Name: biomechanical testing of murine tendons
Uploaded: 2019-10-15T14:30:00
Description: Watch this Scientific Journal Video about Biomechanical Testing of Murine Tendons at JoVE.com

Lo studio è stato sostenuto dal NIH / NIAMS (R01 AR055580, R01 AR057836).

Gli studi sugli animali sono stati approvati dal Comitato istituzionale per la cura e l'uso degli animali della Columbia University. I topi utilizzati in questo studio erano di sfondo C57BL/6J e sono stati acquistati dal Jackson Laboratory (Bar Harbor, ME, USA). Essi sono stati alloggiati in condizioni di barriera senza agenti patogeni e sono stati forniti cibo e acqua al libitum.
1. Sviluppo di apparecchi stampati in 3D personalizzati per afferrare l'osso
<ol><li>Acquisizione di immagini os...

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D., Yamaguchi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+outcome+and+repair+integrity+of+completely+arthroscopically+repaired+large+and+massive+rotator+cuff+tears.">The outcome and repair integrity of completely arthroscopically repaired large and massive rotator cuff tears.</a> The Journal of Bone and Joint Surgery. 86, 219-224 (2004).</li><li>Sher, J. S., Uribe, J. W., Posada, A., Murphy, B. J., Zlatkin, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Abnormal+findings+on+magnetic+resonance+images+of+asymptomatic+shoulders.">Abnormal findings on magnetic resonance images of asymptomatic shoulders.</a> The Journal of Bone and Joint Surgery. 77, 10-15 (1995).</li><li>Ker, R. F., Wang, X. T., Pike, A. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fatigue+quality+of+mammalian+tendons.">Fatigue quality of mammalian tendons.</a> The Journal of Experimental Biology. 203, 1317-1327 (2000).</li><li>Wilson, J. J., Best, T. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Common+overuse+tendon+problems:+A+review+and+recommendations+for+treatment.">Common overuse tendon problems: A review and recommendations for treatment.</a> American Family Physician. 72, 811-818 (2005).</li><li>Fleischer, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanical+strength+and+failure+mechanism+of+different+tubercula+refixation+methods+within+the+framework+of+an+arthroplasty+for+shoulder+fracture.">Biomechanical strength and failure mechanism of different tubercula refixation methods within the framework of an arthroplasty for shoulder fracture.</a> Orthopaedics &amp; Traumatology: Surgery &amp; Research. 103, 165-169 (2017).</li><li>West, J. R., Juncosa, N., Galloway, M. T., Boivin, G. P., Butler, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+in+vivo+Achilles+tendon+forces+in+rabbits+during+treadmill+locomotion+at+varying+speeds+and+inclinations.">Characterization of in vivo Achilles tendon forces in rabbits during treadmill locomotion at varying speeds and inclinations.</a> Journal of Biomechanics. 37, 1647-1653 (2004).</li><li>Cavinatto, L., 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=Early+versus+late+repair+of+rotator+cuff+tears+in+rats.">Early versus late repair of rotator cuff tears in rats.</a> Journal of Shoulder and Elbow Surgery. 27, 606-613 (2018).</li><li>Potter, R., Havlioglu, N., Thomopoulos, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+developing+shoulder+has+a+limited+capacity+to+recover+after+a+short+duration+of+neonatal+paralysis.">The developing shoulder has a limited capacity to recover after a short duration of neonatal paralysis.</a> Journal of Biomechanics. 47, 2314-2320 (2014).</li><li>Connizzo, B. K., Sarver, J. J., Iozzo, R. V., Birk, D. E., Soslowsky, L. J. <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+Age+and+Proteoglycan+Deficiency+on+Collagen+Fiber+Re-Alignment+and+Mechanical+Properties+in+Mouse+Supraspinatus+Tendon.">Effect of Age and Proteoglycan Deficiency on Collagen Fiber Re-Alignment and Mechanical Properties in Mouse Supraspinatus Tendon.</a> Journal of Biomechanical Engineering. 135, 021019 (2013).</li><li>Beason, 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=Hypercholesterolemia+increases+supraspinatus+tendon+stiffness+and+elastic+modulus+across+multiple+species.">Hypercholesterolemia increases supraspinatus tendon stiffness and elastic modulus across multiple species.</a> Journal of Shoulder and Elbow Surgery. 22, 681-686 (2013).</li><li>Miller, K. S., Connizzo, B. K., Soslowsky, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collagen+fiber+re-alignment+in+a+neonatal+developmental+mouse+supraspinatus+tendon+model.">Collagen fiber re-alignment in a neonatal developmental mouse supraspinatus tendon model.</a> Annals of Biomedical Engineering. 40, 1102-1110 (2012).</li><li>Cong, G. 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=Evaluating+the+role+of+subacromial+impingement+in+rotator+cuff+tendinopathy:+Development+and+analysis+of+a+novel+murine+model.">Evaluating the role of subacromial impingement in rotator cuff tendinopathy: Development and analysis of a novel murine model.</a> Journal of Orthopaedic Research. 36, 2780-2788 (2018).</li><li>Thomopoulos, S., Birman, V., Genin, 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=Structural+Interfaces+and+Attachments+in+Biology.">Structural Interfaces and Attachments in Biology.</a> Infection and Immunity. 35, (2013).</li><li>Boivin, G. 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=Biomechanical+properties+and+histology+of+db/db+diabetic+mouse+Achilles+tendon.">Biomechanical properties and histology of db/db diabetic mouse Achilles tendon.</a> Muscles, Ligaments and Tendons Journal. 4, 280-284 (2014).</li><li>Ansorge, H. L., Adams, S., Birk, D. E., Soslowsky, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical,+Compositional,+and+Structural+Properties+of+the+Post-natal+Mouse+Achilles+Tendon.">Mechanical, Compositional, and Structural Properties of the Post-natal Mouse Achilles Tendon.</a> Annals of Biomedical Engineering. 39, 1904-1913 (2011).</li><li>Shu, C. C., Smith, M. M., Appleyard, R. C., Little, C. B., Melrose, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Achilles+and+tail+tendons+of+perlecan+exon+3+null+heparan+sulphate+deficient+mice+display+surprising+improvement+in+tendon+tensile+properties+and+altered+collagen+fibril+organisation+compared+to+C57BL/6+wild+type+mice.">Achilles and tail tendons of perlecan exon 3 null heparan sulphate deficient mice display surprising improvement in tendon tensile properties and altered collagen fibril organisation compared to C57BL/6 wild type mice.</a> PeerJ. 6, 5120 (2018).</li><li>Probst, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+clamping+technique+for+biomechanical+testing+of+tendons+in+small+animals.">A new clamping technique for biomechanical testing of tendons in small animals.</a> Journal of Investigative Surgery. 13, 313-318 (2000).</li><li>Talan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Body+temperature+of+C57BL/6J+mice+with+age.">Body temperature of C57BL/6J mice with age.</a> Experimental Gerontology. 19, 25-29 (1984).</li><li>Newton, M. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+influence+of+testing+angle+on+the+biomechanical+properties+of+the+rat+supraspinatus+tendon.">The influence of testing angle on the biomechanical properties of the rat supraspinatus tendon.