Diese Arbeit wurde von der Abteilung für Zivil- und Umwelttechnik und College of Engineering an der University of Illinois in Urbana-Champaign unterstützt. Wir erkennen die Ravindra Kinra und Kavita Kinra Fellowship für die Unterstützung der graduate Studies der Kavya Mendu. Scanning Electron Microscopy Untersuchung erfolgte in den Einrichtungen des Frederick Seitz Material Research Laboratory und Beckman Institute an der University of Illinois at Urbana-Champaign.

Hinweis: Die hier beschriebene Protokoll erfolgt nach den Richtlinien der Tierbetreuung des Illinois institutionelle Tier Pflege und Verwendung.
1. Probe Beschaffung
<ol><li>Sammeln Sie frisch geerntete bovine Oberschenkelknochen von Vereinigte Staaten Abteilung des Landwirtschaftsministeriums USDA-zertifizierten Schlachthof und transportieren sie in Plastik luftdicht Taschen in einem Kühler. Hinweis: Für die hier durchgeführten Studie wurden Oberschenkelknochen von Tieren gesammelt, die 24-30 Monate alt, Mais gefütterten und wog ca. 1.000 - 1.100 Pfund waren.</li>
	<li>Einfrieren der Oberschenkelknochen am –20 ° C bis zum Beginn des Verfahrens Probe Vorbereitung. Diese Temperatur hält der Oberschenkelknochen frischen12,13,14.</li>
</ol>(2) schneiden, Reinigung und Einbetten der Proben
<ol><li>Die gefrorenen Oberschenkelknochen in einem Behälter mit Wasser für ca. 2 h bei Raumtemperatur auftauen.</li>
	<li>Schneiden Sie mehrere Scheiben ca. 10-15 mm dick, aus der Mitte Diaphyse Region mit einer Tabelle Top Diamant-Bandsäge, um Exemplare mit einheitlichen Querschnittsfläche des kortikalen Knochens zu produzieren.</li>
	<li>Verwenden Sie eine Dissektion Kit, um Weichgewebe oder Fleisch befestigt an der Kortikalis zu entfernen.</li>
	<li>Schnitt der Querschnitte der Oberschenkelknochen im Schritt 2.2 mit einer Diamant-wafering Klinge auf eine niedrige Drehzahl erreicht sah unter nassen Bedingungen entlang der Längsachse des Knochens, mehrere grob quaderförmigen Abschnitte zu erhalten. Hinweis: Hier, nur Probenvorbereitung und Scratch-Tests durchgeführt auf dem kurzen – longitudinal Exemplare werden diskutiert. Außer für die Richtung des Schneidens bleibt jedoch die Vorbereitung-Verfahren für die transversale Ausrichtung gleich.</li>
	<li>Reinigen Sie die Proben in einer Lösung bereit, mit 1,5 % anionischen Reiniger und 5 % Bleichmittel für eine Dauer von 20 Minuten in einem Ultraschallreiniger.</li>
	<li>
Betten Sie die Kortikalis Exemplare in Acrylharz (hierin Polymethyl Methacrylat (PMMA)) für eine einfache Handhabung und Stabilität.
	<ol>
<li>Um die Exemplare einzubetten, Mantel zuerst die Wände der Form mit Trennmittel. Dann mischen Sie Acryl Harz und härter in ein Becherglas, gemäß den Anweisungen des Herstellers der PMMA.</li>
		<li>Legen Sie eine der geschnittenen Kortikalis Exemplare in jeder Form mit der Oberfläche verkratzt werden nach unten. Gießen Sie die Mischung Acrylharz in diese Probenhalter vorbereitet. Lassen Sie die Proben für eine Dauer von bis zu 4-5 Std. zu heilen.</li>
	</ol>
</li>
	<li>Die eingebetteten Proben in 5 mm dicke Scheiben schneiden, aussetzen der Oberfläche verkratzt werden, mit der niedrigen Drehzahl sah und montieren Sie die Proben auf Metall (Aluminium)-Discs der Durchmesser 34 mm und Höhe 5 mm mit Cyanacrylat-Klebstoff.</li>
	<li>Die Exemplare in einem Messgerät in Hanks ausgewogen salzhaltige Lösung (HBSS) getränkten wickeln und im Kühlschrank bei 4 ° C bis zum weiteren Gebrauch15,16.</li>
</ol>3. Schleifen und Polieren von Protokollen
