Name: a cell culture model of resistance arteries
Uploaded: 2017-09-08T12:00:00
Description: Watch this Scientific Journal Video about A Cell Culture Model of Resistance Arteries at JoVE.com

This work was supported by National Heart, Lung and Blood Institute grants R01088554, T32HL007284 and American Heart Association predoctoral fellowship 14PRE20420024. We especially thank the St. Jude Cellular Imaging Shared Research Core, including Randall Wakefield and Linda Horner for the electron microscopy images, Adam Straub for assistance with representative immunofluorescence images,&#160;and Pooneh Bagher for her valuable feedback on the manuscript protocol.

1. Plating Cells for the VCCC
<ol>
	<li>Culture large 225 cm2 flasks of EC and SMC under sterile conditions at 37 &#176;C, until 70-90% confluent. Ensure that more EC than SMC are used; if using primary human EC and SMC, typically 3 large flasks of EC to 1 large flask of SMC.
	<ol>
		<li>Use primary cells at lower passages and do not use past passage 10. Choose the culture media based upon cells to be co-cultured. For primary human coronary artery EC, use EBM-2 EC basal media with EGM2 MV gr...

<ol>
	<li>Isakson, B. E., Duling, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Heterocellular+contact+at+the+myoendothelial+junction+influences+gap+junction+organization.">Heterocellular contact at the myoendothelial junction influences gap junction organization.</a> Circ Res. 97 (1), 44-51 (2005).</li><li>Little, T. L., Xia, J., Duling, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dye+tracers+define+differential+endothelial+and+smooth+muscle+coupling+patterns+within+the+arteriolar+wall.">Dye tracers define differential endothelial and smooth muscle coupling patterns within the arteriolar wall.</a> Circ Res. 76 (3), 498-504 (1995).</li><li>Heberlein, K. R., Straub, A. C., Isakson, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+myoendothelial+junction:+breaking+through+the+matrix?.">The myoendothelial junction: breaking through the matrix?.</a> Microcirculation. 16 (4), 307-322 (2009).</li><li>Straub, A. C., Zeigler, A. C., Isakson, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+myoendothelial+junction:+connections+that+deliver+the+message.">The myoendothelial junction: connections that deliver the message.</a> Physiology (Bethesda). 29 (4), 242-249 (2014).</li><li>Isakson, B. E., Ramos, S. I., Duling, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ca2++and+inositol+1,4,5-trisphosphate-mediated+signaling+across+the+myoendothelial+junction.">Ca2+ and inositol 1,4,5-trisphosphate-mediated signaling across the myoendothelial junction.</a> Circ Res. 100 (2), 246-254 (2007).</li><li>Dora, K. A., Doyle, M. P., Duling, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elevation+of+intracellular+calcium+in+smooth+muscle+causes+endothelial+cell+generation+of+NO+in+arterioles.">Elevation of intracellular calcium in smooth muscle causes endothelial cell generation of NO in arterioles.</a> Proc Natl Acad Sci U S A. 94 (12), 6529-6534 (1997).</li><li>Sonkusare, S. K., 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=Elementary+Ca2++signals+through+endothelial+TRPV4+channels+regulate+vascular+function.">Elementary Ca2+ signals through endothelial TRPV4 channels regulate vascular function.</a> Science. 336 (6081), 597-601 (2012).</li><li>Ledoux, 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=Functional+architecture+of+inositol+1,4,5-trisphosphate+signaling+in+restricted+spaces+of+myoendothelial+projections.">Functional architecture of inositol 1,4,5-trisphosphate signaling in restricted spaces of myoendothelial projections.</a> Proc Natl Acad Sci U S A. 105 (28), 9627-9632 (2008).</li><li>Boerman, E. M., Everhart, J. E., Segal, S. 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A., 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=Two+functionally+distinct+pools+of+eNOS+in+endothelium+are+facilitated+by+myoendothelial+junction+lipid+composition.">Two functionally distinct pools of eNOS in endothelium are facilitated by myoendothelial junction lipid composition.</a> Biochim Biophys Acta. 1861 (7), 671-679 (2016).</li><li>Straub, A. C., 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=Endothelial+cell+expression+of+haemoglobin+alpha+regulates+nitric+oxide+signalling.">Endothelial cell expression of haemoglobin alpha regulates nitric oxide signalling.</a> Nature. 491 (7424), 473-477 (2012).</li><li>Isakson, B. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Localized+expression+of+an+Ins(1,4,5)P3+receptor+at+the+myoendothelial+junction+selectively+regulates+heterocellular+Ca2++communication.">Localized expression of an Ins(1,4,5)P3 receptor at the myoendothelial junction selectively regulates heterocellular Ca2+ communication.</a> J Cell Sci. 121 (Pt 21), 3664-3673 (2008).