</a> Journal of Biomechanics. 49, 4159-4163 (2016).</li><li>Schwartz, A. G., Lipner, J. H., Pasteris, J. D., Genin, G. M., Thomopoulos, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Muscle+loading+is+necessary+for+the+formation+of+a+functional+tendon+enthesis.">Muscle loading is necessary for the formation of a functional tendon enthesis.</a> Bone. 55, 44-51 (2014).</li><li>Gimbel, J. A., Van Kleunen, J. P., Williams, G. R., Thomopoulos, S., Soslowsky, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long+durations+of+immobilization+in+the+rat+result+in+enhanced+mechanical+properties+of+the+healing+supraspinatus+tendon.">Long durations of immobilization in the rat result in enhanced mechanical properties of the healing supraspinatus tendon.</a> Journal of Biomechanical Engineering. 129, 400-404 (2006).</li><li>Freedman, B. R., Sarver, J. J., Buckley, M. R., Voleti, P. B., Soslowsky, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomechanical+and+structural+response+of+healing+Achilles+tendon+to+fatigue+loading+following+acute+injury.">Biomechanical and structural response of healing Achilles tendon to fatigue loading following acute injury.</a> Journal of Biomechanics. 47, 2028-2034 (2014).</li><li>Deymier, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+multiscale+structural+and+mechanical+effects+of+mouse+supraspinatus+muscle+unloading+on+the+mature+enthesis.">The multiscale structural and mechanical effects of mouse supraspinatus muscle unloading on the mature enthesis.</a> Acta Biomaterialia. 83, 302-313 (2019).</li><li>Killian, M. L., Thomopoulos, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scleraxis+is+required+for+the+development+of+a+functional+tendon+enthesis.">Scleraxis is required for the development of a functional tendon enthesis.</a> FASEB Journal. 30, 301-311 (2016).</li><li>Schwartz, A. G., Long, F., Thomopoulos, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enthesis+fibrocartilage+cells+originate+from+a+population+of+Hedgehog-responsive+cells+modulated+by+the+loading+environment.">Enthesis fibrocartilage cells originate from a population of Hedgehog-responsive cells modulated by the loading environment.</a> Development. 142, 196-206 (2015).</li><li>Bell, R., Taub, P., Cagle, P., Flatow, E. L., Andarawis-Puri, N. <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+mouse+model+of+supraspinatus+tendon+insertion+site+healing.">Development of a mouse model of supraspinatus tendon insertion site healing.</a> Journal of Orthopaedic Research. 33, 25-32 (2014).</li><li>Connizzo, B. K., Bhatt, P. R., Liechty, K. W., Soslowsky, L. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diabetes+Alters+Mechanical+Properties+and+Collagen+Fiber+Re-Alignment+in+Multiple+Mouse+Tendons.">Diabetes Alters Mechanical Properties and Collagen Fiber Re-Alignment in Multiple Mouse Tendons.</a> Annals of Biomedical Engineering. 42, 1880-1888 (2014).</li><li>Eekhoff, J. D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functionally+Distinct+Tendons+From+Elastin+Haploinsufficient+Mice+Exhibit+Mild+Stiffening+and+Tendon-Specific+Structural+Alteration.">Functionally Distinct Tendons From Elastin Haploinsufficient Mice Exhibit Mild Stiffening and Tendon-Specific Structural Alteration.</a> Journal of Biomechanical Engineering. 139, 111003 (2017).</li><li>Mikic, B., Bierwert, L., Tsou, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Achilles+tendon+characterization+in+GDF-7+deficient+mice.">Achilles tendon characterization in GDF-7 deficient mice.</a> Journal of Orthopaedic Research. 24, 831-841 (2006).</li><li>Sikes, K. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Knockout+of+hyaluronan+synthase+1,+but+not+3,+impairs+formation+of+the+retrocalcaneal+bursa.">Knockout of hyaluronan synthase 1, but not 3, impairs formation of the retrocalcaneal bursa.</a> Journal of Orthopaedic Research. 36, 2622-2632 (2018).</li><li>Wang, V. M., Banack, T. M., Tsai, C. W., Flatow, E. L., Jepsen, K. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Variability+in+tendon+and+knee+joint+biomechanics+among+inbred+mouse+strains.">Variability in tendon and knee joint biomechanics among inbred mouse strains.</a> Journal of Orthopaedic Research. 24, 1200-1207 (2006).</li><li>Wang, V. 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=Murine+tendon+function+is+adversely+affected+by+aggrecan+accumulation+due+to+the+knockout+of+ADAMTS5.">Murine tendon function is adversely affected by aggrecan accumulation due to the knockout of ADAMTS5.</a> Journal of Orthopaedic Research. 30, 620-626 (2011).</li><li>Zhang, 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=Tendon+mineralization+is+progressive+and+associated+with+deterioration+of+tendon+biomechanical+properties,+and+requires+BMP-Smad+signaling+in+the+mouse+Achilles+tendon+injury+model.">Tendon mineralization is progressive and associated with deterioration of tendon biomechanical properties, and requires BMP-Smad signaling in the mouse Achilles tendon injury model.</a> Matrix Biology. 52-54, 315-324 (2016).</li><li>Rooney, S. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ibuprofen+differentially+affects+supraspinatus+muscle+and+tendon+adaptations+to+exercise+in+a+rat+model.">Ibuprofen differentially affects supraspinatus muscle and tendon adaptations to exercise in a rat model.</a> American Journal of Sports Medicine. 44, 2237-2245 (2016).</li><li>Galasso, O., 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=Quality+of+Life+and+Functional+Results+of+Arthroscopic+Partial+Repair+of+Irreparable+Rotator+Cuff+Tears.">Quality of Life and Functional Results of Arthroscopic Partial Repair of Irreparable Rotator Cuff Tears.</a> Arthroscopy - Journal of Arthroscopic and Related Surgery. 33, 261-268 (2017).</li><li>Sarver, D. 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I modelli animali Murine sono comunemente usati per studiare i disturbi del tendine, ma la caratterizzazione delle loro proprietà meccaniche è impegnativa e non comune nella letteratura. Lo scopo di questo protocollo è quello di descrivere un metodo efficiente e riproducibile nel tempo per il test della tensione dei tendini murini. I nuovi metodi hanno ridotto il tempo necessario per testare un campione da ore a minuti ed eliminato un elemento di presa importante che era un problema comune nei metodi precedenti.
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I disturbi del tendone sono comuni e altamente diffusi tra le popolazioni anziane, atletiche e attive1,2,3. Negli Stati Uniti, ognianno vengono segnalate 16,4 milioni di lesioni ai visibili connettivi e rappresentano il 30% di tutte le visite all'ufficio medico correlate alle lesioni3,5,6,7, 8. I siti più comunemente colpiti includono la cuffia dei rotatori, il tendine di Achille e il tendine rotuleo9. Sebbene siano stati esplorati una varietà di trattamenti non operativi e operativi, tra cui farmaci antinfiammatori, riabilitazione e riparazione chirurgica, gli esiti rimangono scarsi, con un ritorno limitato alla funzione e alti tassi di fallimento5, 6. Questi scarsi esiti clinici hanno motivato studi di base e traslazionali che cercano di comprendere la tendinopatia e di sviluppare nuovi approcci di trattamento.