Hinweis: Voraussetzung für die hochpräzise Tests bei kleinen Längenskalen ist eine glatte und Ebenen Oberfläche der Proben. Frühere Protokolle Polieren13,17 eine große Rauheit der Oberfläche, was zu erheblichen Ungenauigkeiten bei der Messung führen. Die Herausforderung liegt darin, niedrige durchschnittliche Rauheit der Oberfläche, weniger als 100 nm, über eine große Fläche 3 x 8 mm2 Fläche.
<ol><li>Schleifen Sie die bovine Kortikalis Proben bei Raumtemperatur mit Körnung 400 und 600 Korn Siliciumcarbid Papiere für 1 min und 5 min, bzw.. Pflegen Sie der Schleifer-Polierer Basis Geschwindigkeiten von 100 u/min und 150 u/min, bzw..</li>
	<li>Maschine Schleifen die bovine Kortikalis Proben bei Raumtemperatur auf 800 und 1.200 Grit Papieren für eine Dauer von 15 min für jeden Schritt. Pflegen Sie den Schleifer-Polierer Basis Geschwindigkeit von 150 u/min, Geschwindigkeit von 60 u/min sind und die Last von 1 lb.</li>
	<li>Polieren der Proben mit 3 µm, 1 µm und 0,25 µm Diamant Fahrwerkslösungen in der gleichen Reihenfolge auf eine harte, perforierte, Vlies-Tuch für eine Dauer von 90 min bei Raumtemperatur. Pflegen Sie die Betriebslast für jeden Schritt bei 1 lb mit der Basis und Kopf Geschwindigkeiten von der Schleifer bei 300 u/min und 60 u/min, bzw..</li>
	<li>Polieren Sie die Probe mit 0,05 µm Aluminiumoxid Aussetzung-Lösung auf einem weichen, synthetischen Viskose-Tuch für eine Dauer von 90 min bei 1 lb mit base und Kopf Geschwindigkeit von 100 u/min und 60 u/min, bzw. auch bei Raumtemperatur.</li>
	<li>Setzen Sie die Proben in ein Becherglas mit deionisiertes Wasser und setzen Sie den Becher in ein Ultraschallbad für 2 min zwischen einzelnen aufeinander folgenden Schritte Schleifen und Polieren zur Reinigen des Rückstands und zur Vermeidung von Kreuzkontamination.</li>
	<li>Zeigen Sie die Oberflächen-Features mit optischen Mikroskopie und Imaging SEM an Hinweis: Wie in Abbildung 1, Osteons, Haversschen Kanälen, Zement-Linien dargestellt, wurden interstitielle Regionen und Lücken auf die bovine Kortikalis Exemplare beobachtet. Diese bildgebenden Verfahren zeigen die poröse, heterogene und anisotrope Natur der Kortikalis Exemplare. Darüber hinaus wurde erweiterte Oberfläche Untersuchung der Proben durchgeführt, um die Qualität der polierten Oberfläche zu bewerten. Eine repräsentative polierte Oberfläche ist in Abbildung 2dargestellt.</li>
</ol>4. Mikro Scratch-Test
Hinweis: Micro Scratch-Tests werden auf der polierten bovinen kortikalen Knochenproben mit einem Mikro-Scratch-Tester (Abbildung 3) durchgeführt. Die Studie dient ein Diamant Rockwell Eindringkörper mit einem Tip-Radius von 200 µm und Spitze Winkel von 120°. Das Gerät erlaubt die Anwendung der progressiven Linienlast bis zu 30 N. Darüber hinaus verfügt das Instrument über hochpräzise Sensoren zur Messung der Horizontallast, Eindringtiefe und akustische Emissionen, die durch Kratzen. Das Instrument kann die Panoramen der Kratzer Rillen erfassen.
<ol><li>Vor der Prüfung der kortikalen Knochenproben Kalibrieren der Rockwell Eindringkörper Spitze mit Polycarbonat als Referenz Material3.</li>
	<li>Platzieren Sie die Kortikalis-Probe auf der Bühne und wählen Sie die Seite der Scratch-Test das optische Mikroskop integrierten Mikro-Scratch-Tester-Modul eingerichtet.</li>
	<li>Anwenden einer progressiven Linienlast mit einer Start-Belastung von 30 mN und Ende Last von 30 N. Die Raumbelastung sollte 60 N/min und die Kratzer Länge bis 3 mm betragen.</li>
	<li>Reihe von Scratch-Tests ausführen, auf kurze längs-(Abb. 3 b) bovine Kortikalis Exemplare wie in Abbildung 3dargestellt.</li>
	<li>Nass der Probenoberfläche mit HBSS nach einem Satz von jeder drei bis vier Kratztests zu halten hydratisiert.</li>
	<li>Analysieren Sie die Kratzer Testdaten basierend auf nicht-lineare Bruchmechanik Modellierung2.</li>
</ol>

