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

O estudo foi apoiado pelo NIH/NIAMS (R01 AR055580, R01 AR057836).

Os estudos em animais foram aprovados pelo Comitê institucional de cuidados e uso de animais da Universidade de Columbia. Camundongos utilizados neste estudo foram de um fundo C57BL/6J e foram comprados no laboratório Jackson (Bar Harbor, ME, EUA). Eles foram alojados em condições de barreira livre de patógenos e foram fornecidos alimentos e água ad libitum.
1. desenvolvimento de Custom-Fit 3D impresso luminárias para prender o osso
<ol><li>Aquisição de imagem óssea e construção ...

<ol>
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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. 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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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Os modelos animais murinos são comumente usados para estudar distúrbios tendinosos, mas a caracterização de suas propriedades mecânicas é desafiadora e incomum na literatura. A finalidade deste protocolo é descrever um método eficiente e reprodutível do tempo para o teste elástico de tendões murino. Os novos métodos reduziram o tempo necessário para testar uma amostra de horas a minutos e eliminaram um artefato importante que era um problema comum em métodos anteriores.
Diversas ...

As desordens tendíneas são comuns e altamente prevalentes entre as populaçõesdeenvelhecimento, Atléticoe ativo1,2,3. Nos Estados Unidos, 16,4 milhões lesões do tecido conjuntivo são relatadas a cada ano4 e respondem por 30% de todas as visitas de consultório médico relacionadas a lesões3,5,6,7, a 8. Os sítios mais comumente afetados incluem o manguito rotador, o tendão de Aquiles e o tendão patelar9. Embora uma variedade de tratamentos não operativos e operativos tenha sido explorada, incluindo fármacos anti-inflamatórios, reabilitação e reparação cirúrgica, os resultados permanecem pobres, com retorno limitado à função e altas taxas de falha5, a 6. Estes resultados clínicos pobres motivaram estudos básicos e translacional que procuram compreender a tendinopatia e desenvolver aproximações novas do tratamento.
As propriedades biomecânicas elásticas são os desfechos quantitativos primários que definem a função tendínea. Conseqüentemente, a caracterização do laboratório da tendinopatia e da eficácia do tratamento deve incluir um teste rigoroso de propriedades elásticas do tendão. Inúmeros estudos descreveram métodos para determinar as propriedades biomecânicas de tendões de modelos animais como ratos, ovinos, cães e coelhos10,11,12. No entanto, poucos estudos testaram as propriedades biomecânicas dos tendões murinos, principalmente devido às dificuldades em prender os pequenos tecidos para testes de tração. Como os modelos murinos têm inúmeras vantagens para o estudo mecanisticamente tendinopatia, incluindo a manipulação genética, extensas opções de reagentes e baixo custo, o desenvolvimento de métodos precisos e eficientes para testar biomecanicamente os tecidos murinos é necessário.
A fim testar corretamente as propriedades mecânicas dos tendões, o tecido deve ser agarrado eficazmente, sem deslizar ou rasgar vesícula na relação do aperto ou no fraturamento da placa do crescimento. Em muitos casos, particularmente para tendões curtos, o osso é agarrado em uma extremidade e o tendão é agarrado na outra extremidade. Os ossos são tipicamente fixados incorporando-os em materiais tais como aresina de colaEpoxy13 e o polimetilmetacrilato14,15. Os tendões são frequentemente colocados entre duas camadas de lixa, coladas com cianoacrilato, e fixadas usando grampos de compressão (se a seção transversal é plana) ou em um meio congelado (se a seção transversal é grande)15,16,17 . Estes métodos têm sido aplicados a testes biomecânicos de tendões murinos, mas os desafios surgem devido ao pequeno tamanho dos espécimes e à conformidade da placa de crescimento, que nunca ossifica18. Por exemplo, o diâmetro da cabeça úmero murino é somente alguns milímetros, assim fazendo a preensão do osso difícil. Especificamente, os testes de tração de amostras de tendão-osso murino supraespinal muitas vezes resultam em falha na placa de crescimento, em vez de no tendão ou na entese do tendão. Da mesma forma, o teste biomecânico do tendão de Aquiles é desafiador. Embora o tendão de Aquiles seja maior do que outros tendões murinos, o calcâneo é pequeno, dificultando a preensão deste osso. O osso pode ser removido, seguido por agarrar as duas extremidades do tendão; Entretanto, isto impede o teste do acessório do tendão-à-osso. Outros grupos relatam prender o osso do calcâneo usando dispositivos elétricos feitos medida19,20, ancorando pelas braçadeiras21, fixando no cimento plástico22 da cura do auto ou usando um entalhe cônico22, contudo estes os métodos anteriores permanecem limitados pela baixa reprodutibilidade, por taxas de falha de preensão elevadas, e por exigências tediosas da preparação.
O objetivo do presente estudo foi desenvolver um método preciso e eficiente para testes biomecânicos de tração de tendões murinos, com foco nos tendões supraespinal e Aquiles como exemplos. Usando uma combinação de reconstruções 3D da anatomia nativa do osso, da modelagem contínua, e da fabricação aditiva, um método novo foi desenvolvido para segurar os ossos. Estes dispositivos elétricos efetivamente garantiu os ossos, impediu a falha da placa de crescimento, diminuição do tempo de preparação do espécime, e aumento da reprodutibilidade do teste. O novo método é prontamente adaptável para testar outros tendões murinos, bem como tendões em ratos e outros animais.