</li><li>Axel, D. I., 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=Induction+of+cell-rich+and+lipid-rich+plaques+in+a+transfilter+coculture+system+with+human+vascular+cells.">Induction of cell-rich and lipid-rich plaques in a transfilter coculture system with human vascular cells.</a> J Vasc Res. 33 (4), 327-339 (1996).</li><li>Hastings, N. E., Simmers, M. B., McDonald, O. G., Wamhoff, B. R., Blackman, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atherosclerosis-prone+hemodynamics+differentially+regulates+endothelial+and+smooth+muscle+cell+phenotypes+and+promotes+pro-inflammatory+priming.">Atherosclerosis-prone hemodynamics differentially regulates endothelial and smooth muscle cell phenotypes and promotes pro-inflammatory priming.</a> Am J Physiol Cell Physiol. 293 (6), C1824-C1833 (2007).</li><li>Herzog, D. P., Dohle, E., Bischoff, I., Kirkpatrick, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+communication+in+a+coculture+system+consisting+of+outgrowth+endothelial+cells+and+primary+osteoblasts.">Cell communication in a coculture system consisting of outgrowth endothelial cells and primary osteoblasts.</a> Biomed Res Int. , 320123 (2014).</li><li>Jacot, J. G., Wong, J. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+injury+induces+vascular+smooth+muscle+cell+proliferation+in+highly+localized+regions+of+a+direct+contact+co-culture+system.">Endothelial injury induces vascular smooth muscle cell proliferation in highly localized regions of a direct contact co-culture system.</a> Cell Biochem Biophys. 52 (1), 37-46 (2008).</li><li>Scott-Drechsel, 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=A+new+flow+co-culture+system+for+studying+mechanobiology+effects+of+pulse+flow+waves.">A new flow co-culture system for studying mechanobiology effects of pulse flow waves.</a> Cytotechnology. 64 (6), 649-666 (2012).</li><li>van Buul-Wortelboer, M. F., 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=Reconstitution+of+the+vascular+wall+in+vitro.+A+novel+model+to+study+interactions+between+endothelial+and+smooth+muscle+cells.">Reconstitution of the vascular wall in vitro. A novel model to study interactions between endothelial and smooth muscle cells.</a> Exp Cell Res. 162 (1), 151-158 (1986).</li><li>Wilhelm, I., Fazakas, C., Krizbai, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+models+of+the+blood-brain+barrier.">In vitro models of the blood-brain barrier.</a> Acta Neurobiol Exp (Wars). 71 (1), 113-128 (2011).</li><li>Heberlein, K. 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=A+novel+mRNA+binding+protein+complex+promotes+localized+plasminogen+activator+inhibitor-1+accumulation+at+the+myoendothelial+junction.">A novel mRNA binding protein complex promotes localized plasminogen activator inhibitor-1 accumulation at the myoendothelial junction.</a> Arterioscler Thromb Vasc Biol. 32 (5), 1271-1279 (2012).</li><li>Straub, A. C., 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=Compartmentalized+connexin+43+s-nitrosylation/denitrosylation+regulates+heterocellular+communication+in+the+vessel+wall.">Compartmentalized connexin 43 s-nitrosylation/denitrosylation regulates heterocellular communication in the vessel wall.</a> Arterioscler Thromb Vasc Biol. 31 (2), 399-407 (2011).</li><li>Cucina, A., 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=Vascular+endothelial+growth+factor+increases+the+migration+and+proliferation+of+smooth+muscle+cells+through+the+mediation+of+growth+factors+released+by+endothelial+cells.">Vascular endothelial growth factor increases the migration and proliferation of smooth muscle cells through the mediation of growth factors released by endothelial cells.</a> J Surg Res. 109 (1), 16-23 (2003).</li><li>Heberlein, K. 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=Plasminogen+activator+inhibitor-1+regulates+myoendothelial+junction+formation.">Plasminogen activator inhibitor-1 regulates myoendothelial junction formation.</a> Circ Res. 106 (6), 1092-1102 (2010).</li><li>Isakson, B. E., Best, A. K., Duling, B. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Incidence+of+protein+on+actin+bridges+between+endothelium+and+smooth+muscle+in+arterioles+demonstrates+heterogeneous+connexin+expression+and+phosphorylation.">Incidence of protein on actin bridges between endothelium and smooth muscle in arterioles demonstrates heterogeneous connexin expression and phosphorylation.</a> Am J Physiol Heart Circ Physiol. 294 (6), H2898-H2904 (2008).</li><li>Biwer, L. A., Isakson, B. 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The VCCC has a number of advantages in terms of recapitulating MEJs in vitro, but there are points of discussion when determining if the VCCC can be utilized for specific application. For example, if different cell types are to be used with this model, it will need to be optimized. We have used primary human cells but it is possible to isolate cells from bovine aortas24, or wildtype or knockout mice, and use them in the VCCC1,5<su...

