Paramagnetic Fluorinated Nanoemulsions for in vivo F-19 MRI

Molecular Imaging and Biology - We aim to develop perfluorocarbon-based nanoemulsions with improved sensitivity for detection of inflammatory macrophages in situ using F-19 MRI. Towards this goal,...     

Characterization and In Vitro and In Vivo Testing of CB2-Receptor- and NGAL-Targeted Paramagnetic Micelles for Molecular MRI of Vulnerable Atherosclerotic Plaque

Purpose

Atherosclerotic plaque macrophages express the peripheral cannabinoid receptor (CB2-R) and promote fibrous cap degradation by secretion of neutrophil gelatinase-associated lipocalin 2 (NGAL). In this study, we report the preparation, characterization, and in vitro and in vivo testing of double-labeled (MR and fluorescent) CB2-R- and NGAL-targeted micelles.

Procedures/Results

Specific CB2-R agonists or antibodies directed to 24p3 (mouse homolog of NGAL) were incorporated into di-oleoyl-polyethylene glycol-phosphatidylethanolamine 1000 (DOPE-PEG1000) micelles or di-stearoyl-polyethylene glycol-phosphatidylethanolamine 2000 (DSPE-PEG2000) micelles. The hydrodynamic diameter, determined by dynamic light scattering, was 16.5 and 19.0 nm for CB2-R-targeted DOPE-PEG1000 and DSPE-PEG2000 micelles, respectively, and 23.0 nm for Ab-conjugated DSPE-PEG2000 micelles. In vitro and in vivo MRI and fluorescence microscopy showed specific binding of CB2-R-targeted and 24p3-targeted micelles to in vitro systems and to aortic plaque in apoE^?/?/eNOS^?/? mice, respectively.

Conclusions

CB2-R- and NGAL-targeted micelles show promise as tools for in vivo characterization of vulnerable plaque.     

A Trimodal Imaging Platform for Tracking Viable Transplanted Pancreatic Islets In Vivo: F-19 MR,Fluorescence, and Bioluminescence Imaging

Molecular Imaging and Biology - Combining specific and quantitative F-19 magnetic resonance imaging (MRI) with sensitive and convenient optical imaging provides complementary information about the...     

Fluorine-19 Cellular MRI Detection of In Vivo Dendritic Cell Migration and Subsequent Induction of Tumor Antigen-Specific Immunotherapeutic Response

Purpose

A major hurdle in the advancement of cell-based cancer immunotherapies is the inability to track in vivo therapeutic cell migration. With respect to dendritic cell (DC)-based cancer immunotherapies, this lack of knowledge represents an even greater hurdle as the quantity of tumor-antigen specific DC reaching a secondary lymphoid organ post injection is predictive of the magnitude of the ensuing tumor-specific immune response. We propose fluorine-19 (F-19) cellular magnetic resonance imaging (MRI) as a suitable and non-invasive imaging modality capable of detecting and quantifying DC migration in vivo and thus, serving as a surrogate marker of DC-based immunotherapeutic effectiveness.

Procedures

Murine DC were generated from bone marrow precursors and labeled with a [¹⁹F]perfluorocarbon ([¹⁹F]PFC)-based cell labeling agent. DC were characterized by viability and phenotyping assessments as well as characterized by ability to induce in vivo tumor-specific immune responses following immunization in a B16-F10 mouse model of melanoma. The in vivo migration of [¹⁹F]PFC (PFC)-labeled DC was first compared to control unlabeled DC by microscopy and then measured using F-19 cellular MRI.

Results

Culture conditions were optimized such that >?90 % of DC labeled with PFC without affecting viability, phenotype, and function. This optimization permitted consistent detection of PFC-labeled DC migration using F-19 cellular MRI and resulted in the first successful comparison of in vivo migration between PFC-labeled and control unlabeled therapeutic cells of the same origin. PFC-labeled DC are migration-competent in vivo in a B16-F10 tumor-bearing mouse model.

Conclusions

We report a non-invasive and longitudinal imaging modality capable of detecting and quantifying therapeutic cell migration at both 9.4 and 3 Tesla (T) and suitable for therapeutic cell tracking in a tumor-bearing mouse model. F-19 MRI cell tracking is broadly applicable across disease states and is conducive to clinical translation.