<ol>
	<li>Akono, A., Reis, P., Ulm, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scratching+as+a+fracture+process:+From+butter+to+steel.">Scratching as a fracture process: From butter to steel.</a> Phys Rev Lett. 106 (20), 204302-204304 (2011).</li><li>Akono, A. T., Randall, N. X., Ulm, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+determination+of+the+fracture+toughness+via+microscratch+tests:+application+to+polymers,+ceramics,+and+metals.">Experimental determination of the fracture toughness via microscratch tests: application to polymers, ceramics, and metals.</a> J of Mat Res. 27 (02), 485-493 (2012).</li><li>Akono, A. T., Ulm, F. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+technique+for+characterizing+the+fracture+toughness+via+scratch+test+experiments.">An improved technique for characterizing the fracture toughness via scratch test experiments.</a> Wear. 313 (1-2), (2014).</li><li>Akono, A. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Energetic+size+effect+law+at+the+microscopic+scale:+Application+to+progressive-load+scratch+testing.">Energetic size effect law at the microscopic scale: Application to progressive-load scratch testing.</a> J of Nanomech and Micromech. 6 (2), (2016).</li><li>Kataruka, A., Mendu, K., Okeoghene, O., Puthuvelil, J., Akono, A. -. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microscopic+assessment+of+bone+toughness+using+scratch+tests.">Microscopic assessment of bone toughness using scratch tests.</a> Bone Reports. 6, 17-25 (2017).</li><li>Melvin, J. W., Evans, F. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crack+propagation+in+bone.">Crack propagation in bone.</a> ASME Biomech Symp. , (1973).</li><li>Norman, T. L., Vashishth, D., Burr, D. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+groove+on+bone+fracture+toughness.">Effect of groove on bone fracture toughness.</a> J of Biomech. 25 (12), 1489-1492 (1992).</li><li>Behiri, J. C., Bonfield, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Crack+velocity+dependence+of+longitudinal+fracture+in+bone.">Crack velocity dependence of longitudinal fracture in bone.</a> J of Mat Sc. 15 (7), 1841-1849 (1980).</li><li>Mullins, L. P., Bruzzi, M. S., McHugh, P. E. <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+the+microstructural+fracture+toughness+of+cortical+bone+using+indentation+fracture.">Measurement of the microstructural fracture toughness of cortical bone using indentation fracture.</a> J of Biomech. 40 (14), 3285-3288 (2007).</li><li>Harding, D. S., Oliver, W. C., Pharr, 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=Cracking+during+nanoindentation+and+its+use+in+the+measurement+of+fracture+toughness.">Cracking during nanoindentation and its use in the measurement of fracture toughness.</a> MRS Proceedings. 356, 663-668 (1994).</li><li>Islam, A., Dong, X. N., Wang, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanistic+modeling+of+a+nanoscratch+test+for+determination+of+in+situ+toughness+of+bone.">Mechanistic modeling of a nanoscratch test for determination of in situ toughness of bone.</a> J of the Mech Bhvr of Biomed Mat. 5 (1), 156-164 (2012).</li><li>McAlden, R. W., McGeogh, J. A., Barker, M. B., Court-Brown, C. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Age-related+changes+in+the+tensile+properties+of+cortical+bone:+the+relative+importance+of+changes+in+porosity,+mineralization+and+microstructure.">Age-related changes in the tensile properties of cortical bone: the relative importance of changes in porosity, mineralization and microstructure.</a> J. Bone Joint Surg. 75, 1193-1205 (1993).</li><li>Zioupos, P., Gresle, M., Winwood, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fatigue+strength+of+human+cortical+bone:+age,+physical,+and+material+heterogeneity+effects.">Fatigue strength of human cortical bone: age, physical, and material heterogeneity effects.</a> J of Biomed Mat Res Part A. 86 (3), 627-636 (2008).</li><li>Linde, F., S&#248;rensen, H. C. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+different+storage+methods+on+the+mechanical+properties+of+trabecular+bone.">The effect of different storage methods on the mechanical properties of trabecular bone.</a> J of Biomech. 26 (10), 1249-1252 (1993).</li><li>Zioupos, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Accumulation+of+in-vivo+fatigue+microdamage+and+its+relation+to+biomechanical+properties+in+ageing+human+cortical+bone.">Accumulation of in-vivo fatigue microdamage and its relation to biomechanical properties in ageing human cortical bone.</a> J of Microscopy. 201 (2), 270-278 (2001).</li><li>Yan, J., Clifton, K. B., Mecholsky, J. J., Reep, R. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fracture+toughness+of+manatee+rib+and+bovine+femur+using+a+chevron-notched+beam+test.">Fracture toughness of manatee rib and bovine femur using a chevron-notched beam test.</a> J of Biomech. 39 (6), 1066-1074 (2006).</li><li>Xu, J., Rho, J. Y., Mishra, S. R., Fan, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Atomic+force+microscopy+and+nanoindentation+characterization+of+human+lamellar+bone+prepared+by+microtome+sectioning+and+mechanical+polishing+technique.">Atomic force microscopy and nanoindentation characterization of human lamellar bone prepared by microtome sectioning and mechanical polishing technique.</a> J of Biomed Mat ResPart A. 67 (3), 719-726 (2003).</li><li>Yan, J., Mecholsky, J. J., Clifton, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=How+tough+is+bone?+Application+of+elastic–plastic+fracture+mechanics+to+bone.">How tough is bone? Application of elastic–plastic fracture mechanics to bone.</a> Bone. 40 (2), 479-484 (2007).</li><li>Ritchie, R. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+conflicts+between+strength+and+toughness.">The conflicts between strength and toughness.</a> Nat Mater. 10 (11), 817-822 (2011).</li><li>Kim, K. T., Ba&#382;ant, Z. P., Yu, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Non-uniqueness+of+cohesive-crack+stress-separation+law+of+human+and+bovine+bones+and+remedy+by+size+effect+tests.">Non-uniqueness of cohesive-crack stress-separation law of human and bovine bones and remedy by size effect tests.</a> Intrnl J of Frac. 181 (1), 67-81 (2013).</li><li>Bazant, Z. P., Planas, 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> Fracture and size effect in concrete and other quasibrittle materials. 16, (1997).</li></ol>

