Rapid pharmacokinetic and biodistribution studies using cholorotoxin-conjugated iron oxide nanoparticles: a novel non-radioactive method.

PLoS One. 2010;5(3):e9536

Authors: Lee MJ, Veiseh O, Bhattarai N, Sun C, Hansen SJ, Ditzler S, Knoblaugh S, Lee D, Ellenbogen R, Zhang M, Olson JM

BACKGROUND: Recent advances in nanotechnology have led to the development of biocompatible nanoparticles for in vivo molecular imaging and targeted therapy. Many nanoparticles have undesirable tissue distribution or unacceptably low serum half-lives. Pharmacokinetic (PK) and biodistribution studies can help inform decisions determining particle size, coatings, or other features early in nanoparticle development. Unfortunately, these studies are rarely done in a timely fashion because many nanotechnology labs lack the resources and expertise to synthesize radioactive nanoparticles and evaluate them in mice. METHODOLOGY/PRINCIPAL FINDINGS: To address this problem, we developed an economical, radioactivity-free method for assessing serum half-life and tissue distribution of nanoparticles in mice. Iron oxide nanoparticles coated with chitosan and polyethylene glycol that utilize chlorotoxin as a targeting molecule have a serum half-life of 7-8 hours and the particles remain stable for extended periods of time in physiologic fluids and in vivo. Nanoparticles preferentially distribute to spleen and liver, presumably due to reticuloendothelial uptake. Other organs have very low levels of nanoparticles, which is ideal for imaging most cancers in the future. No acute toxicity was attributed to the nanoparticles. CONCLUSIONS/SIGNIFICANCE: We report here a simple near-infrared fluorescence based methodology to assess PK properties of nanoparticles in order to integrate pharmacokinetic data into early nanoparticle design and synthesis. The nanoparticles tested demonstrate properties that are excellent for future clinical imaging strategies and potentially suitable for targeted therapy.

PMID: 20209054 [PubMed - in process]

Unbiased discovery of in vivo imaging probes through in vitro profiling of nanoparticle libraries.

Integr Biol (Camb). 2009 Apr;1(4):311-7

Authors: Kelly KA, Shaw SY, Nahrendorf M, Kristoff K, Aikawa E, Schreiber SL, Clemons PA, Weissleder R

In vivo imaging reveals how proteins and cells function as part of complex regulatory networks in intact organisms, and thereby contributes to a systems-level understanding of biological processes. However, the development of novel in vivo imaging probes remains challenging. Most probes are directed against a limited number of pre-specified protein targets; cell-based screens for imaging probes have shown promise, but raise concerns over whether in vitro surrogate cell models recapitulate in vivo phenotypes. Here, we rapidly profile the in vitro binding of nanoparticle imaging probes in multiple samples of defined target vs. background cell types, using primary cell isolates. This approach selects for nanoparticles that show desired targeting effects across all tested members of a class of cells, and decreases the likelihood that an idiosyncratic cell line will unduly skew screening results. To adjust for multiple hypothesis testing, we use permutation methods to identify nanoparticles that best differentiate between the target and background cell classes. (This approach is conceptually analogous to one used for high-dimensionality datasets of genome-wide gene expression, e.g. to identify gene expression signatures that discriminate subclasses of cancer.) We apply this approach to the identification of nanoparticle imaging probes that bind endothelial cells, and validate our in vitro findings in human arterial samples, and by in vivo intravital microscopy in mice. Overall, this work presents a generalizable approach to the unbiased discovery of in vivo imaging probes, and may guide the further development of novel endothelial imaging probes.

PMID: 20023731 [PubMed - indexed for MEDLINE]

Detecting epidermal growth factor receptor tumor activity in vivo during cetuximab therapy of murine gliomas.