     

Synthesis and Evaluation of Diindole-Based MRI Contrast Agent for In Vivo Visualization of Necrosis

Purpose

Noninvasive imaging of cell necrosis can provide an early evaluation of tumor response to treatments. Here, we aimed to design and synthesize a novel diindole-based magnetic resonance imaging (MRI) contrast agent (Gd-bis-DOTA-diindolylmethane, Gd-DIM) for assessment of tumor response to therapy at an early stage.

Procedures

The oil-water partition coefficient (Log P) and relaxivity of Gd-DIM were determined in vitro. Then, its necrosis avidity was examined in necrotic cells in vitro and in rat models with microwave ablation-induced muscle necrosis (MAMN) and ischemia reperfusion-induced liver necrosis (IRLN) by MRI. Visualization of tumor necrosis induced by combretastatin A-4 disodium phosphate (CA4P) was evaluated in rats bearing W256 orthotopic liver tumor by MRI. Finally, DNA binding assay was performed to explore the possible necrosis-avidity mechanism of Gd-DIM.

Results

The Log P value and T1 relaxivity of Gd-DIM is ??2.15?±?0.01 and 6.61 mM^?1 s^?1, respectively. Gd-DIM showed predominant necrosis avidity in vitro and in vivo. Clear visualization of the tumor necrosis induced by CA4P was achieved at 60 min after administration of Gd-DIM. DNA binding study indicated that the necrosis-avidity mechanism of Gd-DIM may be due to its binding to exposed DNA in necrotic cells.

Conclusion

Gd-DIM may serve as a promising necrosis-avid MRI contrast agent for early assessment of tumor response to therapy.

     

Acute Parathyroid Hormone Response to Epinephrine In Vivo

The acute effects of epinephrine, norepinephrine, and isoproterenol on the plasma immunoreactive parathyroid hormone (iPTH) response were studied in 13 550-600 kg cows. Catecholamines were infused for 7.0 min. During epinephrine infusions at 0.08 mumol/min iPTH increased from 0.48+/-0.12 (mean+/-SE, ng/ml) to 1.09+/-0.18 ng/ml (P < 0.02). Small increases in plasma free fatty acids and glucose could be detected with 0.08 mumol/min epinephrine; the iPTH response to epinephrine was as sensitive as the free fatty acid and glucose responses and possibly of physiological importance. Plasma calcium (total and ionized) and magnesium did not change.The responses were more pronounced at 0.8 mumol/min epinephrine with a mean iPTH increase from 0.49+/-0.16 ng/ml to 1.74+/-0.35 ng/ml (P < 0.01). Small decreases in plasma calcium occurred at 0.8 mumol/min epinephrine, but the plasma magnesium remained unchanged. However, when the plasma calcium was lowered with ethylene glycol bis(beta-aminoethyl ether)-N, N'-tetraacetic acid (EGTA), a much more pronounced lowering of the plasma calcium was required to produce comparable increases of the plasma iPTH concentrations than when epinephrine was infused. It appears that epinephrine has a direct effect on the release of iPTH from the parathyroid glands.Simultaneous infusions of calcium and epinephrine suppressed the stimulation by epinephrine. This points towards a common mechanism of the regulation of parathyroid hormone secretion caused by decreases in the extracellular calcium concentration and/or alterations in the distribution of calcium within parathyroid cells following the administration of epinephrine.The iPTH response to epinephrine was suppressed in the presence of propranolol. Isoproterenol was less active in raising iPTH than epinephrine, and norepinephrine was the least active. The stimulation by isoproterenol and the suppression by propranolol suggest beta adrenergic receptor sites within the parathyroid glands.     

In Vivo Evaluation of Magnetic Targeting in Mice Colon Tumors with Ultra-Magnetic Liposomes Monitored by MRI

Molecular Imaging and Biology - The development of theranostic nanocarriers as an innovative therapy against cancer has been improved by targeting properties in order to optimize the drug delivery...     

