RGD-Targeted Ultrasound Contrast Agent for Longitudinal Assessment of Hep-2 Tumor Angiogenesis In Vivo

Comprehensive Review on Bubbles: Synthesis, Modification, Characterization and Biomedical Applications

Accurate detection, treatment, and imaging of diseases are important for effective treatment outcomes in patients. In this regard, bubbles have gained much attention, due to their versatility. Bubbles usually 1 nm to 10 μm in size can be produced and loaded with a variety of lipids, polymers, proteins, and therapeutic and imaging agents. This review details the different production and loading methods for bubbles, for imaging and treatment of diseases/conditions such as cancer, tumor angiogenesis, thrombosis, and inflammation. Bubbles can also be used for perfusion measurements, important for diagnostic and therapeutic decision making in cardiac disease. The different factors important in the stability of bubbles and the different techniques for characterizing their physical and chemical properties are explained, for developing bubbles with advanced therapeutic and imaging features. Hence, the review provides important insights for researchers studying bubbles for biomedical applications.

Oncogenic miR-1825 promotes head and neck carcinogenesis via targeting FREM1

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignant cancer type worldwide. Although the therapeutic modalities currently used for patients with HNSCC improved in recent decades, HNSCC prognosis is still poor. Therefore, it is an urgent necessity to understand the pathogenesis of HNSCC, to develop novel and effective treatment strategies, and to characterize and identify the oncogenes that are responsible for an aggressive HNSCC phenotype. In this study, we aimed to better understand the roles of miR-1825 in the pathogenesis of HNSCC. We examined the impacts of miR-1825 deregulation on the cancer-associated phenotypes using in vitro tests evaluating cell viability, clonogenicity, cell migration, invasion, apoptosis, and stem cell characteristics. In addition, we investigated the effects of miR-1825 overexpression on the tumor formation capacity of head and neck cancer cells in vivo using nude mice. We searched for potential targets of miR-1825 using microarray analysis and luciferase assay. We found that miR-1825 expression is upregulated in head and neck cells and clinical tumor samples in comparison to corresponding controls, where it potentially acts as an oncogene. We, then, showed that ectopic miR-1825 overexpression promotes cellular phenotypes related to head and neck cancer progression in vitro and has a stimulating potential on cancer formation in vivo. We also identified FREM1 as a direct target of miR-1825 and demonstrated its reduced expression in HNSCC samples using immunohistochemistry analysis. Collectively, we suggest that the miR-1825/FREM1 axis serves as an important mediator of HNSCC development, where miR-1825 acts as an oncogene.

Enhanced treatment of cerebral ischemia-Reperfusion injury by intelligent nanocarriers through the regulation of neurovascular units

Reperfusion injury is one of the major causes of disability and death caused by ischemic stroke, and drug development focuses mainly on single neuron protection. However, different kinds of cells in the neurovascular units (NVUs), including neurons, microglia and vascular endothelial cells, are pathologically changed after cerebral ischemia-reperfusion injury, resulting in an urgent need to develop a drug delivery system to comprehensively protect the kinds of cells involved in the NVU. Herein, we have constructed a c(RGDyK) peptide modified, NF-κB inhibitor caffeic acid phenethyl ester (CAPE)-loaded and reactive nitrogen species (RNS) stimuli-responsive liposomal nanocarrier (R-Lipo-CAPE) to target ischemic lesions and then remodel the NVU to reduce the progression of cerebral ischemia-reperfusion injury. The R-Lipo-CAPE liposomes were approximately 170 nm with a zeta potential of -30.8 ± 0.2 mV. The in vitro CAPE release behavior from R-Lipo-CAPE showed an RNS-dependent pattern. For in vivo studies, transient middle cerebral artery occlusion/reperfusion (MCAO) model mice treated with R-Lipo-CAPE had the least neurological impairment and decreased brain tissue damage, with an infarct area of 13%, compared with those treated with saline of 53% or free CAPE of 38%. Furthermore, microglia in the ischemic brain were polarized to the tissue-repairing M2 phenotype after R-Lipo-CAPE treatment. In addition, R-Lipo-CAPE-treated mice displayed a prominent down-regulated expression of MMP-9 and restored expression of the tight junction protein claudin-5. This proof-of-concept indicates that R-Lipo-CAPE is a promising nanomedicine for the treatment of cerebral ischemia-reperfusion injury through the regulation of neurovascular units. STATEMENT OF SIGNIFICANCE: Based on the complex mechanism and difficulty in treatment of cerebral ischemia-reperfusion injury, the overall regulation of neurovascular unit has become an extremely important target. However, little nanomedicine has been directed to remodel the neurovascular units in targeted cerebral ischemia-reperfusion injury therapy. Here, c(RGDyK) peptide modified reactive nitrogen species (RNS) stimuli-responsive liposomal nanocarrier loaded with a NF-κB inhibitor (CAPE), was designed to simultaneously regulate various cells in the microenvironment of cerebral ischemia-reperfusion injury to remodel the neurovascular units. Our in vitro and in vivo data showed that the intelligent nanocarrier exerted the ability of pathological signal stimuli-responsive drug release, cerebral ischemia-reperfusion injury site targeting and neurovascular units remodeling through reducing neuron apoptosis, regulating microglia polarization and repairing vascular endothelial cell. Overall, the intelligent liposomal drug delivery system was a promising and safe nanomedicine in the perspective of cerebral ischemia-reperfusion injury treatment.

