human carotid atherosclerotic plaques through pathological and molecular biological detection. These results were successively confirmed in vivo (Ldlr−/- mice treated by YKL-40 recombinant protein/neutralizing antibody) and in vitro (macrophages that Ykl40 up-/down-expressed) experiments. The downstream targets were predicted by iTRAQ analysis.Results: In early-stage human carotid plaques and murine plaques, the YKL-40 expression level had a significant positive correlation with the area of the lesion and a significant negative correlation with the macrophage apoptosis rate. In vivo, the plaque area of aortic roots was significantly larger in the recomb-YKL-40 group than that in IgG group (p = 0.0247) and was significantly smaller in the anti-YKL-40 group than in the IgG group (p = 0.0067); the macrophage apoptosis rate of the plaque in aortic roots was significantly lower in the recomb-YKL-40 group than that in IgG group (p = 0.0018) and was higher in anti-YKL-40 group than that in VC group. In vitro, the activation level of caspase-9 was significantly lower in RAW264.7 with Ykl40 overexpressed than that in controls (p = 0.0054), while the expression level of Aven was significantly higher than that in controls (p = 0.0031). The apoptosis rate of RAW264.7 treated by recomb-YKL40 was significantly higher in the Aven down-regulated group than that in the control group (p &lt; 0.001). The apoptosis inhibitor Aven was confirmed as the target molecule of YKL-40. Mechanistically, YKL-40 could inhibit macrophage apoptosis by upregulating Aven to suppress the activation of caspase-9.Conclusion: YKL-40 inhibits macrophage apoptosis by upregulating the apoptosis inhibitor Aven to suppress the activation of caspase-9, which may impede normal PrCR and promote substantial accumulation in early-stage plaques, thereby leading to the progression of atherosclerosis.

scholarly journals Design, Synthesis, Computational, and Preclinical Evaluation of natTi/45Ti-Labeled Urea-Based Glutamate PSMA Ligand

Molecules ◽  
2020 ◽  
Vol 25 (5) ◽  
pp. 1104 ◽  
Author(s):  
Kristina Søborg Pedersen ◽  
Christina Baun ◽  
Karin Michaelsen Nielsen ◽  
Helge Thisgaard ◽  
Andreas Ingemann Jensen ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Ex Vivo ◽  
Design Synthesis ◽  
Psma Ligand ◽  
Pet Tracer ◽  
Positron Emission ◽  
Tumor Accumulation ◽  
Aided Design

Despite promising anti-cancer properties in vitro, all titanium-based pharmaceuticals have failed in vivo. Likewise, no target-specific positron emission tomography (PET) tracer based on the radionuclide 45Ti has been developed, notwithstanding its excellent PET imaging properties. In this contribution, we present liquid–liquid extraction (LLE) in flow-based recovery and the purification of 45Ti, computer-aided design, and the synthesis of a salan-natTi/45Ti-chelidamic acid (CA)-prostate-specific membrane antigen (PSMA) ligand containing the Glu-urea-Lys pharmacophore. The compound showed compromised serum stability, however, no visible PET signal from the PC3+ tumor was seen, while the ex vivo biodistribution measured the tumor accumulation at 1.1% ID/g. The in vivo instability was rationalized in terms of competitive citrate binding followed by Fe(III) transchelation. The strategy to improve the in vivo stability by implementing a unimolecular ligand design is presented.

Abstract 5788: VCAM-1 Targeted PET-CT Detects Inflammatory Atherosclerotic Plaques

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Matthias Nahrendorf ◽  
Edmund Keliher ◽  
Peter Panizzi ◽  
Hanwen Zhang ◽  
Sheena Hembrador ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Atherosclerotic Lesion ◽  
Vascular Anatomy ◽  
High Sensitivity ◽  
Ct Imaging ◽  
Atherosclerotic Plaques ◽  
Mrna Levels ◽  
Pet Ct

Hybrid PET-CT imaging of VCAM-1 expression and vascular anatomy may facilitate simultaneous assessment of atherosclerotic lesion biology and morphology, and enhance risk assessment in individual patients. We used combined in vitro/in vivo screening of candidate affinity ligands and developed a PET reporter for imaging VCAM-1 expression with high sensitivity, specificity and translational potential. Three different phage display-derived VCAM-1 affinity peptides were tested using immobilized VCAM-1, VCAM-1 expressing cells and apoE−/− mice. A compound with a linear peptide and arborising tetrameric design showed high affinity (86.6 nM) and specificity for VCAM-1 (97% inhibition with soluble VCAM-1). This lead compound was derivatized with 18Fluorine to synthesize the clinically viable PET agent 18F-4V. In vivo PET-CT imaging showed robust uptake of 18F-4V in plaque laden arterial sections from 8 apoE−/− mice, significantly higher than in 4 wild type mice and attenuated by atorvastatin treatment (p<0.05). 18F-4V uptake was confirmed in excised aortas, colocalized with atherosclerotic plaques delineated by Oil Red O staining and correlated with mRNA levels of VCAM-1 measured by quantitative RT-PCR (R2=0.62, p=0.03). 18F-4V allows noninvasive PET-CT imaging of VCAM-1 in atheromata, has sufficient dynamic range to quantify treatment effects, and correlates with inflammatory gene expression. This approach lends itself to seamless translation to human PET-CT imaging.