Le proprietà biomeccaniche della tensione sono i principali risultati quantitativi che definiscono la funzione tendinea. Pertanto, la caratterizzazione di laboratorio della tendinopatia e l'efficacia del trattamento devono includere un rigoroso test delle proprietà della tensione del tendine. Numerosi studi hanno descritto metodi per determinare le proprietà biomeccaniche dei tendini da modelli animali come ratti, pecore, cani e conigli10,11,12. Tuttavia, pochi studi hanno testato le proprietà biomeccaniche dei tendini murini, principalmente a causa delle difficoltà nell'afferrare i piccoli tessuti per il test della tensione. Poiché i modelli murini hanno numerosi vantaggi per studiare meccanicamente la tendinopatia, tra cui la manipolazione genetica, ampie opzioni di reagente e i metodi a basso costo, è necessario lo sviluppo di metodi accurati ed efficienti per testare biomeccanicamente i tessuti murini.
Al fine di testare correttamente le proprietà meccaniche dei tendini, il tessuto deve essere attanagliato in modo efficace, senza scivolare o strappo artifeffettiva all'interfaccia di presa o fratturazione della piastra di crescita. In molti casi, in particolare per i tendini corti, l'osso è afferrato su un'estremità e il tendine è afferrato sull'altra estremità. Le ossa sono tipicamente protette incorporandole in materiali come la resina epossidica13 e il polimetilelmethacritil14,15. Tendoni sono spesso collocati tra due strati di carta vetrata, incollati con cianoacrilato, e fissati utilizzando morsetti di compressione (se la sezione trasversale è piatta) o in un mezzo congelato (se la sezione trasversale è grande)15,16,17 . Questi metodi sono stati applicati per testare biomeccanicamente i tendini murini, ma le sfide sorgono a causa delle piccole dimensioni degli esemplari e del rispetto della piastra di crescita, che non ossifica mai18. Ad esempio, il diametro della testa omerale murina è di pochi millimetri, rendendo così difficile la presa dell'osso. In particolare, il test della tensione di campioni di murine supraspinatus tendino-osso spesso si traduce in fallimento alla piastra di crescita piuttosto che nel tendine o nell'entesi del tendine. Allo stesso modo, il test biomeccanico del tendine d'Achille è impegnativo. Anche se il tendine d'Achille è più grande di altri tendini murini, il calcaneus è piccolo, rendendo difficile la presa di questo osso. L'osso può essere rimosso, seguito da afferrare le due estremità del tendine; tuttavia, ciò preclude la prova dell'attaccamento tendine-osso. Altri gruppi riferiscono di afferrare l'osso di calcaneus utilizzando apparecchi su misura19,20, ancoraggio da morsetti21, fissaggio in auto cura cemento plastica22 o utilizzando una forma conica slot22, ma questi i metodi precedenti rimangono limitati da una bassa riproducibilità, da elevati tassi di guasto e da noiosi requisiti di preparazione.
L'obiettivo dello studio attuale era quello di sviluppare un metodo accurato ed efficiente per il test biomeccanico della tensione dei tendini murini, concentrandosi sui tendini sopraspinati e achille come esempi. Utilizzando una combinazione di ricostruzioni 3D dall'anatomia ossea nativa, dalla modellazione solida e dalla produzione additiva, è stato sviluppato un nuovo metodo per afferrare le ossa. Questi apparecchi fissavano efficacemente le ossa, prevenivano il fallimento della piastra di crescita, riducevano i tempi di preparazione dei campioni e aumentavano la riproducibilità dei test. Il nuovo metodo è facilmente adattabile per testare altri tendini murini così come tendini nei ratti e in altri animali.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr >
			<td >Agarose</td>
			<td >Fisher Scientific</td>
			<td >BP160-100</td>
			<td >Dissovle 1g in 100 ml ultrapure water to make 1% agarose&#160;</td>
		</tr>
		<tr >
			<td >Bruker microCT&#160;</td>
			<td >Bruker BioSpin Corp</td>
			<td >Skyscan 1272&#160;</td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >ElectroForce&#160;</td>
			<td >TA Instruments</td>
			<td >3200</td>
			<td>Testing platform</td>
		</tr>
		<tr >
			<td >Ethanol 200 Proof</td>
			<td >Fisher Scientific</td>
			<td >A4094</td>
			<td>Dilute to 70% and use as suggested in protocol</td>
		</tr>
		<tr >
			<td >Fixture to attach grips</td>
			<td >Custom made</td>
			<td ></td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >Kimwipes</td>
			<td >Kimberly-Clark</td>
			<td >&#160;S-8115</td>
			<td>As suggested in protocol</td>
		</tr>
		<tr >
			<td >MicroCT CT-Analyser (Ctan)</td>
			<td >Bruker BioSpin Corp</td>
			<td ></td>
			<td>Used by authors for visualizing and analyzing micro-CT scans&#160;</td>
		</tr>
		<tr >
			<td >MilliQ water (Ultrapure water)</td>
			<td>Millipore Sigma</td>
			<td>QGARD00R1 (or related purifier)</td>
			<td>100 ml&#160;</td>
		</tr>
		<tr >
			<td >Meshmixer</td>
			<td >Autodesk</td>
			<td >http://www.meshmixer.com/</td>
			<td >Free engineering software used by authors to refine mesh</td>
		</tr>
		<tr >
			<td >Objet EDEN 260VS&#160;</td>
			<td >Stratasys LTD</td>
			<td ></td>
			<td>Precision Prototyping</td>
		</tr>
		<tr >
			<td >Objet Studio</td>
			<td >Stratasys LTD</td>
			<td ></td>
			<td>Used by authors with 3D printer</td>
		</tr>
		<tr >
			<td >PBS - Phosphate-Buffered Saline</td>
			<td >ThermoFisher Scientific</td>
			<td >10010031</td>
			<td >2.5 L of 10% PBS&#160;</td>
		</tr>
		<tr >
			<td >S&#38;T Forceps</td>
			<td >Fine Science Tools</td>
			<td >00108-11</td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >Scalpel Blade - #11</td>
			<td >Fine Science Tools</td>
			<td >10011-00</td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >Scalpel Handle - #3</td>
			<td >Fine Science Tools</td>
			<td >10003-12</td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >SkyScan 1272</td>
			<td >Bruker BioSpin Corp</td>
			<td ></td>
			<td>Used by authors for visualizing and analyzing micro-CT scans&#160;</td>
		</tr>
		<tr >
			<td >Skyscan CT-Vox</td>
			<td >Bruker BioSpin Corp</td>
			<td ></td>
			<td>Used by authors for visualizing and analyzing micro-CT scans&#160;</td>
		</tr>
		<tr >
			<td >SkyScan NRecon</td>
			<td >Bruker BioSpin Corp</td>
			<td ></td>
			<td>Used by authors for visualizing and analyzing micro-CT scans&#160;</td>
		</tr>
		<tr >
			<td >SolidWorks CAD</td>
			<td >Dassault Syst&#232;mes</td>
			<td >SolidWorks Research Subsription</td>
			<td>Solid modeling computer-aided design used by authors</td>
		</tr>
		<tr >
			<td >SuperGlue</td>
			<td >Loctite</td>
			<td >234790</td>
			<td>As suggested in protocol</td>
		</tr>
		<tr >
			<td >Testing bath</td>
			<td >Custom made</td>
			<td ></td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >Thin film grips&#160;</td>
			<td >Custom made</td>
			<td ></td>
			<td>Used by authors</td>
		</tr>
		<tr >
			<td >VeroWhitePlus</td>
			<td >Stratasys LTD</td>
			<td >NA</td>
			<td>3D printing material used by authors</td>
		</tr>
		<tr >
			<td >WinTest&#160;</td>
			<td >WinTest Software</td>
			<td ></td>
			<td>Used by authors to collect data</td>
		</tr>
	</tbody>
</table>

