This work was supported by Kyoto Innovative Medical Technology Research &amp; Development Support System, and by the Translational Research program; Strategic PRomotion for practical application of INnovative medical Technology (TR-SPRINT) from Japan Agency for Medical Research and Development (AMED).

The following protocol follows the animal care guidelines of the Kyoto Prefectural University of Medicine.
1. Preparation of Specimens Using a Porcine Stomach
NOTE: The first step is to prepare specimens to be used in the ex vivo model (Figure 1). The thickness of the porcine gastric wall varies in different areas of the stomach. Use the upper third of the porcine stomach, which is relatively similar to the human stomach. Exclude inappropriate specimens where submucosal elevation is not found due to fibrosis.
<ol>
	<li>Cut&#160;gastric specimens into squares with approximate dimensions of 6&#160;&#215; 6&#160;cm.</li>
	<li>Store the gastric specimens immediately at a temperature of -30 &#176;C.</li>
	<li>Thaw frozen gastric specimens right before the measurement procedure to ensure uniform measurement conditions.</li>
</ol>
2. Detailed Setup Methodology of a New Ex Vivo Model
NOTE: Stretch out the thawed specimen&#160;on a board in two different ways. In the conventional ex vivo model, fix the specimen with pins (Figure 1A)19,20,21,22. On the other hand, in the new ex vivo model, fix or stretch both ends of the specimen with clips to produce a constant tension (Figure 1B, C). All parts of the new model are easy to obtain, and the setup of the new model can be completed quickly (Figure 2). The procedure of the new model is as follows (Figure 3):
<ol>
	<li>Connect the stainless-steel clip and&#160;the key wire and the S shaped hook (Figure 3A).</li>
	<li>Connect the wire and&#160;the S shaped hook and the weight (Figure 3A).</li>
	<li>Connect the hook to the other end of the wire. A traction device is completed in the above process (Figure 3B).</li>
	<li>Fix the pulleys (Figure 2b) at both ends of the base (Figure 3C).</li>
	<li>Place the rubber plate (6&#160;x 6&#160;cm) on the center of the base (Figure 3C).</li>
	<li>Place the gastric specimen on the rubber plate and pinch the specimen ends with the clip of the traction device.</li>
	<li>Hang the weight through the pulley (both side). Thereby, constant tension can be applied to the specimen (Figure 4).</li>
	<li>Start the measurement of SEH, because&#160;after the setup of the new model is completely finished (See Step 3 below).</li>
</ol>
3. Evaluation of SIM Performance
NOTE: In this study, we used normal saline (NS) and 0.4% sodium hyaluronate (HA) as SIMs to be tested, and measure SEH of the two SIMs. Three independent measurements are performed. The obtained data are expressed as the mean and standard deviation (S.D.). Statistical analysis was performed by using the statistical analysis software (GraphPad Prism 7). We analyzed continuous variables (SEH) with the Student&#39;s t-test, and the magnitudes with P &#60; 0.05 were considered significant. The measurement of SEH is as follows (Figure 5).
<ol>
	<li>Perform zero-point adjustment of the height gauge, based on the height of mucosa before a submucosal elevation procedure. In detail, perform zero-point adjustment by pushing the PRESET button after fixing the scriber at the height of the mucosal surface.</li>
	<li>Inject 2.0 mL of each solution horizontally into the submucosa from the specimen margins using a 2.5-mL syringe and 23-gauge&#160;needle, to perform a submucosal elevation procedure (Figure 5A-C).</li>
	<li>Measure&#160;SEH promptly using a digital height gage at 0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 30, 45, and 60 min after the injection (Figure 5D). In detail, record the height displayed on the height gauge when fixing the scriber to the top of the submucosal elevation.</li>
	<li>Perform three independent measurements, and express the obtained results as the mean and standard deviation.</li>
	<li>Analyze the obtained data using appropriate statistical software and evaluate the performance of SIMs (The performance can be compared between each SIM.)</li>
</ol>