Die Autoren haben nichts preisgeben.

Mikro Kratztests induzieren eine mixed-Mode-Fraktur-3. Darüber hinaus werden in den kurzen längs bovine Kortikalis Proben Bruchvorgänge aktiviert, wie die Sonde tiefer gräbt. Für einen 3 mm langen Kratzer ist der prismatischen Band sondiert rund 3.600 µm lang und 600 µm breite 480 µm Tiefe. Diese große Menge half bei der Vorhersage einer homogenisierten Antwort. Eine nicht-lineare Fraktur Mechanik Modell konnten wir extrahieren die Bruchfestigkeit, basierend auf der J-integrale B...

In dieser Studie messen wir die Bruchzähigkeit von Rindern kompakten Knochen aus der mesoskaligen (Osteons), Microscale (lamellare Ebene) über eine neuartige Mikro-Kratzer-Technik1,2,3,4, 5. Bruchvorgänge einschließlich Rissausbreitung Initiierung und Riss im Knochen sind Längenskalen aufgrund der unterschiedlichen strukturellen Bestandteile und Organisation auf verschiedenen Ebenen der Hierarchie direkt beeinflusst. Daher unbedingt Beurteilung Knochenbruch bei kleineren Längenskalen nachgeben ein grundlegendes Verständnis der Knochenbrüchigkeit. Auf der einen Seite konventionelle Prüfungen wie z. B. die drei-Punkt-Biegung, kompakte Spannung und Biegung Untersuchungen sind häufig auf bovine Femur und Tibia zur Charakterisierung der Fraktur im makroskopischen Maßstab6,7, 8. auf der anderen Seite um die Bruchzähigkeit auf der mikroskopischen Skala zu messen, Vickerss Einrückung Fraktur vorgeschlagene9war. Mikro Einzug erfolgte mittels der Vickers Eindringkörpers radiale Risse erzeugen. Darüber hinaus erfolgte die Oliver Pharr Nanoindentation Fraktur Zähigkeit Methode mittels eine scharfe Cube Ecke Eindringkörpers10.
In den oben genannten Nanoindentation basierte Fraktur Zähigkeit Studien die Längen der so erzeugten Risse wurden vom Beobachter gemessen und eine semi-empirische Modell wurde verwendet, um die Bruchzähigkeit berechnen. Aber diese Methoden sind nachvollziehbar, subjektiv, und die Ergebnisse sind stark abhängig von der Fähigkeit des Beobachters wegen der Notwendigkeit, die Riss-Längen mit optischen Mikroskopie oder Rasterelektronenmikroskopie messen. Darüber hinaus Scratch-Tests wurden durchgeführt im Nano-Maßstab, aber die zugrunde liegenden mathematischen Modells ist nicht Physik-basiertes wie es nicht die Verringerung der Stärke durch Risse berücksichtigt und11 Defekte. So existiert eine Wissenslücke: eine Methode zur Beurteilung der Fraktur auf mikroskopischer Ebene basierend auf einem Physik-basiertes mechanistischen Modell. Diese Wissenslücke motiviert die Anwendung von Mikro-Kratzer-Tests um Knochen zu komprimieren, indem Sie zuerst auf porcinen Exemplare5. Die Studie hat jetzt erweitert um bovinen kortikalen Knochen zu verstehen.
Zwei verschiedene Ausrichtungen der Exemplare sind möglich: längs-quer und kurzen längs. Längs-quer entspricht Eigenschaften senkrecht zur Längsachse des Femur Fraktur. In der Erwägung, kurze längs-entspricht der Fraktur Eigenschaften entlang der Längsachse des Femur-5. In dieser Studie wenden wir kratzen Tests an bovinen kortikalen Knochen Bruchfestigkeit der Knochen in Längsrichtung kurz zu charakterisieren.

<table>
	<tbody>
		<tr>
			<td>Table Top Diamond Band Saw</td>
			<td>McMaster Carr, Elmhurst, IL</td>
			<td>Model&#160; C-40</td>
			<td>Blade speed of 40 mph; Blade dimensions: 37 inch in diameter, 0.02 inch wide and 0.14 inch deep</td>
		</tr>
		<tr>
			<td>Buehler Isomet 5000 Precision Cutter</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>112780</td>
			<td>Blade speed in the range of 200-5000 rpm in 50 rpm incrments; 8 inch diamond wafering blade</td>
		</tr>
		<tr>
			<td>Branson 5800 Ultrasonic Cleanser</td>
			<td>(Through) Grainger, Peoria, Illinois</td>
			<td>39J365</td>
			<td>Bransonic CPXH ultrasonic bath has a tank capacity of 2.5 gal</td>
		</tr>
		<tr>
			<td>Buehler Ecomet 250 Grinder - Polisher</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>497250</td>
			<td>8 inch base plate with a speed range from 10-500 rpm</td>
		</tr>
		<tr>
			<td>Anton Paar, CSM Instruments Micro scratch tester</td>
			<td>Anton Paar Switzerland AG</td>
			<td>163251</td>
			<td>Compact Platform, Acoutstic Emission Sensor</td>
		</tr>
		<tr>
			<td>JEOL 6060LV general purpose scanning electron microscope</td>
			<td>JEOL USA, Inc., Peabody, MA</td>
			<td></td>
			<td>Environmental scanning electron microscope which enables imaging at low vacuum levels.</td>
		</tr>
		<tr>
			<td>Philips XL30 ESEM FEG&#160;</td>
			<td>FEI Company</td>
			<td></td>
			<td>Wet mode working of the instrument enables imaging of non conductive samples without altering them&#160;</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Consumables</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bovine Femur</td>
			<td>L&#38;M Slaughter house, Georgetown, IL</td>
			<td></td>
			<td>Corn fed, 24-30 month old mature bovine specimens.</td>
		</tr>
		<tr>
			<td>Alconox Powdered Precision Cleaner</td>
			<td>Alconox, Inc., 30 Glenn St., Ste. 309, White Plains, NY, 10603</td>
			<td>1104-1</td>
			<td>Biodegradable, Non caustic, Interfering-residue free</td>
		</tr>
		<tr>
			<td>Acrylic Plastic Casting</td>
			<td>Electron Microscopy Sciences</td>
			<td>24210-02</td>
			<td>Polymethyl Methacrylate</td>
		</tr>
		<tr>
			<td>CarbiMet SiC Abrasive Paper 400 grit, 8 inch, PSA backed</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>36080400</td>
			<td>Grinding - Abrasive Papers</td>
		</tr>
		<tr>
			<td>CarbiMet SiC Abrasive Paper 600 grit, 8 inch, PSA backed</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>36080600</td>
			<td>Grinding - Abrasive Papers</td>
		</tr>
		<tr>
			<td>MicroCut Discs 800 grit, 8 inch, PSA backed</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>36080800</td>
			<td>Grinding - Abrasive Papers</td>
		</tr>
		<tr>
			<td>MicroCut Discs 800 grit, 8 inch, PSA backed</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>16081200</td>
			<td>Grinding - Abrasive Papers</td>
		</tr>
		<tr>
			<td>Texmet P For 8&#39;&#39; Wheel PSA</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>407638</td>
			<td>Polishing Cloth</td>
		</tr>
		<tr>
			<td>8&#39;&#39; Microcloth PSA</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>407518</td>
			<td>Polishing Cloth</td>
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		<tr>
			<td>Meta Di Supreme Polycrystalline Diamond Suspension, 3 &#181;m</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>406631</td>
			<td>Polishing suspension</td>
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			<td>Meta Di Supreme Polycrystalline Diamond Suspension, 1 &#181;m</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>406630</td>
			<td>Polishing suspension</td>
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			<td>Meta Di Supreme Polycrystalline Diamond Suspension, 0.25 &#181;m</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>406629</td>
			<td>Polishing suspension</td>
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			<td>MasterPrep Polishing Suspension, 0.05&#181;m</td>
			<td>Buehler,41 Waukegan Rd, Lake Bluff, IL 60044</td>
			<td>40-6377-032</td>
			<td>Polishing suspension</td>
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			<td>HBSS, calcium, magnesium, no phenol red</td>
			<td>Thermo Fisher Scientific</td>
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fragility assessment of bovine cortical bone using scratch tests