A Peptide-based Vector for Efficient Gene Transfer In Vitro and In Vivo

Finding suitable nonviral delivery vehicles for nucleic acid–based therapeutics is a landmark goal in gene therapy. Cell-penetrating peptides (CPPs) are one class of delivery vectors that has been exploited for this purpose. However, since CPPs use endocytosis to enter cells, a large fraction of peptides remain trapped in endosomes. We have previously reported that stearylation of amphipathic CPPs, such as transportan 10 (TP10), dramatically increases transfection of oligonucleotides in vitro partially by promoting endosomal escape. Therefore, we aimed to evaluate whether stearyl-TP10 could be used for the delivery of plasmids as well. Our results demonstrate that stearyl-TP10 forms stable nanoparticles with plasmids that efficiently enter different cell-types in a ubiquitous manner, including primary cells, resulting in significantly higher gene expression levels than when using stearyl-Arg9 or unmodified CPPs. In fact, the transfection efficacy of stearyl-TP10 almost reached the levels of Lipofectamine 2000 (LF2000), however, without any of the observed lipofection-associated toxicities. Most importantly, stearyl-TP10/plasmid nanoparticles are nonimmunogenic, mediate efficient gene delivery in vivo, when administrated intramuscularly (i.m.) or intradermally (i.d.) without any associated toxicity in mice.     

In Vivo and In Vitro Acquisition of Resistance to Voriconazole by Candida krusei

Candida krusei is an important agent of opportunistic infections that often displays resistance to several antifungals. We describe here the in vivo acquisition of resistance to voriconazole (VRC) by C. krusei isolates recovered from a leukemia patient during a long period of VRC therapy. In order to mimic the in vivo development of VRC resistance, a susceptible C. krusei isolate was exposed daily to 1 μg/ml of VRC in vitro. Interestingly, after 5 days of exposure to VRC, a MIC of 4 μg/ml was achieved; this value remained constant after 25 additional days of treatment with VRC and also after 30 consecutive days of incubation in VRC-free medium. Our objective was to determine the associated molecular resistance mechanisms, such as expression of efflux pump genes and ERG11 gene mutations, among the resistant strains. Synergistic effects between the efflux blocker tacrolimus (FK506) and VRC were found in all of the resistant strains. Moreover, ABC1 gene expression increased over time in both the in vivo- and in vitro-induced resistant strains, in contrast to the ABC2 and ERG11 genes, whose expression was invariably lower and constant. ERG11 gene sequencing showed two different types of mutations, i.e., heterozygosity at T1389T/C, corresponding to synonymous mutations, in C. krusei strains and a missense mutation at position T418C, resulting in a change from Tyr to His, among resistant C. krusei clinical isolates. This study highlights the relevance of ATP-dependent efflux pump (namely, Abc1p) activity in VRC resistance and describes new mutations in the ERG11 gene among resistant C. krusei clinical isolates.     

Introduction: feature issue on In Vivo Microcirculation Imaging

The editors introduce the Biomedical Optics Express feature issue, "In Vivo Microcirculation Imaging," which includes 14 contributions from the biomedical optics community, covering such imaging techniques as optical coherence tomography, photoacoustic microscopy, laser Doppler /speckle imaging, and near infrared spectroscopy and fluorescence imaging.     

Nanoparticle-mediated Gene Silencing Confers Radioprotection to Salivary Glands In Vivo

Radiation treatment of head and neck cancers causes irreversible damage of the salivary glands (SG). Here, we introduce a preclinical mouse model for small-interfering RNA (siRNA)-based gene silencing to provide protection of SG from radiation-induced apoptosis. Novel, pH-responsive nanoparticles complexed with siRNAs were introduced into mouse submandibular glands (SMG) by retroductal injection to modulate gene expression in vivo. To validate this approach, we first targeted Nkcc1, an ion transporter that is essential for saliva secretion. Nkcc1 siRNA delivery resulted in efficient knockdown, as quantified at the mRNA and the protein levels, and the functional result of Nkcc1 knockdown phenocopied the severe decrease in saliva secretion, characteristic of the systemic Nkcc1 gene knockout. To establish a strategy to prevent apoptotic cell loss due to radiation damage, siRNAs targeting the proapoptotic Pkcδ gene were administered into SMG before ionizing radiation. Knockdown of Pkcδ not only reduced the number of apoptotic cells during the acute phase of radiation damage, but also markedly improved saliva secretion at 3 months in irradiated animals, indicating that this treatment confers protection from hyposalivation. These results demonstrate that nanoparticle delivery of siRNAs targeting a proapoptotic gene is a localized, nonviral, and effective means of conferring radioprotection to the SGs.     