<ol>
	<li>Ono, H., 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=Endoscopic+mucosal+resection+for+treatment+of+early+gastric+cancer.">Endoscopic mucosal resection for treatment of early gastric cancer.</a> Gut. 48 (2), 225-229 (2001).</li><li>Conio, M., Ponchon, T., Blanchi, S., Filiberti, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+mucosal+resection.">Endoscopic mucosal resection.</a> The American journal of gastroenterology. 101 (3), 653-663 (2006).</li><li>Soetikno, R. M., Gotoda, T., Nakanishi, Y., Soehendra, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endoscopic+mucosal+resection.">Endoscopic mucosal resection.</a> Gastrointestinal endoscopy. 57 (4), 567-579 (2003).</li><li>Iishi, H., 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=Endoscopic+resection+of+large+sessile+colorectal+polyps+using+a+submucosal+saline+injection+technique.">Endoscopic resection of large sessile colorectal polyps using a submucosal saline injection technique.</a> Hepato-gastroenterology. 44 (15), 698-702 (1997).</li><li>Katsinelos, P., 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+comparative+study+of+50%+dextrose+and+normal+saline+solution+on+their+ability+to+create+submucosal+fluid+cushions+for+endoscopic+resection+of+sessile+rectosigmoid+polyps.">A comparative study of 50% dextrose and normal saline solution on their ability to create submucosal fluid cushions for endoscopic resection of sessile rectosigmoid polyps.</a> Gastrointestinal endoscopy. 68 (4), 692-698 (2008).</li><li>Yamamoto, H., 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+method+of+endoscopic+mucosal+resection+using+sodium+hyaluronate.">A novel method of endoscopic mucosal resection using sodium hyaluronate.</a> Gastrointestinal endoscopy. 50 (2), 251-256 (1999).</li><li>Yamamoto, H., 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+successful+single-step+endoscopic+resection+of+a+40+millimeter+flat-elevated+tumor+in+the+rectum:+endoscopic+mucosal+resection+using+sodium+hyaluronate.">A successful single-step endoscopic resection of a 40 millimeter flat-elevated tumor in the rectum: endoscopic mucosal resection using sodium hyaluronate.</a> Gastrointestinal endoscopy. 50 (5), 701-704 (1999).</li><li>Yamamoto, H., 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=Usefulness+and+safety+of+0.4%+sodium+hyaluronate+solution+as+a+submucosal+fluid+&amp;#34;cushion&amp;#34;+in+endoscopic+resection+for+gastric+neoplasms:+a+prospective+multicenter+trial.">Usefulness and safety of 0.4% sodium hyaluronate solution as a submucosal fluid &amp;#34;cushion&amp;#34; in endoscopic resection for gastric neoplasms: a prospective multicenter trial.</a> Gastrointestinal endoscopy. 67 (6), 830-839 (2008).</li><li>Yamamoto, H., 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=Successful+en-bloc+resection+of+large+superficial+tumors+in+the+stomach+and+colon+using+sodium+hyaluronate+and+small-caliber-tip+transparent+hood.">Successful en-bloc resection of large superficial tumors in the stomach and colon using sodium hyaluronate and small-caliber-tip transparent hood.</a> Endoscopy. 35 (8), 690-694 (2003).</li><li>Kishihara, T., 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=Usefulness+of+sodium+hyaluronate+solution+in+colorectal+endoscopic+mucosal+resection.">Usefulness of sodium hyaluronate solution in colorectal endoscopic mucosal resection.</a> Digestive endoscopy. 24 (5), 348-352 (2012).</li><li>Yoshida, 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=Endoscopic+mucosal+resection+with+0.13%+hyaluronic+acid+solution+for+colorectal+polyps+less+than+20+mm:+a+randomized+controlled+trial.">Endoscopic mucosal resection with 0.13% hyaluronic acid solution for colorectal polyps less than 20 mm: a randomized controlled trial.</a> Journal of gastroenterology and hepatology. 27 (8), 1377-1383 (2012).</li><li>Uraoka, T., 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=Effectiveness+of+glycerol+as+a+submucosal+injection+for+EMR.">Effectiveness of glycerol as a submucosal injection for EMR.</a> Gastrointestinal endoscopy. 61 (6), 736-740 (2005).