biomechanical testing of murine tendons

I disturbi del tendone sono comuni, colpiscono persone di tutte le età e sono spesso debilitanti. I trattamenti standard, come i farmaci antinfiammatori, la riabilitazione e la riparazione chirurgica, spesso falliscono. Al fine di definire la funzione del tendine e dimostrare l'efficacia di nuovi trattamenti, le proprietà meccaniche dei tendini dei modelli animali devono essere determinate con precisione. I modelli animali Murine sono ora ampiamente utilizzati per studiare disturbi del tendine e valutare nuovi trattamenti per le tendinopatie; tuttavia, determinare le proprietà meccaniche dei tendini del topo è stato difficile. In questo studio è stato sviluppato un nuovo sistema per i test meccanici tendini che include apparecchi stampati in 3D che corrispondono esattamente alle anatomie dell'omero e del calcano per testare meccanicamente i tendini supraspinati e i tendini di Achille, rispettivamente. Questi apparecchi sono stati sviluppati utilizzando ricostruzioni 3D di anatomia ossea nativa, modellazione solida e produzione additiva. Il nuovo approccio ha eliminato i fallimenti di presa reali (ad esempio, il fallimento al guasto della piastra di crescita piuttosto che nel tendine), ha ridotto i tempi complessivi di test e ha aumentato la riproducibilità. Inoltre, questo nuovo metodo è facilmente adattabile per testare altri tendini murini e tendini di altri animali.

Gli apparecchi stampati in 3D sono stati utilizzati per testare i tendini di murine supraspinatus e Achille di 8 settimane. Tutti i campioni testati meccanicamente hanno avuto esito negativo durante l'ittesi, come caratterizzato da scansioni microCT, ispezione visiva e analisi video dopo test di tensile. Un confronto uno-a-uno dei metodi precedenti e correnti per il test del tendine supraspinatus nel nostro laboratorio è mostrato Figura 3. Nel metodo precedente28<sup...

Watch this Scientific Journal Video about Biomechanical Testing of Murine Tendons at JoVE.com

Biomechanical Testing of Murine Tendons

Il protocollo descrive metodi di test biomeccanici tesi efficienti e riproducibili per i tendini murini attraverso l'uso di apparecchi stampati in 3D personalizzati.

Test biomeccanici di Murine Tendons

Tendon disorders are common, affect people of all ages, and are often debilitating. Standard treatments, such as anti-inflammatory drugs, rehabilitation, ...

