Near-infrared Fluorescence Molecular Imaging Research Articles

Magnetic-optical dual-modality imaging monitoring chemotherapy efficacy of pancreatic ductal adenocarcinoma with a low-dose fibronectin-targeting Gd-based contrast agent.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal hypovascular tumor surrounded by dense fibrosis. Albumin-bound paclitaxel and gemcitabine (AG) chemotherapy is the mainstay of PDAC treatment through depleting peritumoral fibrosis and killing tumor cells; however, it remains challenging due to the lack of a noninvasive imaging method evaluating fibrotic changes during AG chemotherapy. In this study, we developed a dual-modality imaging platform that enables noninvasive, dynamic, and quantitative assessment of chemotherapy-induced fibrotic changes through near-infrared fluorescence molecular imaging (FMI) and magnetic resonance imaging (MRI) using an extradomain B fibronectin (EDB-FN)-targeted imaging probe (ZD2-Gd-DOTA-Cy7). The ZD2-Gd-DOTA-Cy7 probe was constructed by conjugating a peptide (Cys-TVRTSAD) to Gd-DOTA and the near-infrared dye Cy7. PDAC murine xenograft models were intravenously injected with ZD2-Gd-DOTA-Cy7 at a Gd concentration of 0.05 mmol/kg or free Cy7 and Gd-DOTA as control. The normalized tumor background ratio (TBR) on FMI and the T1 reduction ratio on MRI were quantitatively analyzed. For models receiving AG chemotherapy or saline, MRI/FMI was performed before and after treatment. Histological analyses were performed for validation. The ZD2-Gd-DOTA-Cy7 concentration showed a linear correlation with the fluorescence intensity and T1 relaxation time in vitro. The optimal imaging time was 30min after injection of the ZD2-Gd-DOTA-Cy7 (0.05 mmol/kg), only half of the clinic dosage of gadolinium. Additionally, ZD2-Gd-DOTA-Cy7 generated a 1.44-fold and 1.90-fold robust contrast enhancement compared with Cy7 (P < 0.05) and Gd-DOTA (P < 0.05), respectively. For AG chemotherapy monitoring, the T1 reduction ratio and normalized TBR in the fibrotic tumor areas were significantly increased by 1.99-fold (P < 0.05) and 1.78-fold (P < 0.05), respectively, in the control group compared with those in the AG group. MRI/FMI with a low dose of ZD2-Gd-DOTA-Cy7 enables sensitive imaging of PDAC and the quantitative assessment of fibrotic changes during AG chemotherapy, which shows potential clinical applications for precise diagnosis, post-treatment monitoring, and disease management.

A non-invasive osteopontin-targeted phase changeable fluorescent nanoprobe for molecular imaging of myocardial fibrosis.

Due to the elevated fatality rate of cardiovascular diseases, myocardial fibrosis emerges as a prominent pathological alteration in the majority of heart ailments and their associated pathologies, thereby augmenting the likelihood of sudden cardiac death. Consequently, the prompt and obligatory identification of myocardial fibrosis assumes paramount importance in averting malignant incidents among patients afflicted with cardiac disorders. Herein, with higher expression osteopontin (OPN) found in cardiac fibrosis tissue, we have developed a dual-modality imaging probe, namely OPN targeted nanoparticles (OPN@PFP-DiR NPs), which loaded perfluoropentane (PFP) for ultrasound (US) and 1,1-dioctadecyl-3,3,3,3-tetramethylindotricarbocyanine iodide (DiR) for near-infrared fluorescence (NIR) of molecular imaging, to investigate the molecular features of cardiac fibrosis using US and NIR imaging. Subsequently, the OPN@PFP-DiR NPs were administered intravenously to a mouse model of myocardial infarction (MI). The US and NIR molecular imaging techniques were employed to visualize the accumulation of the nanoparticles in the fibrotic myocardium. Hence, this research presents a valuable noninvasive, cost-effective, and real-time imaging method for evaluating cardiac fibrosis, with promising clinical applications.

Preclinical Evaluation of CD36-Targeting Antiangiogenic Peptide ABT-510 for Near-Infrared Fluorescence Molecular Imaging of Colorectal Cancer.