</li><li>Conio, 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=Comparative+performance+in+the+porcine+esophagus+of+different+solutions+used+for+submucosal+injection.">Comparative performance in the porcine esophagus of different solutions used for submucosal injection.</a> Gastrointestinal endoscopy. 56 (4), 513-516 (2002).</li><li>Moss, A., Bourke, M. J., Metz, A. 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+randomized,+double-blind+trial+of+succinylated+gelatin+submucosal+injection+for+endoscopic+resection+of+large+sessile+polyps+of+the+colon.">A randomized, double-blind trial of succinylated gelatin submucosal injection for endoscopic resection of large sessile polyps of the colon.</a> The American journal of gastroenterology. 105 (11), 2375-2382 (2010).</li><li>Lee, S. H., 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+method+of+EMR:+submucosal+injection+of+a+fibrinogen+mixture.">A new method of EMR: submucosal injection of a fibrinogen mixture.</a> Gastrointestinal endoscopy. 59 (2), 220-224 (2004).</li><li>Hurlstone, D. P., 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=EMR+using+dextrose+solution+versus+sodium+hyaluronate+for+colorectal+Paris+type+I+and+0-II+lesions:+a+randomized+endoscopist-blinded+study.">EMR using dextrose solution versus sodium hyaluronate for colorectal Paris type I and 0-II lesions: a randomized endoscopist-blinded study.</a> Endoscopy. 40 (2), 110-114 (2008).</li><li>Huai, Z. Y., Feng Xian, W., Chang Jiang, L., Xi Chen, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Submucosal+injection+solution+for+endoscopic+resection+in+gastrointestinal+tract:+a+traditional+and+network+meta-analysis.">Submucosal injection solution for endoscopic resection in gastrointestinal tract: a traditional and network meta-analysis.</a> Gastroenterology research and practice. 2015, 702768 (2015).</li><li>Yandrapu, H., 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=Normal+saline+solution+versus+other+viscous+solutions+for+submucosal+injection+during+endoscopic+mucosal+resection:+a+systematic+review+and+meta-analysis.">Normal saline solution versus other viscous solutions for submucosal injection during endoscopic mucosal resection: a systematic review and meta-analysis.</a> Gastrointestinal endoscopy. , (2016).</li><li>Fernandez-Esparrach, G., Shaikh, S. N., Cohen, A., Ryan, M. B., Thompson, C. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficacy+of+a+reverse-phase+polymer+as+a+submucosal+injection+solution+for+EMR:+a+comparative+study+(with+video).">Efficacy of a reverse-phase polymer as a submucosal injection solution for EMR: a comparative study (with video).</a> Gastrointestinal endoscopy. 69 (6), 1135-1139 (2009).</li><li>Tran, R. T., Palmer, M., Tang, S. J., Abell, T. L., Yang, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Injectable+drug-eluting+elastomeric+polymer:+a+novel+submucosal+injection+material.">Injectable drug-eluting elastomeric polymer: a novel submucosal injection material.</a> Gastrointestinal endoscopy. 75 (5), 1092-1097 (2012).</li><li>Akagi, T., 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=Sodium+alginate+as+an+ideal+submucosal+injection+material+for+endoscopic+submucosal+resection:+preliminary+experimental+and+clinical+study.">Sodium alginate as an ideal submucosal injection material for endoscopic submucosal resection: preliminary experimental and clinical study.</a> Gastrointestinal endoscopy. 74 (5), 1026-1032 (2011).</li><li>Eun, S. H., 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=Effectiveness+of+sodium+alginate+as+a+submucosal+injection+material+for+endoscopic+mucosal+resection+in+animal.">Effectiveness of sodium alginate as a submucosal injection material for endoscopic mucosal resection in animal.</a> Gut and Liver. 1 (1), 27-32 (2007).</li><li>Hirose, 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=Development+of+a+new+ex+vivo+model+for+evaluation+of+endoscopic+submucosal+injection+materials+performance.">Development of a new ex vivo model for evaluation of endoscopic submucosal injection materials performance.</a> Journal of the Mechanical Behavior of Biomedical Materials. 79, 219-225 (2018).</li></ol>