Il protocollo descrive un metodo efficiente e riproducibile per il test biomeccanico dei tendini del mouse attraverso apparecchi stampati 3D riutilizzabili su misura. I nuovi metodi riducono il tempo necessario per testare il campione da ore a minuti ed eliminano un artefatto di presa principale che era un problema comune nei metodi precedenti. Questo metodo non si limita ai tendini sopraspinato e Achille.Può essere facilmente adattato per testare altri tendini e tendini di topo da animali più grandi. Per garantire la riproducibilità e l'efficienza dell'approccio, potrebbero essere necessari più cicli di prototipazione e convalida della progettazione per gli apparecchi non descritti qui. Per iniziare, eseguire una tomografia microcalcografica dell'intero osso nel gel di agarosio.Dopo la ricostruzione in immagini di sezione trasversale, selezionare il comando Apri file per aprire il set di dati del file. Aprire il file di dialogo Preferenze e selezionare la scheda Avanzate. Usa l'algoritmo di rendering adattivo per costruire i modelli 3D che forniscono dettagli superficiali più fluidi.Utilizzare 10 come parametro di località che definisce la distanza in pixel rispetto al punto adiacente utilizzato per trovare il bordo dell'oggetto. Ridurre al minimo la tolleranza a 0,1 per ridurre le dimensioni del file. Per specificare il volume di interesse, selezionare manualmente due immagini da impostare come parte superiore e inferiore dell'intervallo VOI selezionato, quindi passare alla seconda pagina, Regione di interesse.Selezionare manualmente l'area di interesse in una singola immagine di sezione trasversale. Ripetere la selezione del ROI per ogni 10-15 immagini di sezione trasversale. Passare quindi alla terza pagina, Selezione binaria.Scegliere Da Set di dati dal menu Istogramma per visualizzare la distribuzione dell'istogramma della luminosità da tutte le immagini del set di dati. Sempre nel menu Istogramma fare clic sul menu Crea file modello 3D. Salvate un modello 3D dell'osso in formato file STL.Nel software Meshmixer importate mesh e selezionate Tutto da modificare. Scegliete Produce dalla modifica Set di strumenti, quindi selezionate Budget triangolo (Triangle Budget) dal set di strumenti Riduci destinazione (Reduce target). Ridurre il numero e accettare le modifiche.Ritagliare il file appena ridotto in formato STL scegliendo Esporta As.To progettare un osso omerale tendineo sopraspinatus, utilizzare un programma di progettazione a modellazione solida computer-aided per creare un modello personalizzato di apparecchio che afferra l'omero. Aprite il file di formato STL dell'osso omero in un programma di modellazione solida e salvate come file di parte in formato SLDPRT. Quindi aprite il file parte per creare manualmente tre piani anatomicamente rilevanti, ad esempio sagittale, coronale e trasversale.Fate clic su Nuovo file (File New) per creare la parte componente a blocchi solidi. Fate clic su File nuovo (File New) per creare un modello di assieme con due componenti, il blocco solido e l'osso omero destro o sinistro. Definire l'orientamento dell'osso all'interno del blocco per garantire che l'angolo tra il tendine e l'osso sia di 180 gradi.Assicurarsi che l'intero volume osseo si adatti all'interno del blocco. Nella finestra Assieme (Assembly), selezionate il blocco e fate clic su Modifica componente (Edit Component) dalla barra degli strumenti Assieme (Assembly). Fate clic su Inserisci (Insert), Feature (Features), Cavità (Cavity).Selezionate Ridimensionamento uniforme (Uniform Scaling) e immettete lo 0% come valore da ridimensionare in tutte le direzioni. Sopprimete la parte ossea e salvate l'assieme come parte. Aprire il cilindro con parte cavità.Create uno schizzo, assicuratevi di lasciare solo 0,5 millimetri sopra la testa omerale. In Feature (Features), selezionate Taglio estruso (Extruded Cut). Tagliare l'assieme lungo il piano sagittale per creare due componenti simmetrici che si adattano all'osso anteriore e posteriore.Tagliare la parte di assieme lungo il piano sagittale per creare due componenti simmetrici che si adattano all'osso anteriore e posteriore. È fondamentale garantire che la testa omerale prevengano il guasto della piastra di crescita e definire una distanza ravvicinata che eviti il disimpegno dell'omero dal modello durante il test. Procedere come descritto nel manoscritto per completare la componente posteriore e la componente anteriore.Salvare entrambi i componenti come file di parte separati. Premete Inserisci serie (Insert Pattern), Specchia (Mirror) e Specchia (Mirror) per creare modelli di specchi 3D per ogni componente dello staffaggio per l'arto opposto. Selezionate la faccia anteriore come faccia a specchio.Selezionate la parte come corpo da specchiare. Selezionate il piano specchio e create uno schizzo che includa tutto il materiale. Da Feature (Features), selezionate Taglio estruso (Extruded Cut) per rimuovere la parte originale e mantenere solo la parte specchiata.Fate clic sulla parte inferiore della parte e utilizzate come piano per creare uno schizzo. Fate clic su Testo sketch (Sketch Text) e aggiungete L o R.Questo aggiunge un'incisione nella parte inferiore degli staffaggi per distinguere tra i lati sinistro e destro. Salvare tutte le parti dello staffaggio in formato file standard STL in preparazione alla stampa 3D.Per sezionare il tendine muscolare sopraspinato, l'esemplare osseo omero, posizionare prima il topo eutanasiato in una posizione prona e fare un'incisione nella pelle dall'alto del gomito della ara verso la spalla. Utilizzare le forcep per rimuovere con cura la pelle con dissezione smussata in modo che la muscolatura della spalla sia visibile. Rimuovere il tessuto che circonda l'omero fino a quando l'osso non è esposto.Tenere l'omero con pinza e rimuovere con cura i muscoli deltoidi e trapezio per esporre l'arco coracoacromiale. Identificare l'articolazione CA e separare accuratamente la clavicola dall'acromione con una lama bisturi. Facendo attenzione a non danneggiare il tendine sopraspinatus e il suo attaccamento osseo, rimuovere il muscolo dal suo attacco scapolare usando una lama bisturi.Staccare la testa omerale dal glenoide e lacerare la capsula articolare e l'infraspinatus subscapularis e teres tendini minori. Disarticolare l'articolazione del gomito per separare l'omero dall'ulna e dal raggio. Isolare l'esemplare muscolare del tendine omero-sopraspinato e pulire i tessuti molli in eccesso sull'omero e sulla testa omerale.Per sezionare il tendine d'Achille, l'osso calcaneo, posizionare un topo eutanasiato in una posizione soggetta. Facendo attenzione a non danneggiare il tendine d'Achille e il suo attaccamento osseo, rimuovere la pelle con dissezione smussata in modo che la muscolatura intorno alle articolazioni della caviglia e del ginocchio sia esposta. Usando una lama bisturi, a partire dall'attacco tendine-calcaneo di Achille, staccare con cura il muscolo gastrocnemio dai suoi attacchi prossimali.Disarticolare con cura il calcaneo dalle varie ossa adiacenti e isolare il campione di tendine-calcaneo d'Achille e pulire i tessuti molli in eccesso. Per determinare l'area della sezione trasversale del tendine, inserire l'osso capovolto per sospendere l'esemplare nel criotubo riempito con gel di agarosio con l'osso nel gel di agarosio e il tendine e il muscolo all'esterno. Dopo la scansione con tomografia microcalcolata, rimuovere delicatamente il muscolo dal tendine usando una lama bisturi.Inserire l'osso nello staffaggio stampato in 3D e attaccarlo alle griglie di prova. Inserire e incollare il tendine tra una carta velina sottile piegata e bloccarlo utilizzando impugnature sottili. Inserire il campione e le impugnature in un bagno di prova di PBS a 37 gradi Celsius ed eseguire un test meccanico.In questo studio, utilizzando apparecchi stampati in 3D riutilizzabili per afferrare l'osso, il tempo di preparazione del campione è stato ridotto da ore a minuti. Le curve rappresentative di deformazione del carico per il test di trazione del tendine sopraspinato utilizzando i metodi attuali eliminavano i principali artefatti di presa come il cedimento della piastra di crescita. Le proprietà meccaniche dei tendini sopraspinato e Achille dimostrano un effetto significativo del sesso basato su test T non accoppiati con valore P inferiore a 0,05.Micro CT ha misurato con successo l'area della sezione trasversale lungo la lunghezza del tendine sopraspinatus lungo la lunghezza del tendine d'Achille. È importante ricordare che ogni sito anatomico ha criteri di progettazione specifici necessari per una presa efficace. Pertanto, il design per ogni apparecchio dovrebbe essere adattato di conseguenza.Oltre al test di trazione al guasto, questi apparecchi possono essere utilizzati per test di carico ciclici, che forniscono informazioni sull'affaticamento del tendine e sulle proprietà viscoeleastiche. Caratterizzare le proprietà meccaniche dei tendini murini è raro in letteratura a causa di una serie di motivi, tra cui la difficoltà di afferrare questi piccoli tessuti, i metodi di preparazione dei campioni noiosi e dispendiosi in termini di tempo e le fratture delle piastre di crescita. Questo protocollo presenta un metodo efficiente in termini di tempo e riproducibile per testare i tendini del mouse che ha eliminato i guasti di presa artefatto e ha triplicato il numero di campioni che possono essere testati in un giorno.

