Name: in vivo study of human endothelial-pericyte interaction using the matrix gel plug assay in mouse
Uploaded: 2016-12-19T14:00:00
Description: Watch this Scientific Journal Video about In Vivo Study of Human Endothelial-Pericyte Interaction Using the Matrix Gel Plug Assay in Mouse at JoVE.com

Dr. K. Yuan was supported by an American Heart Association Scientist Development Grant (15SDG25710448) and the Pulmonary Hypertension Association Proof of Concept Award (SPO121940). Dr. V. de Jesus Perez was supported by a career development award from the Robert Wood Johnson Foundation, an NIH K08 HL105884-01 award, a Pulmonary Hypertension Association Award, a Biomedical Research Award from the American Lung Association and a Translational Research and Applied Medicine award from Stanford University.

Ethics Statement: Procedures involving animal subjects have been approved by the Institutional Animal Care and Use Committee at Stanford University School of Medicine.
NOTE: Animals are under anesthetization with 3% vaporizer isoflurane and 3% supply of O2 gas. Use of vet ointment on eyes may help to prevent dryness while under anesthesia.
1. Cell Preparation
<ol>
	<li>Grow human endothelial and pericyte cell cultures in 100 mm plates with 10 ml of the appropriate media. Replace 10 ml of fresh ...

<ol>
	<li>Risau, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+of+angiogenesis.">Mechanisms of angiogenesis.</a> Nature. 386 (6626), 671-674 (1997).</li><li>Ribatti, D., Nico, B., Crivellato, 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+role+of+pericytes+in+angiogenesis.">The role of pericytes in angiogenesis.</a> Int J Dev Biol. 55 (3), 261-268 (2011).</li><li>Koh, W., Stratman, A. N., Sacharidou, A., Davis, G. E. <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+three+dimensional+collagen+matrix+models+of+endothelial+lumen+formation+during+vasculogenesis+and+angiogenesis.">In vitro three dimensional collagen matrix models of endothelial lumen formation during vasculogenesis and angiogenesis.</a> Methods Enzymol. 443, 83-101 (2008).</li><li>Liu, Y., Senger, D. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Matrix-specific+activation+of+Src+and+Rho+initiates+capillary+morphogenesis+of+endothelial+cells.">Matrix-specific activation of Src and Rho initiates capillary morphogenesis of endothelial cells.</a> FASEB J. 18 (3), 457-468 (2004).</li><li>Grant, D. S., 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=Interaction+of+endothelial+cells+with+a+laminin+A+chain+peptide+(SIKVAV)+in+vitro+and+induction+of+angiogenic+behavior+in+vivo.">Interaction of endothelial cells with a laminin A chain peptide (SIKVAV) in vitro and induction of angiogenic behavior in vivo.</a> J Cell Physiol. 153 (3), 614-625 (1992).</li><li>Madri, J. A., Pratt, B. M., Tucker, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phenotypic+modulation+of+endothelial+cells+by+transforming+growth+factor-beta+depends+upon+the+composition+and+organization+of+the+extracellular+matrix.">Phenotypic modulation of endothelial cells by transforming growth factor-beta depends upon the composition and organization of the extracellular matrix.</a> J Cell Biol. 106 (4), 1375-1384 (1988).</li><li>Brooks, P. C., Montgomery, A. M., Cheresh, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+of+the+10-day-old+chick+embryo+model+for+studying+angiogenesis.">Use of the 10-day-old chick embryo model for studying angiogenesis.</a> Methods Mol Biol. 129, 257-269 (1999).</li><li>Yuan, 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=Activation+of+the+Wnt/planar+cell+polarity+pathway+is+required+for+pericyte+recruitment+during+pulmonary+angiogenesis.">Activation of the Wnt/planar cell polarity pathway is required for pericyte recruitment during pulmonary angiogenesis.</a> Am J Pathol. 185 (1), 69-84 (2015).</li><li>Johns, A., Freay, A. D., Fraser, W., Korach, K. S., Rubanyi, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+of+estrogen+receptor+gene+prevents+17+beta+estradiol-induced+angiogenesis+in+transgenic+mice.">Disruption of estrogen receptor gene prevents 17 beta estradiol-induced angiogenesis in transgenic mice.</a> Endocrinology. 137 (10), 4511-4513 (1996).</li><li>Chen, C. W., 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=Human+pericytes+for+ischemic+heart+repair.">Human pericytes for ischemic heart repair.</a> Stem Cells. 31 (2), 305-316 (2013).</li><li>Richards, O. C., Raines, S. M., Attie, A. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+blood+vessels,+endothelial+cells,+and+vascular+pericytes+in+insulin+secretion+and+peripheral+insulin+action.">The role of blood vessels, endothelial cells, and vascular pericytes in insulin secretion and peripheral insulin action.</a> Endocr Rev. 31 (3), 343-363 (2010).</li><li>Ricard, N., 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=Increased+pericyte+coverage+mediated+by+endothelial-derived+fibroblast+growth+factor-2+and+interleukin-6+is+a+source+of+smooth+muscle-like+cells+in+pulmonary+hypertension.">Increased pericyte coverage mediated by endothelial-derived fibroblast growth factor-2 and interleukin-6 is a source of smooth muscle-like cells in pulmonary hypertension.</a> Circulation. 129 (15), 1586-1597 (2014).</li><li>Buchwalow, I. B., Bocker, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Immunohistochemistry: Basics and Methods. , 1-153 (2010).</li><li>Tata, D. A., Anderson, B. J. <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+method+for+the+investigation+of+capillary+structure.">A new method for the investigation of capillary structure.</a> J Neurosci Methods. 113 (2), 199-206 (2002).</li></ol>

