Apoiado pelo NIH concessão HD052670.

1. Revestimento de placas com ECM proteínas <ol><li> Sob condições estéreis, misturar 120 ug de laminina com 12 ml de frio estéril 1X PBS por placa. </li><li> Tome Bioflex placas não tratadas e adicionar 2 ml da solução a cada poço (concentração final de laminina é 2 ug / cm 2). Alternativamente, outras proteínas de ECM podem ser utilizados, tais como colagénio-1 [10 ug / cm 2], fibronectina [5 ug / cm 2], vitronectina [0,5 ug / cm 2] ou elastina [10 ug / cm 2]. A técnica de revestimento é semelhante ao que é descrito para a laminina-revestimento. Assegure-se os poços são completamente cobertas pela solução. </li><li> Enrole as placas de plástico e colocado a 4 ° C sobre uma superfície plana durante a noite para permitir que o laminina para adsorver para o fundo dos poços. Nestas condições, as placas podem ser armazenadas durante pelo menos uma semana, mantendo a função de ECM boa. </li><li> No dia seguinte, sob condições estéreis, lavar os poços 3 vezes com PBS 1X. </li><li&gt; Adicionar 1 ml de BSA a 1% em PBS 1X a cada poço e incubar a 37 ° C durante 1 h para bloquear não-locais de ligação específicos nas membranas. </li><li> Lavam-se as placas 3 vezes com PBS 1X para remover as proteínas unadsorbed. </li><li> Manter as placas a 37 ° C em DMEM até que as células são isoladas a partir do passo 2,14. </li></ol> 2. Isolamento de células fetais de roedores pulmão do tipo II epiteliais Um dia antes de isolamento têm os copos de tela com malhas de diferentes tamanhos de nylon autoclavado e pronto. <ol><li> Obter pulmões fetais de timed-grávida mouse / rato em E17-19 da gestação. Transferir o tecido para um tubo de 50 ml cónico contendo meio DMEM e colocá-lo em gelo. </li><li> Fazer tampão de digestão num tubo cónico de 50 ml: (10 ml). Para este volume, o tecido de pulmão a partir de cerca de 20 fetos de rato / rato é usado. 8,5 ml de DMEM 0,5 ml 500mM pH 7.4 HEPES 5 mg de colagenase 1 5 mg de colagenase 1A 1 ml de galinha soro, inactivado pelo calor </li><li>Misturar bem até que todos os componentes são dissolvidos e filtrar através de um filtro de seringa de 0,2 micron dentro do capuz estéril. Colocar o tubo cónico contendo o tampão de digestão num banho de água a 37 ° C. </li><li> Remover o meio DMEM a partir do tubo cónico a partir do passo 2.1 e transferir o tecido em uma placa de Petri estéril. </li><li> Picar os pulmões bem com uma tesoura estéreis ou lâmina de barbear para fazer peças de tecido inferior a 1 mm e transferir o tecido para dentro do tubo cónico contendo o tampão de digestão de pré-aquecida a partir do passo 2.3. </li><li> Digerir o tecido pipetando cima e para baixo: 100 vezes com 10 ml de pipeta 100 vezes com 5 ml de pipeta 100 vezes com uma pipeta de Pasteur </li><li> Centrifugar o homogeneizado a 1300 rpm durante 5 minutos à temperatura ambiente. </li><li> Cuidadosamente remover o sobrenadante por aspiração e re-suspender o sedimento contendo as células em 15 ml de DMEM mais 20% de FBS. </li><li> Retire os copos de tela com 100 -, 30 - e malhas de 15 mícron de náilon e po lugarem em estéreis de 150 ml copos. </li><li> Adicionar homogenato celular a partir do passo 2,8 e sequencialmente filtrar através de 100 -, 30 -, e 15 micras copos tela de malha. </li><li> Collect agregada não filtrados células a partir da 30 - e 15 micron-malhas após várias lavagens com DMEM mais 10% FBS para facilitar a filtração de células não-epiteliais. </li><li> Descartar o filtrado a partir da malha 15 micron, que contém principalmente fibroblastos. </li><li> Purifica-se células do tipo II adicionais por incubação de células a partir do passo 2,11 em 75-cm 2 frascos para 30 min (approximatelly10 ml de suspensão de células por frasco). </li><li> Recolher o sobrenadante e centrifugar a 1300 rpm durante 5 minutos à temperatura ambiente para sedimentar as células. </li><li> Cuidadosamente remover o sobrenadante por aspiração e re-suspender o sedimento contendo as células em DMEM isento de soro. O volume de ressuspensão depende da quantidade de tecido processado. Aproximadamente, nós chapa do equivalente de células obtido a partir de um feto em cada poço (2 ml), a fim de achieve entre 60-70% de confluência no dia seguinte. </li><li> Suspensão placa da célula em Bioflex seis poços pré-revestidos com laminina ou