<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

As desordens do tendão são comuns, afetam povos de todas as idades, e são frequentemente debilitantes. Tratamentos padrão, como drogas anti-inflamatórias, reabilitação e reparo cirúrgico, muitas vezes falham. A fim de definir a função tendínea e demonstrar a eficácia de novos tratamentos, as propriedades mecânicas dos tendões de modelos animais devem ser determinadas com precisão. Os modelos animais murinos são agora amplamente utilizados para estudar distúrbios tendíneos e avaliar novos tratamentos para tendinopatias; no entanto, determinar as propriedades mecânicas dos tendões do mouse tem sido desafiador. Neste estudo, um novo sistema foi desenvolvido para testes mecânicos tendinosos que incluem luminárias impressas em 3D que correspondem exatamente às anatomias do úmero e do calcâneo para testar mecanicamente tendões supraespinal e tendões de Aquiles, respectivamente. Estes dispositivos elétricos foram desenvolvidos usando reconstruções 3D de anatomia óssea nativa, modelagem sólida e manufatura aditiva. A nova abordagem eliminou falhas de preensão vesícula (por exemplo, falha na falha da placa de crescimento em vez do tendão), tempo de teste global diminuído e maior reprodutibilidade. Além disso, este novo método é prontamente adaptável para o teste de outros tendões e tendões murinos de outros animais.

os dispositivos elétricos 3D-Printed foram usados para testar o supraespinal murino velho de 8 semanas e os tendões de Achilles. Todas as amostras testadas mecanicamente falharam na entese, caracterizada por exames de microtomografia, inspeção visual e análise de vídeo após testes de tração. Uma comparação um-para-um dos métodos anteriores e atuais para o teste do tendão do supraespinal em nosso laboratório é mostrada na Figura 3. No método anterior28<...

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

Biomechanical Testing of Murine Tendons

O protocolo descreve métodos de teste biomecânicos de tração eficientes e reprodutíveis para tendões murinos através do uso de luminárias impressas em 3D personalizadas.