Acad Radiol. 2010 Jan;17(1):7-17

Authors: Gibbs-Strauss SL, Samkoe KS, O'Hara JA, Davis SC, Hoopes PJ, Hasan T, Pogue BW

RATIONALE AND OBJECTIVES: Noninvasive molecular imaging of glioma tumor receptor activity was assessed with diagnostic in vivo fluorescence monitoring during targeted therapy. The study goals were to assess the range of use for treatment monitoring and stratification of tumor types using epidermal growth factor (EGF) receptor (EGFR) status with administration of fluorescently labeled EGF and determine its utility for tumor detection compared to magnetic resonance imaging (MRI). MATERIALS AND METHODS: EGFR+ and EGFR- glioma tumor lines (human glioma [U251-GFP] and rat gliosarcoma [9L-GFP], respectively) were used to assess these goals, having a 20-fold difference between their EGF uptakes. RESULTS: Treatment with cetuximab in the EGFR+ tumor-bearing animals led to decreased EGF tumor uptake, whereas for the EGFR- tumors, no change in fluorescence signal followed treatment. This diagnostic difference in EGFR expression could be used to stratify the tumor-bearing animals into groups of potential responders and nonresponders, and receiver-operating characteristic curve analysis revealed an area under the curve (AUC) of 0.92 in separating these tumors. The nonlocalized growth pattern of U251-GFP tumors resulted in detection difficulty on standard MRI, but high EGFR expression made them detectable by fluorescence imaging (AUC = 1.0). The EGFR+ U251-GFP tumor-bearing animals could be noninvasively stratified into treated and untreated groups on the basis of fluorescence intensity difference (P = .035, AUC = 0.90). CONCLUSIONS: EGFR expression was tracked in vivo with fluorescence and determined to be of use for the stratification of EGFR+ and EGFR- tumors, the detection of EGFR+ tumors, and monitoring of molecular therapy.

PMID: 19796971 [PubMed - indexed for MEDLINE]

Second harmonic generation imaging via nonlinear endomicroscopy.

Opt Express. 2010 Jan 18;18(2):1255-60

Authors: Bao H, Boussioutas A, Jeremy R, Russell S, Gu M

A compact endomicroscope is the only solution for transferring second harmonic generation (SHG) imaging into in vivo imaging and real time monitoring the content and structure of collagen. This is important for early diagnoses of different diseases associated with collagen change. A compact nonlinear endomicroscope using a double clad fiber (DCF) is newly employed in SHG imaging. The experiment shows the core of the DCF can maintain the linear polarization of the excitation laser beam in particular directions, and the degree of polarization of the excitation laser beam directly affects signal to noise ratio of SHG imaging. The nonlinear endomicroscope can display clear three dimensional (3D) SHG images of mouse tail tendon without the aid of contrast agents, which reveals the collagen fiber structure at different depths. The high resolution of SHG imaging from the endomicroscope shows that SHG imaging can reveal additional information about the orientation and degree of organisation of proteins and collagen fibers than two-photon-excited fluorescence imaging. Therefore SHG imaging offers endomicroscopy with additional channel of imaging for understanding more about biological phenomena.

PMID: 20173949 [PubMed - in process]

Imaging leukocyte trafficking in vivo with two-photon-excited endogenous tryptophan fluorescence.

Opt Express. 2010 Jan 18;18(2):988-99

Authors: Li C, Pastila RK, Pitsillides C, Runnels JM, Puoris'haag M, Côté D, Lin CP

We describe a new method for imaging leukocytes in vivo by exciting the endogenous protein fluorescence in the ultraviolet (UV) spectral region where tryptophan is the major fluorophore. Two-photon excitation near 590 nm allows noninvasive optical sectioning through the epidermal cell layers into the dermis of mouse skin, where leukocytes can be observed by video-rate microscopy to interact dynamically with the dermal vascular endothelium. Inflammation significantly enhances leukocyte rolling, adhesion, and tissue infiltration. After exiting the vasculature, leukocytes continue to move actively in tissue as observed by time-lapse microscopy, and are distinguishable from resident autofluorescent cells that are not motile. Because the new method alleviates the need to introduce exogenous labels, it is potentially applicable for tracking leukocytes and monitoring inflammatory cellular reactions in humans.

PMID: 20173920 [PubMed - in process]

Ring-opening metathesis polymerization-based synthesis of polymeric nanoparticles for enhanced tumor imaging in vivo: Synergistic effect of folate-receptor targeting and PEGylation.

