This work was supported by the ELSE-Kr&#246;ner-Stiftung and the DFG (Deutsche Forschungsgemeinschaft, German Research Foundation) SFB 854 (Sonderforschungsbereich, collaborative research center). Special thanks to Hans-Holger G&#228;rtner, Audiovisuelles Medienzentrum, Otto-von-Guericke University Magdeburg, Magdeburg, Germany, for technical support.

Our study was performed with permission of the state of Saxony-Anhalt, Landesverwaltungsamt Halle, according to section 8 of the German law for animal protection. (&#167; 8, paragraph 1 of the German law for animal protection from 18.05.2016 - BGBI. I S. 1206, 1313, &#167; 31 TierSchVersV from 13.08.2013).

NOTE: For the experiments here, 8 to 12 week old male BALB/c mice were used, and human monocytes from blood donors were used for the visualization of monocytes via intravital microsc...

<ol>
	<li>Volz, K. S., Miljan, E., Khoo, A., Cooke, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+pluripotent+stem+cells+for+vascular+therapy.">Development of pluripotent stem cells for vascular therapy.</a> Vascular pharmacology. 56 (5-6), 288-296 (2012).</li><li>Henry, T. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+VIVA+trial:+Vascular+endothelial+growth+factor+in+Ischemia+for+Vascular+Angiogenesis.">The VIVA trial: Vascular endothelial growth factor in Ischemia for Vascular Angiogenesis.</a> Circulation. 107 (10), 1359-1365 (2003).</li><li>Wagner, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+intravenous+injection+of+murine+bone+marrow+derived+monocytes.">Isolation and intravenous injection of murine bone marrow derived monocytes.</a> Journal of visualized experiments JoVE. (94), (2014).</li><li>Herold, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplantation+of+monocytes:+a+novel+strategy+for+in+vivo+augmentation+of+collateral+vessel+growth.">Transplantation of monocytes: a novel strategy for in vivo augmentation of collateral vessel growth.</a> Human gene therapy. 15 (1), 1-12 (2004).</li><li>Ito, W. D., Arras, M., Scholz, D., Winkler, B., Htun, P., Schaper, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Angiogenesis+but+not+collateral+growth+is+associated+with+ischemia+after+femoral+artery+occlusion.">Angiogenesis but not collateral growth is associated with ischemia after femoral artery occlusion.</a> The American journal of physiology. 273 (3 Pt 2), H1255-H1265 (1997).</li><li>Herold, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tetanus+toxoid-pulsed+monocyte+vaccination+for+augmentation+of+collateral+vessel+growth.">Tetanus toxoid-pulsed monocyte vaccination for augmentation of collateral vessel growth.</a> Journal of the American Heart Association. 3 (2), e000611 (2014).</li><li>. Matrigel Matrix Available from: <a target="_blank" href="https://www.corning.com/au/en/products/life-sciences/products/surfaces/matrigel-matrix.html">https://www.corning.com/au/en/products/life-sciences/products/surfaces/matrigel-matrix.html</a> (2017)</li><li>Eubank, T. D., Galloway, M., Montague, C. M., Waldman, W. J., Marsh, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=M-CSF+induces+vascular+endothelial+growth+factor+production+and+angiogenic+activity+from+human+monocytes.">M-CSF induces vascular endothelial growth factor production and angiogenic activity from human monocytes.</a> Journal of immunology (Baltimore, Md. 1950). 171 (5), 2637-2643 (2003).</li><li>Fridman, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhanced+tumor+growth+of+both+primary+and+established+human+and+murine+tumor+cells+in+athymic+mice+after+coinjection+with+Matrigel.">Enhanced tumor growth of both primary and established human and murine tumor cells in athymic mice after coinjection with Matrigel.</a> Journal of the National Cancer Institute. 83 (11), 769-774 (1991).</li><li>Woodman, S. 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C., Herold, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transplantation+of+bone+marrow+derived+monocytes:+a+novel+approach+for+augmentation+of+arteriogenesis+in+a+murine+model+of+femoral+artery+ligation.">Transplantation of bone marrow derived monocytes: a novel approach for augmentation of arteriogenesis in a murine model of femoral artery ligation.</a> American journal of translational research. 5 (2), 155-169 (2013).</li><li>Houthuys, E., Movahedi, K., Baetselier, P., de Van Ginderachter, J. o. A., Brouckaert, 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+method+for+the+isolation+and+purification+of+mouse+peripheral+blood+monocytes.">A method for the isolation and purification of mouse peripheral blood monocytes.</a> J. Immunol. Methods. 359 (1-2), 1-10 (2010).</li><li>Berthold, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+human+monocytes+by+Ficoll+density+gradient+centrifugation.">Isolation of human monocytes by Ficoll density gradient centrifugation.</a> Blut. 43 (6), 367-371 (1981).</li></ol>