Surgical resection constitutes the first choice of treatment for colorectal cancer (CRC). Despite advancements in intraoperative navigation, there remains a considerable lack of effective targeting probes for the imaging-guided surgical navigation of CRC owing to their high heterogeneity. Hence, developing a suitable fluorescent probe to detect the specific types of CRC populations is crucial. Herein, we labeled ABT-510, a small, CD36-targeting thrombospondin-1-mimetic peptide overexpressed in various cancer types, with fluorescein isothiocyanate or near-infrared dye MPA. We found that fluorescence-conjugated ABT-510 exhibited excellent selectivity and specificity toward cells or tissues with high CD36 expression. The tumor-to-colorectal signal ratios were 11.28 ± 0.61 (95% confidence interval) and 10.74 ± 0.07 (95% confidence interval) in subcutaneous HCT-116 and HT-29 tumor-bearing nude mice, respectively. Moreover, high signal contrast was observed in the orthotopic and liver metastatic CRC xenograft mouse models. Furthermore, MPA-PEG4-r-ABT-510 exhibited an antiangiogenic effect via tube information assay with human umbilical vein endothelial cells. Overall, MPA-PEG4-r-ABT-510 presents rapid and precise tumor delineation characteristics, thereby making it a desirable tool for CRC imaging and surgical navigation.

Abstract 14256: Dual-Targeted NIRF Molecular Imaging Combined With Intravascular OCT for Inflammatory Micro-Calcification in the High-Risk Plaque

Background/Objectives: Micro-calcification is a major target for high-risk plaque but the mechanistic linkage with macrophage-driven inflammation remains questionable. To address this issue, we newly innovated dual-targeted multimodal imaging strategy for calcifying inflammatory activity by integration of intravascular OCT with near-infrared fluorescence (NIRF) molecular imaging. Methods/Results: We fully integrated dual-targeted NIRF molecular imaging with intravascular OCT. Novel NIRF emitting probe targeting micro-calcification was fabricated by chemically coupling alendronate and Cy5.5 to the ends of azide-PEG-NHS ester (Al-Cy5.5). Based on whole body biodistribution, OCT/dual-NIRF in vivo imaging of rabbit aortoiliac atheroma was acquired 48 hrs and 72 hrs after intravenous injection of Al-Cy5.5 (5.0 mg/kg) and macrophage mannose receptor targeted Cy7-emitting probe (7.5 mg/kg), respectively. NIRF signals of Cy5.5 and Cy7 were highly enhanced at the area of micro-calcification and macrophage accumulation within the plaque (Figure) (p&lt;0.01). Fluorescence microscopy and immunostainings from the corresponding sections well corroborated the in vivo findings and concomitantly elevated dual-NIRF signals indicated the presence of calcifying inflammatory activity in atheroma. Intriguingly, osteogenic activity (TRAP stain) was closely interconnected with macrophages in superficial micro-calcification rather inner dense calcification (p&lt;0.01). Conclusions: Our intravascular OCT/dual-NIRF imaging was feasible to simultaneously visualize micro-calcification, osteogenic activity and macrophages in the coronary-sized atheroma. This novel imaging strategy is expected to expand our pathophysiologic insight for the biological behavior of calcifying inflammatory activity existing on the superficial fibrous cap portion of high-risk plaques.

Design and Validation of Site-Specifically Labeled Single-Domain Antibody-Based Tracers for in Vivo Fluorescence Imaging and Image-Guided Surgery.

Near-infrared fluorescence molecular imaging has become an established preclinical technique to investigate molecular processes in vivo and to study novel therapies. Furthermore, fluorescence molecular imaging is gaining significant interest from clinicians as an intra-operative guidance tool. This technique makes use of targeted fluorescent tracers as contrast agents that recognize specific biomarkers expressed at the site of disease. Single-domain antibodies have shown to possess excellent properties for in vivo imaging in comparison to conventional antibodies. In this chapter, we describe a method for site-specific conjugation of a near-infrared fluorophore to single-domain antibodies by exploiting cysteine-maleimide chemistry. As opposed to random conjugation, site-specific conjugation results in a homogenously labeled fluorescent tracer and avoids inference with antigen binding.