Knochen ist ein komplexes hierarchisches Material mit fünf verschiedenen Ebenen der Organisation. Faktoren wie Alterung und Krankheiten wie Osteoporose erhöhen die Fragilität der Knochen, so dass es anfällig für Frakturen. Aufgrund der großen sozio-ökonomischen Auswirkungen von Knochenbrüchen in unserer Gesellschaft gibt es eine Notwendigkeit für neuartige Möglichkeiten zur Beurteilung der mechanischen Leistung jeder Hierarchiestufe des Knochens. Obwohl Steifigkeit und Festigkeit auf allen Skalen – Nano-, Mikro-, Meso-, sondiert können und makroskopischen – Fraktur Bewertung bisher worden zu makroskopischen Prüfung beschränkt hat. Diese Einschränkung schränkt unser Verständnis von Knochenbrüchen und schränkt den Anwendungsbereich der Labor- und klinische Studien. In dieser Studie untersuchen wir die Bruchfestigkeit des Knochens aus der mikroskopischen auf der mesoskopischen Längenskalen mit Mikro Scratch-Tests kombiniert mit nichtlinearen Bruchmechanik. Die Tests sind in der kurzen längs Ausrichtung auf bovine Kortikalis Proben durchgeführt. Ein sorgfältige experimentelle Protokoll entwickelt und eine große Anzahl (102) von Tests werden durchgeführt, um die Bruchzähigkeit der Kortikalis Exemplare unter Berücksichtigung der Heterogenität zugeordnet Knochen Mikrostruktur zu beurteilen.

Rasterkraftmikroskopie wurde verwendet, um die Rauheit der polierten Oberfläche zu messen. Als Faustregel gilt qualifiziert das Exemplar als eine gut polierte, wenn die Rauheit der Oberfläche eine Größenordnung kleiner als die Oberflächen-Features von Interesse ist. In diesem Fall die gemessenen Oberflächenrauhigkeit von 60 nm 40 µm, 40 µm großflächig fällt eindeutig unter dieses Kriterium.
Abbild...

Watch this Scientific Journal Video about Fragility Assessment of Bovine Cortical Bone Using Scratch Tests at JoVE.com

Fragility Assessment of Bovine Cortical Bone Using Scratch Tests

Zerbrechlichkeit Bewertung der bovinen kortikalen Knochen mit Kratztests

Diese Studie bewertet die Bruchzähigkeit von bovinen kortikalen Knochen auf Sub-Meso-Ebene mit mikroskopischen Kratztests. Dies ist ein original, Ziel, streng, und reproduzierbare Methode vorgeschlagen, Bruchzähigkeit unterhalb der makroskopischen Skala zu erforschen. Anwendungsmöglichkeiten sind Änderungen in Knochenbrüchigkeit aufgrund von Krankheiten wie Osteoporose studieren.

Bone is a complex hierarchical material with five distinct levels of organization. Factors like aging and diseases like osteoporosis increase the ...

fragility-assessment-of-bovine-cortical-bone-using-scratch-tests

Research

JoVE Journal

Bioengineering

9.2K Aufrufe.  University of Illinois at Urbana Champaign. Diese Studie bewertet die Bruchzähigkeit von bovinen kortikalen Knochen auf Sub-Meso-Ebene mit mikroskopischen Kratztests. Dies ist ein original, Ziel, streng, und reproduzierbare Methode vorgeschlagen, Bruchzähigkeit unterhalb der makroskopischen Skala zu erforschen. Anwendungsmöglichkeiten sind Änderungen in Knochenbrüchigkeit aufgrund von Krankheiten wie Osteoporose studieren.

Serie: Fragility Assessment of Bovine Cortical Bone Using Scratch Tests

Use of Human Perivascular Stem Cells for Bone Regeneration

Human perivascular stem cells (PSCs) can be isolated in sufficient numbers from multiple tissues for purposes of skeletal tissue engineering1-3. PSCs are a FACS-sorted population of 'pericytes' (CD146+CD34-CD45-) and 'adventitial cells' (CD146-CD34+CD45-), each of which we have previously reported to have properties of mesenchymal stem cells. PSCs, like MSCs, are able to undergo osteogenic differentiation, as well as secrete pro-osteogenic cytokines1,2. In the present protocol, we demonstrate the osteogenicity of PSCs in several animal models including a muscle pouch implantation in SCID (severe combined immunodeficient) mice, a SCID mouse calvarial defect and a femoral segmental defect (FSD) in athymic rats. The thigh muscle pouch model is used to assess ectopic bone formation. Calvarial defects are centered on the parietal bone and are standardly 4 mm in diameter (critically sized)8. FSDs are bicortical and are stabilized with a polyethylene bar and K-wires4. The FSD described is also a critical size defect, which does not significantly heal on its own4. In contrast, if stem cells or growth factors are added to the defect site, significant bone regeneration can be appreciated. The overall goal of PSC xenografting is to demonstrate the osteogenic capability of this cell type in both ectopic and orthotopic bone regeneration models.