The authors have nothing to disclose.

The porcine stomach used for the new model should be stored in a freezer immediately after&#160;resection, and be used within a few months after freezing, since the freshness of the swine stomach is essential for SEH measurement. (We measured&#160;SEH using both frozen and unfrozen gastric specimens, and confirmed that there was no difference in the result of SEH measurement.)
The quality of gastric specimens is greatly influenced by the individual differences of porcine stomachs. Hence, it is...

Both endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) are currently common treatments for early-stage gastrointestinal cancer1,2. Injecting a submucosal injection material (SIM) into the submucosa is one of the most important steps for both the EMR and ESD procedures2,3. High submucosal elevation and maintenance of submucosal elevation are critical criteria for safely conducting EMR/ESD.
Although normal saline (NS) has been used as a SIM since the invention of endoscopic therapy4,5, sodium hyaluronate (HA) was introduced as a treatment in recent years6,7. HA became widely used in endoscopic treatments as a superior SIM due to its high performance8,9,10,11. Currently, a performance comparison between the existing SIMs was conducted, and high-performance SIMs were developed to identify another superior SIM5,12,13,14,15,16,17,18.
The ex vivo model using a porcine stomach specimen has been used to evaluate SIM performance, because the estimation of SIM performance in the human gastrointestinal tract is very difficult19,20,21,22. However, this conventional ex vivo model is extremely simple, and has the scope for improvement. Reproducing an environment closer to the human gastrointestinal mucosa will enable accurate evaluation of SIM performance.
In our previous study, we developed a new ex vivo model that can be used to evaluate the performance of various SIMs in detail by applying constant tension to the specimen&#39;s ends. We also confirmed that the proposed new ex vivo model, allows accurate SHE measurement under uniform conditions and a detailed comparison of the performances of various types of SIMs23.
In this study, we present a complete appearance of the new ex vivo model, and the detailed setup methodology of the new ex vivo model is explained in detail using videos and figures. The&#160;new ex vivo model consists of parts that are&#160;easily available and can be quickly set up. Descriptions of detailed setup methodology will contribute to the dissemination of the new model.

<table>
	<tbody>
		<tr>
			<td>weight (153.1 g)</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>fixed type pulley</td>
			<td>H.H.H. MANUFACTURING</td>
			<td>VS25</td>
			<td></td>
		</tr>
		<tr>
			<td>stainless steel wire with a diameter of 0.45 mm</td>
			<td>Nissa Chain</td>
			<td>Cut wire Y-5</td>
			<td></td>
		</tr>
		<tr>
			<td>stainless steel clip of width 147 mm</td>
			<td>KOKUYO</td>
			<td>none</td>
			<td></td>
		</tr>
		<tr>
			<td>stainless steel key wire with a length of 12 cm</td>
			<td>Nissa Chain</td>
			<td>P-702</td>
			<td></td>
		</tr>
		<tr>
			<td>stainless steel S shaped hook</td>
			<td>TRUSCO NAKAYAMA</td>
			<td>TCS1.2</td>
			<td></td>
		</tr>
		<tr>
			<td>lockable stainless steel S-shaped hook</td>
			<td>Mizumoto Machine Mfg</td>
			<td>B2054</td>
			<td></td>
		</tr>
		<tr>
			<td>rectangular wooden base (45 x 60 cm)</td>
			<td>none</td>
			<td>none</td>
			<td></td>
		</tr>
		<tr>
			<td>rubber plate (5 x 5 cm)</td>
			<td>none</td>
			<td>none</td>
			<td></td>
		</tr>
		<tr>
			<td>digital height gage</td>
			<td>Mitutoyo</td>
			<td>HDS-20C</td>
			<td></td>
		</tr>
		<tr>
			<td>2.5-mL syringe</td>
			<td>Terumo</td>
			<td>SS-02SZ</td>
			<td></td>
		</tr>
		<tr>
			<td>23-gauge needle</td>
			<td>Terumo</td>
			<td>NN-2332R</td>
			<td></td>
		</tr>
		<tr>
			<td>MucoUp</td>
			<td>Boston Scientific</td>
			<td>none</td>
			<td>0.4% sodium hyaluronate (HA)</td>
		</tr>
		<tr>
			<td>saline (20 mL)</td>
			<td>Otsuka Pharmaceutical</td>
			<td>none</td>
			<td>normal saline (NS)</td>
		</tr>
		<tr>
			<td>GraphPad Prism 7 software</td>
			<td>GraphPad Inc</td>
			<td>none</td>
			<td></td>
		</tr>
	</tbody>
</table>

a new ex vivo model for the evaluation of endoscopic submucosal injection material performance