Intravascular Fluorescence Molecular Imaging of Atherosclerosis.

Optical molecular imaging using near-infrared fluorescence (NIRF) light is an emerging high-resolution imaging approach to image a wide range of molecular and cellular species in vivo. Imaging using NIR wavelengths (650-900nm) enables deeper photon penetration into tissue and reduced tissue autofluorescence, resulting in higher sensitivity to detect exogenously administered NIR fluorophores (injectable molecular imaging agents). Greater imaging depth of several centimeters is further achievable in the NIR window as blood absorption is as an order of magnitude lower than in the visible range. Furthermore, as optical imaging is routinely performed in the cardiac catheterization laboratory (e.g., optical coherence tomography), intravascular NIRF offers a promising translational approach for clinical coronary and peripheral arterial imaging. To this point, the first human intravascular NIRF imaging study recently demonstrated the ability to detect NIR autofluorescence in patients with coronary atherosclerosis. This study provides a foundation for targeted intravascular NIRF molecular imaging studies in coronary patients. In this chapter, we detail system engineering, imaging agents and translational applications of intravascular NIRF molecular imaging.

Abstract 12629: Intravascular Dual Targeted NIRF Molecular Imaging Integrated With OCT for Calcifying Inflammatory Activity in the Plaque

Background/Objectives: Spotty calcification linked with macrophage activity is a major target for high-risk plaque but the biological interconncetion remains questionable. To address this issue, we newly developed intravascular multimodal imaging strategy by fully integration of OCT with dual-targeted near-infrared fluorescence (NIRF) molecular imaging using customized osteogenic activity and macrophage targetable probes. Methods/Results: We newly integrated intravascular OCT structural imaging with dual-targeted NIRF imaging. Scale-up novel NIRF emitting probe targeting osteogenic activity was fabricated by chemically coupling alendronate ligand and Cy5.5 to the ends of azide-PEG-NHS ester (Al-Cy5.5). Based on biodistribution, OCT/dual-NIRF in vivo imaging of rabbit aortoiliac atheroma was acquired 72 hrs after intravenous injection of Al-Cy5.5 (5.0 mg/kg) and macrophage mannose receptor targeted Cy7-emitting probe (7.5 mg/kg). NIRF signals of Cy5.5 and Cy7 were highly enhanced in spotty calcification and inflammatory sites of the plaque, respectively (Figure) (p&lt;0.01). Fluorescence microscopy and immunostainings from the corresponding sections well corroborated the in vivo findings. Intriguingly, an interconnection of osteogenic activity (TRAP stain) with macrophages was more prominent in superficial spotty calcification rather than outer dense calcification (Figure) (p&lt;0.01). Conclusions: Our intravascular OCT/dual-NIRF imaging was feasible to simultaneously image osteogenic activity and macrophages in the coronary-sized atheroma. This novel imaging strategy is expected to expand the understanding for the biological behavior of calcifying inflamed activity in the high-risk plaques existing on cap microcalcification.

Ferritin nanocages for early theranostics of tumors via inflammation-enhanced active targeting.

Engineered nanocarriers have been widely developed for tumor theranostics. However, the delivery of imaging probes or therapeutic drugs to the tumor pre-formation site for early and accurate detection and therapy remains a major challenge. Here, by using tailor-functionalized human H-ferritin (HFn), we developed a triple-modality nanoprobe IRdye800-M-HFn and achieved the early imaging of tumor cells before the formation of solid tumor tissues. Then, we developed an HFn-doxorubicin (Dox) drug delivery system by loading Dox into the HFn protein cage and achieved early-stage tumor therapy. The intravenous injection of HFn nanoprobes enabled the imaging of tumor cells as early as two days after tumor implantation, and the triple-modality imaging techniques, namely, near-infrared fluorescence molecular imaging (NIR-FMI), magnetic resonance imaging (MRI), and photoacoustic imaging (PAI), ensured the accuracy of detection. Further exploration indicated that HFn could specifically penetrate into pre-solid tumor sites by tumor-associated inflammation-mediated blood vessel leakage, followed by effective accumulation in tumor cells by the specific targeting property of HFn to transferrin receptor 1. Thus, the HFn-Dox drug delivery system delivered Dox into the tumor pre-formation site and effectively killed tumor cells at early stage. IRDye800-M-HFn nanoprobes and HFn-Dox provide promising strategies for early-stage tumor diagnosis and constructive implications for early-stage tumor treatment.