The matrix gel plug assay has proven to be a convenient and powerful method to evaluate gene regulation in angiogenesis, angiogenic and antiangiogenic compounds in vivo, and to supplement in vitro tests. Here, we describe in detail a novel matrix gel plug assay of human angiogenesis that investigates the interaction between endothelial cells and pericytes during vessel formation.
There are a few novel and critical steps in this protocol. Cells in low passage (passage 1 - 4) a...

Angiogenesis is the process by which new blood vessels are formed from a pre-existing vascular network1 and is the focus of ongoing research across many areas ranging from normal development to disease. This dynamic process involves the proliferation and migration of endothelial cells (ECs) and recruitment of pericytes to construct a vascular tube that is directed toward the site that needs oxygen and nutrient delivery2. To study this process requires an equally dynamic assay, most importantly one that can recapitulate the three-dimensional nature of tube formation. In vitro 3D matrix assays have been developed to address this need and have worked well to allow researchers to define the discrete steps in space and time in which angiogenesis takes place3,4,5,6. However, these in vitro 3D matrix models are limited to studying non-perfused vessels and therefore lack critical components pertinent to the angiogenesis process (e.g., circulating growth and inhibitory factors, unnatural tension/forces across the vascular bed) and fail to simulate the complex environment present in live tissue. To address this limitation, several in vivo angiogenesis assays have been developed7, including the matrix gel plug assay which will be the focus of our report8,9.
The matrix gel plug assay is a well-established in vivo angiogenesis assay that appeals to researchers as it provides a robust platform to test the roles of different cells and substances in angiogenesis. Matrix gel is a commercially available basement membrane solution that is secreted by the Engelbreth-Holm-Swarm (EHS) mouse sarcoma cell line that solidifies into a gel-like material at 37 &#176;C. The matrix gel can be mixed with cells and/or substances, such as growth factors, and injected subcutaneously into the mouse. The host ECs will invade the plug over 14 days, form a vascular network, and become perfused with the host&#39;s blood. To date, matrix gel plug assays have focused exclusively on the study of endothelial cell behavior during angiogenesis, however, to the best of our knowledge no effort has yet been made to determine whether this assay can be used to co-culture endothelial cells and pericytes to study how these two cell types interact during angiogenesis. Specifically, understanding the relationship between ECs and pericytes is valuable for studying diseases where blood vessel loss is pathologic, including microvascular ischemia and peripheral vascular disease10,11,12.
Here, we describe a protocol that introduces human-derived pericytes to the matrix gel mixture along with human ECs and fibroblast growth factor (bFGF). This mixture can then be injected subcutaneously in the dorsum of SCID mice to allow formation of fully functional, pericyte coated, hybrid vessels. Our protocol describes how to prepare matrix gel plugs containing human ECs either with or without human pericytes, placement into SCID mice and how to analyze the histological sections for critical angiogenesis endpoints.