Biomaterials. 2010 Feb;31(5):934-42

Authors: Miki K, Oride K, Inoue S, Kuramochi Y, Nayak RR, Matsuoka H, Harada H, Hiraoka M, Ohe K

We have synthesized amphiphilic copolymers using ring-opening metathesis polymerization (ROMP), a copper-catalyzed dipolar click reaction, and osmium-catalyzed dihydroxylation. The resulting copolymers were easily conjugated with folate and dye (indocyanine green) moieties, using a transamidation method. The copolymers exhibited high water solubility and formed nanometer-sized self-assemblies in aqueous medium. The amphiphilic copolymers modified by dihydroxylation of the polymer backbone exhibited much lower cmc values than the non dihydroxylated copolymer. Copolymers conjugated with folate moieties reduced the fluorescence intensity of aqueous polymer solutions both in vitro and in vivo, but their self-assemblies efficiently accumulated at tumor sites because of folate-receptor recognition at tumor tissue. The PEGylation of copolymers improved the stability of the self-assemblies in aqueous medium as well as the tumor site selectivity in vivo. Furthermore, the fluorescent nanoparticles consisting of PEG- and folate-conjugated ROMP-based copolymers accumulated in tumor tissue selectively and efficiently, whereas accumulation in all other normal organs was reduced. The PEGylation and folate conjugation can synergistically improve the in vivo tumor site selectivity of ROMP-based copolymers.

PMID: 19853909 [PubMed - indexed for MEDLINE]

Direct evidence of mesenchymal stem cell tropism for tumor and wounding microenvironments using in vivo bioluminescent imaging.

Stem Cells. 2009 Oct;27(10):2614-23

Authors: Kidd S, Spaeth E, Dembinski JL, Dietrich M, Watson K, Klopp A, Battula VL, Weil M, Andreeff M, Marini FC

Multipotent mesenchymal stromal/stem cells (MSC) have shown potential clinical utility. However, previous assessments of MSC behavior in recipients have relied on visual detection in host tissue following sacrifice, failing to monitor in vivo MSC dispersion in a single animal and limiting the number of variables that can be observed concurrently. In this study, we used noninvasive, in vivo bioluminescent imaging to determine conditions under which MSC selectively engraft in sites of inflammation. MSC modified to express firefly luciferase (ffLuc-MSC) were injected into healthy mice or mice bearing inflammatory insults, and MSC localization was followed with bioluminescent imaging. The inflammatory insults investigated included cutaneous needle-stick and surgical incision wounds, as well as xenogeneic and syngeneic tumors. We also compared tumor models in which MSC were i.v. or i.p. delivered. Our results demonstrate that ffLuc-expressing human MSC (hMSC) systemically delivered to nontumor-bearing animals initially reside in the lungs, then egress to the liver and spleen, and decrease in signal over time. However, hMSC in wounded mice engraft and remain detectable only at injured sites. Similarly, in syngeneic and xenogeneic breast carcinoma-bearing mice, bioluminescent detection of systemically delivered MSC revealed persistent, specific colocalization with sites of tumor development. This pattern of tropism was also observed in an ovarian tumor model in which MSC were i.p. injected. In this study, we identified conditions under which MSC tropism and selective engraftment in sites of inflammation can be monitored by bioluminescent imaging over time. Importantly, these consistent findings were independent of tumor type, immunocompetence, and route of MSC delivery.

PMID: 19650040 [PubMed - indexed for MEDLINE]

A route to brightly fluorescent carbon nanotubes for near-infrared imaging in mice.

Nat Nanotechnol. 2009 Nov;4(11):773-80

Authors: Welsher K, Liu Z, Sherlock SP, Robinson JT, Chen Z, Daranciang D, Dai H

The near-infrared photoluminescence intrinsic to semiconducting single-walled carbon nanotubes is ideal for biological imaging owing to the low autofluorescence and deep tissue penetration in the near-infrared region beyond 1 microm. However, biocompatible single-walled carbon nanotubes with high quantum yield have been elusive. Here, we show that sonicating single-walled carbon nanotubes with sodium cholate, followed by surfactant exchange to form phospholipid-polyethylene glycol coated nanotubes, produces in vivo imaging agents that are both bright and biocompatible. The exchange procedure is better than directly sonicating the tubes with the phospholipid-polyethylene glycol, because it results in less damage to the nanotubes and improves the quantum yield. We show whole-animal in vivo imaging using an InGaAs camera in the 1-1.7 microm spectral range by detecting the intrinsic near-infrared photoluminescence of the 'exchange' single-walled carbon nanotubes at a low dose (17 mg l(-1) injected dose). The deep tissue penetration and low autofluorescence background allowed high-resolution intravital microscopy imaging of tumour vessels beneath thick skin.