In small diameter resistance arteries, a thin internal elastic lamina (IEL) separates endothelial (EC) and smooth muscle cells (SMC). The cells can project through holes in this elastic matrix and make direct cytoplasmic connections via gap junction channels1,2. This unique structure is termed the myoendothelial junction (MEJ). The MEJ is a small (approximately 0.5 &#181;m x 0.5 &#181;m, depending on the vascular bed), cellular projection composed predominantly of endothelial cells but may originate from smooth muscle as well3,4. A number of investigators have demonstrated the immense complexity of signaling networks that occur selectively at the MEJ, rendering it an especially important location for facilitating bi-directional signaling between endothelium and smooth muscle5,6,7,8,9,10.
However, a mechanistic dissection of signaling pathways at the MEJ is difficult in an intact artery. Because the MEJ is a cellular projection, it is not currently possible to isolate an in vivo MEJ from the vascular wall. For this reason, the VCCC model1 was developed. Importantly, the VCCC replicates physiological endothelial morphology11 and polarization of signaling between the apical and MEJ portions of the cell12. It was this unique model that facilitated the discovery that alpha hemoglobin is in the endothelial cell, polarized to the MEJ. This is in contrast to conventionally cultured endothelial cells which do not express alpha hemoglobin13. For researchers interested in microvascular endothelium, it may be more appropriate to use endothelial cells that have been cultured in the VCCC, particularly if the intent is to dissect signaling pathways that occur in small diameter resistance arteries.
Using a sturdy plastic insert containing a filter with small diameter pores (0.4 &#181;m in diameter) to co-culture two distinct cell types prevents the cells from migrating between layers. It results in a 10 &#181;m distance between the cells, which is significantly longer than in vivo, but still replicates many of the in vivo characteristics of MEJs, including protein localization and second messenger signaling1,14. In addition, the VCCC allows for targeting of cell type-specific signaling via the addition of an agonist or antagonist to the specific cellular compartment. For example, loading the EC with BAPTA-AM to chelate calcium, and stimulating the SMC with phenylephrine14. In contrast to other descriptions of co-culture models15,16,17,18,19,20,21, this provides instructions on isolating the distinct fractions for mRNA and protein, including the distinct MEJ fraction within the filter pores. The addition of this technique to the VCCC allows for specific investigation of changes in mRNA localization or transcription22, protein phosphorylation12,23, and protein activity12. This article will describe plating of EC on top of the filter and SMC on the bottom, although it is possible to culture the two cell types in different conformations11,18,24.