Atorvastatin Reduces In Vivo Fibrin Deposition and Macrophage Accumulation, and Improves Primary Patency Duration and Maturation of Murine Arteriovenous Fistula.

Arteriovenous fistulas placed surgically for dialysis vascular access have a high primary failure rate resulting from excessive inward remodeling, medial fibrosis, and thrombosis. No clinically established pharmacologic or perisurgical therapies currently address this unmet need. Statins' induction of multiple anti-inflammatory and antithrombotic effects suggests that these drugs might reduce arteriovenous fistula failure. Yet, the in vivo physiologic and molecular effects of statins on fistula patency and maturation remain poorly understood. We randomized 108 C57Bl/6J mice to receive daily atorvastatin 1.14 mg/kg or PBS (control) starting 7 days before end-to-side carotid artery-jugular vein fistula creation and for up to 42 days after fistula creation. We then assessed longitudinally the effects of statin therapy on primary murine fistula patency and maturation. We concomitantly analyzed the in vivo arteriovenous fistula thrombogenic and inflammatory macrophage response to statin therapy, using the fibrin-targeted, near-infrared fluorescence molecular imaging agent FTP11-CyAm7 and dextranated, macrophage-avid nanoparticles CLIO-VT680. In vivo molecular-structural imaging demonstrated that atorvastatin significantly reduced fibrin deposition at day 7 and macrophage accumulation at days 7 and 14, findings supported by histopathologic and gene-expression analyses. Structurally, atorvastatin promoted favorable venous limb outward remodeling, preserved arteriovenous fistula blood flow, and prolonged primary arteriovenous fistula patency through day 42 (P<0.05 versus control for all measures). These findings provide new in vivo evidence that statins improve experimental arteriovenous fistula patency and maturation, indicating that additional clinical evaluation of statin therapy in patients on dialysis undergoing arteriovenous fistula placement is warranted.

Intravascular Molecular Imaging to Detect High-Risk Vulnerable Plaques: Current Knowledge and Future Perspectives

To describe vulnerable plaque pathobiology and summarize potential targets for molecular imaging with a focus on intravascular near-infrared fluorescence (NIRF) and its translatable applications. Structural imaging alone is unable to precisely identify high-risk plaques in patients with coronary artery disease (CAD). Intravascular near-infrared fluorescence (NIRF) imaging is an emerging translational approach that can image specific in vivo molecular processes and cells that characterize vulnerable plaques. High-priority NIRF targets imaged by intravascular NIRF imaging thus far include macrophages, cathepsin protease activity, oxidized low-density lipoprotein (oxLDL), and abnormal endothelial permeability. The newest generation of NIRF catheters is multimodal in nature and combines NIRF with either IVUS or OCT, providing simultaneous co-registered morphological and pathobiological assessment of atherosclerotic plaques. While most intravascular NIRF studies have been performed in a preclinical environment, a first-in-human NIR autofluorescence-OCT trial has recently been performed. These developments suggest that clinical intravascular NIRF molecular imaging will be available within the next 3 years. Molecular imaging is a powerful approach to enhance our understanding of atherosclerosis pathophysiology. Intravascular NIRF/OCT and NIRF/IVUS molecular imaging is nearing its use in atherosclerosis patients and will initially leverage indocyanine green (ICG) as an FDA-approved NIRF agent that reports on abnormal plaque permeability. Clinical trials are needed to assess the value of intravascular NIRF imaging using ICG as well as other novel NIRF imaging agents to better understand vulnerable plaque pathobiology, event prediction, and to enable personalized pharmacotherapy of high-risk plaques and patients.

Tri-functional platform for construction of modular antibody fragments for in vivo 18F-PET or NIRF molecular imaging.