Detection of Mice Colorectal Tumors by Endoluminal Ultrasound Biomicroscopic Images and Quantification of Image Augmented Gray Values Following Injection of VEGFR-2 Targeted Contrast Agent

RATIONALE AND OBJECTIVES

Ultrasound biomicroscopy (UBM) is a noninvasive imaging technique that can be applied in detecting colonic tumors and, once associated with an ultrasound contrast agent (UCA), can identify the molecular expression of cancer-related biomarkers, such as the vascular endothelial growth factor receptor 2 (VEGFR-2). The present work aimed to detect colonic tumors and quantify augmented gray values of endoluminal UBM (eUBM) images from colonic tumors following the injection of VEGFR-2 targeted UCA (VEGFR2-UCA) into a mouse model of colorectal cancer.

MATERIAL AND METHODS

A 40 MHz miniprobe catheter inserted through the biopsy channel of a pediatric flexible bronchofiberscope was used to obtain colonoscopic and B-mode eUBM images simultaneously. Seventeen tumor-bearing mice had their colons inspected and six of them were subjected to a VEGFR2-UCA injection to predict VEGFR-2 expression.

RESULTS

All animals developed distal colon tumors and eUBM was able to detect all of them and also to characterize the tumors, with 71.4% being in situ lesions and 28.6% being tumors invading the mucosa + muscularis mucosae + submucosa layers, as confirmed by histopathology. After VEGFR2-UCA injection, gray values from the eUBM tumoral images increased significantly (p < 0.01). Tumor sites with increased eUBM image gray values corresponded to areas with increased VEGFR-2 expression, as confirmed by immunohistochemistry.

CONCLUSION

The results confirm eUBM as a powerful noninvasive and real-time tool for detecting colon tumor and its invasiveness and once associated with VEGFR2-UCA may become a tool for the detection of VEGFR-2 expression in colonic tumors.

Dual-Mode Contrast Agents with RGD-Modified Polymer for Tumour-Targeted US/NIRF Imaging

BACKGROUND

Cancer diagnosis and treatment during the early stages of disease remain extremely challenging clinical tasks. The development of effective multimode contrast agents could greatly facilitate the early detection of cancer.

MATERIALS AND METHODS

We prepared dual-mode contrast agents using a biotin/avidin bioamplification system. Through in vivo and in vitro experiments, we verified the imaging performance of this contrast agents in both fluorescence and ultrasound and its targeting specificity for MDA-MB-231 cells.

RESULTS

The RGD peptide-labelled microbubbles showed excellent targeting of αvβ3 integrin expressed by MDA-MB-231 cells in vitro and in vivo. The signal intensity and time duration of ultrasound imaging using these particles were superior to those obtained with a typical ultrasound contrast agent in the clinic. The tumour areas also demonstrated high Cy5.5 accumulation by fluorescence imaging.

CONCLUSION

The results show that this targeted dual-mode imaging system yields outstanding US/NIRF imaging results, possibly allowing the early clinical diagnosis of cancer.