PMID: 19893526 [PubMed - indexed for MEDLINE]

MRI-coupled Fluorescence Tomography Quantifies EGFR Activity in Brain Tumors.

Acad Radiol. 2010 Mar;17(3):271-276

Authors: Davis SC, Samkoe KS, O'Hara JA, Gibbs-Strauss SL, Payne HL, Hoopes PJ, Paulsen KD, Pogue BW

RATIONALE AND OBJECTIVES: This report demonstrates the diagnostic potential of magnetic resonance imaging (MRI)-coupled fluorescence molecular tomography (FMT) to determine epidermal growth factor receptor (EGFR) status in brain cancer. MATERIALS AND METHODS: Two orthotopic glioma xenograft models were used in this study: one represented high EGFR expression and the other low expression. Nude mice were inoculated with cells from either one of the tumor lines or were used in a sham surgery control group. Animals were imaged using a unique MRI-FMT scanner 48 hours after intravenous injection of a near-infrared fluorophore bound to epidermal growth factor (EGF) ligand. Coronal images of fluorescence activity of the injected dye in the mouse brain were recovered using the MRI images as anatomical templates. RESULTS: In vivo images of fluorescence activity showed significant differences between animal populations, an observation confirmed by receiver operating characteristic analysis that revealed 100% sensitivity and specificity between animal groups implanted with EGFR((+)) and EGFR((-)) tumor lines. Similar performance was observed between EGFR((+)) and sham surgery control animals. CONCLUSIONS: This preclinical study suggests that MRI-FMT with fluorescent EGF provides excellent discrimination between tumors based on EGFR status. Reliable quantification of receptor status using minimally invasive techniques would be an important innovation for investigating new and existing cancer treatments that target these cellular mechanisms in research animals, and may be applied to identify receptor amplification in human brain cancer patients. This study represents the first systematic multianimal validation of receptor-specific imaging using MRI-guided fluorescence tomography.

PMID: 20152724 [PubMed - as supplied by publisher]

Tumor targeting of functionalized lipid nanoparticles: assessment by in vivo fluorescence imaging.

Eur J Pharm Biopharm. 2010 Feb 8;

Authors: Goutayer M, Dufort S, Josserand V, Royère A, Heinrich E, Vinet F, Bibette J, Coll JL, Texier I

Lipid nanoparticles (LNP) coated by a poly(oxyethylene) polymer have been manufactured from low cost and human use-approved materials, by an easy, robust, and up-scalable process. The incorporation in the formulation of maleimide-grafted surfactants allows the functionalization of the lipid cargos by targeting ligands such as the cRGD peptide binding to alpha(V)beta(3) integrin, a well-known angiogenesis biomarker. LNP are able to encapsulate efficiently lipophilic molecules such as a fluorescent dye, allowing their in vivo tracking using fluorescence imaging. In vitro study on HEK293(beta3) cells over-expressing the alpha(v)beta(3) integrins demonstrates the functionalization, specific targeting and internalization of cRGD-functionalized LNP in comparison with LNP-cRAD or LNP-OH used as negative controls. Following their intravenous injection in Nude mice, LNP-cRGD can accumulate actively in slow-growing HEK293(beta3) cancer xenografts, leading to tumor over skin fluorescence ratio of 1.53 +/- 0.07 (n = 3) 24 hours after injection. In another fast-growing tumor model (TS/A-pc), tumor over skin fluorescence ratio is improved (2.60 +/- 0.48, n = 3), but specificity between the different LNP functionalizations is no more observed. The different results obtained for the two tumor models are discussed in terms of active cRGD targeting and/or passive nanoparticle accumulation due to the Enhanced Permeability and Retention effect.