Positron emission tomography (PET) molecular imaging is a powerful tool for interrogating physiological and biochemical processes to understand the biology of disease and advance therapeutic developments. Near-infrared fluorescence (NIRF) optical imaging has become increasingly popular for intraoperative staging to enable cellular resolution imaging of tumor margins during surgical resection. In addition, engineered antibody fragments have emerged as promising molecular imaging agents given their exquisite target selectivity, rapid systemic clearance and site-selective chemical modification. We report a tri-functional platform for construction of a modular antibody fragment that can rapidly be labeled with radionuclides or fluorophores for PET or NIRF molecular imaging of prostate stem cell antigen (PSCA).

18F-Fluoride Signal Amplification Identifies Microcalcifications Associated With Atherosclerotic Plaque Instability in Positron Emission Tomography/Computed Tomography Images.

Microcalcifications in atherosclerotic plaques are destabilizing, predict adverse cardiovascular events, and are associated with increased morbidity and mortality.18F-fluoride positron emission tomography (PET)/computed tomography (CT) imaging has demonstrated promise as a useful clinical diagnostic tool in identifying high-risk plaques; however, there is confusion as to the underlying mechanism of signal amplification seen in PET-positive, CT-negative image regions. This study tested the hypothesis that 18F-fluoride PET/CT can identify early microcalcifications. 18F-fluoride signal amplification derived from microcalcifications was validated against near-infrared fluorescence molecular imaging and histology using an in vitro 3-dimensional hydrogel collagen platform, ex vivo human specimens, and a mouse model of atherosclerosis. Microcalcification size correlated inversely with collagen concentration. The 18F-fluoride ligand bound to microcalcifications formed by calcifying vascular smooth muscle cell derived extracellular vesicles in the in vitro 3-dimensional collagen system and exhibited an increasing signal with an increase in collagen concentration (0.25 mg/mL collagen -33.8×102±12.4×102 counts per minute; 0.5 mg/mL collagen -67.7×102±37.4×102 counts per minute; P=0.0014), suggesting amplification of the PET signal by smaller microcalcifications. We further incubated human atherosclerotic endarterectomy specimens with clinically relevant concentrations of 18F-fluoride. The 18F-fluoride ligand labeled microcalcifications in PET-positive, CT-negative regions of explanted human specimens as evidenced by 18F-fluoride PET/CT imaging, near-infrared fluorescence, and histological analysis. Additionally, the 18F-fluoride ligand identified micro and macrocalcifications in atherosclerotic aortas obtained from low-density lipoprotein receptor-deficient mice. Our results suggest that 18F-fluoride PET signal in PET-positive, CT-negative regions of human atherosclerotic plaques is the result of developing microcalcifications, and high surface area in regions of small microcalcifications may amplify PET signal.

Everolimus-eluting stents stabilize plaque inflammation in vivo: assessment by intravascular fluorescence molecular imaging.

Inflammation drives atherosclerosis complications and is a promising therapeutic target for plaque stabilization. At present, it is unknown whether local stenting approaches can stabilize plaque inflammation in vivo. Here, we investigate whether everolimus-eluting stents (EES) can locally suppress plaque inflammatory protease activity in vivo using intravascular near-infrared fluorescence (NIRF) molecular imaging. Balloon-injured, hyperlipidaemic rabbits with atherosclerosis received non-overlapping EES and bare metal stents (BMS) placement into the infrarenal aorta (n = 7 EES, n = 7 BMS, 3.5 mm diameter x 12 mm length). Four weeks later, rabbits received an injection of the cysteine protease-activatable NIRF imaging agent Prosense VM110. Twenty-four hours later, co-registered intravascular 2D NIRF, X-ray angiography and intravascular ultrasound imaging were performed. In vivo EES-stented plaques contained substantially reduced NIRF inflammatory protease activity compared with untreated plaques and BMS-stented plaques (P = 0.006). Ex vivo macroscopic NIRF imaging of plaque protease activity corroborated the in vivo results (P = 0.003). Histopathology analyses revealed that EES-treated plaques showed reduced neointimal and medial arterial macrophage and cathepsin B expression compared with unstented and BMS-treated plaques. EES-stenting stabilizes plaque inflammation as assessed by translational intravascular NIRF molecular imaging in vivo. These data further support that EES may provide a local approach for stabilizing inflamed plaques.

