Name: hemocompatibility testing of blood-contacting implants in a flow loop model mimicking human blood flow
Uploaded: 2020-03-05T14:00:00
Description: Watch this Scientific Journal Video about Hemocompatibility Testing of Blood-Contacting Implants in a Flow Loop Model Mimicking Human Blood Flow at JoVE.com

For the performance of scanning electron microscopy, we thank Ernst Schweizer from the section of Medical Materials Science and Technology of the University Hospital Tuebingen. The research was supported by the Ministry of Education, Youth and Sports of the CR within National Sustainability Program II (Project BIOCEV-FAR LQ1604) and by Czech Science Foundation project No. 18-01163S.

The blood sampling procedure was approved by the Ethics Committee of the medical faculty at the University of Tuebingen (project identification code: 270/2010BO1). All subjects provided written, informed consent for inclusion before participation.
1. Preparation of Heparin-loaded Monovettes
<ol>
	<li>Mix the undiluted heparin (5,000 IU/mL) with sodium chloride (NaCl, 0.9%) solution and prepare a solution with a resulting concentration of 15 IU/mL of heparin.</li>
	<li>Add 900 &#181;L of the ...

<ol>
	<li>ISO. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Biological evaluation of medical devices. , (2002).</li><li>Weber, 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=Blood-Contacting+Biomaterials:+In+Vitro+Evaluation+of+the+Hemocompatibility.">Blood-Contacting Biomaterials: In Vitro Evaluation of the Hemocompatibility.</a> Frontiers in Bioengineering and Biotechnology. 6, 99 (2018).</li><li>Li, Y., Boraschi, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endotoxin+contamination:+a+key+element+in+the+interpretation+of+nanosafety+studies.">Endotoxin contamination: a key element in the interpretation of nanosafety studies.</a> Nanomedicine (Lond). 11 (3), 269-287 (2016).</li><li>Cattaneo, G., 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=In+vitro+investigation+of+chemical+properties+and+biocompatibility+of+neurovascular+braided+implants.">In vitro investigation of chemical properties and biocompatibility of neurovascular braided implants.</a> Journal of Materials Science: Materials in Medicine. 30 (6), 67 (2019).</li><li>Stang, 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=Hemocompatibility+testing+according+to+ISO+10993-4:+discrimination+between+pyrogen-+and+device-induced+hemostatic+activation.">Hemocompatibility testing according to ISO 10993-4: discrimination between pyrogen- and device-induced hemostatic activation.</a> Materials Science and Engineering: C Materials for Biological Applications. 42, 422-428 (2014).</li><li>van Oeveren, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Obstacles+in+haemocompatibility+testing.">Obstacles in haemocompatibility testing.</a> Scientifica (Cairo). , 392584 (2013).</li><li>Engels, G. 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M., Heemskerk, J. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+whole+blood+thrombus+formation+using+parallel-plate+flow+chambers-a+practical+guide.">Measurement of whole blood thrombus formation using parallel-plate flow chambers-a practical guide.</a> Platelets. 23 (3), 229-242 (2012).</li><li>M&#252;ller, M., Krolitzki, B., Glasmacher, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+in+vitro+hemocompatibility+testing-improving+the+signal+to+noise+ratio.">Dynamic in vitro hemocompatibility testing-improving the signal to noise ratio.</a> Biomedical Engineering/Biomedizinische Technik. 57, 549-552 (2012).</li><li>Ritz-Timme, S., Eckelt, N., Schmidtke, E., Thomsen, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genesis+and+diagnostic+value+of+leukocyte+and+platelet+accumulations+around+"air+bubbles"+in+blood+after+venous+air+embolism.">Genesis and diagnostic value of leukocyte and platelet accumulations around "air bubbles" in blood after venous air embolism.</a> International Journal of Legal Medicine. 111 (1), 22-26 (1998).</li><li>Miller, 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=Characterisation+of+the+initial+period+of+protein+adsorption+by+dynamic+surface+tension+measurements+using+different+drop+techniques.">Characterisation of the initial period of protein adsorption by dynamic surface tension measurements using different drop techniques.</a> Colloids and Surfaces A: Physicochemical and Engineering Aspects. 131 (1), 225-230 (1998).</li><li>van Oeveren, W., Tielliu, I. 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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=Silicon-carbide+coated+coronary+stents+have+low+platelet+and+leukocyte+adhesion+during+platelet+activation.">Silicon-carbide coated coronary stents have low platelet and leukocyte adhesion during platelet activation.</a> Journal of Investigative Medicine. 47 (6), 304-310 (1999).</li><li>Amoroso, G., van Boven, A. J., Volkers, C., Crijns, H. 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The presented protocol describes a comprehensive and reliable method for the hemocompatibility testing of blood-contacting implants in accordance with ISO 10993-4 in a shear flow model imitating human blood flow. This study is based on the testing of laser-cut neurovascular implants but can be performed with a variety of samples. The results demonstrate that this method enables the broad analysis of various parameters such as the blood cell count, prevalence of several hemocompatibility markers, and microscopic visualiza...