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential to establish an ex vivo model that can evaluate SIM performance accurately, for developing high-performance SIMs. In our previous study, we developed a new ex vivo model that can be used to evaluate the performance of various SIMs in detail by applying constant tension to the specimen&#39;s ends. We also confirmed that the proposed new ex vivo model allows accurate submucosal elevation height (SEH) measurement under uniform conditions and detailed comparisons of the performances of various types of SIMs. Here, we describe the new ex vivo model and explain the detailed setup methodology of this model. Since all parts of the new model were easy to obtain, the setup of the new model could be completed quickly. SEH of various SIMs could be measured more accurately by using the new model. The critical factor that determines SIM performance can be identified using the new model. SIM development speed will drastically increase after the factor has been identified.

SEH was measured over time in the new ex vivo model or conventional ex vivo model. The values of SEH (NS) measured using the conventional model [NS was injected into the submucosa of the specimen fixed with pins (0.0 N)] were 5.7 mm (0 min), 3.6 mm (5 min), 3.0 mm (10 min), and 2.2 mm (30 min).In this way, the values of SEH decreased with increasing post injection time.A similar analysis was performed using 0.4% HA instead of NS. The values of SEH (0.4% HA) were 6.5 mm (...

Watch this Scientific Journal Video about A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance at JoVE.com

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

We developed a new ex vivo model that applies constant tension to the porcine gastric specimen. This development made it possible to evaluate the performance (the height and duration of the submucosal elevation) of various SIMs accurately.&#160; The detailed setup methodology of this new model is explained.

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

Increasing the performance of submucosal injection materials (SIMs) is important for endoscopic therapy of early gastrointestinal cancer. It is essential ...

a-new-ex-vivo-model-for-evaluation-endoscopic-submucosal-injection

Research

JoVE Journal

Bioengineering

6.1K Views.  Kyoto Prefectural University of Medicine. We developed a new ex vivo model that applies constant tension to the porcine gastric specimen. This development made it possible to evaluate the performance (the height and duration of the submucosal elevation) of various SIMs accurately.  The detailed setup methodology of this new model is explained.

Video: A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced birth defects and many later studies afterwards proved the opposite. Today several harmful xenobiotics like nicotine, heroin, methadone or drugs as well as environmental pollutants were described to overcome this barrier. With the growing use of nanotechnology, the placenta is likely to come into contact with novel nanoparticles either accidentally through exposure or intentionally in the case of potential nanomedical applications. Data from animal experiments cannot be extrapolated to humans because the placenta is the most species-specific mammalian organ 1. Therefore, the ex vivo dual recirculating human placental perfusion, developed by Panigel et al. in 1967 2 and continuously modified by Schneider et al. in 1972 3, can serve as an excellent model to study the transfer of xenobiotics or particles.
Here, we focus on the ex vivo dual recirculating human placental perfusion protocol and its further development to acquire reproducible results.
The placentae were obtained after informed consent of the mothers from uncomplicated term pregnancies undergoing caesarean delivery. The fetal and maternal vessels of an intact cotyledon were cannulated and perfused at least for five hours. As a model particle fluorescently labelled polystyrene particles with sizes of 80 and 500 nm in diameter were added to the maternal circuit. The 80 nm particles were able to cross the placental barrier and provide a perfect example for a substance which is transferred across the placenta to the fetus while the 500 nm particles were retained in the placental tissue or maternal circuit. The ex vivo human placental perfusion model is one of few models providing reliable information about the transport behavior of xenobiotics at an important tissue barrier which delivers predictive and clinical relevant data.

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

The ex vivo dual recirculating human placental perfusion model can be used to investigate the transfer of xenobiotics and nanoparticles across the human placenta. In this video protocol we describe the equipment and techniques required for a successful execution of a placenta perfusion.

Decades ago the human placenta was thought to be an impenetrable barrier between mother and unborn child. However, the discovery of thalidomide-induced ...