Abstract 656: In Vivo Plaque Inflammation and Endothelial Permeability Independently Predict Atherosclerosis Progression: A Serial Multimodality Imaging Study

Background: Atheroma inflammation impairs plaque stability and promotes plaque progression and complications. However, it is unknown how measures of plaque biology relate to changes in plaque burden, and whether plaque biology can independently predict plaque progression in coronary-sized arteries. This study evaluated the ability of intravascular near-infrared fluorescence (NIRF) biological imaging to inform experimental atheroma progression in vivo. Methods: Atherosclerosis was induced by balloon-injury in the aorta of 14 cholesterol-fed rabbits. Serial intravascular ultrasound (IVUS) and dual-modality intravascular NIRF - optical coherence tomography (OCT) imaging was performed following injection of a NIRF molecular imaging agent of plaque inflammatory protease activity (ProSense VM110; n=7), or impaired plaque endothelial permeability (indocyanine green (ICG); n=7). Plaque progression was further assessed by IVUS change in plaque burden. Regression analysis was used to evaluate the association of NIRF with plaque progression. In vivo imaging results were corroborated by ex vivo fluorescence reflectance imaging, fluorescence microscopy, and histopathology. Results: Quantitative analysis of 1,811 axial images spanning individual plaques, the change in NIRF plaque biological signals from 8 to 12 weeks strongly correlated with IVUS plaque burden from 8 to 12 weeks (ProSense VM110: r=0.774; ICG: r=0.572; p&lt;0.0001). This finding remained significant on multivariate analysis adjusted for IVUS plaque burden, lumen area, and remodeling index (p&lt;0.001). In additional multivariate analyses, the baseline NIRF signal at 8 weeks further predicted the magnitude of plaque progression even after adjustment for baseline plaque burden (p&lt;0.001 for Prosense VM110; p=0.004 for ICG). Histology demonstrated NIRF agent uptake in inflamed, lipid-rich plaques. Conclusion: Plaque pathobiology and plaque burden progress in concert as assessed by translatable intravascular NIRF imaging technology. The baseline NIRF inflammation and impaired plaque permeability signals independently predict plaque progression. Integrated biological-microstructural imaging may enhance the ability to detect high-risk plaques at risk of progression.

Intravascular NIRF Molecular Imaging Approaches in Coronary Artery Disease.

Progression of vulnerable coronary atherosclerotic plaques underlies the majority of acute myocardial infarction and sudden cardiac death episodes. Recent advances in biological/molecular imaging technology are now enabling the accurate identification of high-risk plaques and stents in living subjects. Due to their smaller caliber and susceptibility to cardiorespiratory motion, noninvasive molecular imaging of human coronary arteries remains challenging. Therefore, intravascular high-resolution molecular imaging approaches appear necessary to resolve molecular features of human coronary arteries and stents. Here we present recent progress in intravascular near-infrared fluorescence (NIRF) molecular imaging, including the evolution from standalone NIRF systems to those integrated with structural imaging methods including optical coherence tomography and intravascular ultrasound. Preclinical demonstrations of imaging inflammation, fibrin, and endothelial impairment are highlighted. We then close with a discussion of translation of NIRF imaging to the cardiac catheterization laboratory and showcase first-in-human intracoronary imaging results of NIR autofluorescence in CAD.