PMID: 20149869 [PubMed - as supplied by publisher]

Intravital Imaging of IL-1beta Production in Skin.

J Invest Dermatol. 2010 Feb 11;

Authors: Matsushima H, Ogawa Y, Miyazaki T, Tanaka H, Nishibu A, Takashima A

IL-1 is a prototypic inflammatory cytokine that has pathogenic roles in various skin disorders. Although Langerhans cells (LCs) have been reported to express IL-1beta mRNA upon application of contact sensitizers, it remains unclear whether other cell types produce IL-1beta in skin. Thus, we sought to directly identify IL-1beta-producing cells in living animals by construction of transgenic mice expressing DsRed fluorescence protein gene under the control of IL-1beta promoter. Little DsRed fluorescence signal was detected in skin under steady-state conditions. Striking increases in DsRed signal were observed after topical application of a contact sensitizer, oxazolone, which also induced markedly elevated IL-1beta mRNA and protein expression. DsRed signal was expressed primarily by CD45(+)/CD11b(+) myeloid leukocytes in both epidermal and dermal compartments and was detected only in small fractions of epidermal LCs. Interestingly, DsRed(+) cells emerged preferentially as clusters around hair follicles. Intravital confocal imaging experiments revealed highly motile potentials of DsRed(+) cells-they constantly crawled around hair follicles via amoeba-like movements with a mean velocity of 1.0+/-0.4 mum min(-1) (epidermis) or 2.7+/-1.4 mum min(-1) (dermis). The newly developed in vivo imaging system represents a useful tool for studying spatial regulation of IL-1beta production in skin.Journal of Investigative Dermatology advance online publication, 11 February 2010; doi:10.1038/jid.2010.11.

PMID: 20147964 [PubMed - as supplied by publisher]

Polylactide nanoparticles containing stably incorporated cyanine dyes for in vitro and in vivo imaging applications.

Microsc Res Tech. 2010 Feb 9;

Authors: Tong R, Coyle VJ, Tang L, Barger AM, Fan TM, Cheng J

Stably incorporating fluorescent molecules to polymeric nanoparticles (NPs) or micelles can facilitate the prolonged tracking of these drug-delivery vehicles in vitro and in vivo. However, incorporation of fluorescent molecules, usually charged and thereby water-soluble, through the encapsulation strategy to hydrophobic polymer matrices is challenging. The encapsulated fluorescent agents are also subject to rapid release when the polymeric NPs are exposed to biological media. To address this issue, we developed Cy5-conjugated polylactide (Cy5-PLA) NPs through Cy5/(BDI)ZnN(TMS)(2) [(BDI) = 2-((2,6-diisopropylphenyl)amido)-4-((2,6-diisopropylphenyl)-imino)-2-pentene]-mediated ring-opening polymerization of lactide (LA) followed by nanoprecipitation. This process allows for covalent conjugation of Cy5 to PLA with quantitative incorporation efficiency and formulation of Cy5-PLA NPs with controlled particles size ( approximately 100 nm). As much as 80% of Cy5 was still present in the Cy5-PLA NPs after theses NPs were incubated in PBS at 37 degrees C for 12 days. Cy5-PLA NPs were conjugated to the A10 RNA aptamer that binds to the prostate-specific membrane antigen (PSMA). The resulting Cy5-PLA/aptamer NPs were found to only bind to and get internalized by LNCaP and canine prostate adenocarcinoma cells (PSMA-positive), but not to PC3 cells (PSMA-negative). The Cy5-PLA NPs were administered to balb/c mice intravenously and found to have excellent signals with low-background fluorescence in various organs. Microsc. Res. Tech. 2010. (c) 2010 Wiley-Liss, Inc.

PMID: 20146347 [PubMed - as supplied by publisher]

Tumor Detection by Imaging Proteolytic Activity.