fibronectina. </li></ol> 3. Isolamento de fibroblastos de pulmão de feto de roedores <ol><li> Siga os mesmos passos descritos acima para o tipo de isolamento das células II até 2,11. </li><li> Tome-se o filtrado a partir da malha 15-micron (sem lavagem anterior; volume aproximado é de 10-15 ml) e da placa em 75 cm de 2 a 37 ° C durante 30-60 min para permitir que os fibroblastos de aderir. </li><li> Aspirar o supernantant e substituir com DMEM isento de soro e incubar durante a noite. </li><li> No dia seguinte, a colheita das células com 0,25% (peso / vol) de tripsina em 0,4 mM de EDTA e da placa-as em placas Bioflex pré-revestidas com fibronectina. </li></ol> 4. Sistema experimental para proporcionar a estimulação mecânica para as células do pulmão <ol><li> De sementes as células (cerca de 50% confluentes) em placas de cultura de Bioflex em DMEM isento de soro (2 ml / poço) e deixá-los anexar e SPREanúncio por pelo menos 6h antes dos experimentos. Em geral nosso laboratório mantém células em cultura por cerca de 24 horas antes de aplicar tensão mecânica. Se um número específico de células são necessárias para as experiências, após isolamento, as células do tipo II são mantidas em DMEM isento de soro de 75-cm 2 frascos e no dia seguinte, as células são tripsinizadas, contadas e então semeadas. </li><li> No dia seguinte, os meios são substituídos com fresco DMEM isento de soro (2 ml / poço) e as placas Bioflex são montados numa Unidade Strain Flexcell FX-5000. Monocamadas não deve ser maior do que 80% confluente antes do início das experiências. </li><li> Estirpe Equibiaxial é aplicada às membranas. O regime de tensão varia dependendo de simulação de forças mecânicas in vivo (ver discussão). </li><li> Células cultivadas em não-esticado membranas cultivadas em paralelo são utilizados como controlos. </li><li> No final dos ensaios, as monocamadas pode ser processada para analisar as mudanças na expressão de genes (por exemplo C de proteína surfactante)por abundância de proteínas em tempo real-PCR, por Western blot, etc Além disso, as monocamadas pode ser fixado para experiências imunocitoquímica. Para esta técnica, após a fixação, as membranas de silastic são cortados a partir das placas e montadas em lâminas de vidro usando 10-20 ul de água como agente de montagem antes permeabilização e incubação com anticorpos. Sobrenadante pode também ser usado para investigar a presença de factores de crescimento, citocinas, etc </li></ol> 5. Os resultados representativos A Figura 1 ea Figura 2 mostram representativos contraste de fase fotografias de E18 fetais de rato células de tipo II isolado utilizando a técnica descrita no presente manuscrito. A Figura 3 demonstra que a esforços mecânicos induz a diferenciação de células de tipo II fetais epiteliais utilizando surfactante proteína C, como um marcador. <img src="/files/ftp_upload/3543/3543fig1.jpg" /> Figura 1. Repfotografia de contraste de fase representativa tirada logo após o isolamento mostrando a aparência agregado de células fetais do tipo II. <img src="/files/ftp_upload/3543/3543fig2.jpg" /> Figura 2. E18 células de tipo II fetais epiteliais foram isolados como descrito aqui e plaqueadas em placas de Bioflex revestidas com laminina. Fotografia foi tirada no dia seguinte após não esticados as células foram fixadas em paraformaldeído. A pureza das células foi determinada ser de 90 ± 5% por análise microscópica da morfologia das células epiteliais e imunocoloração para SP-C. <img src="/files/ftp_upload/3543/3543fig3.jpg" /> Figura 3. Células de tipo II Fetal epiteliais foram expostas a estirpe cíclico de 5% a 40 ciclos / min durante 16 h. Um blot) Northern de surfactante de proteína C (SP-C) a expressão do mRNA que mostra que a estirpe tipo induz a diferenciação das células II utilizando diferentes substratos ECM . Sinais + / - representam a exposição ou não streinar, respectivamente. Os dados são apresentados como média + / - SEM, n = 3; * P &lt;0,05 B) imagens de fluorescência imunocitoquímica demonstrando níveis de proteína SP-C (verde) em células de tipo II fetais expostos ou não (controle) a uma tensão mecânica.. Os núcleos foram contrastadas com DAPI (azul). Bar, 10 uM. C) Os resultados de Western blot de três experiências que mostram que estiramento mecânico aumenta SP-C da proteína. N = 3; * P &lt;0,05.