Microinjection Wound Assay and In vivo Localization of Epidermal Wound Response Reporters in Drosophila Embryos.

The Drosophila embryo develops a robust epidermal layer that serves both to protect the internal cells from a harsh external environment as well as to maintain cellular homeostasis. Puncture injury with glass needles provides a direct method to trigger a rapid epidermal wound response that activates wound transcriptional reporters, which can be visualized by a localized reporter signal in living embryos or larvae. Puncture or laser injury also provides signals that promote the recruitment of hemocytes to the wound site. Surprisingly, severe (through and through) puncture injury in late stage embryos only rarely disrupts normal embryonic development, as greater than 90% of such wounded embryos survive to adulthood when embryos are injected in an oil medium that minimizes immediate leakage of hemolymph from puncture sites. The wound procedure does require micromanipulation of the Drosophila embryos, including manual alignment of the embryos on agar plates and transfer of the aligned embryos to microscope slides. The Drosophila epidermal wound response assay provides a quick system to test the genetic requirements of a variety of biological functions that promote wound healing, as well as a way to screen for potential chemical compounds that promote wound healing. The short life cycle and easy culturing routine make Drosophila a powerful model organism. Drosophila clean wound healing appears to coordinate the epidermal regenerative response, with the innate immune response, in ways that are still under investigation, which provides an excellent system to find conserved regulatory mechanisms common to Drosophila and mammalian epidermal wounding.

Microinjection Wound Assay and In vivo Localization of Epidermal Wound Response Reporters in Drosophila Embryos.

The embryonic epidermis of very late stage Drosophila embryos provides an in vivo system for rapid puncture wound response analysis and can be combined with genetic manipulations or chemical microinjection treatments to advance studies in wound healing for translation into mammalian models.

The Drosophila embryo develops a robust epidermal layer that serves both to protect the internal cells from a harsh external environment as well as to ...

Establishment of a Surgically-induced Model in Mice to Investigate the Protective Role of Progranulin in Osteoarthritis

Destabilization of medial meniscus (DMM) model is an important tool for studying the pathophysiological roles of numerous arthritis associated molecules in the pathogenesis of osteoarthritis (OA) in vivo. However, the detailed, especially the visualized protocol for establishing this complicated model in mice, is not available. Herein we took advantage of wildtype and progranulin (PGRN)-/- mice as examples to introduce a protocol for inducing DMM model in mice, and compared the onset of OA following establishment of this surgically induced model. The operations performed on mice were either sham operation, which just opened joint capsule, or DMM operation, which cut the menisco-tibial ligament and caused destabilization of medial meniscus. Osteoarthritis severity was evaluated using histological assay (e.g. Safranin&#160;O staining), expressions of OA-associated genes, degradation of cartilage extracellular matrix molecules, and osteophyte formation. DMM operation successfully induced OA initiation and progression in both wildtype and PGRN-/- mice, and loss of PGNR growth factor led to a more severe OA phenotype in this surgically induced model.

We describe a protocol for the destabilization of the medial meniscus (DMM) model in mice, an effective tool for osteoarthritis (OA) research. In addition, we have demonstrated that deficiency of progranulincan exaggerate OA development and progression by using this model, indicating that progranulin plays a protective role in the pathogenesis of OA.

Destabilization of medial meniscus (DMM) model is an important tool for studying the pathophysiological roles of numerous arthritis associated molecules ...

Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides

Collagen is a major structural component of the extracellular matrix that supports tissue formation and maintenance. Although collagen remodeling is an integral part of normal tissue renewal, excessive amount of remodeling activity is involved in tumors, arthritis, and many other pathological conditions. During collagen remodeling, the triple helical structure of collagen molecules is disrupted by proteases in the extracellular environment. In addition, collagens present in many histological tissue samples are partially denatured by the fixation and preservation processes. Therefore, these denatured collagen strands can serve as effective targets for biological imaging. We previously developed a caged collagen mimetic peptide (CMP) that can be photo-triggered to hybridize with denatured collagen strands by forming triple helical structure, which is unique to collagens. The overall goals of this procedure are i)&#160;to image denatured collagen strands resulting from normal remodeling activities in vivo, and ii) to visualize collagens in ex vivo tissue sections using the photo-triggered caged CMPs. To achieve effective hybridization and successful in vivo and ex vivo imaging, fluorescently labeled caged CMPs are either photo-activated immediately before intravenous injection, or are directly activated on tissue sections. Normal skeletal collagen remolding in nude mice and collagens in prefixed mouse cornea tissue sections are imaged in this procedure. The imaging method based on the CMP-collagen hybridization technology presented here could lead to deeper understanding of the tissue remodeling process, as well as allow development of new diagnostics for diseases associated with high collagen remodeling activity.

Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides

This procedure demonstrates in vivo near IR fluorescence imaging of collagen remodeling activities in mice as well as ex vivo staining of collagens in tissue sections using caged collagen mimetic peptides that can be photo-triggered to hybridize with denatured collagen strands.

Collagen is a major structural component of the extracellular matrix that supports tissue formation and maintenance. Although collagen remodeling is an ...

Surgical Technique for the Implantation of Tissue Engineered Vascular Grafts and Subsequent In Vivo Monitoring

The development of Tissue Engineered Vessels (TEVs) is advanced by the ability to routinely and effectively implant TEVs (4-5 mm in diameter) into a large animal model. A step by-step protocol for inter-positional placement of the TEV and real-time digital assessment of the TEV and native carotid arteries is described here. In vivo monitoring is made possible by the implantation of flow probes, catheters and ultrasonic crystals (capable of recording dynamic diameter changes of implanted TEVs and native carotid arteries) at the time of surgery. Once implanted, researchers can calculate arterial blood flow patterns, invasive blood pressure and artery diameter yielding parameters such as pulse wave velocity, augmentation index, pulse pressures and compliance. Data acquisition is accomplished using a single computer program for analysis throughout the duration of the experiment. Such invaluable data provides insight into TEV matrix remodeling, its resemblance to native/sham controls and overall TEV performance in vivo.

Surgical Technique for the Implantation of Tissue Engineered Vascular Grafts and Subsequent In Vivo Monitoring

A step-by-step protocol for the inter-positional placement of Tissue Engineered Vessels (TEVs) into the carotid artery of a sheep using end-to-end anastomosis and real-time digital assessment in vivo until animal sacrifice.

The development of Tissue Engineered Vessels (TEVs) is advanced by the ability to routinely and effectively implant TEVs (4-5 mm in diameter) into a large ...

Athymic Rat Model for Evaluation of Engineered Anterior Cruciate Ligament Grafts

Anterior cruciate ligament (ACL) rupture is a common ligamentous injury that often requires surgery because the ACL does not heal well without intervention. Current treatment strategies include ligament reconstruction with either autograft or allograft, which each have their associated limitations. Thus, there is interest in designing a tissue-engineered graft for use in ACL reconstruction. We describe the fabrication of an electrospun polymer graft for use in ACL tissue engineering. This polycaprolactone graft is biocompatible, biodegradable, porous, and is comprised of aligned fibers. Because an animal model is necessary to evaluate such a graft, this paper describes an intra-articular athymic rat model of ACL reconstruction that can be used to evaluate engineered grafts, including those seeded with xenogeneic cells. Representative histology and biomechanical testing results at 16 weeks postoperatively are presented, with grafts tested immediately post-implantation and contralateral native ACLs serving as controls. The present study provides a reproducible animal model with which to evaluate tissue engineered ACL grafts, and demonstrates the potential of a regenerative medicine approach to treatment of ACL rupture.

Animal models are important tools for the evaluation of tissue-engineered grafts. This paper presents the protocol for preparing an electrospun biodegradable polymer graft for use in anterior cruciate ligament tissue engineering, as well as a surgical protocol for implantation in a rat model.

Anterior cruciate ligament (ACL) rupture is a common ligamentous injury that often requires surgery because the ACL does not heal well without ...