Cancer Res. 2010 Feb 9;

Authors: Darragh MR, Schneider EL, Lou J, Phojanakong PJ, Farady CJ, Marks JD, Hann BC, Craik CS

The cell surface protease membrane-type serine protease-1 (MT-SP1), also known as matriptase, is often upregulated in epithelial cancers. We hypothesized that dysregulation of MT-SP1 with regard to its cognate inhibitor hepatocyte growth factor activator inhibitor-1 (HAI-1), a situation that increases proteolytic activity, might be exploited for imaging purposes to differentiate malignant from normal tissue. In this study, we show that MT-SP1 is active on cancer cells and that its activity may be targeted in vivo for tumor detection. A proteolytic activity assay with several MT-SP1-positive human cancer cell lines showed that MT-SP1 antibodies that inhibit recombinant enzyme activity in vitro also bind and inhibit the full-length enzyme expressed on cells. In contrast, in the same assay, MT-SP1-negative cancer cell lines were inactive. Fluorescence microscopy confirmed the cell surface localization of labeled antibodies bound to MT-SP1-positive cells. To evaluate in vivo targeting capability, 0.7 to 2 nmoles of fluorescently labeled antibodies were administered to mice bearing tumors that were positive or negative for MT-SP1. Antibodies localized to MT-SP1-positive tumors (n = 3), permitting visualization of MT-SP1 activity, whereas MT-SP1-negative tumors (n = 2) were not visualized. Our findings define MT-SP1 activity as a useful biomarker to visualize epithelial cancers using a noninvasive antibody-based method. Cancer Res; 70(4); 1505-12.

PMID: 20145119 [PubMed - as supplied by publisher]

Magnetic Resonance Molecular Imaging of Thrombosis in an Arachidonic Acid Mouse Model Using an Activated Platelet Targeted Probe.

Arterioscler Thromb Vasc Biol. 2010 Feb 5;

Authors: Klink A, Lancelot E, Ballet S, Vucic E, Fabre JE, Gonzalez W, Medina C, Corot C, Mulder WJ, Mallat Z, Fayad ZA

OBJECTIVE: Atherosclerotic plaque rupture leads to acute thrombus formation and may trigger serious clinical events such as myocardial infarction or stroke. Therefore, it would be valuable to identify atherothrombosis and vulnerable plaques before the onset of such clinical events. We sought to determine whether the noninvasive in vivo visualization of activated platelets was effective when using a target-specific MRI contrast agent to identify thrombi, hallmarks of vulnerable or high-risk atherosclerotic plaques. METHODS AND RESULTS: Inflammatory thrombi were induced in mice via topical application of arachidonic acid on the carotid. Thrombus formation was imaged with intravital fluorescence microscopy and molecular MRI. To accomplish the latter, a paramagnetic contrast agent (P975) that targets the glycoprotein alphaIIbbeta3, expressed on activated platelets, was investigated. The specificity of P975 for activated platelets was studied in vitro. In vivo, high spatial-resolution MRI was performed at baseline and longitudinally over 2 hours after injecting P975 or a nonspecific agent. The contralateral carotid, a sham surgery group, and a competitive inhibition experiment served as controls. P975 showed a good affinity for activated platelets, with an IC50 (concentration of dose that produces 50% inhibition) value of 2.6 mumol/L. In thrombosed animals, P975 produced an immediate and sustained increase in MRI signal, whereas none of the control groups revealed any significant increase in MRI signal 2 hours after injection. More important, the competitive inhibition experiment with an alphaIIbbeta3 antagonist suppressed the MRI signal enhancement, which is indicative for the specificity of P975 for the activated platelets. CONCLUSIONS: P975 allowed in vivo target-specific noninvasive MRI of activated platelets.

PMID: 20139362 [PubMed - as supplied by publisher]

In vivo Fluorescence Imaging of Muscle Cell Regeneration by Transplanted EGFP-labeled Myoblasts.