scholarly journals Design, Synthesis, In Vitro and In Vivo Evaluation of Heterobivalent SiFAlin-Modified Peptidic Radioligands Targeting Both Integrin αvβ3 and the MC1 Receptor—Suitable for the Specific Visualization of Melanomas?

2021 ◽  
Vol 14 (6) ◽  
pp. 547
Author(s):  
Xia Cheng ◽  
Ralph Hübner ◽  
Valeska von von Kiedrowski ◽  
Gert Fricker ◽  
Ralf Schirrmacher ◽  
...  
Keyword(s):  
Malignant Melanoma ◽  
Ex Vivo ◽  
Integrin Αvβ3 ◽  
In Vivo Evaluation ◽  
Design Synthesis ◽  
Pet Ct ◽  
In Vivo Testing ◽  
Radiochemical Yields

Combining two peptides addressing two different receptors to a heterobivalent peptidic ligand (HBPL) is thought to enable an improved tumor-targeting sensitivity and thus tumor visualization, compared to monovalent peptide ligands. In the case of melanoma, the Melanocortin-1 receptor (MC1R), which is stably overexpressed in the majority of primary malignant melanomas, and integrin αvβ3, which is involved in lymph node metastasis and therefore has an important role in the transition from local to metastatic disease, are important target receptors. Thus, if a radiolabeled HBPL could be developed that was able to bind to both receptor types, the early diagnosis and correct staging of the disease would be significantly increased. Here, we report on the design, synthesis, radiolabeling and in vitro and in vivo testing of different SiFAlin-modified HBPLs (SiFA = silicon fluoride acceptor), consisting of an MC1R-targeting (GG-Nle-c(DHfRWK)) and an integrin αvβ3-affine peptide (c(RGDfK)), being connected by a symmetrically branching framework including linkers of differing length and composition. Kit-like 18F-radiolabeling of the HBPLs 1–6 provided the labeled products [18F]1–[18F]6 in radiochemical yields of 27–50%, radiochemical purities of ≥95% and non-optimized molar activities of 17–51 GBq/µmol within short preparation times of 25 min. Besides the evaluation of radiotracers regarding logD(7.4) and stability in human serum, the receptor affinities of the HBPLs were investigated in vitro on cell lines overexpressing integrin αvβ3 (U87MG cells) or the MC1R (B16F10). Based on these results, the most promising compounds [18F]2, showing the highest affinity to both target receptors (IC50 (B16F10) = 0.99 ± 0.11 nM, IC50 (U87MG) = 1300 ± 288 nM), and [18F]4, exhibiting the highest hydrophilicity (logD(7.4) = −1.39 ± 0.03), were further investigated in vivo and ex vivo in a xenograft mouse model bearing both tumors. For both HBPLs, clear visualization of B16F10, as well as U87MG tumors, was feasible. Blocking studies using the respective monospecific peptides demonstrated both peptide binders of the HBPLs contributing to tumor uptake. Despite the somewhat lower target receptor affinities (IC50 (B16F10) = 6.00 ± 0.47 nM and IC50 (U87MG) = 2034 ± 323 nM) of [18F]4, the tracer showed higher absolute tumor uptakes ([18F]4: 2.58 ± 0.86% ID/g in B16F10 tumors and 3.92 ± 1.31% ID/g in U87MG tumors; [18F]2: 2.32 ± 0.49% ID/g in B16F10 tumors and 2.33 ± 0.46% ID/g in U87MG tumors) as well as higher tumor-to-background ratios than [18F]2. Thus, [18F]4 demonstrates to be a highly potent radiotracer for the sensitive and bispecific imaging of malignant melanoma by PET/CT imaging and impressively illustrates the suitability of the underlying concept to develop heterobivalent integrin αvβ3- and MC1R-bispecific radioligands for the sensitive and specific imaging of malignant melanoma by PET/CT.

scholarly journals Long-Term Treatment of Azathioprine in Rats Induces Vessel Mineralization

Biomedicines ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 327
Author(s):  
Mirjam Schuchardt ◽  
Jaqueline Herrmann ◽  
Cornelia Henkel ◽  
Milen Babic ◽  
Markus van der Giet ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Calcium Content ◽  
Immunosuppressive Drugs ◽  
Term Treatment ◽  
Aortic Tissue ◽  
Long Term Treatment ◽  
Vessel Structure ◽  
Vascular Stiffening