Efficacy evaluation and mechanism study on inhibition of breast cancer cell growth by multimodal targeted nanobubbles carrying AMD070 and ICG

To construct targeted nanobubbles carrying both small-molecule CXCR4 antagonist AMD070 and light-absorbing material indocyanine green (ICG), and to study their in vitro multimodal imaging, as well as their mechanism and efficacy of inhibition of breast cancer cell growth. Nanobubbles carrying AMD070 and ICG (ICG-TNBs) were constructed by carbodiimide reaction and mechanical oscillation. The physical characteristics and in vitro multimodal imaging were determined. The binding potential of ICG-TNBs to human breast cancer cells were observed by laser confocal microscopy. CCK-8 and flow cytometry were used to analyze the role of ICG-TNBs + US in inhibiting proliferation and inducing apoptosis of tumor cells. Flow cytometry and Western blotting are used to analyse the ROS generation and molecular mechanisms. ICG-TNBs had a particle size of 497.0 ± 29.2 nm and a Zeta potential of -8.05 ± 0.73 mV. In vitro multimodal imaging showed that the image signal intensity of ICG-TNBs increased with concentration. Targeted binding assay confirmed that ICG-TNBs could specifically bind to MCF-7 cells (CXCR4 positive), but not to MDA-MB-468 cells (CXCR4 negative). CCK-8 assay and flow cytometry analysis showed that ICG-TNBs + US could significantly inhibit the growth of MCF-7 breast cancer cells and promote their apoptosis. Flow cytometry and Western blotting showed that ICG-TNBs + US could significantly raise generation of ROS, reduce the expression of CXCR4, inhibit phosphorylation of Akt, and increase the expression of Caspase3 and Cleaved-caspase3. This indicated that ICG-TNBs could effectively inhibit and block the SDF-1/CXCR4 pathway, thus leading to the apoptosis of MCF-7 cells. ICG-TNBs can specifically bind to CXCR4 positive breast cancer cells, furthermore inhibit growth and promote apoptosis of breast cancer cells combined with ultrasonic irradiation by blocking the SDF-1/CXCR4 pathway. This study introduces a novel concept, method and mechanism for integration of targeted diagnosis and treatment of breast cancer.

Scoping Review of Targeted Ultrasound Contrast Agents in the Detection of Angiogenesis

A systematic search was conducted to categorize targeted ultrasound contrast agents (UCAs) used in cancer-related angiogenesis detection. We identified 15 unique contrast agents from 2008 to March 2018. Most primary research articles studied UCAs targeted to vascular endothelial growth factor receptor or αv β3 -integrin. Breast cancer and colon cancer are the most common neoplastic processes in which these agents were studied. BR55 (Bracco Research SA, Geneva, Switzerland), a vascular endothelial growth factor receptor-targeting UCA, is the first targeted UCA that has completed phase 0 trials. Our review identifies a gap in the literature regarding the application of targeted UCAs in cancer models beyond breast and colon cancers and identifies other promising UCAs.

When spider and snake get along: Fusion of a snake disintegrin with a spider phospholipase D to explore their synergistic effects on a tumor cell

Venoms of spiders and snakes contain toxins extremely active and, thus, provide a natural source for the development of new biotechnological tools. Among the diversity of toxins present in the venom of spiders from genus Loxosceles, the phospholipases D (PLDs) show high hydrolytic activity upon lysophosphatidylcholine (LPC) and sphingomyelin (SM), generating bioactive phospholipids such as cyclic phosphatidic acid (cPA). Since this mediator has been shown to play a major role in complex signaling pathways, including inhibition of tumor cells, the PLDs may hold the key to learn how toxins could be used for therapeutic purposes. However, the strong platelet aggregation of PLDs and their lack of selectivity impose a major limitation. On the other hand, disintegrins present in the venoms of Viperidae snakes are a potent inhibitor of platelet aggregation and possess high affinity and specificity to molecules called integrins that are highly expressed in some tumor cells, such as murine melanoma B16F10. Therefore, disintegrins might be suitable molecules to carry the PLDs to the malignant cells, so both toxins may work synergistically to eliminate these cells. Thus, in this work, a recombinant PLD from Loxosceles gaucho spider was recombinantly fused to a disintegrin from Echis carinatus snake to form a hybrid toxin called Rechistatin. This recombinant toxin was successfully expressed in bacteria, showed binding activity in B16F10 murine melanoma cells and exerted a synergistic cytotoxicity effect on these cells. Therefore, the approach presented in this work may represent a new strategy to explore new potential applications for spider PLDs.

Evaluation of the Expression of Matrix Metalloproteinase-1 of Laryngeal Squamous Cell Carcinoma by Ultrasound Molecular Imaging

Purpose: The aims of this study were to evaluate the expression of matrix metalloproteinase-1 (MMP-1) on laryngeal squamous cell carcinoma (LSCC) and improve the early diagnosis rate via ultrasound molecular imaging (USMI).