<table>
	<tbody>
		<tr>
			<td>24mm diameter, 0.4&#181;m Transwell Polyester membrane filter insert</td>
			<td>Corning</td>
			<td>3450</td>
			<td>This is one 6 well plate of inserts</td>
		</tr>
		<tr>
			<td>225cm2 flask</td>
			<td>Corning</td>
			<td>431082</td>
			<td></td>
		</tr>
		<tr>
			<td>6 well plates (without filter inserts)</td>
			<td>Corning</td>
			<td>3506</td>
			<td></td>
		</tr>
		<tr>
			<td>Primary human coronary artery endothelial cells</td>
			<td>Lonza</td>
			<td>CC-2585</td>
			<td></td>
		</tr>
		<tr>
			<td>Primary human coronary artery smooth muscle cells</td>
			<td>Lonza</td>
			<td>CC-2583</td>
			<td></td>
		</tr>
		<tr>
			<td>EBM-2 EC Basal media</td>
			<td>Lonza</td>
			<td>CC-3156</td>
			<td></td>
		</tr>
		<tr>
			<td>EC growth factors (EGM2 MV Single quots)</td>
			<td>Lonza</td>
			<td>CC-4147</td>
			<td>Add to basal media before use</td>
		</tr>
		<tr>
			<td>SmBM SMC basal media</td>
			<td>Lonza</td>
			<td>CC-3181</td>
			<td></td>
		</tr>
		<tr>
			<td>SMC growth factors (SmGM-2 SingleQuot)</td>
			<td>Lonza</td>
			<td>CC-4149</td>
			<td>Add to basal media before use</td>
		</tr>
		<tr>
			<td>0.5% Trypsin-EDTA 10X</td>
			<td>Gibco</td>
			<td>15400-054</td>
			<td>Dilute to 2X with sterile dPBS</td>
		</tr>
		<tr>
			<td>Hemocytometer</td>
			<td>VWR</td>
			<td>15170-208</td>
			<td></td>
		</tr>
		<tr>
			<td>large petri dishes for SMC Plating (150mm)</td>
			<td>Corning</td>
			<td>353025</td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine gelatin</td>
			<td>Sigma</td>
			<td>G-9382</td>
			<td></td>
		</tr>
		<tr>
			<td>Human fibronectin</td>
			<td>Corning</td>
			<td>356008</td>
			<td>5&#181;g/ml of fibronectin and store at -20</td>
		</tr>
		<tr>
			<td>10X Hanks&#39; Buffered salt solution (HBSS)</td>
			<td>Gibco</td>
			<td>14065-056</td>
			<td>Dilute to 1x with sterile water</td>
		</tr>
		<tr>
			<td>10X Dulbecco&#39;s Phosphate buffered saline (dPBS)</td>
			<td>Gibco</td>
			<td>14200-075</td>
			<td>Dilute to 1x with sterile water</td>
		</tr>
		<tr>
			<td>Disposable Curved Scalpel (30mm cutting edge) with handle</td>
			<td>Amazon</td>
			<td>MDS15210</td>
			<td></td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Fisher</td>
			<td>17-467-201</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell lifter</td>
			<td>Corning</td>
			<td>3008</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell scraper</td>
			<td>BD Falcon</td>
			<td>353085</td>
			<td></td>
		</tr>
		<tr>
			<td>50mL conical tube</td>
			<td>Corning</td>
			<td>352070</td>
			<td></td>
		</tr>
		<tr>
			<td>10mm petri dishes</td>
			<td>Falcon</td>
			<td>35-1008</td>
			<td></td>
		</tr>
		<tr>
			<td>Rneasy mini kit</td>
			<td>Qiagen</td>
			<td>74104</td>
			<td></td>
		</tr>
		<tr>
			<td>RNA lysis reagent</td>
			<td>Qiagen</td>
			<td>79306</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma</td>
			<td>158127</td>
			<td>Make 4% solution with dPBS</td>
		</tr>
		<tr>
			<td>70% ethanol</td>
			<td>Fisher</td>
			<td>04-355-305</td>
			<td></td>
		</tr>
		<tr>
			<td>Cavicide disinfectant</td>
			<td>Fisher</td>
			<td>131000</td>
			<td></td>
		</tr>
		<tr>