The method described here sheds light on the development of collateral arteries, the behavior of monocytes in these vessels, and the process of arteriogenesis. The steps for applying this protocol are easy to learn and can be used in other fields of science. Despite these advantages, there are some disadvantages. For instance, microscopic equipment is required to execute the described techniques. Obtaining equipment for one experiment is unsustainable, so it is important to collaborate with other institutions to share th...

Cardiovascular diseases, including coronary heart disease or peripheral arterial disease, are the most common causes of death globally1. Cell therapy is a promising approach to treat cardiovascular disease, particularly for people who are not able to undergo surgical interventions. There are several approaches to use cells or their secreted substances as a therapeutic tool2,3, with the overall goal to improve the perfusion and maintain function of ischemic and underperfused tissue. One attempt to achieve this goal is to improve arteriogenesis, which enhances the development of collateral arteries. Monocytes are an important cell type associated with collateralization. Our group has focused on researching the effects of monocytes in areas of inflammation4,5, in particular using the hindlimb ischemia model to induce ischemia and subsequent inflammation6. Monocytes home to areas of inflammation and cause complex systemic responses that lead to the development of collateralization7.
With the use of intravital microscopy, we can study the behavior of these cells in vivo and observe the homing of injected monocytes to areas of inflammation. Most former studies only describe post mortem analyses, which hold disadvantages including an introduction of histological artifacts and large numbers of animal required for preparations. With our approach, we can investigate immunological processes and collateral formation via live imaging at multiple time points.
In addition to the development of collateral arteries in ischemic areas, monocytes also influence tumor growth. To investigate these processes, we inject a basement membrane-like matrix extracted from the Engelbreth-Holm-Swarm mouse sarcoma, a tumor rich in extracellular matrix proteins8, and analyze using intravital microscopy. This matrix is used to screen test molecules for either endothelial cell network formation or anti-cancer therapies through angiogenic inhibition; in this case, we will assess the tumor angiogenic potential of monocytes for cell therapy9,10,11.
The aim of this protocol is to demonstrate an easy and efficient way to study immunological processes caused by ischemia in an in vivo model. We can generate a more realistic test environment compared to histological workup of post mortem muscle tissue.