Methods: The microsized MMP-1-targeted microbubbles (MB_MMP-1) and the control MBs (MB_IgG) based on perfluorocarbon-filled lipid-shelled MBs were constructed and characterized. The in vitro binding experiment was performed with human epidermoid laryngeal cancer cells (HEp-2) and tested the binding efficiency of MB_MMP-1 and MB_IgG. In the in vivo study, the LSCC model was established in 10 mice. The MB_MMP-1 and MB_IgG were randomly injected into tumor-bearing mice via the tail vein at Day 7, Day 12, and Day 17 to dynamically evaluate the differential targeted enhancement (dTE) signals via USMI. Subsequent immunofluorescence analysis was used for confirmation of MMP-1 expression.

Result: The effective adhesion rate of MB_MMP-1 and MB_IgG to HEp-2 was 298.42 ± 16.57 versus 12.38 ± 3.26 bubbles/per field in vitro experiment, which shows a significant difference (P < 0.01). The in vivo ultrasound molecular imaging (USMI) results demonstrated that dTE signal intensity from MB_MMP-1 was significantly higher than that from the MB_IgG at Day 7, Day 12, and Day 17 (Day 7, 41.21 ± 15.00 versus 2.25 ± 0.6 a.u., P < 0.05; Day 12, 124.64 ± 5.19 versus 11.13 ± 1.13 a.u., P < 0. 05; Day 17, 332.01 ± 64.88 versus 42.99 ± 11.9 a.u., P < 0.01). Moreover, immunofluorescence analysis further confirmed the expression of MMP-1 in LSCC with a gradual increase with the tumor growth.

Conclusion: MB_MMP-1 could be a potential probe that can be used in the early diagnosis of LSCC by USMI.

Photoacoustic imaging of integrin-overexpressing tumors using a novel ICG-based contrast agent in mice

PhotoAcoustic Imaging (PAI) is a biomedical imaging modality currently under evaluation in preclinical and clinical settings. In this work, ICG is coupled to an integrin binding vector (ICG-RGD) to combine the good photoacoustic properties of ICG and the favourable α_vβ₃-binding capabilities of a small RGD cyclic peptidomimetic. ICG-RGD is characterized in terms of physicochemical properties, biodistribution and imaging performance. Tumor uptake was assessed in subcutaneous xenograft mouse models of human glioblastoma (U-87MG, high α_vβ₃ expression) and epidermoid carcinoma (A431, low α_vβ₃ expression). ICG and ICG-RGD showed high PA signal in tumors already after 15 min post-injection. At later time points the signal of ICG rapidly decreased, while ICG-RGD showed sustained uptake in U-87MG but not in A431 tumors, likely due to the integrin-mediated retention of the probe. In conclusion, ICG-RGD is a novel targeted contrast agents for PAI with superior biodistribution, tumor uptake properties and diagnostic value compared to ICG.

Construction of ultrasonic nanobubbles carrying CAIX polypeptides to target carcinoma cells derived from various organs

Background

Ultrasound molecular imaging is a novel diagnostic approach for tumors, whose key link is the construction of targeted ultrasound contrast agents. However, available targeted ultrasound contrast agents for molecular imaging of tumors are only achieving imaging in blood pool or one type tumor. No targeted ultrasound contrast agents have realized targeted ultrasound molecular imaging of tumor parenchymal cells in a variety of solid tumors so far. Carbonic anhydrase IX (CAIX) is highly expressed on cell membranes of various malignant solid tumors, so it’s a good target for ultrasound molecular imaging. Here, targeted nanobubbles carrying CAIX polypeptides for targeted binding to a variety of malignant tumors were constructed, and targeted binding ability and ultrasound imaging effect in different types of tumors were evaluated.

Results

The mean diameter of lipid targeted nanobubbles was (503.7 ± 78.47) nm, and the polypeptides evenly distributed on the surfaces of targeted nanobubbles, which possessed the advantages of homogenous particle size, high stability, and good safety. Targeted nanobubbles could gather around CAIX-positive cells (786-O and Hela cells), while they cannot gather around CAIX-negative cells (BxPC-3 cells) in vitro, and the affinity of targeted nanobubbles to CAIX-positive cells were significantly higher than that to CAIX-negative cells (P < 0.05). Peak intensity and duration time of targeted nanobubbles and blank nanobubbles were different in CAIX-positive transplanted tumor tissues in vivo (P < 0.05). Moreover, targeted nanobubbles in CAIX-positive transplanted tumor tissues produced higher peak intensity and longer duration time than those in CAIX-negative transplanted tumor tissues (P < 0.05). Finally, immunofluorescence not only confirmed targeted nanobubbles could pass through blood vessels to enter in tumor tissue spaces, but also clarified imaging differences of targeted nanobubbles in different types of transplanted tumor tissues.