Human perivascular stem cells (PSCs) are a novel stem cell class for skeletal tissue regeneration similar to mesenchymal stem cells (MSCs). PSCs can be isolated by FACS (fluorescence activated cell sorting) from adipose tissue procured during standard liposuction procedures, then combined with an osteoinductive scaffold to achieve bone formation in vivo.

Verwenden Sie für Menschenrechte Perivaskuläre Stammzellen für die Knochenregeneration

Human perivascular stem cells (PSCs) can be isolated in sufficient numbers from multiple tissues for purposes of skeletal tissue engineering1-3. PSCs are ...

Forschung

Biotechnik

Preparation of Intact Bovine Tail Intervertebral Discs for Organ Culture

The intervertebral disc (IVD) is the joint of the spine connecting vertebra to vertebra. It functions to transmit loading of the spine and give flexibility to the spine. It composes of three compartments: the innermost nucleus pulposus (NP) encompassing by the annulus fibrosus (AF), and two cartilaginous endplates connecting the NP and AF to the vertebral body on both sides. Discogenic pain possibly caused by degenerative intervertebral disc disease (DDD) and disc herniations has been identified as a major problem in our modern society. To study possible mechanisms of IVD degeneration, in vitro organ culture systems with live disc cells are highly appealing. The in vitro culture of intact bovine coccygeal IVDs has advanced to a relevant model system, which allows the study of mechano-biological aspects in a well-controlled physiological and mechanical environment. Bovine tail IVDs can be obtained relatively easy in higher numbers and are very similar to the human lumbar IVDs with respect to cell density, cell population and dimensions. However, previous bovine caudal IVD harvesting techniques retaining cartilaginous endplates and bony endplates failed after 1-2 days of culture since the nutrition pathways were obviously blocked by clotted blood. IVDs are the biggest avascular organs, thus, the nutrients to the cells in the NP are solely dependent on diffusion via the capillary buds from the adjacent vertebral body. Presence of bone debris and clotted blood on the endplate surfaces can hinder nutrient diffusion into the center of the disc and compromise cell viability. Our group established a relatively quick protocol to "crack"-out the IVDs from the tail with a low risk for contamination. We are able to permeabilize the freshly-cut bony endplate surfaces by using a surgical jet lavage system, which removes the blood clots and cutting debris and very efficiently reopens the nutrition diffusion pathway to the center of the IVD. The presence of growth plates on both sides of the vertebral bone has to be avoided and to be removed prior to culture. In this video, we outline the crucial steps during preparation and demonstrate the key to a successful organ culture maintaining high cell viability for 14 days under free swelling culture. The culture time could be extended when appropriate mechanical environment can be maintained by using mechanical loading bioreactor. The technique demonstrated here can be extended to other animal species such as porcine, ovine and leporine caudal and lumbar IVD isolation.

This protocol illustrates a harvesting technique for coccygeal bovine intervertebral discs for organ culture for in vitro organ culture.

Vorbereitung von Intact Bovine Rute Bandscheiben für Orgel Kultur

The intervertebral disc (IVD) is the joint of the spine connecting  vertebra to vertebra. It functions to transmit loading of the spine and give  ...

In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that MicroCT provides quantitative high-resolution three-dimensional (3D) anatomical data non-destructively and longitudinally. Most importantly, with the development of a novel preclinical iodinated contrast agent called eXIA160, functional and metabolic assessment of the heart became possible. However, prior to the advent of commercial MicroCT scanners equipped with X-ray flat-panel detector technology and easy-to-use cardio-respiratory gating, preclinical studies of cardiovascular disease (CVD) in small animals required a MicroCT technologist with advanced skills, and thus were impractical for widespread implementation. The goal of this work is to provide a practical guide to the use of the high-speed Quantum FX MicroCT system for comprehensive determination of myocardial global and regional function along with assessment of myocardial perfusion, metabolism and viability in healthy mice and in a cardiac ischemia mouse model induced by permanent occlusion of the left anterior descending coronary artery (LAD).

In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography

This method outlines the use of Quantum Micro-Computed Tomography (MicroCT) to assess cardiac morphology, function, perfusion, metabolism and viability with iodinated contrast agent in mice with experimentally-induced myocardial ischemia. The technique can be applied for non-destructive high-throughput longitudinal in vivo imaging of various animal models of human heart disease.

In Vivo quantitative Bewertung der myokardialen Struktur, Funktion, Perfusion und Lebensfähigkeit Mit Herz Micro-Computertomographie

The use of Micro-Computed Tomography (MicroCT) for in vivo studies of small animals as models of human disease has risen tremendously due to the fact that ...

Modified Drop Tower Impact Tests for American Football Helmets

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

This article provides a novel technique to assess the performance characteristics of American football helmets by inclusion of faceguards during NOCSAE Standard drop tests. Additionally, two more impact locations are proposed to be added to the NOCSAE certification.

Modifizierte Fallturm Auswirkungen Tests für American Football Helme

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards ...