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	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">PBS (Phosphate buffered saline)</td>
			<td style="width:115px;">Corning</td>
			<td style="width:119px;">21-031-CV</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">0.25% Trypsin/0.53mM EDTA</td>
			<td style="width:115px;">Corning</td>
			<td style="width:119px;">25-053-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">Endothelial Cell Media (ECM) kit</td>
			<td style="width:115px;">Sciencell</td>
			<td style="width:119px;">1001</td>
			<td>includes media, EC growth supplement, and penicillin/streptomycin, each supplied at the appropriate volume for easy mixing</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">Pericyte Media (PM) kit</td>
			<td style="width:115px;">Sciencell</td>
			<td style="width:119px;">1201</td>
			<td>includes media, Pericyte growth supplement, and penicillin/streptomycin, each supplied at the appropriate volume for easy mixing</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:405px;">primary human pulmonary microvascular endothelial cells</td>
			<td style="width:115px;">Pulmonary Hypertension Breakthrough Initiative</td>
			<td style="width:119px;"></td>
			<td>this cell type is also available commercially. Cells used at passage 1-4</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:405px;">primary human pulmonary pericytes</td>
			<td style="width:115px;">Pulmonary Hypertension Breakthrough Initiative</td>
			<td style="width:119px;"></td>
			<td>this cell type is not available commercially, but brain paricytes are.&#160; Cells used at passage 1-4</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">bFGF (basic Fibroblast Growth Factor)</td>
			<td style="width:115px;">Peprotech</td>
			<td style="width:119px;">100-18B</td>
			<td>stock solution is 50ug/ml in 0.1% BSA in PBS, aliquots at 50 uL and stored at -20 degrees</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">Matrigel Basement Membrane Matrix</td>
			<td style="width:115px;">BD</td>
			<td style="width:119px;">356237</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">28G 1cc Insluin Syringe</td>
			<td style="width:115px;">BD</td>
			<td style="width:119px;">329410</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">SCID (Severe Combined Immune Deficiency) mice</td>
			<td style="width:115px;">The Jackson Laboratory</td>
			<td>5557</td>
			<td>NOD.SCID IL2R gamma knockout strain is the best strain; 4-6 weeks of age</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">1.5mL microcentrifuge tubes, sterile</td>
			<td style="width:115px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">05-408-129</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">15 mL screw top tubes, sterile</td>
			<td style="width:115px;">BD Biosciences</td>
			<td style="width:119px;">352096</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">PAP pen</td>
			<td style="width:115px;">Life Technologies</td>
			<td style="width:119px;">8899</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">hemocytometer</td>
			<td style="width:115px;">ThermoFisher Scientific</td>
			<td style="width:119px;">02-671-6</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">Nair hair removal cream</td>
			<td style="width:115px;">Walmart</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">anti-human CD31 primary antibody</td>
			<td style="width:115px;">LifeSpan Biosciences</td>
			<td>LS-B4737</td>
			<td>working solution is 1:50</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-human Smooth Muscle actin CY3 primary fluorescent antibody</td>
			<td style="width:115px;">Sigma</td>
			<td>C6198</td>
			<td>working solution is 1:300</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">goat anti-rabbit secondary antibody; 488/green</td>
			<td style="width:115px;">ThermoFisher Scientific</td>
			<td style="width:119px;">A-11008</td>
			<td>working solution is 1:250</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">Prolong Gold DAPI solution</td>
			<td style="width:115px;">Cell Signaling</td>
			<td style="width:119px;">8961S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">microscope slides</td>
			<td style="width:115px;">VWR</td>
			<td style="width:119px;">48300-047</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">no. 1.5 cover slips</td>
			<td style="width:115px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">12-544-D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">citrate buffer 10x</td>
			<td style="width:115px;">Millipore</td>
			<td style="width:119px;">21545</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">extra fine surgical scissors</td>
			<td style="width:115px;">Fine Science Tools</td>
			<td style="width:119px;">14084-08</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:405px;">Formalin (paraformaldehyde)</td>
			<td style="width:115px;">Thermo Fisher Scientific</td>
			<td style="width:119px;">245-685</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">Tissue cassettes</td>
			<td style="width:115px;">Simport</td>
			<td>M492-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:405px;">goat serum</td>
			<td style="width:115px;">Dako</td>
			<td style="width:119px;">X0907</td>
			<td></td>
		</tr>
	</tbody>
</table>