The in vivo application of implants and biomaterials, which interact with human blood, requires intense preclinical testing focusing on the investigation of various markers of the hemostatic system. The International Organization for Standardization 10993-4 (ISO 10993-4) specifies the central principles for the evaluation of blood-contacting devices (i.e., stents and vascular grafts) and considers the device design, clinical utility, and materials needed1.
Human blood is a fluid that contains various plasma proteins and cells, including leukocytes (white blood cells [WBCs]), erythrocytes (red blood cells [RBCs]), and platelets, which carry out complex functions in the human body2. The direct contact of foreign materials with blood can cause adverse effects, such as activation of the immune or coagulation system, which can lead to inflammation or thrombotic complications and serious issues after implantation3,4,5. Therefore, in vitro hemocompatibility validation offers an opportunity prior to implantation to detect and exclude any hematologic complications that may be induced upon contact of the blood with a foreign surface6.
The presented flow loop model was established to assess the hemocompatibility of neurovascular stents and similar devices by applying a flow rate of 150 mL/min in tubing (diameter of 3.2 mm) to mimic cerebral flow conditions and artery diameters2,7. Besides the need for an optimal in vitro model, the source of blood is an important factor in gaining reliable and unaltered results when analyzing hemocompatibility of a biomaterial8. The collected blood should be used immediately after sampling to prevent changes caused by prolonged storage. In general, a gentle collection of blood without stasis using a 21 G needle should be performed to minimize the preactivation of platelets and the coagulation cascade during blood drawing. Furthermore, donor exclusion criteria include those who smoke, are pregnant, are in a poor state of health, or have taken oral contraceptives or painkillers during the previous 14 days.
This study describes an in vitro model for the extensive hemocompatibility testing of stent implants under flow conditions. When comparing uncoated to fibrin-heparin-coated stents, results of the comprehensive hemocompatibility tests reflect improved hemocompatibility of the fibrin-heparin-coated stents9. In contrast, the uncoated stents induce activation of the coagulation cascade, as demonstrated by an increase in thombin-antithrombin III (TAT) concentrations and loss of blood platelet numbers due to the adhesion of platelets to stent surface. Overall, integrating this hemocompatibility model as a preclinical test is recommended to detect any adverse effects on the hemostatic system that are caused by the device.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>aqua ad iniectabilia</td>
			<td>Fresenius-Kabi, Bad-Homburg, Germany</td>
			<td>1088813</td>
			<td></td>
		</tr>
		<tr>
			<td>beta-TG ELISA</td>
			<td>Diagnostica Stago, Duesseldorf, Germany</td>
			<td>00950</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge Rotana 460 R</td>
			<td>Andreas Hettich, Tuttlingen, Germany</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Citrat monovettes (1.4 mL)</td>
			<td>Sarstedt, N&#252;mbrecht, Germany</td>
			<td>6,16,68,001</td>
			<td></td>
		</tr>
		<tr>
			<td>CTAD monovettes (2.7 mL)</td>
			<td>BD Biosciences, Heidelberg, Germany</td>
			<td>367562</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA monovettes (1.2 mL)</td>
			<td>Sarstedt, N&#252;mbrecht, Germany</td>
			<td>6,16,62,001</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol p.A. (1000 mL)</td>
			<td>AppliChem, Darmstadt, Germany</td>
			<td>1,31,08,61,611</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutaraldehyde (25 % in water)</td>
			<td>SERVA Electrophoresis, Heidelberg, Germany</td>
			<td>23114.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin coating for tubes</td>
			<td>Ension, Pittsburgh, USA</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Heparin-Natrium (25.000 IE/ 5 mL)</td>
			<td>LEO Pharma, Neu-Isenburg, Germany</td>
			<td>PZN 15261203</td>
			<td></td>
		</tr>
		<tr>
			<td>Multiplate Reader Mithras LB 940</td>
			<td>Berthold, Bad Wildbad, Germany</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>NaCl 0,9%</td>
			<td>Fresenius-Kabi, Bad-Homburg, Germany</td>
			<td>1312813</td>
			<td></td>
		</tr>
		<tr>
			<td>Neutral monovettes (9 mL)</td>
			<td>Sarstedt, N&#252;mbrecht, Germany</td>
			<td>2,10,63,001</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS buffer (w/o Ca2+/Mg2+)</td>
			<td>Thermo Fisher Scientific, Darmstadt, Germany</td>
			<td>70011044</td>
			<td></td>
		</tr>
		<tr>
			<td>Peristaltic pump ISM444B</td>
			<td>Cole Parmer, Wertheim, Germany</td>
			<td>3475</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette (100 &#181;L)</td>
			<td>Eppendorf, Wesseling-Berzdorf, Germany</td>
			<td>3124000075</td>
			<td></td>
		</tr>
		<tr>
			<td>Pipette (1000 &#181;L)</td>
			<td>Eppendorf, Wesseling-Berzdorf, Germany</td>
			<td>3123000063</td>
			<td></td>
		</tr>
		<tr>
			<td>Plastic container (100 mL)</td>
			<td>Sarstedt, N&#252;mbrecht, Germany</td>
			<td>7,55,62,300</td>
			<td></td>
		</tr>
		<tr>
			<td>PMN-Elastase ELISA</td>
			<td>Demeditec Diagnostics, Kiel Germany</td>
			<td>DEH3311</td>
			<td></td>
		</tr>
		<tr>
			<td>Polyvinyl chloride tube</td>
			<td>Saint-Gobain Performance Plastics Inc., Courbevoie France</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Reaction Tubes (1.5 mL)</td>
			<td>Eppendorf, Wesseling-Berzdorf, Germany</td>
			<td>30123328</td>
			<td></td>
		</tr>
		<tr>
			<td>neurovascular laser-cut implants</td>
			<td>Acandis GmbH, Pforzheim</td>
			<td>01-0011x</td>
			<td></td>
		</tr>
		<tr>
			<td>SC5b-9 ELISA</td>
			<td>TECOmedical, Buende, Germany</td>
			<td>A029</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning electron microscope</td>
			<td>Cambridge Instruments, Cambridge, UK</td>
			<td>-</td>
			<td></td>
		</tr>
		<tr>
			<td>Sealing tape (96 well plate)</td>
			<td>Thermo Fisher Scientific, Darmstadt, Germany</td>
			<td>15036</td>
			<td></td>
		</tr>
		<tr>
			<td>Syringe 10/12 mL Norm-Ject</td>
			<td>Henke-Sass-Wolf, Tuttlingen, Germany</td>
			<td>10080010</td>
			<td></td>
		</tr>
		<tr>
			<td>TAT micro kit</td>
			<td>Siemens Healthcare, Marburg, Germany</td>
			<td>OWMG15</td>
			<td></td>
		</tr>
		<tr>
			<td>Waterbath Type 1083</td>
			<td>Gesellschaft f&#252;r Labortechnik, Burgwedel, Germany</td>
			<td>-</td>
			<td></td>
		</tr>
	</tbody>
</table>