Teste biomecânico de tendões murinos

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

O protocolo descreve um método eficiente e reprodutível para testes biomecânicos de tendões do mouse através de luminárias impressas 3D personalizadas reutilizáveis. Os novos métodos reduzem o tempo necessário para testar a amostra de horas a minutos e eliminam um artefato de agarramento importante que era um problema comum em métodos anteriores. Este método não se limita aos tendões supraespinhal e aquiles.Pode ser facilmente adaptado para testar outros tendões e tendões do rato de animais maiores. Para garantir a reprodutibilidade e a eficiência da abordagem, podem ser necessários vários ciclos de prototipagem e validação de design para luminárias não descritas aqui. Para começar, realize uma tomografia microcomputada de todo o osso do gel agarose.Após a reconstrução em imagens de seção transversal, selecione o arquivo de comando Aberto para abrir o conjunto de dados do arquivo. Abra o arquivo de diálogo Preferências e selecione a guia Avançado. Use o algoritmo de renderização adaptativa para construir os modelos 3D que fornecem detalhes de superfície mais suaves.Use 10 como parâmetro de localidade que define a distância em pixels até o ponto vizinho usado para encontrar a borda do objeto. Minimize a tolerância a 0.1 para diminuir o tamanho do arquivo. Para especificar o volume de interesse, selecione manualmente duas imagens para definir como a parte superior e inferior da faixa VOI selecionada e, em seguida, mova-se para a segunda página, Região de Interesse.Selecione manualmente a região de interesse em uma única imagem transversal. Repita a seleção do ROI para cada 10 a 15 imagens de seção transversal. Em seguida, passe para a terceira página, Seleção Binária.No menu Histograma, clique em Dataset para mostrar a distribuição histograma de brilho de todas as imagens do conjunto de dados. Também no menu Histograma, clique no menu criar um menu de arquivo modelo 3D. Salve um modelo 3D do osso no formato de arquivo STL.No software Meshmixer, importe malha e selecione Tudo para editar. Escolha Produzir na edição do Conjunto de ferramentas e selecione O Orçamento do Triângulo na ferramenta definida Reduzir a meta. Reduza a triconta e aceite mudanças.Resesse o arquivo recém-reduzido em formato STL, escolhendo exportar As.To projetar um osso do tendão do tendão do supraspinato, use um programa de design auxiliado por computador de modelagem sólida para criar um modelo personalizado de luminária de agarramento de úmero. Abra o arquivo de formato STL do osso do úmero em um programa de modelagem sólida e salve como um arquivo de peça no formato SLDPRT. Em seguida, abra o arquivo Part para criar manualmente três planos anatomicamente relevantes, por exemplo, sagital, coronal e transverso.Clique em Arquivo Novo para criar a parte do componente de bloco sólido. Clique em Arquivo Novo para criar um modelo de montagem com dois componentes, o bloco sólido e o osso do úmero direito ou esquerdo. Defina a orientação do osso dentro do bloco para garantir que o ângulo entre o tendão e o osso seja de 180 graus.Certifique-se de que todo o volume ósseo se encaixa dentro do bloco. Na janela Assembly, selecione o bloco e clique em Editar componente na barra de ferramentas Do Conjunto. Clique em Inserir, Recursos, Cavidade.Selecione Dimensionamento uniforme e digite 0%como o valor para escalar em todas as direções. Suprimir a parte óssea e salvar a montagem como parte. Abra o cilindro com parte da cavidade.Crie um esboço, certifique-se de deixar apenas 0,5 milímetros acima da cabeça do erúrmetro. De Recursos, selecione Corte Extrudado. Corte o conjunto ao longo do plano sagital para criar dois componentes simétricos que se encaixam no osso anteriormente e posteriormente.Corte a parte de montagem ao longo do plano sagital para criar dois componentes simétricos que se encaixam no osso anteriormente e posteriormente. É fundamental garantir que a cabeça do úmero evite a falha da placa de crescimento e defina uma folga apertada que evite o desligamento do úmero do modelo durante o teste. Proceda como descrito no manuscrito para terminar o componente posterior e o componente anterior.Salve ambos os componentes como arquivos de peças separados. Agora pressione Insert Pattern, Mirror e selecione Espelho para criar modelos de espelho 3D para cada componente da luminária para o membro oposto. Selecione a face frontal como uma face espelhada simples.Selecione a peça como o corpo para espelhar. Selecione o plano espelho e crie um esboço que inclua todo o material. De Recursos, selecione Corte Extrudado para remover a peça original e para manter apenas a peça espelhada.Clique na parte inferior da peça e use como plano para fazer um esboço. Clique em Sketch Text e adicione L ou R.Isso adiciona uma gravação na parte inferior das luminárias para distinguir entre os lados esquerdo e direito. Salve todas as peças de fixação no formato de arquivo padrão STL em preparação para impressão 3D.Para dissecar o tendão muscular supraspinato, amostra óssea do úmero, primeiro posicione o rato eutanizado em posição propensa e faça uma incisão na pele acima do cotovelo da forepaw em direção ao ombro. Use fórceps para remover cuidadosamente a pele com dissecção sem cortes para que a musculatura do ombro seja visível. Remova o tecido ao redor do úmero até que o osso seja exposto.Segure o úmero com fórceps e remova cuidadosamente os músculos deltoide e trapézio para expor o arco coracoacromial. Identifique a articulação AC e separe cuidadosamente a clavícula do acromion com uma lâmina de bisturi. Tomando cuidado para não danificar o tendão do supraespinhal e seu acessório ósseo, remova o músculo de seu acessório escárculo usando uma lâmina de bisturi.Retire a cabeça úmeral do glenóide e lacera a cápsula articular e os subscapulares infraspinato e teres tendões menores. Desarticular a articulação do cotovelo para separar o úmero da ulna e do raio. Isole a amostra muscular do tendão do úmero-supraespinhal e limpe o excesso de tecidos moles no úmero e na cabeça do úmero.Para dissecar o tendão de Aquiles, o osso do calcâneo, posicione um rato eutanizado em uma posição propensa. Tomando cuidado para não danificar o tendão de Aquiles e seu acessório ósseo, remova a pele com dissecção contundente para que a musculatura ao redor das articulações do tornozelo e joelho seja exposta. Usando uma lâmina de bisturi, começando pelo acessório tendinoso-calcâneo de Aquiles, desprende cuidadosamente o músculo gastrocnemius de seus acessórios proximais.Desarticula cuidadosamente o calcâneo dos vários ossos adjacentes e isole o espécime de tendão-calcâneo de Aquiles e limpe o excesso de tecidos moles. Para determinar a área transversal do tendão, insira o osso de cabeça para baixo para suspender o espécime no crioboto cheio de gel de agarose com o osso no gel de agarose e o tendão e músculo fora. Após a varredura usando tomografia microcomputada, remova suavemente o músculo do tendão usando uma lâmina de bisturi.Insira o osso na luminária impressa em 3D e conecte-os às grades de teste. Insira e cole o tendão entre um papel de tecido fino dobrado e fixe-o usando apertos finos de filme. Insira a amostra e as garras em um banho de teste de PBS a 37 graus Celsius e realize um teste mecânico.Neste estudo, utilizando luminárias impressas 3D reutilizáveis para segurar osso, o tempo de preparação da amostra foi reduzido de horas para minutos. Curvas representativas de deformação de carga para testes de tração do tendão do supraespinhal usando métodos atuais eliminaram artefatos principais de agarramento, como falha da placa de crescimento. As propriedades mecânicas dos tendões supraespinhal e aquiles demonstram um efeito significativo do sexo com base em testes T não pagos com valor P inferior a 0,05.A Micro CT mediu com sucesso a área transversal ao longo do comprimento do tendão do supraespinhal ao longo do comprimento do tendão de Aquiles. É importante lembrar que cada site anatômico tem critérios específicos de projeto necessários para uma efetiva responsabilidade. Portanto, o design de cada luminária deve ser adaptado em conformidade.Além do teste de tração à falha, essas luminárias podem ser usadas para testes de carregamento cíclico, que fornecem informações sobre fadiga tendinosa e propriedades viscoeleasticas. Caracterizar as propriedades mecânicas dos tendões murinos é incomum na literatura devido a uma série de razões, incluindo a dificuldade em agarrar esses pequenos tecidos, métodos tediosos e demorados de preparação de espécimes e fraturas de placas de crescimento. Este protocolo apresenta um método eficiente e reprodutível para testar tendões de camundongos que eliminou falhas de aderência artefatosas e triplicou o número de amostras que podem ser testadas em um dia.

