1. Preparation of the Contrast Agent
<ol>
	<li>For FITC-dextran 70 kDa, the dose injected is 500 mg/kg (10 mg of FITC-dextran diluted in 0.1 ml of saline for a mouse weighing 20 g).</li>
	<li>The agent should not be exposed too long to light. To avoid bleaching, it is recommended to cover the tube with aluminum foil.</li>
</ol>
2. Anesthesia
<ol>
	<li>Mice were anesthetized by an intraperitoneal injection of a mixture of 1:4 of xylazine (Rompun 2%, Bayer, Puteaux, France) and Ketamine (K&#233;...

<ol>
	<li>Folkman, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundamental+concepts+of+the+angiogenic+process.">Fundamental concepts of the angiogenic process.</a> Curr Mol Med. 3 (7), 643-651 (2003).</li><li>Laemmel, E., Genet, M., Le Goualher, G., Perchant, A., Le Gargasson, J. F., Vicaut, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fibered+confocal+fluorescence+microscopy+(Cell-viZio)+facilitates+extended+imaging+in+the+field+of+microcirculation.+A+comparison+with+intravital+microscopy.">Fibered confocal fluorescence microscopy (Cell-viZio) facilitates extended imaging in the field of microcirculation. A comparison with intravital microscopy.</a> J Vasc Res. 41 (5), 400-411 (2004).</li><li>Charnley, N., Donaldson, S., Price, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Imaging+angiogenesis.">Imaging angiogenesis.</a> Methods Mol Biol. 467, 25-51 (2009).</li><li>Faye, N., Fournier, L., Balvay, D., Taillieu, F., Cuenod, C., Siauve, N., Clement, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+contrast+enhanced+optical+imaging+of+capillary+leakage.">Dynamic contrast enhanced optical imaging of capillary leakage.</a> Technol Cancer Res Treat. 10 (1), 49-57 (2011).</li><li>Kurose, I., Kubes, P., Wolf, R., Anderson, D. C., Paulson, J., Miyasaka, M., Granger, D. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibition+of+nitric+oxide+production.+Mechanisms+of+vascular+albumin+leakage.">Inhibition of nitric oxide production. Mechanisms of vascular albumin leakage.</a> Circ Res. 73 (1), 164-171 (1993).</li><li>Faye, N. F. L., Balvay, D., Thiam, R., Orliaguet, G., Clement, O., Dewachter, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Macromolecular+capillary+leakage+is+involved+in+the+onset+of+anaphylactic+hypotension.">Macromolecular capillary leakage is involved in the onset of anaphylactic hypotension.</a> Anesthesiology. , (2012).</li><li>Faye, N., Fournier, L., Balvay, D., Thiam, R., Orliaguet, G., Clement, O., Dewachter, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Macromolecular Capillary Leakage Is Involved in the Onset of Anaphylactic Hypotension. Anesthesiology. 117 (5), 1072-1079 (2012).</li><li>Tozer, G. M., Kanthou, C., Baguley, B. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disrupting+tumour+blood+vessels.">Disrupting tumour blood vessels.</a> Nat Rev Cancer. 5 (6), 423-435 (2005).</li><li>Ntziachristos, V., Schellenberger, E. A., Ripoll, J., Yessayan, D., Graves, E., Bogdanov, A., Josephson, L., Weissleder, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Visualization+of+antitumor+treatment+by+means+of+fluorescence+molecular+tomography+with+an+annexin+V-Cy5.5+conjugate.">Visualization of antitumor treatment by means of fluorescence molecular tomography with an annexin V-Cy5.5 conjugate.</a> Proc Natl Acad Sci U S A. 101 (33), 12294-12299 (2004).</li><li>Cuccia, D. J., Bevilacqua, F., Durkin, A. J., Merritt, S., Tromberg, B. J., Gulsen, G., Yu, H., Wang, J., Nalcioglu, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+quantification+of+optical+contrast+agent+dynamics+in+rat+tumors+by+use+of+diffuse+optical+spectroscopy+with+magnetic+resonance+imaging+coregistration.">In vivo quantification of optical contrast agent dynamics in rat tumors by use of diffuse optical spectroscopy with magnetic resonance imaging coregistration.</a> Appl Opt. 42 (16), 2940-2950 (2003).</li></ol>

We have nothing to disclose.

The study of tumor microcirculation has become essential in understanding the pathophysiology of tumor growth, dissemination and response to therapy 1. Optical imaging is one of the techniques that can be used to observe the capillaries using a fluorescent contrast agent and to quantify morphological (Functional Capillary Density) and functional (index leakage) parameters.
The fluorescence microscopy imaging we used in this study has both advantages and limits. One advantage is bein...