			<td>RIPA protein lysis buffer</td>
			<td>Sigma</td>
			<td>R0278</td>
			<td></td>
		</tr>
		<tr>
			<td>Sonic dismembranator</td>
			<td>Fisher</td>
			<td>Model 50</td>
			<td></td>
		</tr>
		<tr>
			<td>1X PBS for harvesting EC/SMC and immunocytochemistry</td>
			<td>Gibco</td>
			<td>10010023</td>
			<td>does not need to be sterile</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Embedding/Sectioning/Staining</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Paraffin</td>
			<td>Fisher</td>
			<td>P31-500</td>
			<td></td>
		</tr>
		<tr>
			<td>Automated tissue processer</td>
			<td>Excelsior</td>
			<td>ES</td>
			<td></td>
		</tr>
		<tr>
			<td>Embedding station + cold plate</td>
			<td>Leica</td>
			<td>HistoCore Arcadia</td>
			<td></td>
		</tr>
		<tr>
			<td>Tissue Tek Accu-Edge Microtome blade</td>
			<td>VWR</td>
			<td>25608-961 or 25608-964</td>
			<td></td>
		</tr>
		<tr>
			<td>Microscope slides</td>
			<td>Thermo Fisher</td>
			<td>22-230-900</td>
			<td></td>
		</tr>
		<tr>
			<td>Coverslips</td>
			<td>Thermo Fisher</td>
			<td>12-548-5E</td>
			<td></td>
		</tr>
		<tr>
			<td>Prolong Gold mounting medium</td>
			<td>Thermo Fisher</td>
			<td>P36931</td>
			<td></td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Other Solutions</td>
			<td></td>
			<td></td>
			<td>**Perform all steps in sterile conditions if using the solution on live cells</td>
		</tr>
		<tr>
			<td>Sterile dPBS</td>
			<td></td>
			<td></td>
			<td>Autoclave water to sterilize. Using the sterile water make DPBS (450mL sterile water: 50mL 10X DPBS), mix and filter sterilize (0.2&#181;m filter). 
			Final concentration: 1X</td>
		</tr>
		<tr>
			<td>sterile HBSS</td>
			<td></td>
			<td></td>
			<td>Autoclave water to sterilize. Using the sterile water make HBSS (450mL sterile water: 50mL 10X HBSS), mix and filter sterilize (0.2&#181;m filter). 
			Final concentration: 1X</td>
		</tr>
		<tr>
			<td>Fibronectin stock solution</td>
			<td></td>
			<td></td>
			<td>Use 50mL of sterile water to fibronectin to make stock of 1mL aliquots, then freeze until needed 
			Final concentration: 100&#181;g/mL</td>
		</tr>
		<tr>
			<td>Fibronectin to coat SMC side of VCCC</td>
			<td></td>
			<td></td>
			<td>thaw one aliquot and add 1mL of fibronectin (100&#181;g/mL) to 19mLs of 1X HBSS to reach a final concentration of 5&#181;g/mL. 
			Final concentration: 5&#181;g/mL</td>
		</tr>
		<tr>
			<td>2x Trypsin EDTA solution</td>
			<td></td>
			<td></td>
			<td>Dilute the 10X 0.5% Trypsin-EDTA to 2X with 1X dPBS (40mL DPBS: 10mL 10X Trypsin) . 
			Final concentration: 2X</td>
		</tr>
		<tr>
			<td>Blocking/antibody solution</td>
			<td></td>
			<td></td>
			<td>(9mL 1X PBS, 25mL Triton X100, 50mg bovine serum albumin, 500mL normal serum)</td>
		</tr>
		<tr>
			<td>Bovine gelatin to coat EC VCCC</td>
			<td></td>
			<td></td>
			<td>Mix 0.5g bovine gelatin into 100mL distilled water. Autoclave prior to first use and store at room temperature. Keep in sterile conditions. 
			Final concentration: 0.50%</td>
		</tr>
		<tr>
			<td>1X PBS for harvesting cells</td>
			<td></td>
			<td></td>
			<td>does not need to be sterile</td>
		</tr>
	</tbody>
</table>