An Experimental Protocol for Assessing the Performance of New Ultrasound Probes Based on CMUT Technology in Application to Brain Imaging

The possibility to perform an early and repeatable assessment of imaging performance is fundamental in the design and development process of new ultrasound (US) probes. Particularly, a more realistic analysis with application-specific imaging targets can be extremely valuable to assess the expected performance of US probes in their potential clinical field of application.
The experimental protocol presented in this work was purposely designed to provide an application-specific assessment procedure for newly-developed US probe prototypes based on Capacitive Micromachined Ultrasonic Transducer (CMUT) technology in relation to brain imaging.
The protocol combines the use of a bovine brain fixed in formalin as the imaging target, which ensures both realism and repeatability of the described procedures, and of neuronavigation techniques borrowed from neurosurgery. The US probe is in fact connected to a motion tracking system which acquires position data and enables the superposition of US images to reference Magnetic Resonance (MR) images of the brain. This provides a means for human experts to perform a visual qualitative assessment of the US probe imaging performance and to compare acquisitions made with different probes. Moreover, the protocol relies on the use of a complete and open research and development system for US image acquisition, i.e. the Ultrasound Advanced Open Platform (ULA-OP) scanner.
The manuscript describes in detail the instruments and procedures involved in the protocol, in particular for&#160;the calibration, image acquisition and registration of US and MR images. The obtained results prove the effectiveness of the overall protocol presented, which is entirely open (within the limits of the instrumentation involved), repeatable, and covers the entire set of acquisition and processing activities for US images.

The development of new ultrasound (US) probes based on Capacitive Micromachined Ultrasonic Transducer (CMUT) technology requires an early realistic assessment of imaging capabilities. We describe a repeatable experimental protocol for US image acquisition and comparison with magnetic resonance images, using an ex vivo bovine brain as an imaging target.

The possibility to perform an early and repeatable assessment of imaging performance is fundamental in the design and development process of new ...

A High-performance Compact Photoacoustic Tomography System for In Vivo Small-animal Brain Imaging

In vivo small-animal imaging has an important role to play in preclinical studies. Photoacoustic tomography (PAT) is an emerging hybrid imaging modality that shows great potential for both preclinical and clinical applications. Conventional optical parametric oscillator-based PAT (OPO-PAT) systems are bulky and expensive and cannot provide high-speed imaging. Recently, pulsed-laser diodes (PLDs) have been successfully demonstrated as an alternative excitation source for PAT. Pulsed-laser diode PAT (PLD-PAT) has been successfully demonstrated for high-speed imaging on photoacoustic phantoms and biological tissues. This work provides a visualized experimental protocol for in vivo brain imaging using PLD-PAT. The protocol includes the compact PLD-PAT system configuration and its description, animal preparation for brain imaging, and a typical experimental procedure for 2D cross-sectional rat brain imaging. The PLD-PAT system is compact and cost-effective and can provide high-speed, high-quality imaging. Brain images collected in vivo at various scan speeds are presented.

A High-performance Compact Photoacoustic Tomography System for In Vivo Small-animal Brain Imaging

A compact pulsed-laser diode-based photoacoustic tomography (PLD-PAT) system for high-speed in vivo brain imaging in small animals is demonstrated.

In vivo small-animal imaging has an important role to play in preclinical studies. Photoacoustic tomography (PAT) is an emerging hybrid imaging modality ...

A New Ex Vivo Model for the Evaluation of Endoscopic Submucosal Injection Material Performance

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Chapters in this video

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Determination of the Transport Rate of Xenobiotics and Nanomaterials Across the Placenta using the ex vivo Human Placental Perfusion Model

Microinjection Wound Assay and In vivo Localization of Epidermal Wound Response Reporters in Drosophila Embryos.

Establishment of a Surgically-induced Model in Mice to Investigate the Protective Role of Progranulin in Osteoarthritis

Imaging Denatured Collagen Strands In vivo and Ex vivo via Photo-triggered Hybridization of Caged Collagen Mimetic Peptides

Surgical Technique for the Implantation of Tissue Engineered Vascular Grafts and Subsequent In Vivo Monitoring

Athymic Rat Model for Evaluation of Engineered Anterior Cruciate Ligament Grafts

An Experimental Protocol for Assessing the Performance of New Ultrasound Probes Based on CMUT Technology in Application to Brain Imaging

A High-performance Compact Photoacoustic Tomography System for In Vivo Small-animal Brain Imaging