Mol Ther. 2010 Feb 2;

Authors: Xu X, Yang Z, Liu Q, Wang Y

In vivo fluorescence imaging (FLI) enables monitoring fluorescent protein (FP)-labeled cells and proteins in living organisms noninvasively. Here, we examined whether this modality could reach a sufficient sensitivity to allow evaluation of the regeneration process of enhanced green fluorescent protein (eGFP)-labeled muscle precursors (myoblasts). Using a basic FLI station, we were able to detect clear fluorescence signals generated by 40,000 labeled cells injected into a tibialis anterior (TA) muscle of mouse. We observed that the signal declined to ~25% on the 48 hours of cell injection followed by a recovery starting at the second day and reached a peak of ~45% of the original signal by the 7th day, suggesting that the survived population underwent a limited run of proliferation before differentiation. To assess whether transplanted myoblasts could form satellite cells, we injured the transplanted muscles repeatedly with cardiotoxin. We observed a recovery of fluorescence signal following a disappearance of the signal after each cardiotoxin injection. Histology results showed donor-derived cells located underneath basal membrane and expressing Pax7, confirming that the regeneration observed by imaging was indeed mediated by donor-derived satellite cells. Our results show that FLI is a powerful tool that can extend our ability to unveil complicated biological processes such as stem cell-mediated regeneration.

PMID: 20125125 [PubMed - as supplied by publisher]

In vivo imaging of ocular MCMV infection.

Invest Ophthalmol Vis Sci. 2010 Jan;51(1):369-74

Authors: Zinkernagel MS, Petitjean C, Fleming P, Chinnery HR, Constable IJ, McMenamin PG, Degli-Esposti MA

PURPOSE: To develop a technique by which murine cytomegalovirus (MCMV) infection can be confirmed and monitored in vivo in various ocular compartments and to investigate the dynamics and time course of primary ocular CMV infection. METHODS: The ability of recombinant MCMV-expressing enhanced green fluorescent protein (eGFP) to serve as a tool to monitor the in vivo dynamics of experimental intraocular CMV infection was examined. Immunocompetent BALB/c mice were infected subretinally with eGFP-MCMV. Confocal scanning laser ophthalmoscopy (SLO) was used to visualize viral spread in vivo on sequential days after infection. Eyes were processed for histology and immunofluorescence microscopy to confirm viral infection and replication by means of GFP signal. RESULTS: Retina was readily permissive to primary infection with eGFP-mCMV, and fluorescent signal was detected by SLO 24 hours after subretinal injection, with scattered foci around the posterior pole of the retina. GFP levels in the retina reached a maximum on day 6. Signal in the iris developed from day 4 and lasted until day 25. Examinations of retinal and iris tissue wholemounts by immunofluorescence revealed signal localized to the outer retina, iris stroma, and anterior lens capsule. CONCLUSIONS: The ability to noninvasively monitor infectious agents in the eye may improve current knowledge of the course and pathogenesis of intraocular infections and could lead to further clarification of the mechanisms by which the immune system responds to intraocular pathogens.

PMID: 19684003 [PubMed - indexed for MEDLINE]

In-vivo studies on intraperitoneally administrated poly(vinyl alcohol).

J Biomed Mater Res B Appl Biomater. 2010 Jan 29;

Authors: Jiang Y, Schädlich A, Amado E, Weis C, Odermatt E, Mäder K, Kressler J

The fate of poly(vinyl alcohol) (PVA, 195,000 g/mol) was studied in rabbits and nude mice after intraperitoneal (i.p.) administration. In-vivo fluorescence imaging using nude mice allowed for studies of tetramethylrhodamine labeled PVA distribution in the body and tracking the urinary excretion. The excreted PVA was studied in detail after collecting the urine of rabbits over a time period of 28 days. The PVA was separated from the urine by dialysis and analyzed by FTIR spectroscopy, (1)H-NMR spectroscopy, and size exclusion chromatography (SEC). Even after extensive dialysis, it was found that the excreted PVA showed a characteristic brownish color. The spectroscopic techniques revealed that this color was caused by the urine pigment (a metabolite of bilirubin) that could not be separated completely from the PVA. SEC showed unambiguously that the PVA with the very high molar mass had a glomerular permeability in the kidneys. Simultaneously, histological studies of the kidneys and the liver demonstrated that the tissues did not show any obvious damage. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.

PMID: 20119945 [PubMed - as supplied by publisher]

A reporter gene imaging system for monitoring microRNA biogenesis.