a cell culture model of resistance arteries

The myoendothelial junction (MEJ), a unique signaling microdomain in small diameter resistance arteries, exhibits localization of specific proteins and signaling processes that can control vascular tone and blood pressure. As it is a projection from either the endothelial or smooth muscle cell, and due to its small size (on average, an area of ~1 &#181;m2), the MEJ is difficult to study in isolation. However, we have developed a cell culture model called the vascular cell co-culture (VCCC) that allows for in vitro MEJ formation, endothelial cell polarization, and dissection of signaling proteins and processes in the vascular wall of resistance arteries. The VCCC has a multitude of applications and can be adapted to suit different cell types. The model consists of two cell types grown on opposite sides of a filter with 0.4 &#181;m pores in which the in vitro MEJs can form. Here we describe how to create the VCCC via plating of cells and isolation of endothelial, MEJ, and smooth muscle fractions, which can then be used for protein isolation or activity assays. The filter with intact cell layers can be fixed, embedded, and sectioned for immunofluorescent analysis. Importantly, many of the discoveries from this model have been confirmed using intact resistance arteries, underscoring its physiological relevance.

The filter inserts used for the VCCC have small, 0.4 &#181;m holes. Figure 1A, an en face view of the VCCC filter inset, shows the pores in which the MEJ can form in vitro. The schematic depicts the smooth muscle cells plated on the lower side of the filter one day before the endothelial cells are plated on the opposite side (Figure 1B). Once the cells are plated, the EC, MEJ, and SMC fractions can be isolated t...

Watch this Scientific Journal Video about A Cell Culture Model of Resistance Arteries at JoVE.com

A Cell Culture Model of Resistance Arteries

A cell culture model of resistance arteries is described, allowing for the dissection of signaling pathways in endothelium, smooth muscle, or between endothelium and smooth muscle (the myoendothelial junction). The selective application of agonists or protein isolation, electron microscopy, or immunofluorescence can be utilized using this cell culture model.

The myoendothelial junction (MEJ), a unique signaling microdomain in small diameter resistance arteries, exhibits localization of specific proteins and ...