A Method to Estimate Cadaveric Femur Cortical Strains During Fracture Testing Using Digital Image Correlation

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral surface obtained from mechanical testing. This optical method requires a texture of many contrasting fiduciary marks on a solid white background for accurate tracking of surface deformation as loading is applied to the specimen. Immediately prior to testing, the surface of interest in the camera view is painted with a water-based white primer and allowed to dry for several minutes. Then, a black paint is speckled carefully over the white background with special consideration for the even size and shape of the droplets. Illumination is carefully designed and set such that there is optimal contrast of these marks while minimizing reflections through the use of filters. Images were obtained through high speed video capture at up to 12,000 frames/s. The key images prior to and including the fracture event are extracted and deformations are estimated between successive frames in carefully sized interrogation windows over a specified region of interest. These deformations are then used to compute surface strain temporally during the fracture test. The strain data is very useful for identifying fracture initiation within the femur, and for eventual validation of proximal femur fracture strength models derived from Quantitative Computed Tomography-based Finite Element Analysis (QCT/FEA).

In this protocol, the femur surface strains are estimated during fracture testing using the digital image correlation technique. The novelty of the method involves application of a high-contrast stochastic speckle pattern on the femur surface, carefully specified illumination, high speed video capture, and digital image correlation analysis for strain calculations.

Eine Methode, um Cadaveric Femur kortikalen Stämme während Fraktur Tests mit digitaler Bildkorrelation schätzen

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral ...

Biological Compatibility Profile on Biomaterials for Bone Regeneration

Large non-union bone fractures are a significant challenge in orthopedic surgery. Although auto- and allogeneic bone grafts are excellent for healing such lesions, there are potential complications with their use. Thus, material scientists are developing synthetic, biocompatible biomaterials to overcome these problems. In this study, we present a multidisciplinary platform for evaluating biomaterials for bone repair. We combined expertise from bone biology and immunology to develop a platform including in vitro osteoclast (OC) and osteoblast (OB) assays and in vivo mouse models of bone repair, immunogenicity, and allergenicity. We demonstrate how to perform the experiments, summarize the results, and report on biomaterial biocompatibility. In particular, we tested OB viability, differentiation, and mineralization and OC viability and differentiation in the context of &#946;-tricalcium phosphate (&#946;-TCP) disks. We also tested a &#946;-TCP/Collagen (&#946;-TCP/C) foam which is a commercially available material used clinically for bone repair in a critical-sized calvarial bone defect mouse model to determine the effects on the early phase of bone healing. In parallel experiments, we evaluated immune and allergic responses in mice. Our approach generates a biological compatibility profile of a bone biomaterial with a range of parameters necessary for predicting the biocompatibility of biomaterials used for bone healing and repair in patients.

The number of novel biomaterials engineered for repairing large bone lesions is continuously expanding with the aim to enhance bone healing and overcome the complications associated with bone transplantation. Here, we present a multidisciplinary strategy for pre-clinical biocompatibility testing of biomaterials for bone repair.

Biologische Verträglichkeit Profil auf Biomaterialien für Knochenregeneration

Large non-union bone fractures are a significant challenge in orthopedic surgery. Although auto- and allogeneic bone grafts are excellent for healing such ...

Calvarial Model of Bone Augmentation in Rabbit for Assessment of Bone Growth and Neovascularization in Bone Substitution Materials

The basic principle of the rabbit calvarial model is to grow new bone tissue vertically on top of the cortical part of the skull. This model allows assessment of bone substitution materials for oral and craniofacial bone regeneration in terms of bone growth and neovascularization support. Once animals are anesthetized and ventilated (endotracheal intubation), four cylinders made of polyether ether ketone (PEEK) are screwed onto the skull, on both sides of the median and coronal sutures. Five intramedullary holes are drilled within the bone area delimited by each cylinder, allowing influx of bone marrow cells. The material samples are placed into the cylinders which are then closed. Finally, the surgical site is sutured, and animals are awaken. Bone growth may be assessed on live animals by using microtomography. Once animals are euthanized, bone growth and neovascularization may be evaluated by using microtomography, immune-histology and immunofluorescence. As the evaluation of a material requires maximum standardization and calibration, the calvarial model appears ideal. Access is very easy, calibration and standardization are facilitated by the use of defined cylinders and four samples may be assessed simultaneously. Furthermore, live tomography may be used and ultimately a large decrease in animals to be euthanized may be anticipated.

Here we present a surgical protocol in rabbits with the aim to assess bone substitution materials in terms of bone regeneration capacities. By using PEEK cylinders fixed onto rabbit skulls, osteoconduction, osteoinduction, osteogenesis and vasculogenesis induced by the materials may be evaluated either on live or euthanized animals.

Calvarial-Modell der Knochenvergrößerung bei Kaninchen zur Beurteilung des Knochenwachstums und der Neovaskularisation in Knochensubstitutionsmaterialien

The basic principle of the rabbit calvarial model is to grow new bone tissue vertically on top of the cortical part of the skull. This model allows ...

Measuring 3D In-vivo Shoulder Kinematics using Biplanar Videoradiography

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, multiple ligaments, and approximately 20 muscles. Unfortunately, shoulder pathologies (e.g., rotator cuff tears, joint dislocations, arthritis) are common, resulting in substantial pain, disability, and decreased quality of life. The specific etiology for many of these pathologic conditions is not fully understood, but it is generally accepted that shoulder pathology is often associated with altered joint motion. Unfortunately, measuring shoulder motion with the necessary level of accuracy to investigate motion-based hypotheses is not trivial. However, radiographic-based motion measurement techniques have provided the advancement necessary to investigate motion-based hypotheses and provide a mechanistic understanding of shoulder function. Thus, the purpose of this article is to describe the approaches for measuring shoulder motion using a custom biplanar videoradiography system. The specific objectives of this article are to describe the protocols to acquire biplanar videoradiographic images of the shoulder complex, acquire CT scans, develop 3D bone models, locate anatomical landmarks, track the position and orientation of the humerus, scapula, and torso from the biplanar radiographic images, and calculate the kinematic outcome measures. In addition, the article will describe special considerations unique to the shoulder when measuring joint kinematics using this approach.