hemocompatibility testing of blood-contacting implants in a flow loop model mimicking human blood flow

The growing use of medical devices (e.g., vascular grafts, stents, and cardiac catheters) for temporary or permanent purposes that remain in the body&#39;s circulatory system demands a reliable and multiparametric approach that evaluates the possible hematologic complications caused by these devices (i.e., activation and destruction of blood components). Comprehensive in vitro hemocompatibility testing of blood-contacting implants is the first step towards successful in vivo implementation. Therefore, extensive analysis according to the International Organization for Standardization 10993-4 (ISO 10993-4) is mandatory prior to clinical application. The presented flow loop describes a sensitive model to analyze the hemostatic performance of stents (in this case, neurovascular) and reveal adverse effects. The use of fresh human whole blood and gentle blood sampling are essential to avoid the preactivation of blood. The blood is perfused through a heparinized tubing containing the test specimen by using a peristaltic pump at a rate of 150 mL/min at 37 &#176;C for 60 min. Before and after perfusion, hematologic markers (i.e., blood cell count, hemoglobin, hematocrit, and plasmatic markers) indicating the activation of leukocytes (polymorphonuclear [PMN]-elastase), platelets (&#946;-thromboglobulin [&#946;-TG]), the coagulation system (thombin-antithrombin III [TAT]), and the complement cascade (SC5b-9) are analyzed. In conclusion, we present an essential and reliable model for extensive hemocompatibility testing of stents and other blood-contacting devices prior to clinical application.

Briefly summarized, human whole blood was collected in heparin-loaded monovettes then pooled and used to evaluate the baseline levels of cell counts as well as plasmatic hemocompatibility markers.
Subsequently, the tubing containing the neurovascular implant samples was filled, and the blood was perfused for 60 min at 150 mL/min and 37 &#176;C using a peristaltic pump. Again, the number of cells was analyzed in all groups, and the plasma samples were prepared for ELISA analyses (<strong class=...

Watch this Scientific Journal Video about Hemocompatibility Testing of Blood-Contacting Implants in a Flow Loop Model Mimicking Human Blood Flow at JoVE.com

Hemocompatibility Testing of Blood-Contacting Implants in a Flow Loop Model Mimicking Human Blood Flow

This protocol describes a comprehensive hemocompatibility evaluation of blood-contacting devices using laser-cut neurovascular implants. A flow loop model with fresh, heparinized human blood is applied to mimic blood flow. After perfusion, various hematologic markers are analyzed and compared to the values gained directly after blood collection for hemocompatibility evaluation of the tested devices.

The growing use of medical devices (e.g., vascular grafts, stents, and cardiac catheters) for temporary or permanent purposes that remain in the ...

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