Conclusions

Targeted nanobubbles carrying CAIX polypeptides can specifically enhance ultrasound imaging in CAIX-positive transplanted tumor tissues and could potentially be used in early diagnosis of a variety of solid tumors derived from various organs.

Electronic supplementary material

The online version of this article (doi:10.1186/s12951-017-0307-0) contains supplementary material, which is available to authorized users.

In vitro characterization and in vivo ultrasound molecular imaging of nucleolin-targeted microbubbles

Nucleolin (NCL) plays an important role in tumor vascular development. An increased endothelial expression level of NCL has been related to cancer aggressiveness and prognosis and has been detected clinically in advanced tumors. Here, with a peptide targeted to NCL (F3 peptide), we created an NCL-targeted microbubble (MB) and compared the performance of F3-conjugated MBs with non-targeted (NT) MBs both in vitro and in vivo. In an in vitro study, F3-conjugated MBs bound 433 times more than NT MBs to an NCL-expressing cell line, while pretreating cells with 0.5 mM free F3 peptide reduced the binding of F3-conjugated MBs by 84%, n = 4, p < 0.001. We then set out to create a method to extract both the tumor wash-in and wash-out kinetics and tumor accumulation following a single injection of targeted MBs. In order to accomplish this, a series of ultrasound frames (a clip) was recorded at the time of injection and subsequent time points. Each pixel within this clip was analyzed for the minimum intensity projection (MinIP) and average intensity projection (AvgIP). We found that the MinIP robustly demonstrates enhanced accumulation of F3-conjugated MBs over the range of tumor diameters evaluated here (2-8 mm), and the difference between the AvgIP and the MinIP quantifies inflow and kinetics. The inflow and clearance were similar for unbound F3-conjugated MBs, control (non-targeted) and scrambled control agents. Targeted agent accumulation was confirmed by a high amplitude pulse and by a two-dimensional Fourier Transform technique. In summary, F3-conjugated MBs provide a new imaging agent for ultrasound molecular imaging of cancer vasculature, and we have validated metrics to assess performance using low mechanical index strategies that have potential for use in human molecular imaging studies.

The principles and applications of avidin-based nanoparticles in drug delivery and diagnosis

Avidin-biotin interaction is one of the strongest non-covalent interactions in the nature. Avidin and its analogues have therefore been extensively utilized as probes and affinity matrices for a wide variety of applications in biochemical assays, diagnosis, affinity purification, and drug delivery. Recently, there has been a growing interest in exploring this non-covalent interaction in nanoscale drug delivery systems for pharmaceutical agents, including small molecules, proteins, vaccines, monoclonal antibodies, and nucleic acids. Particularly, the ease of fabrication without losing the chemical and biological properties of the coupled moieties makes the avidin-biotin system a versatile platform for nanotechnology. In addition, avidin-based nanoparticles have been investigated as diagnostic systems for various tumors and surface antigens. In this review, we will highlight the various fabrication principles and biomedical applications of avidin-based nanoparticles in drug delivery and diagnosis. The structures and biochemical properties of avidin, biotin and their respective analogues will also be discussed.

Molecular Imaging of Angiogenesis in Cardiac Regeneration

PURPOSE OF REVIEW

Myocardial infarction (MI) leading to heart failure displays an important cause of death worldwide. Adequate restoration of blood flow to prevent this transition is a crucial factor to improve long-term morbidity and mortality. Novel regenerative therapies have been thoroughly investigated within the past decades.

RECENT FINDINGS

Increased angiogenesis in infarcted myocardium has shown beneficial effects on the prognosis of MI; therefore, the proangiogenic capacity of currently tested treatments is of specific interest. Molecular imaging to visualize formation of new blood vessels in vivo displays a promising option to monitor proangiogenic effects of regenerative substances.

SUMMARY

Based on encouraging results in preclinical models, molecular angiogenesis imaging has recently been applied in a small set of patients. This article reviews recent literature on noninvasive in vivo molecular imaging of angiogenesis after MI as an integral part of cardiac regeneration.