Correction: Development of hollow ferrogadolinium nanonetworks for dual-modal MRI guided cancer chemotherapy

Correction for ‘Development of hollow ferrogadolinium nanonetworks for dual-modal MRI guided cancer chemotherapy’ by Ting Tang et al., RSC Adv., 2019, 9, 2559–2566.

The authors regret that Scheme 1 in the original article included some incorrect data under the cancer chemotherapy part of the scheme. The correct version of Scheme 1 is presented below.Open in a separate windowScheme 1The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

SCE-129, Antipseudomonal Cephalosporin: In Vitro and In Vivo Antibacterial Activities

SCE-129 [3-(4-carbamoyl-1-pyridiniomethyl)-7beta-(d-alpha-sulfophenylacetamido)-ceph-3-em-4-carboxylate monosodium salt], a new semisynthetic cephalosporin, shows potent in vitro antibacterial activities against Pseudomonas aeruginosa and some gram-positive bacteria, whereas it shows lower activity against many gram-negative rods. Against clinical isolates of P. aeruginosa this cephalosporin exhibited higher activity than did carbenicillin, and against the strains of Staphylococcus aureus, SCE-129 had similar activity to carbenicillin. Variations in pH, addition of horse serum, and type of growth medium had no significant effects on the activity of the cephalosporin; however, the inoculum size had some effect on the activity. SCE-129 is an effective bactericidal agent against P. aeruginosa and S. aureus. The protective effects of SCE-129 in mice infected with P. aeruginosa and S. aureus were more potent than those of carbenicillin. The protective effects of SCE-129 on Pseudomonas infection in mice varied according to the dosage schedule and the challenge dose. In a multiple dose schedule, a smaller amount of SCE-129 was necessary than that in a single dose schedule. The effects of SCE-129 after subcutaneous or intraperitoneal administration were more potent than were those by intravenous administration. No protective effect was observed by oral administration.     

Ultraviolet irradiation of platelet concentrates: In Vitro and In Vivo preclinical evaluation

Ultraviolet B (UV-B) irradiation abolishes lymphocyte function in mixed lymphocyte culture (MLC) and could theoretically prevent alloimmunization against HLA class I antigens. We describe a system available in transfusion practice for such a treatment of platelet concentrates (PC). PC obtained from the Haemonetics V50 cell separator or by cytapheresis (Cobe 2997) were evaluated using two irradiators and three different bags: Stericell^TM from DuPont and two bags from Macopharma (PVC MP and EVA MP). The Stericell bag and the EVA MP bags allow a complete abolition of lymphocyte activity without platelet function impairment (as measured by aggregation tests) and without reduction of survival of transfused platelets (autologous or allogeneic). The temperature increase during irradiation is negligible. The time of irradiation is very short (less than 3 min). These results show that the necessary conditions for clinical evaluation of UV-B irradiated patelet concentrates in preventing HLA alloimmunization are obtained.     

Elastography: Elasticity Imaging Using Ultrasound with Application to Muscle and Breast In Vivo

Changes in tissue elasticity are generally correlated with its pathological state. In many cases, despite the difference in elasticity, the small size of a lesion or its location deep in the body preclude its detection by palpation. In general, such a lesion may or may not posses echogenic properties that would make it ultrasonically detectable. Elastography is an ultrasonic method for imaging the elasticity of compliant tissues. The method estimates the local longitudinal strain of tissue elements by ultrasonically assessing the one dimensional local displacements. This information can be combined with first order theoretical estimates of the local stress to yield a quantitative measure of the local elastic properties of tissue. The elasticity information is displayed in the form of a gray scale image called an elastogram. An experimental system for elastography in phantoms based on a single element transducer has been described previously [1]. Here we introduce a new elastography system based on a linear array transducer that is suitable for in vivo scanning. We describe tissue mimicking phantom experiments and preliminary in vivo breast and muscle elastograms confirming the feasibility of performing elastography in vivo. An elastogram of a breast containing an 8 mm palpable cancer nodule clearly shows the lesion. Elastograms and their corresponding sonograms show some similarities and differences in the depiction of tissue structures.