in vivo study of human endothelial-pericyte interaction using the matrix gel plug assay in mouse

Angiogenesis is the process by which new blood vessels are formed from existing vessels. New vessel growth requires coordinated endothelial cell proliferation, migration, and alignment to form tubular structures followed by recruitment of pericytes to provide mural support and facilitate vessel maturation. Current in vitro cell culture approaches cannot fully reproduce the complex biological environment where endothelial cells and pericytes interact to produce functional vessels. We present a novel application of the in vivo matrix gel plug assay to study endothelial-pericyte interactions and formation of functional blood vessels using severe combined immune deficiency mutation (SCID) mice. Briefly, matrix gel is mixed with a solution containing endothelial cells with or without pericytes followed by injection into the back of anesthetized SCID mice. After 14 days, the matrix gel plugs are removed, fixed and sectioned for histological analysis. The length, number, size and extent of pericyte coverage of mature vessels (defined by the presence of red blood cells in the lumen) can be quantified and compared between experimental groups using commercial statistical platforms. Beyond its use as an angiogenesis assay, this matrix gel plug assay can be used to conduct genetic studies and as a platform for drug discovery. In conclusion, this protocol will allow researchers to complement available in vitro assays for the study of endothelial-pericyte interactions and their relevance to either systemic or pulmonary angiogenesis.

Representative H&#38;E and immunofluorescent staining of matrix gel plug sections are shown in Figure 2. Sections from EC only plugs display some vessels that are mostly not perfused with blood (Figure 2 top left, black arrows) whereas plugs containing both ECs and pericytes display several perfused vessels with larger diameters and complete pericyte coverage, as evidenced by positive SMA staining immediately adjacent to CD31-positive ECs. These results s...

Watch this Scientific Journal Video about In Vivo Study of Human Endothelial-Pericyte Interaction Using the Matrix Gel Plug Assay in Mouse at JoVE.com

In Vivo Study of Human Endothelial-Pericyte Interaction Using the Matrix Gel Plug Assay in Mouse

We present a protocol to study human endothelial-pericyte interactions in mouse using a variation of the matrix gel plug angiogenesis assay.

In Vivo Study of Human Endothelial-Pericyte Interaction Using the Matrix Gel Plug Assay in Mouse

Angiogenesis is the process by which new blood vessels are formed from existing vessels. New vessel growth requires coordinated endothelial cell ...