Research

JoVE Journal

Bioengineering

Directed Cellular Self-Assembly to Fabricate Cell-Derived Tissue Rings for Biomechanical Analysis and Tissue Engineering

Each year, hundreds of thousands of patients undergo coronary artery bypass surgery in the United States.1 Approximately one third of these patients do not have suitable autologous donor vessels due to disease progression or previous harvest. The aim of vascular tissue engineering is to develop a suitable alternative source for these bypass grafts. In addition, engineered vascular tissue may prove valuable as living vascular models to study cardiovascular diseases. Several promising approaches to engineering blood vessels have been explored, with many recent studies focusing on development and analysis of cell-based methods.2-5 Herein, we present a method to rapidly self-assemble cells into 3D tissue rings that can be used in vitro to model vascular tissues.
To do this, suspensions of smooth muscle cells are seeded into round-bottomed annular agarose wells. The non-adhesive properties of the agarose allow the cells to settle, aggregate and contract around a post at the center of the well to form a cohesive tissue ring.6,7 These rings can be cultured for several days prior to harvesting for mechanical, physiological, biochemical, or histological analysis. We have shown that these cell-derived tissue rings yield at 100-500 kPa ultimate tensile strength8 which exceeds the value reported for other tissue engineered vascular constructs cultured for similar durations (&lt;30 kPa).9,10 Our results demonstrate that robust cell-derived vascular tissue ring generation can be achieved within a short time period, and offers the opportunity for direct and quantitative assessment of the contributions of cells and cell-derived matrix (CDM) to vascular tissue structure and function.

This article outlines a versatile method to create cell-derived tissue rings by cellular self-assembly. Smooth muscle cells seeded into ring-shaped agarose wells aggregate and contract to form robust three-dimensional (3D) tissues within 7 days. Millimeter-scale tissue rings are conducive to mechanical testing and serve as building blocks for tissue assembly.

Diretto Cellular Self-Assembly di fabbricare Cell-Derived Anelli tessuto per l&#39;analisi biomeccanica e di ingegneria dei tessuti

Each year, hundreds of thousands of patients undergo coronary artery bypass surgery in the United States.1 Approximately one third of these patients do ...

Ricerca

Bioingegneria

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.

Determinazione del tasso di trasporto di xenobiotici e nanomateriali attraverso la placenta con il<em&gt; Ex vivo</em&gt; Umano Modello perfusione placentare

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

Biomechanical Characterization of Human Soft Tissues Using Indentation and Tensile Testing

Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should mimic the human tissues they are aiming to replace; to provide the required anatomical shape, the materials must be able to sustain the mechanical forces they will experience when implanted at the defect site. Although the mechanical properties of tissue-engineered scaffolds are of great importance, many human tissues that undergo restoration with engineered materials have not been fully biomechanically characterized. Several compressive and tensile protocols are reported for evaluating materials, but with large variability it is difficult to compare results between studies. Further complicating the studies is the often destructive nature of mechanical testing. Whilst an understanding of tissue failure is important, it is also important to have knowledge of the elastic and viscoelastic properties under more physiological loading conditions.
This report aims to provide a minimally destructive protocol to evaluate the compressive and tensile properties of human soft tissues. As examples of this technique, the tensile testing of skin and the compressive testing of cartilage are described. These protocols can also be directly applied to synthetic materials to ensure that the mechanical properties are similar to the native tissue. Protocols to assess the mechanical properties of human native tissue will allow a benchmark by which to create suitable tissue-engineered substitutes.