Molecular imaging-guided photothermal/photodynamic therapy against tumor by iRGD-modified indocyanine green nanoparticles

Multifunctional near-infrared (NIR) nanoparticles demonstrate great potential in tumor theranostic applications. To achieve the sensitive detection and effective phototherapy in the early stage of tumor genesis, it is highly desirable to improve the targeting of NIR theranostic agents to biomarkers and to enhance their accumulation in tumor. Here we report a novel targeted multifunctional theranostic nanoparticle, internalized RGD (iRGD)-modified indocyanine green (ICG) liposomes (iRGD–ICG-LPs), for molecular imaging-guided photothermal therapy (PTT) and photodynamic therapy (PDT) therapy against breast tumor. The iRGD peptides with high affinity to αvβ3 integrin and effective tumor-internalized property were firstly used to synthesize iRGD-PEG2000-DSPE lipopeptides, which were further utilized to fabricate the targeted ICG liposomes. The results indicated that iRGD–ICG-LPs exhibited excellent stability and could provide an accurate and sensitive detection of breast tumor through NIR fluorescence molecular imaging. We further employed this nanoparticle for tumor theranostic application, demonstrating significantly higher tumor accumulation and tumor inhibition efficacy through PTT/PDT effects. Histological analysis further revealed much more apoptotic cells, confirming the advantageous anti-tumor effect of iRGD–ICG-LPs over non-targeted ICG-LPs. Notably, the targeting therapy mediated by iRGD provides almost equivalent anti-tumor efficacy at a 12.5-fold lower drug dose than that by monoclonal antibody, and no tumor recurrence and obvious treatment-induced toxicity were observed in our study. Our study provides a promising strategy to realize the sensitive detection and effective treatment of tumors by integrating molecular imaging into PTT/PDT therapy.

Intravascular fibrin molecular imaging improves the detection of unhealed stents assessed by optical coherence tomography in vivo.

Fibrin deposition and absent endothelium characterize unhealed stents that are at heightened risk of stent thrombosis. Optical coherence tomography (OCT) is increasingly used for assessing stent tissue coverage as a measure of healed stents, but cannot precisely identify whether overlying tissue represents physiological neointima. Here we assessed and compared fibrin deposition and persistence on bare metal stent (BMS) and drug-eluting stent (DES) using near-infrared fluorescence (NIRF) molecular imaging in vivo, in combination with simultaneous OCT stent coverage. Rabbits underwent implantation of one BMS and one DES without overlap in the infrarenal aorta (N = 20 3.5 × 12 mm). At Days 7 and/or 28, intravascular NIRF-OCT was performed following the injection of fibrin-targeted NIRF molecular imaging agent FTP11-CyAm7. Intravascular NIRF-OCT enabled high-resolution imaging of fibrin overlying stent struts in vivo, as validated by histopathology. Compared with BMS, DES showed greater fibrin deposition and fibrin persistence at Days 7 and 28 (P < 0.01 vs. BMS). Notably, for edge stent struts identified as covered by OCT on Day 7, 92.8 ± 9.5% of DES and 55.8 ± 23.6% of BMS struts were NIRF fibrin positive (P < 0.001). At Day 28, 18.6 ± 10.6% (DES) and 5.1 ± 8.7% (BMS) of OCT-covered struts remained fibrin positive (P < 0.001). Intravascular NIRF fibrin molecular imaging improves the detection of unhealed stents, using clinically translatable technology that complements OCT. A sizeable percentage of struts deemed covered by OCT are actually covered by fibrin, particularly in DES, and therefore such stents might remain prothrombotic. These findings have implications for the specificity of standalone clinical OCT assessments of stent healing.

Near-infrared fluorescence molecular imaging of amyloid beta species and monitoring therapy in animal models of Alzheimer’s disease

Near-infrared fluorescence (NIRF) molecular imaging has been widely applied to monitoring therapy of cancer and other diseases in preclinical studies; however, this technology has not been applied successfully to monitoring therapy for Alzheimer's disease (AD). Although several NIRF probes for detecting amyloid beta (Aβ) species of AD have been reported, none of these probes has been used to monitor changes of Aβs during therapy. In this article, we demonstrated that CRANAD-3, a curcumin analog, is capable of detecting both soluble and insoluble Aβ species. In vivo imaging showed that the NIRF signal of CRANAD-3 from 4-mo-old transgenic AD (APP/PS1) mice was 2.29-fold higher than that from age-matched wild-type mice, indicating that CRANAD-3 is capable of detecting early molecular pathology. To verify the feasibility of CRANAD-3 for monitoring therapy, we first used the fast Aβ-lowering drug LY2811376, a well-characterized beta-amyloid cleaving enzyme-1 inhibitor, to treat APP/PS1 mice. Imaging data suggested that CRANAD-3 could monitor the decrease in Aβs after drug treatment. To validate the imaging capacity of CRANAD-3 further, we used it to monitor the therapeutic effect of CRANAD-17, a curcumin analog for inhibition of Aβ cross-linking. The imaging data indicated that the fluorescence signal in the CRANAD-17-treated group was significantly lower than that in the control group, and the result correlated with ELISA analysis of brain extraction and Aβ plaque counting. It was the first time, to our knowledge, that NIRF was used to monitor AD therapy, and we believe that our imaging technology has the potential to have a high impact on AD drug development.