The overall goal of this technique is to culture endothelial and smooth muscle cells together in-vitro to create myoendothelial junctions that occur in small diameter resistance arteries. This method can help answer key questions in the cardiovascular field such as, protein localization and activation of signaling cascades in the arterial wall. The main advantage of this technique is that you can specifically isolate myoendothelial junction fractions from the endothelium and smooth muscle, which is impossible to do using an actual artery.Visual demonstration of a paraffin embedding is particularly critical, as the embedding steps can be difficult to learn without seeing the process. Begin construction of the vascular cell co-culture or VCCC, by spraying 150 millimeter petri dishes and lids with disinfectant and then wiping with a paper towel or lint-free wipes. Then, spray the petri dishes with 70%ethanol and place them in the hood to air dry.Open the plate of filter inserts under sterile conditions. Coat the bottom side of the filters with fiberactin solution by pipetting up to one milliliter of fiberactin solution through the side slits into the bottom of the plate. Make sure, that the bottom half of the filter is covered and leave the inserts in the hood, keeping the plate cover.After 30 minutes of treatment with fiberaction solution, vacuum any excess solution without disturbing the filter inserts. Then, invert the plate, placing the filters into the bottom half of the clean petri dish. Trypsinize a 225 square centimeter flask of smooth muscle cells with three milliliters of pre-warmed trypsin EDTA solution.Once the cells have lifted off, add nine milliliters of SMC medium to neutralize the trypsin. Transfer to a conical tube and mix well. Then, pipette 10 microliters onto a hemocytometer to determine cell number.After performing a cell count, carefully plate 750 microliters of the cell suspension containing approximately 75, 000 smooth muscle cells onto the bottom side of each filter. Incubate the plate at 37 degree celsius overnight. On day two, fill each well of a clean six well plate with two milliliters of fresh pre-warmed SMC medium.Remove the medium from an insert by suction and transfer it to the six well plate with SMC medium. Add one milliliter of a 0.5%bovine gelatin solution to the upper side of the inserts and place at 37 degree celsius, for at least 30 minutes. Trypsinize a 225 square centimeter flask of endothelial cells with three milliliters of pre-warmed trypsin EDTA solution.With gentle tapping of the flask to lift the cells off the plate. After re-suspending the cells in EC medium and performing a cell count, remove the gelatin from the filter. Then, plate 360, 000 ECs in a one milliliter volume onto the top side of each filter insert.Let the cells incubate undisturbed at 37 degree celsius for 24 hours. Begin fractionation, by suctioning off the medium from one six well plate of inserts in the cell culture hood and then, transport to a cold room on ice. In the cold room, pipette 10 microliters of PBS onto the SMC side of the inserts.Use the cell lifter to scrape down the SMCs. Then, transfer the cells from the scrapper to a labeled petri dish containing lysis buffer. Once the cell scrapper has touched the lysis buffer, do not allow it to touch the insert filter until it has been completely wiped and dried off on paper towels.Repeat the scrapping of the SMC filter once or twice more, to fully remove the remaining SMC cell debris. Next, pipette 10 microliters of PBS onto the endothelial cell side of the insert filter. Scrape the cells into an appropriately labeled petri dish of lysis buffer, as just demonstrated.Collect the cell slurry from the EC side of the filter with the pipette and transfer to an appropriately labeled petri dish. Be very thorough in scrapping the cells off both sides of the filters to ensure minimal cell contamination in the myoendothelial junction fraction. Next, carefully use the scalpel to cut out the filters from the plastic insert.Do this by cutting 70 to 80%of it away from the plastic and using forceps to pull the filter completely off the plastic insert structure. Point each filter into a labeled 50 milliliter conical tube containing lysis buffer. Ensure that the filters are immersed in buffer and remain wet.After all the cells have been harvested from the filters, vortex the 50 milliliter MEJ tube on full strength for 15 seconds or until mixed well. Remove the filters from the MEJ conical with forceps, dragging them along the side walls of the tube as to leave the maximum amount of proteins and liquids in the tube. Once all the filters have been removed from the MEJ conical tube, do a quick spin in a centrifuge to pull all the liquid and proteins to the bottom of the tube.After the spin, transfer the contents of the MEJ tube and the SMC and EC petri dishes into separate smaller centrifuge tubes. Then, centrifuge the tubes at close to 16, 000 x G for 15 minutes at four degree celsius. Remove the supernatants.Then, assay cell lysates for protein content using a byzinconetic assay. On day five of VCCC incubation, add 4%PFA to each well containing a rinsed filter insert and incubate overnight with shaking at four degree celsius. After approximately 24 hours, transfer the inserts to 70%ethanol for at least 24 hours.Process the filters on a long run on an automated tissue processor. After the run, remove a filter from its cassette using forceps to hold the filter at the edge and then, cut the filter in half with scissors. Lay each of the two halves on a cold plate and fill the embedding mold with liquid paraffin.Very briefly touch the filled embedding mold to the cold plate, then embed each half of the filter into the embedding mold with the cut side down to ensure that the filter is sectioned from the center. Use forceps to hold the filter in place to prevent the halves from falling into each other until the paraffin is cool enough for them to stand alone. Then, move the embedding mold to a cold plate until completely solidify.Embed and section the filtered insert in a vertical orientation. After sectioning, the VCCC can be immunostained for transverse immunofluorescence. This immunotransmission electron microscope image shows a mouse artery with expression of alpha globin at the MEJ labeled with gold beads, which appear as black dots.This western blot demonstrates that plasminogen activator inhibitor one expression is enriched in the MEJ fraction versus the EC or SMC fractions. Plastic EC indicates ECs grown on a plastic dish which do not form MEJ. Immunostaining reveals the tight compartmentalization of the VCCC model.The alpha-1 adrenergic receptor one is seen only in the smooth muscle cell layer, the bradykinin receptor is seen only in the endothelial cell layer. F actin staining is throughout both cell types at the in-vitro MEJ as indicated by the white arrow. While attempting this procedure, it is important to remember to keep everything sterile until the time of harvest, carefully plate the cells and thoroughly scrape the filters.Following this procedure, other methods like western blotting or immunofluorescence can be performed in order to answer additional questions lik protein localization, expression levels or activation.

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