Tissue biomechanics is important for maintaining cell shape and function and for determining phenotype. This report demonstrates non-destructive mechanical protocols for characterizing elastic and viscoelastic properties of human soft tissues, which can be directly applied to tissue-engineered substrates to allow a close matching of engineered materials to native tissue.

Caratterizzazione biomeccanica di morbidi tessuti umani usando una indentazione e prove di trazione

Regenerative medicine aims to engineer materials to replace or restore damaged or diseased organs. The mechanical properties of such materials should ...

An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular cartilage impairs its load-bearing function substantially as it experiences tremendous chemical degradation, i.e. proteoglycan loss and collagen fibril disruption. One promising way to investigate chemical damage mechanisms during OA is to expose the cartilage specimens to an external solute and monitor the diffusion of the molecules. The degree of cartilage damage (i.e. concentration and configuration of essential macromolecules) is associated with collisional energy loss of external solutes while moving across articular cartilage creates different diffusion characteristics compared to healthy cartilage. In this study, we introduce a protocol, which consists of several steps and is based on previously developed experimental micro-Computed Tomography (micro-CT) and finite element modeling. The transport of charged and uncharged iodinated molecules is first recorded using micro-CT, which is followed by applying biphasic-solute and multiphasic finite element models to obtain diffusion coefficients and fixed charge densities across cartilage zones.

We propose a protocol to investigate the transport of charged and uncharged molecules across articular cartilage with the aid of recently developed experimental and numerical methods.

Uno Sperimentale e Finite Element protocollo per indagare il trasporto di soluti neutri e carichi attraverso cartilagine articolare

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular ...

A Test Bed to Examine Helmet Fit and Retention and Biomechanical Measures of Head and Neck Injury in Simulated Impact

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during an impact are important factors in protecting the helmet wearer from impact-induced injury. This manuscript aims to investigate impact-induced injury mechanisms in different helmet fit scenarios through analysis of simulated helmeted impacts with an anthropometric test device (ATD), an array of headform acceleration transducers and neck force/moment transducers, a dual high speed camera system, and helmet-fit force sensors developed in our research group based on Bragg gratings in optical fiber. To simulate impacts, an instrumented headform and flexible neck fall along a linear guide rail onto an anvil. The test bed allows simulation of head impact at speeds up to 8.3 m/s, onto impact surfaces that are both flat and angled. The headform is fit with a crash helmet and several fit scenarios can be simulated by making context specific adjustments to the helmet position index and/or helmet size. To quantify helmet retention, the movement of the helmet on the head is quantified using post-hoc image analysis. To quantify head and neck injury potential, biomechanical measures based on headform acceleration and neck force/moment are measured. These biomechanical measures, through comparison with established human tolerance curves, can estimate the risk of severe life threatening and/or mild diffuse brain injury and osteoligamentous neck injury. To our knowledge, the presented test-bed is the first developed specifically to assess biomechanical effects on head and neck injury relative to helmet fit and retention.

Using an anthropometric head and neck, optical fiber-based fit force transducers, an array of head acceleration and neck force/moment transducers, and a dual high speed camera system, we present a test bed to study helmet retention and effects on biomechanical measures of head and neck injury secondary to head impact.

Un banco di prova per esaminare la calzata del casco e conservazione e misure biomeccaniche della testa e lesioni al collo nei impatto simulato

Conventional wisdom and the language in international helmet testing and certification standards suggest that appropriate helmet fit and retention during ...

Methods for In Vivo Biomechanical Testing on Brachial Plexus in Neonatal Piglets

Neonatal brachial plexus palsy (NBPP) is a stretch injury that occurs during the birthing process in nerve complexes located in the neck and shoulder regions, collectively referred to as the brachial plexus (BP). Despite recent advances in obstetrical care, the problem of NBPP continues to be a global health burden with an incidence of 1.5 cases per 1,000 live births. More severe types of this injury can cause permanent paralysis of the arm from the shoulder down. Prevention and treatment of NBPP warrants an understanding of the biomechanical and physiological responses of newborn BP nerves when subjected to stretch. Current knowledge of the newborn BP is extrapolated from adult animal or cadaveric BP tissue instead of in vivo neonatal BP tissue. This study describes an in vivo mechanical testing device and procedure to conduct in vivo biomechanical testing in neonatal piglets. The device consists of a clamp, actuator, load cell, and camera system that apply and monitor in vivo strains and loads until failure. The camera system also allows monitoring of the failure location during rupture. Overall, the presented method allows for a detailed biomechanical characterization of neonatal BP when subjected to stretch.

Methods for In Vivo Biomechanical Testing on Brachial Plexus in Neonatal Piglets

Presented here are methods to perform in vivo biomechanical testing on brachial plexus in a neonatal piglet model.

Metodi per il test biomeccanico In Vivo su plexus brachiale in porcellini neoatali

Neonatal brachial plexus palsy (NBPP) is a stretch injury that occurs during the birthing process in nerve complexes located in the neck and shoulder ...

Biaxial Basal Tone and Passive Testing of the Murine Reproductive System Using a Pressure Myograph

The female reproductive organs, specifically the vagina and cervix, are composed of various cellular components and a unique extracellular matrix (ECM). Smooth muscle cells exhibit a contractile function within the vaginal and cervical walls. Depending on the biochemical environment and the mechanical distension of the organ walls, the smooth muscle cells alter the contractile conditions. The contribution of the smooth muscle cells under baseline physiological conditions is classified as a basal tone. More specifically, a basal tone is the baseline partial constriction of smooth muscle cells in the absence of hormonal and neural stimulation. Furthermore, the ECM provides structural support for the organ walls and functions as a reservoir for biochemical cues. These biochemical cues are vital to various organ functions, such as inciting growth and maintaining homeostasis. The ECM of each organ is composed primarily of collagen fibers (mostly collagen types I, III, and V), elastic fibers, and glycosaminoglycans/proteoglycans. The composition and organization of the ECM dictate the mechanical properties of each organ. A change in ECM composition may lead to the development of reproductive pathologies, such as pelvic organ prolapse or premature cervical remodeling. Furthermore, changes in ECM microstructure and stiffness may alter smooth muscle cell activity and phenotype, thus resulting in the loss of the contractile force.
In this work, the reported protocols are used to assess the basal tone and passive mechanical properties of the nonpregnant murine vagina and cervix at 4-6 months of age in estrus. The organs were mounted in a commercially available pressure myograph and both pressure-diameter and force-length tests were performed. Sample data and data analysis techniques for the mechanical characterization of the reproductive organs are included. Such information may be useful for constructing mathematical models and rationally designing therapeutic interventions for women&#8217;s health pathologies.