Angiogenesis is a complex process 1 that involves the formation of new blood vessels from pre-existing vessels. Pathological changes in tissue microcirculation, composed of arterioles, capillaries, and venules, are implicated in a large range of diseases such as cancer, inflammation, or diabetes. It is therefore essential to develop methods to quantitatively assess microvessel structure and function. Imaging enables the study of microvessels in a non- or micro-invasive manner, in real-time and in vivo, and repeated measures over time in the same animal 2.
Currently, dynamic contrast-enhanced (DCE) imaging 3 is commonly used to assess tissue microcirculation. Dynamic contrast-enhanced imaging is a technique which follows over time the biodistribution of a tracer injected intravenously. From this acquisition, quantitative parameters can be extracted reflecting tissue vascularization. DCE imaging has been most often used with CT, MRI or ultrasound. However, these imaging techniques do not allow direct viewing of the microvessels, since their resolution, other than with the use of specific experimental devices, most often remains macroscopic.
In this paper, we propose to study the tumor vasculature at the microscopic scale and in vivo using dynamic contrast-enhanced optical imaging, with fibered confocal videomicroscopy. We used a macromolecular contrast agent (FITC-dextran) which remains exclusively within vessels or leaks through the endothelial barrier into the interstitium, according to its molecular weight and the characteristics of the endothelium of the tissue studied 4. This allowed the study of both microvessel structure, by correctly delineating vessels, and capillary permeability, by leaking and accumulating in the interstitium.

<table border="1">
<tbody>
 <tr>
 <td>Name</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments (optional)</td>
 </tr>
 <tr>
 <td>Insulin serynge 
 Myjector 1ml 
 29G</td>
 <td>Terumo Europe </td>
 <td>BS-05M2913</td>
 <td></td>
 </tr>
 <tr>
 <td>Fluorescein isothiocyanate-dextran 70 kDa </td>
 <td>Sigma-Aldrich</td>
 <td>01619HH</td>
 <td>100 mg/mL 
 diluted in saline</td>
 </tr>
 <tr>
 <td>Fibered confocal videomicroscopy</td>
 <td>Cellvizio - MaunaKea Technologies</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Calibration and Cleaning Kit for LEICAFCM1000</td>
 <td>Leica Microsystems</td>
 <td>LSU-488</td>
 <td>Store at 4 &deg;C</td>
 </tr>
 <tr>
 <td>Probe ProFlexTM Z</td>
 <td>MaunaKea Technologies</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Mosaicing software</td>
 <td>MaunaKea Technologies</td>
 <td></td>
 <td></td>
 </tr>
 <tr>
 <td>Vessel detection software</td>
 <td>MaunaKea Technologies</td>
 <td></td>
 <td></td>
 </tr>
 </tbody>
</table>

in vivo imaging of tumor angiogenesis using fluorescence confocal videomicroscopy

Fibered confocal fluorescence in vivo imaging with a fiber optic bundle uses the same principle as fluorescent confocal microscopy. It can excite fluorescent in situ elements through the optical fibers, and then record some of the emitted photons, via the same optical fibers. The light source is a laser that sends the exciting light through an element within the fiber bundle and as it scans over the sample, recreates an image pixel by pixel. As this scan is very fast, by combining it with dedicated image processing software, images in real time with a frequency of 12 frames/sec can be obtained.
We developed a technique to quantitatively characterize capillary morphology and function, using a confocal fluorescence videomicroscopy device. The first step in our experiment was to record 5 sec movies in the four quadrants of the tumor to visualize the capillary network. All movies were processed using software (ImageCell, Mauna Kea Technology, Paris France) that performs an automated segmentation of vessels around a chosen diameter (10 &mu;m in our case). Thus, we could quantify the 'functional capillary density', which is the ratio between the total vessel area and the total area of the image. This parameter was a surrogate marker for microvascular density, usually measured using pathology tools.
The second step was to record movies of the tumor over 20 min to quantify leakage of the macromolecular contrast agent through the capillary wall into the interstitium. By measuring the ratio of signal intensity in the interstitium over that in the vessels, an 'index leakage' was obtained, acting as a surrogate marker for capillary permeability.

Using the data collected, we could quantitatively analyze different parameters reflecting microcirculation.
We studied in vivo the peripheral vascular network of a colon tumor implanted in balb-c mice using a fibered confocal fluorescence videomicroscopy system (Cellvizio, Maunakea Technology, Paris, France 2), after injection of a macromolecular fluorescent contrast agent Fluorescein IsoThioCyanate-dextran (FITC-dextran) with a molecular weight of 70 kDa (Sigma-Aldrich, Sa...

Watch this Scientific Journal Video about In vivo Imaging of Tumor Angiogenesis using Fluorescence Confocal Videomicroscopy at JoVE.com

In vivo Imaging of Tumor Angiogenesis using Fluorescence Confocal Videomicroscopy

In this paper, we present a method to analyze tumor microvessels in vivo using dynamic contrast-enhanced fluorescence videomicroscopy. Two quantitative parameters were acquired: functional capillary density reflecting the vascularity of the tumor, and index leakage reflecting the leakiness of the endothelial wall.

In vivo Imaging of Tumor Angiogenesis using Fluorescence Confocal Videomicroscopy

Fibered confocal fluorescence in vivo imaging with a fiber optic bundle uses the same principle as fluorescent confocal microscopy. It can excite ...

in-vivo-imaging-tumor-angiogenesis-using-fluorescence-confocal

Research

JoVE Journal

Medicine

10.6K vues.  Université Paris Descartes Sorbonne Paris Cité, INSERM UMR-S970.  Dans cet article, nous présentons une méthode pour analyser les microvaisseaux tumoraux in vivo en utilisant la fluorescence dynamique vidéomicroscopie de contraste amélioré. Deux paramètres quantitatifs ont été acquises: densité capillaire fonctionnelle réfléchissant la vascularisation de la tumeur, et les fuites d'index reflétant la perméabilité de la paroi endothéliale. 