Biplane videoradiography can quantify shoulder kinematics with a high degree of accuracy. The protocol described herein was specifically designed to track the scapula, humerus, and the ribs during planar humeral elevation, and outlines the procedures for data collection, processing, and analysis. Unique considerations for data collection are also described.

Messung der 3D-In-vivo-Schulterkinematik mittels biplanarer Videoradiographie

The shoulder is one of the human body's most complex joint systems, with motion occurring through the coordinated actions of four individual joints, ...

3D Bioprinting of Murine Cortical Astrocytes for Engineering Neural-Like Tissue

Astrocytes are glial cells with an essential role in the central nervous system (CNS), including neuronal support and functionality. These cells also respond to neural injuries and act to protect the tissue from degenerative events. In vitro studies of astrocytes&#39; functionality are important to elucidate the mechanisms involved in such events and contribute to developing therapies to treat neurological disorders. This protocol describes a method to biofabricate a neural-like tissue structure rich in astrocytes by 3D bioprinting astrocytes-laden bioink. An extrusion-based 3D bioprinter was used in this work, and astrocytes were extracted from C57Bl/6 mice pups&#39; brain cortices. The bioink was prepared by mixing cortical astrocytes from up to passage 3 to a biomaterial solution composed of gelatin, gelatin-methacryloyl (GelMA), and fibrinogen, supplemented with laminin, which presented optimal bioprinting conditions. The 3D bioprinting conditions minimized cell stress, contributing to the high viability of the astrocytes during the process, in which 74.08% &#177; 1.33% of cells were viable right after bioprinting. After 1 week of incubation, the viability of astrocytes significantly increased to 83.54% &#177; 3.00%, indicating that the 3D construct represents a suitable microenvironment for cell growth. The biomaterial composition allowed cell attachment and stimulated astrocytic behavior, with cells expressing the specific astrocytes marker glial fibrillary acidic protein (GFAP) and possessing typical astrocytic morphology. This&#160;reproducible protocol provides a valuable method to biofabricate 3D neural-like tissue rich in astrocytes that resembles cells&#39; native microenvironment, useful to researchers that aim to understand astrocytes&#39; functionality and their relation to the mechanisms involved in neurological diseases.

Here we report a method of 3D bioprinting murine cortical astrocytes for biofabricating neural-like tissues to study the functionality of astrocytes in the central nervous system and the mechanisms involving glial cells in neurological diseases and treatments.

3D-Bioprinting von murinen kortikalen Astrozyten für die Entwicklung von neuralähnlichem Gewebe

Astrocytes are glial cells with an essential role in the central nervous system (CNS), including neuronal support and functionality. These cells also ...

3D-Co-Kultur-Assay: Vaskularisierte osteogene Nischen für das Screening von Krebsmedikamenten

Simple Establishment of a Vascularized Osteogenic Bone Marrow Niche Using Pre-Cast Poly(ethylene Glycol) (PEG) Hydrogels in an Imaging Microplate

The bone and bone marrow are highly vascularized and structurally complex organs, and are sites for cancer and metastasis formation. In vitro models recapitulating bone- and bone marrow-specific functions, including vascularization, that are compatible with drug screening are highly desirable. Such models can bridge the gap between simplistic, structurally irrelevant two-dimensional (2D) in vitro models and the more expensive, ethically challenging in vivo models. This article describes a controllable three-dimensional (3D) co-culture assay based on engineered poly(ethylene glycol) (PEG) matrices for the generation of vascularized, osteogenic bone-marrow niches. The PEG matrix design allows the development of 3D cell cultures through a simple cell seeding step requiring no encapsulation, thus enabling the development of complex co-culture systems. Furthermore, the matrices are transparent and pre-cast onto glass-bottom 96-well imaging plates, rendering the system suitable for microscopy. For the assay described here, human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) are cultured first until a sufficiently developed 3D cell network is formed. Subsequently, GFP-expressing human umbilical vein endothelial cells (HUVECs) are added. The culture development is followed by bright-field and fluorescence microscopy. The presence of the hBM-MSC network supports the formation of vascular-like structures that otherwise&#160;would not form and that remain stable for at least 7 days. The extent of vascular-like network formation can easily be quantified. This model can be tuned toward an osteogenic bone-marrow niche by supplementing the culture medium with bone morphogenetic protein 2 (BMP-2), which promotes the osteogenic differentiation of the hBM-MSCs, as assessed by increased alkaline phosphatase (ALP) activity at day 4 and day 7 of co-culture. This cellular model can be used as a platform for culturing various cancer cells and studying how they interact with bone- and bone marrow-specific vascular niches. Moreover, it is suitable for automation and high-content analyses, meaning it would enable cancer drug screening under highly reproducible culture conditions.

Autor im Rampenlicht: Einfache Etablierung einer vaskularisierten osteogenen Knochenmarknische mit vorgegossenen Poly(ethylenglykol) (PEG)-Hydrogelen in einer bildgebenden Mikroplatte  

An in vitro model of the bone marrow vascular niche is established by seeding mesenchymal and endothelial cells onto pre-cast 3D PEG hydrogels. The endothelial networks, ECM components, and ALP activity of the niches vary depending on the growth factor used. The platform can be used for advanced cancer models.

Einfache Etablierung einer vaskularisierten osteogenen Knochenmarksnische unter Verwendung von vorgegossenen Poly(ethylenglykol) (PEG)-Hydrogelen in einer bildgebenden Mikrotiterplatte

The bone and bone marrow are highly vascularized and structurally complex organs, and are sites for cancer and metastasis formation. In vitro models ...