Medial vascular calcification (mVC) is closely related to cardiovascular disease, especially in patients suffering from chronic kidney disease (CKD). Even after successful kidney transplantation, cardiovascular mortality remains increased. There is evidence that immunosuppressive drugs might influence pathophysiological mechanisms in the vessel wall. Previously, we have shown in vitro that mVC is induced in vascular smooth muscle cells (VSMCs) upon treatment with azathioprine (AZA). This effect was confirmed in the current study in an in vivo rat model treated with AZA for 24 weeks. The calcium content increased in the aortic tissue upon AZA treatment. The pathophysiologic mechanisms involve AZA catabolism to 6-thiouracil via xanthine oxidase (XO) with subsequent induction of oxidative stress. Proinflammatory cytokines, such as interleukin (IL)-1ß and IL-6, increase upon AZA treatment, both systemically and in the aortic tissue. Further, VSMCs show an increased expression of core-binding factor α-1, alkaline phosphatase and osteopontin. As the AZA effect could be decreased in NLRP3−/− aortic rings in an ex vivo experiment, the signaling pathway might be, at least in part, dependent on the NLRP3 inflammasome. Although human studies are necessary to confirm the harmful effects of AZA on vascular stiffening, these results provide further evidence of induction of VSMC calcification under AZA treatment and its effects on vessel structure.

scholarly journals Synthesis and Biological Evaluation of a Radiolabeled PET Probe for Visualization of In Vivo α-Fucosidase Expression

2021 ◽  
Vol 14 (8) ◽  
pp. 745
Author(s):  
Jonathan Cotton ◽  
Chris Marc Goehring ◽  
Anna Kuehn ◽  
Andreas Maurer ◽  
Kerstin Fuchs ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Sodium Hydride ◽  
Biological Evaluation ◽  
Tracer Uptake ◽  
Mouse Serum ◽  
Molar Activity ◽  
Pet Tracer ◽  
Positron Emission

The acidic hydrolase α-fucosidase (AF) is a biomarker for maladies such as cancer and inflammation. The most advanced probes for α-fucosidase are unfortunately constrained to ex vivo or in vitro applications. The in vivo detection and quantification of AF using positron emission tomography would allow for better discovery and diagnosis of disease as well as provide better understanding of disease progression. We synthesized, characterized, and evaluated a radiolabeled small molecule inhibitor of AF based on a known molecule. The radiosynthesis involved the 11C methylation of a phenoxide, which was generated in situ by ultrasonification of the precursor with sodium hydride. The tracer was produced with a decay corrected yield of 41.7 ± 16.5% and had a molar activity of 65.4 ± 30.3 GBq/μmol. The tracer was shown to be stable in mouse serum at 60 min. To test the new tracer, HCT116 colorectal carcinoma cells were engineered to overexpress human AF. In vitro evaluation revealed 3.5-fold higher uptake in HCT116AF cells compared to HCT116 controls (26.4 ± 7.8 vs. 7.5 ± 1.0 kBq/106 cells). Static PET scans 50 min post injection revealed 2.5-fold higher tracer uptake in the HCT116AF tumors (3.0 ± 0.8%ID/cc (n = 6)) compared with the controls (1.2 ± 0.8 (n = 5)). Dynamic scans showed higher uptake in the HCT116AF tumors at all time-points (n = 2). Ex vivo analysis of the tumors, utilizing fluorescent DDK2 antibodies, confirmed the expression of human AF in the HCT116AF xenografts. We have developed a novel PET tracer to image AF in vivo and will now apply this to relevant disease models.

scholarly journals Research Models for Studying Vascular Calcification

2020 ◽  
Vol 21 (6) ◽  
pp. 2204 ◽  
Author(s):  
Jaqueline Herrmann ◽  
Milen Babic ◽  
Markus Tölle ◽  
Markus van der Giet ◽  
Mirjam Schuchardt
Keyword(s):  
Animal Models ◽  
Vascular Calcification ◽  
Ex Vivo ◽  
Systemic Disease ◽  
Treatment Options ◽  
Aortic Tissue ◽  
Cardiovascular Morbidity And Mortality ◽  
Culture Models

Calcification of the vessel wall contributes to high cardiovascular morbidity and mortality. Vascular calcification (VC) is a systemic disease with multifaceted contributing and inhibiting factors in an actively regulated process. The exact underlying mechanisms are not fully elucidated and reliable treatment options are lacking. Due to the complex pathophysiology, various research models exist evaluating different aspects of VC. This review aims to give an overview of the cell and animal models used so far to study the molecular processes of VC. Here, in vitro cell culture models of different origins, ex vivo settings using aortic tissue and various in vivo disease-induced animal models are summarized. They reflect different aspects and depict the (patho)physiologic mechanisms within the VC process.

Sign in / Sign up

Export Citation Format

Share Document