Nat Protoc. 2009;4(11):1663-9

Authors: Ko HY, Hwang do W, Lee DS, Kim S

MicroRNAs (miRNAs), non-coding RNA molecules, have emerged as a part of key gene regulation, participating in a variety of biological processes such as cell development. Current research methods, including northern blot and real-time PCR analysis, have been used to quantify miRNA expression. Major disadvantages of these methods include invasive techniques, such as a tissue biopsy, and the absence of repetitive studies. In this protocol we describe a simple non-invasive imaging method for monitoring miRNAs during neurogenesis. This novel method includes the design of an miRNA reporter gene vector, cell transfection, in vitro luciferase assay and in vivo bioluminescence imaging of miRNAs. Our reporter imaging system allows for repetitive, non-invasive detection of miRNAs, illustrating the miRNA124a (miR124a)-dependent decrease of Gaussian reporter activity during neuronal differentiation. Using this method, construction of a reporter-imaging vector, in vitro and in vivo signal detection steps can be carried out in approximately 10 d.

PMID: 19876026 [PubMed - indexed for MEDLINE]

Fluorescence-based monitoring of in vivo neural activity using a circuit-tracing pseudorabies virus.

PLoS One. 2009;4(9):e6923

Authors: Granstedt AE, Szpara ML, Kuhn B, Wang SS, Enquist LW

The study of coordinated activity in neuronal circuits has been challenging without a method to simultaneously report activity and connectivity. Here we present the first use of pseudorabies virus (PRV), which spreads through synaptically connected neurons, to express a fluorescent calcium indicator protein and monitor neuronal activity in a living animal. Fluorescence signals were proportional to action potential number and could reliably detect single action potentials in vitro. With two-photon imaging in vivo, we observed both spontaneous and stimulated activity in neurons of infected murine peripheral autonomic submandibular ganglia (SMG). We optically recorded the SMG response in the salivary circuit to direct electrical stimulation of the presynaptic axons and to physiologically relevant sensory stimulation of the oral cavity. During a time window of 48 hours after inoculation, few spontaneous transients occurred. By 72 hours, we identified more frequent and prolonged spontaneous calcium transients, suggestive of neuronal or tissue responses to infection that influence calcium signaling. Our work establishes in vivo investigation of physiological neuronal circuit activity and subsequent effects of infection with single cell resolution.

PMID: 19742327 [PubMed - indexed for MEDLINE]

Identification of a novel water soluble activator of wild-type and F508del CFTR: GPact-11a.

Eur Respir J. 2010 Jan 28;

Authors: Bertrand J, Boucherle B, Billet A, Melin-Heschel P, Dannhoffer L, Vandebrouck C, Jayle C, Routaboul C, Molina MC, Décout JL, Becq F, Norez C

One of the major therapeutic strategy in Cystic Fibrosis aims at developing modulators of Cystic Fibrosis Transmembrane conductance Regulator (CFTR) channels. We recently discovered methylglyoxal alpha-aminoazaheterocycle adducts, as a new family of CFTR inhibitors. In a structure-activity relationship study, we now identified GPact-11a, a compound able not to inhibit but to activate CFTR.Here, we present the effect of GPact-11a on CFTR activity using in vitro (iodide efflux, fluorescence imaging and patch-clamp recordings), ex vivo (short-circuit current measurements) and in vivo (salivary secretion) experiments.We report that GPact-11a (i) is an activator of CFTR in several airway epithelial cell lines, (ii) activates rescued F508del-CFTR in nasal, tracheal, bronchial, pancreatic cell lines and in human CF ciliated epithelial cells freshly dissociated from lung samples, (iii) stimulates ex vivo the colonic chloride secretion and increases in vivo the salivary secretion in cftr(+/+) but not cftr(-/-) mice, (iv) is selective for CFTR because its effect is inhibited by CFTRinh-172, GlyH-101, glibenclamide and GPinh-5a.To conclude, this work identifies a selective activator of wild-type and rescued F508del-CFTR. This non-toxic and water-soluble agent represents a good candidate alone or in combination with a F508del-CFTR corrector, for the development of a CFTR modulator in cystic fibrosis.

PMID: 20110398 [PubMed - as supplied by publisher]