Monitoring Tumor Targeting and Treatment Effects of IRDye 800CW and GX1-Conjugated Polylactic Acid Nanoparticles Encapsulating Endostar on Glioma by Optical Molecular Imaging

Molecular imaging used in cancer diagnosis and therapeutic response monitoring is important for glioblastoma (GBM) research. Antiangiogenic therapy currently is one of the emerging approaches for GBM treatment. In this study, a multifunctional nanoparticle was fabricated that can facilitate the fluorescence imaging of tumor and deliver a therapeutic agent to the tumor region in vivo and therefore possesses broad application in cancer diagnosis and treatment. This particle was polylactic acid (PLA) nanoparticles encapsulating Endostar, which was further conjugated with GX1 peptide and the near-infrared (NIR) dye IRDye 800CW (IGPNE). We demonstrated noninvasive angiogenesis targeting and therapy of IGPNE on U87MG xenografts in vivo using dual-modality optical molecular imaging including NIR fluorescence molecular imaging (FMI) and bioluminescence imaging (BLI). The NIR FMI results demonstrated that IGPNE had more accumulation to the tumor site compared to free IRDye 800CW. To further evaluate the antitumor treatment efficacy of IGPNE, BLI and immunohistochemistry analysis were performed on tumor-bearing mice. With the aid of molecular imaging, the results confirmed that IGPNE enhanced antitumor treatment efficacy compared to free Endostar. In conclusion, IGPNE realizes real-time imaging of U87MG tumors and improves the antiangiogenic therapeutic efficacy in vivo.

Selective Cathepsin S Inhibition Attenuates Atherosclerosis in Apolipoprotein E–Deficient Mice with Chronic Renal Disease

Chronic renal disease (CRD) accelerates the development of atherosclerosis. The potent protease cathepsin S cleaves elastin and generates bioactive elastin peptides, thus promoting vascular inflammation and calcification. We hypothesized that selective cathepsin S inhibition attenuates atherogenesis in hypercholesterolemic mice with CRD. CRD was induced by 5/6 nephrectomy in high-fat high-cholesterol fed apolipoprotein E-deficient mice. CRD mice received a diet admixed with 6.6 or 60 mg/kg of the potent and selective cathepsin S inhibitor RO5444101 or a control diet. CRD mice had significantly higher plasma levels of osteopontin, osteocalcin, and osteoprotegerin (204%, 148%, and 55%, respectively; P < 0.05), which were inhibited by RO5444101 (60%, 40%, and 36%, respectively; P < 0.05). Near-infrared fluorescence molecular imaging revealed a significant reduction in cathepsin activity in treated mice. RO5444101 decreased osteogenic activity. Histologic assessment in atherosclerotic plaque demonstrated that RO5444101 reduced immunoreactive cathepsin S (P < 0.05), elastin degradation (P = 0.01), plaque size (P = 0.01), macrophage accumulation (P < 0.01), growth differentiation factor-15 (P = 0.0001), and calcification (alkaline phosphatase activity, P < 0.01; osteocalcin, P < 0.05). Furthermore, cathepsin S inhibitor or siRNA significantly decreased expression of growth differentiation factor-15 and monocyte chemotactic protein-1 in a murine macrophage cell line and human primary macrophages. Systemic inhibition of cathepsin S attenuates the progression of atherosclerotic lesions in 5/6 nephrectomized mice, serving as a potential treatment for atherosclerosis in patients with CRD.