This protocol utilized a commercially available pressure myograph system to perform pressure myograph testing on the murine vagina and cervix. Utilizing media with and without calcium, the contributions of the smooth muscle cells (SMC) basal tone and passive extracellular matrix (ECM) were isolated for the organs under estimated physiological conditions.

Tono basale biassiale e test passivi del sistema riproduttivo Murine utilizzando un miografo a pressione

The female reproductive organs, specifically the vagina and cervix, are composed of various cellular components and a unique extracellular matrix (ECM). ...

The Quantification of Injectability by Mechanical Testing

Injectable biomaterials are becoming increasingly popular for the minimally invasive delivery of drugs and cells. These materials are typically more viscous than traditional aqueous injections and may be semi-solid, therefore, their injectability cannot be assumed. This protocol describes a method to objectively assess the injectability of these materials using a standard mechanical tester. The syringe plunger is compressed by the crosshead at a set rate, and the force is measured. The maximum or plateau force value can then be used for comparison between samples, or to an absolute force limit. This protocol can be used with any material, and any syringe and needle size or geometry. The results obtained may be used to make decisions about formulations, syringe and needle sizes early in the translational process. Further, the effects of altering formulations on injectability may be quantified, and the optimum time to inject temporally changing materials determined. This method is also suitable as a reproducible way to examine the effects of injection on a material, to study phenomena such as self-healing and filter pressing or study the effects of injection on cells. This protocol is faster and more directly applicable to injectability than rotational rheology, and requires minimal post processing to obtain key values for direct comparisons.

Presented here is a protocol for quantitatively evaluating the injectability of a material through a syringe-needle system using a standard mechanical testing rig.

La quantificazione dell'iniettabilità mediante prove meccaniche

Injectable biomaterials are becoming increasingly popular for the minimally invasive delivery of drugs and cells. These materials are typically more ...

Optical Coherence Tomography Based Biomechanical Fluid-Structure Interaction Analysis of Coronary Atherosclerosis Progression

In this paper, we present a complete workflow for the biomechanical analysis of atherosclerotic plaque in the coronary vasculature. With atherosclerosis as one of the leading causes of global death, morbidity and economic burden, novel ways of analyzing and predicting its progression are needed. One such computational method is the use of fluid-structure interaction (FSI) to analyze the interaction between the blood flow and artery/plaque domains. Coupled with in vivo imaging, this approach could be tailored to each patient, assisting in differentiating between stable and unstable plaques. We outline the three-dimensional reconstruction process, making use of intravascular Optical Coherence Tomography (OCT) and invasive coronary angiography (ICA). The extraction of boundary conditions for the simulation, including replicating the three-dimensional motion of the artery, is discussed before the setup and analysis is conducted in a commercial finite element solver. The procedure for describing the highly nonlinear hyperelastic properties of the artery wall and the pulsatile blood velocity/pressure is outlined along with setting up the system coupling between the two domains. We demonstrate the procedure by analyzing a non-culprit, mildly stenotic, lipid-rich plaque in a patient following myocardial infarction. Established and emerging markers related to atherosclerotic plaque progression, such as wall shear stress and local normalized helicity, respectively, are discussed and related to the structural response in the artery wall and plaque. Finally, we translate the results to potential clinical relevance, discuss limitations, and outline areas for further development. The method described in this paper shows promise for aiding in the determination of sites at risk of atherosclerotic progression and, hence, could assist in managing the significant death, morbidity, and economic burden of atherosclerosis.

There is a need to determine which atherosclerotic lesions will progress in the coronary vasculature to guide intervention before myocardial infarction occurs. This article outlines the biomechanical modeling of arteries from Optical Coherence Tomography using fluid-structure interaction techniques in a commercial finite element solver to help predict this progression.

Tomografia a coerenza ottica basata sull'analisi dell'interazione fluido-struttura biomeccanica della progressione dell'aterosclerosi coronarica

In this paper, we present a complete workflow for the biomechanical analysis of atherosclerotic plaque in the coronary vasculature. With atherosclerosis ...

Construction of a Human Aorta Smooth Muscle Cell Organ-On-A-Chip Model for Recapitulating Biomechanical Strain in the Aortic Wall

Conventional two-dimensional cell culture techniques and animal models have been used in the study of human thoracic aortic aneurysm and dissection (TAAD). However, human TAAD sometimes cannot be characterized by animal models. There is an apparent species gap between clinical human studies and animal experiments that may hinder the discovery of therapeutic drugs. In contrast, the conventional cell culture model is unable to simulate in vivo biomechanical stimuli. To this end, microfabrication and microfluidic techniques have developed greatly in recent years, providing novel techniques for establishing organoids-on-a-chip models that replicate the biomechanical microenvironment. In this study, a human aorta smooth muscle cell organ-on-a-chip (HASMC-OOC) model was developed to simulate the pathophysiological parameters of aortic biomechanics, including the amplitude and frequency of cyclic strain experienced by human aortic smooth muscle cells (HASMCs) that play a vital role in TAAD. In this model, the morphology of HASMCs became elongated in shape, aligned perpendicularly to the strain direction, and presented a more contractile phenotype under strain conditions than under static conventional conditions. This was consistent with the cell orientation and phenotype in native human aortic walls. Additionally, using bicuspid aortic valve-related TAAD (BAV-TAAD) and tricuspid aortic valve-related TAAD (TAV-TAAD) patient-derived primary HASMCs, we established BAV-TAAD and TAV-TAAD disease models, which replicate HASMC characteristics in TAAD. The HASMC-OOC model provides a novel in vitro platform that is complementary to animal models for further exploring the pathogenesis of TAAD and discovering therapeutic targets.

Here, we developed a human aorta smooth muscle cell organ-on-a-chip model to replicate the in vivo biomechanical strain of smooth muscle cells in the human aortic wall.

Costruzione di un modello organ-on-a-chip di cellule muscolari lisce dell'aorta umana per ricapitolare la tensione biomeccanica nella parete aortica

Conventional two-dimensional cell culture techniques and animal models have been used in the study of human thoracic aortic aneurysm and dissection ...