The overall goal of this in-vivo matrix gel assay is to investigate the interaction of endothelial cells with parasites. This matrigel assay is designed to help investigators study the major steps in androgenesis. It also will allow the identification of signaling pathways responsible for major steps in blood vessel formation as well as genes who's disfunction can lead to vascular disorders and other aberrations of androgenesis.The main advantage of this technique is that it allows us to study the in-vivo blood vessel formation involving both endothelial cells and their support cells, pericytes. To begin, grow human endothelial and parasite cell cultures on 100-millimeter plates with 10 milliliters of the appropriate media. Change the media every two to three days until the cells reach 80%confluency.In order to prepare the matrix gel solution to mix with the cells, thaw a stock of matrix gel overnight at four degrees Celsius. Then make 1.5 milliliter aliquots for storage at negative-20 degrees Celsius long-term, or at four degrees Celsius for up to two weeks. Each experimental plug will require 200 microliters of matrix gel.So one stocked tube can supply six plugs with a 25%excess. Prepare each required aliquot for use by adding 15 microliters of thawed 100x beta-FGF stock. Mix the beta-FGF into solution by pipetting, then incubate on ice for at least 30 minutes prior to adding cells.At this point, chill some 28-gauge 1cc insulin syringes for the injections. To collect the cells from the culture plates, remove the media and wash the cells once with PBS. After removing the PBS, add one milliliter of trypsin solution and return the plates to the incubator for one minute.Then, pipette two milliliters of culture media over the plates to detach the cells and collect the medium into a 15 milliliter tube. Now, check the concentration of the collections using a hemocytometer. Then, prepare aliquots of cells in 15 milliliter tubes.A combination of one million endothelial cells and 200, 000 parasites is used here for the experimental group. Next, centrifuge the cell aliquots at 400g for five minutes. Then, add the calculated volume of matrix gel to the cell pellet, and mix with gentle pipetting so no foam is made, as air bubbles cannot be injected.Now keep the preparations on ice until the mice are ready to inject. After anesthetizing a mouse with isoflurane, and confirming the anesthetized state with a toe pinch, attach the mouse to the non-rebreathing system supplying isoflurane and place it on the heating pad, ventral side down. Now remove about a square-centimeter of hair from both lateral hind-regions.Then, wipe the exposed skin clean using 70%alcohol. Next, load one milliliter of the prepared cell solution into a chilled syringe, which is enough for four plugs. To make an injection, lift the back-skin to locate the subcutaneous space.Then slowly inject 200 microliters evenly into the subcutaneous space posterior of the ribcage, and slowly remove the needle to prevent leaking. After the injection, a bump will form at the site. Wipe the site with alcohol, then outline the bump with permanent marker so it can be found later.Then, repeat the injection procedure on the other side of the mouse. Be sure to inject all the cells within three minutes or they will start sticking to the syringe. The injection step is critical to do well to ensure that the matrix gel plug will form between the skin and muscle layers so that the plug maintains good shape and it does not become diffuse.Before proceeding to inject the next mouse, let the injected mouse stay on the heat pad for a minute to give the matrix time to gel. After euthanasia, set-up the mouse on the operating stage. After removing any regrown hair from the injection site, find the marker lines that identify the location of the plug.Then, using fine surgical scissors, make an incision along the marked border of the plug, perpendicular to the skin and through to the muscle beneath. Carefully cut around the periphery of the marked border. Then remove the plug, keeping it sandwiched between the skin and muscle layers.Immediately rinse the plug off in a small beaker of PBS to remove the blood. Then, place the entire plug in a 50 milliliter tube with 25 milliliters of 4%paraformaldehyde. Let it fix at room temperature for 24 hours without any agitation.The next day, transfer the plugs into 25 milliliters of 70%ethanol for 24 hours. Then, proceed with paraffin embedding. Sections of plugs containing only endothelial cells show that some vessels do not get perfused with the host's blood after 14 days in-vivo.By contrast, plugs containing both endothelial cells and parasites, display many perfused vessels after 14 days in-vivo. These plugs have cells that are positive for smooth muscle actin staining, seen in red, immediately adjacent to CD31 positive endothelial cells, seen in green. Therefore, parasites may play a substantial role in nascent blood vessel formation.After watching this video, you should have a good understanding of how to apply this powerful in-vivo technique to study blood vessel formation in use in multiple cell types. This technique will pave the way for researchers to explore various topics of vascular biology in mouse models. Following this procedure, other methods, such as quantitative PCR, and Western immunoblotting can also be run to answer additional questions such as changes in gene expression and proteomics.This powerful technique will allow the investigator to study in-vivo how endothelial cells and parasites interact during blood vessel formation. Which is a key step in androgenesis. This powerful technique will also allow the investigator to study other cell-cell interactions that are relevant to understanding vascular diseases such as pulmonary hyper-tension, among others.

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