<table border="0" cellpadding="0" cellspacing="0" width="1433">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:304px;">10% fetal calf serum (FCS)</td>
			<td style="width:495px;">Sigma Aldrich, Hamburg, Germany</td>
			<td style="width:179px;"></td>
			<td style="width:456px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1% penicillin/streptomycin</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1mL Omnifix -F insuline syringe</td>
			<td>B. Braun, Melsungen AG, Melsungen, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">50 ml syringe&#160;</td>
			<td>Fresenius Kabi AG, Bad Homburg, Germany</td>
			<td style="width:179px;"></td>
			<td>Injectomat- syringe 50 ml with canule</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">6-well-ultra-low-attachement-plates</td>
			<td>Corning Incorporated, NY, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">8- 12 week old, male, C57BL/6, BalbC mice&#160;</td>
			<td>Charles River, Sulzfeld, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Adhesive tape</td>
			<td>TESA SE, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acquisition Software</td>
			<td>Leica, Wetzlar, Deutschland&#160;</td>
			<td></td>
			<td>Leica Application Suite Advanced Fluorescence (LAS AF); Version: 2.7.3.9723</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Canules</td>
			<td>B. Braun, Melsungen AG, Melsungen, Germany</td>
			<td style="width:179px;"></td>
			<td>29G, 30G</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture dish</td>
			<td>Greiner Bio-One GmbH, Frickenhausen, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Cell culture medium</td>
			<td>Manufactured by our group with single components</td>
			<td style="width:179px;"></td>
			<td>Medium199, 10% Fetal calf serum, 1% Antibiotic (penicillin/streptomycin)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Centrifuge</td>
			<td>Beckman Coulter GmbH, Krefeld, Germany</td>
			<td style="width:179px;"></td>
			<td>Allegra X-15R centrifuge</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Depilatory cream</td>
			<td>Veet, Mannheim, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">DiO</td>
			<td>Invitrogen Eugene, Oregon, USA</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disinfection agent</td>
			<td>Sch&#252;lke&#38;Mayr GmbH, Norderstedt, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disposable scalpel No.10&#160;</td>
			<td>Feather safety razor Co.Ltd, Osaka, Japan&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EDTA</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Erlenmeyer flask</td>
			<td>GVB, Herzogenrath, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ethanol 70%</td>
			<td>Otto Fischar GmbH und Co KG, Saarbr&#252;cken, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fetal Calf Serum</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Fine Forceps</td>
			<td>Rubis, Stabio, Switzerland</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Flurophor/Rhodamindextran</td>
			<td>Thermo Fischer Scientific, Waltham, MA USA</td>
			<td>Katalognummer: D-1819</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Gloves</td>
			<td>R&#246;sner-Matby Meditrade GmbH, Kiefersfelden, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Heating pad&#160;</td>
			<td>Labotect GmbH, G&#246;ttingen, Germany&#160;</td>
			<td style="width:179px;"></td>
			<td>Hot Plate 062</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human macrophage-colony stimulating factor</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td>SRP3110&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Humane leucocyte filters</td>
			<td>Blood preservation</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Incubator</td>
			<td>Ewald Innovationstechnik GmbH, Bad Nenndorf, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Isoflurane</td>
			<td>Baxter Deutschland GmbH, Unterschlei&#223;heim, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ketamine (10%)</td>
			<td>Ketavet, Pfizer Deutschland GmbH, Berlin , Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Leukocyte separation tubes (tubes with filter)&#160;</td>
			<td>Bio one GmbH, Frickenhausen, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Light microscope&#160;</td>
			<td>Carl Zeiss SMT GmbH, Oberkochen, Germany</td>
			<td style="width:179px;"></td>
			<td>Axiovert 40 C</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lymphocyte separation medium LSM1077</td>
			<td>GE Healthcare, Pasching, Austria</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Matrigel&#160;</td>
			<td>Becton, Dickinson and Company, Franklyn Lakes, New Jersey, USA</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Medium M199&#160;</td>
			<td>PAA Laboratories GmbH, Pasching, Austria</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microbiological work bench</td>
			<td>Thermo Electron, LED GmbH, Langenselbold, Germany</td>
			<td style="width:179px;"></td>
			<td>Hera safe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microscope slide</td>
			<td>Carl Roth GmbH + Co. KG, Karlsruhe</td>
			<td>Art. Nr. 1879</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microscope stand with incubator and heating unit</td>
			<td>&#160;Leica DMI 6000, Pecon, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Monocyte wash buffer</td>
			<td>Manufactured by our group with single components</td>
			<td style="width:179px;"></td>
			<td>PBS, 0,5% BSA, 2mM EDTA</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse restrainer</td>
			<td>Various</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Multi-photon microscope&#160;</td>
			<td>Leica, Wetzlar, Deutschland&#160;</td>
			<td></td>
			<td>Leica SP5 Confocal microscope, Cameleon, Coherent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NaCl (0,9%)</td>
			<td>Berlin Chemie AG, Berlin, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Neubauer counting chamber&#160;</td>
			<td>Paul Marienfeld GmbH und Co.KG, Lauda-K&#246;nigshofen, Germany</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Objective</td>
			<td>Leica, Wetzlar, Deutschland&#160;</td>
			<td></td>
			<td>Leica HC PL APO 10x/0.4 CS</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PBS</td>
			<td>Life technologies GmbH, Darmstadt, Germany</td>
			<td style="width:179px;"></td>
			<td>ph 7,4 sterile</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin/Streptomycin</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Percoll</td>
			<td>Manufactured by our group with single components</td>
			<td style="width:179px;"></td>
			<td>90 % Percoll, 10% 1,5M NaCl, &#961;= 1,064 g cm-3</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Percoll solution</td>
			<td>GE Healthcare, Bio-Science AB, Uppsala, Sweden</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pipettes</td>
			<td>Eppendorf AG, Hamburg, Germany</td>
			<td style="width:179px;"></td>
			<td>10&#181;L/100&#181;L/200&#181;L/1000&#181;L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pipettes serological</td>
			<td>Greiner Bio-One GmbH, Frickenhausen, Germany</td>
			<td style="width:179px;"></td>
			<td>&#160;Cellstar2ml, 5ml, 10ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pipetting heads</td>
			<td>Eppendorf AG, Hamburg, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Pipetus</td>
			<td>Eppendorf AG, Hamburg, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Polystyrol tube</td>
			<td>Cellstar, Greiner Bio-One GmbH, Frickenhausen, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Scissor</td>
			<td>Word Precision Instruments, Inc., Sarasota, USA</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Scale</td>
			<td>Mettler PM4800 Delta Range, Mettler-Toledo GmbH, Gie&#223;en, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Suction unit</td>
			<td>Integra bioscience, Fernwald, Germany</td>
			<td style="width:179px;"></td>
			<td>Vacusafe comfort</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Surgical scissors</td>
			<td>Word Precision Instruments, Inc., Sarasota, USA</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Trypan blue solution 0,4 %</td>
			<td>Sigma Aldrich, Hamburg, Germany</td>
			<td style="width:179px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Tubes with cap</td>
			<td>Greiner Bio-One GmbH, Frickenhausen, Germany</td>
			<td style="width:179px;"></td>
			<td>15ml, 50ml Cellstar</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Xylazine (2 %)</td>
			<td>Ceva Tiergesundheit GmbH, D&#252;sseldorf, Germany</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