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.

Dirigido Cellular Automontagem para Fabricar Anéis Cell-Derived Tecido para Análise Biomecânica e Engenharia de Tecidos

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

Bioengenharia

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.

Determinação da taxa de transporte de xenobióticos e nanomateriais através da placenta usando o<em&gt; Ex vivo</em&gt; Modelo de perfusão da placenta humana

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.

Caracterização biomecânica de tecidos moles Humanos Usando recuo e testes de tração

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.

Um Experimental e Finite Element protocolo para investigar o transporte de solutos neutras e carregadas em toda a cartilagem articular

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.

Uma cama de teste para examinar o capacete Fit e retenção e medidas biomecânicas de cabeça e pescoço lesão em impacto simulado

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.

Métodos para testes biomecânicos in vivo em plexo braquial em leitões neonatais

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.

Tom basal biaxial e teste passivo do sistema reprodutivo murino usando um Miografo de pressão

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.

A Quantificação da Injeção por Testes Mecânicos

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.

Análise de interação biomecânica de fluido-estrutura biomecânica baseada em coerência óptica da progressão da aterosclerose coronária

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.

Construção de um Modelo de Organ-On-A-Chip de Células Musculares Lisas da Aorta Humana para Recapitulação da Deformação Biomecânica na Parede Aórtica

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