intravital microscopy of monocyte homing and tumor-related angiogenesis in a murine model of peripheral arterial disease

The therapeutic goal for peripheral arterial disease and ischemic heart disease is to increase blood flow to ischemic areas caused by hemodynamic stenosis. Vascular surgery is a viable option in selected cases, but for patients without indications for surgery such as progression to rest pain, critical limb ischemia, or major disruptions to life or work, there are few possibilities for mitigating their disease. Cell therapy via monocyte-enhanced perfusion through the stimulation of collateral formation is one of a few non-invasive options.
Our group examines arteriogenesis after monocyte transplantation into mice using the hindlimb ischemia model. Previously, we have demonstrated improvement in hindlimb perfusion using tetanus-stimulated syngeneic monocyte transplantation. In addition to the effects on the collateral formation, tumor growth could be affected by this therapy as well. To investigate these effects, we use a basement membrane-like matrix mouse model by injecting the extracellular matrix of the Engelbreth-Holm-Swarm sarcoma into the flank of the mouse, after occlusion of the femoral artery.
After the artificial tumor studies, we use intravital microscopy to study in vivo tumor-angiogenesis and monocyte homing within collateral arteries. Previous studies have described the histological examination of animal models, which presupposes subsequent analysis to post-mortem artifacts. Our approach visualizes monocyte homing to areas of collateralization in real time sequences, is easy to perform, and investigates the process of arteriogenesis and tumor angiogenesis in vivo.

Intravital microscopy for the examination of tumor and collateral vessel growth triggered by monocytes can help reveal new aspects in the molecular mechanisms of tumor angiogenesis and arteriogenesis. Cells must be prepared and injected carefully using the steps of the protocol. Differences can lead to variations between single experiments. The monocytes must be injected into the venous system (Figure 1) to maintain systemic effects and avoid emboli, which ca...

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Intravital Microscopy of Monocyte Homing and Tumor-Related Angiogenesis in a Murine Model of Peripheral Arterial Disease

Monocytes are important mediators of arteriogenesis in the context of peripheral arterial disease. Using a basement membrane-like matrix and intravital microscopy, this protocol investigates monocyte homing and tumor-related angiogenesis after monocyte injection in the femoral artery ligation murine model.

The therapeutic goal for peripheral arterial disease and ischemic heart disease is to increase blood flow to ischemic areas caused by hemodynamic ...

Hello, my name is Christian Deffge. I'm a medical doctor at university hospital in Magdeburg and I'm working in the cardiovascular research group of Dr.Herold and Professor Braun-Dullaeus. We investigate the augmentation of collateral growth.Therefore, we use imaging. In this video, we want to explain our methods. Resuspend the cells in serum-free culture medium with a density of one times 10 to the sixth cells per milliliter.Add five microliters of one millimolar DIO and dimethylformamide to one milliliter of the cell suspension and resuspend carefully. Incubate the cell solution at 37 degrees Centigrade for 20 minutes. Centrifugate the cells at 500 g for five minutes.Dislodge the supernatant and resuspend the cells with 37 degrees Centigrade warm FCS supplemented medium. Repeat this step twice. Count the cells with the help of a Neubauer counting chamber and light microscopy.Resuspend the cells with sodium chloride solution. Inject the cells into the tail vein. Matrigel matrix is a reconstituted basement membrane preparation extracted from the squamous sarcoma.It screens test molecules for either endothelial cell network formation or anti-cancer therapies through angiogenic inhibition. Reassess the tumor angiogenic potential of monocytes we strive to use for cell therapy. Add 100 nanogram BFGF, 300 nanogram VEGFA and 26 international units heparin under sterile conditions to the Matrigel.After vortexing the solution, fill it up into one milliliter insulin syringe and store on ice until usage. For better visibility of the subcutaneous Matrigel plaque, shave the skin of the mouse at the injection site. You can use a sharp scalpel or depilatory cream.Lay the animal on the table and hold the skin of the mouse next to the injection site on the flank. Inject 500 microliters of Matrigel subcutaneously. For practical reasons, it is necessary to inject the Matrigel compactly at one location to avoid subcutaneous dispersion.It will be easier to dislodge the Matrigel matrix from the tissue after sacrificing the mouse at the end of the experiment. Practice the monocyte injection with sodium chloride solution before experimentation. If the monocytes cannot be applied systemically, there will be no systemic effect.Within this protocol, we injected 2.5 million monocytes. Try to inject no more than five microliters per gram. Make sure the mouse is warmed with the help of a heating pad while the whole procedure.For systemic application of the cells, you will need a restrainer and one milliliter insulin syringe, a 30 g needle and the monocytes resuspended and sodium chloride solution. Carefully handle the mouse and restrain the animal in the restrainer. Make sure the mouse is not harmed and has adequate space for breathing.Put the restrainer on the heating pad so that the tail can contact the plate. Make sure you disinfect the injection site to avoid an infection. Identify the tail veins which are located on the lateral side of the tail.Turn the tail 90 degrees so the tail vein appears on the upper side of the tail. Try to inject the monocyte solution in a flat angle. Observe the animal for 30 minutes to look for systemic side effects.Place the mouse in its cage after the animal has fully recovered. Place the anesthetized mouse on the prewarmed microscope stage after the microscope has reached stable conditions and the settings have been tested by a dummy. Fix the paws with adhesive tape.Disinfect the skin at the site of the leg or flank that is used for microscopy. Shave the region of interest for better handling and to avoid interference with hair. Keep the region of interest moist.Otherwise, the quality of images and tissue will be compromised. Place the leg between two adjustable stems. Position a cover glass on top of the stems.Start the microscopy and adjust the position of the leg if needed. Microscope settings depend on the software that is used. Please see the protocol for further information.Our data demonstrates that intravital microscopy represents a potent tool for visualization of transplanted monocytes within the blood flow in small animal models. The monocytes must be injected into the venous system to maintain systemic effects and to avoid emboli which can occur if the injection is conducted in the arterial system. If Matrigel is used, injecting slowly to avoid dispersion will help with plaque explantation for further histological examination.Within the Matrigel plaque, we are able to measure vascularization by counting capillaries within different experimental settings. Intravital microscopy findings can be verified by histological examination. We are able to find monocytes detected by intravital microscopy within all tissue sections.If much time is required for the acquisition of images, the amount of rhodamine dextran within the vessel decreases. For better visibility of the vessels, the application of the rhodamine dextran must be repeated. The use of positive probes for cells on Matrigel can help obtain optimal settings.The goal for peripheral arterial disease or ischemic heart disease therapeutics is to increase blood flow to other perfused areas caused by hemodynamic stenosis. Cell therapy via monocyte-enhanced perfusion through the stimulation of collateral formation is a noninvasive option for patients without indications for surgery. In addition to the development of collateral arteries in ischemic areas, monocytes can also influence the growth of tumors.To investigate these processes, we use Matrigel injection in connection with intravital microscopy. Our aim with this protocol is to demonstrate an easy and efficient way to study immunological processes caused by ischemia in an in vivo model. With this new method, we are able to generate a more realistic test environment compared to histological workup of postmortem muscle tissue.

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7.1K vistas.  University of Magdeburg. Hello, my name is Christian Deffge. I'm a medical doctor at university hospital in Magdeburg and I'm working in the cardiovascular research group of Dr.Herold and Professor Braun-Dullaeus. We investigate the augmentation of collateral growth.Therefore, we use imaging. In this video, we want to explain our methods. Resuspend the cells in serum-free culture medium with a density of one times 10 to the sixth cells per milliliter.Add five microliters of one millimolar DIO and dimeth...