<ol>
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P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+mechanical+stretch+inhibits+cell+proliferation+and+induces+apoptosis+in+fetal+rat+lung+fibroblasts.">Cyclic mechanical stretch inhibits cell proliferation and induces apoptosis in fetal rat lung fibroblasts.</a> Am. J. Physiol. Lung. Cell. Mol. Physiol. 282, L448-L456 (2002).</li><li>Sanchez-Esteban, J., Wang, Y., Cicchiello, L. A., Rubin, L. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cyclic+mechanical+stretch+inhibits+cell+proliferation+and+induces+apoptosis+in+fetal+rat+lung+fibroblasts.">Cyclic mechanical stretch inhibits cell proliferation and induces apoptosis in fetal rat lung fibroblasts.</a> Am. J. Physiol. Lung. Cell. Mol. Physiol. 282, L448-L456 (2002).</li><li>Sanchez-Esteban, J., Wang, Y., Gruppuso, P. A., Rubin, L. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+stretch+induces+fetal+type+II+cell+differentiation+via+an+epidermal+growth+factor+receptor-extracellular-regulated+protein+kinase+signaling+pathway.">Mechanical stretch induces fetal type II cell differentiation via an epidermal growth factor receptor-extracellular-regulated protein kinase signaling pathway.</a> Am. J. Respir. Cell. Mol. Biol. 30, 76-83 (2004).</li><li>Wang, Y., Maciejewski, B. S., Lee, N., Silbert, O., McKnight, N. L., Frangos, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strain-induced+fetal+type+II+epithelial+cell+differentiation+is+mediated+via+cAMP-PKA-dependent+signaling+pathway.">Strain-induced fetal type II epithelial cell differentiation is mediated via cAMP-PKA-dependent signaling pathway.</a> Am. J. Physiol. Lung. Cell. Mol. Physiol. 291, L820-L827 (2006).</li><li>Sanchez-Esteban, J., Wang, Y., Filardo, E. J., Rubin, L. P., Ingber, D. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrins+{beta}1,+{alpha}6,+and+{alpha}3+contribute+to+mechanical+strain-induced+differentiation+of+fetal+lung+type+II+epithelial+cells+via+distinct+mechanisms.">Integrins {beta}1, {alpha}6, and {alpha}3 contribute to mechanical strain-induced differentiation of fetal lung type II epithelial cells via distinct mechanisms.</a> Am. J. Physiol. Lung. Cell. Mol. Physiol. 290, L343-L350 (2006).</li><li>Wang, Y., Maciejewski, B. S., Soto-Reyes, D., Lee, H. 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S., Esho, K., Fulton, C., Sharma, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interleukin-10+protects+cultured+fetal+rat+type+II+epithelial+cells+from+injury+induced+by+mechanical+stretch.">Interleukin-10 protects cultured fetal rat type II epithelial cells from injury induced by mechanical stretch.</a> Am. J. Physiol. Lung. Cell. Mol. Physiol. 294, L225-L232 (2008).</li><li>Hawwa, R. L., Hokenson, M. A., Wang, Y., Huang, Z., Sharma, S., Sanchez-Esteban, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=IL-10+inhibits+inflammatory+cytokines+released+by+fetal+mouse+lung+fibroblasts+exposed+to+mechanical+stretch.">IL-10 inhibits inflammatory cytokines released by fetal mouse lung fibroblasts exposed to mechanical stretch.</a> Pediatric Pulmonology. , (2011).</li><li>Kitterman, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effects+of+mechanical+forces+on+fetal+lung+growth.">The effects of mechanical forces on fetal lung growth.</a> Clin. Perinatol. 23, 727-740 (1996).</li><li>Harding, R., Crystal, R. G., West, J. B., Banes, P. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fetal+breathing+movements.">Fetal breathing movements.</a> The Lung: Scientific Fountations. , 2093-2104 (1997).</li><li>Harding, R., Liggins, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Changes+in+thoracic+dimensions+induced+by+breathing+movements+in+fetal+sheep.">Changes in thoracic dimensions induced by breathing movements in fetal sheep.</a> Reprod. Fertil. Dev. 8, 117-124 (1996).</li></ol>

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Neste artigo, nós descrevemos um método para isolar as células fetais do tipo II epiteliais e fibroblastos e expô-los a estimulação mecânica usando o aparelho Strain Flexcell. Usámos esta técnica para avaliar a diferenciação de células epiteliais 1,2 e para estudar receptor e vias de sinalização activados por estiramento 3-9. Além disso, este método também pode ser usado para investigar as respostas das células induzidas por lesão mecânica 10,11. O procedimento baseia...

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Company</td>
			<td>Catalogue number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Sigma</td>
			<td>D5648</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma</td>
			<td>H3375</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Collagenase 1</td>
			<td>Sigma</td>
			<td>C0130</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Collagenase 1A</td>
			<td>Sigma</td>
			<td>C9891</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Chicken serum</td>
			<td>Sigma</td>
			<td>C5405</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Screen cups</td>
			<td>Sigma</td>
			<td>CD1-1KT</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Syringe filters</td>
			<td>Fisher Scientific</td>
			<td>09-754-25</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>100 micron nylon mesh</td>
			<td>Small Parts, INC</td>
			<td>CMN-100-D</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>30 micron mesh</td>
			<td>Small Parts, INC</td>
			<td>CMN-30-D</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>15 micron mesh</td>
			<td>Dynamic Aqua-Supply Ltd.</td>
			<td>NTX15</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Laminin</td>
			<td>Sigma</td>
			<td>L2020</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Collagen-1</td>
			<td>Collagen Biomed</td>
			<td>PC0701</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Fibronectin</td>
			<td>Sigma</td>
			<td>F1141</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Vitronectin</td>
			<td>Sigma</td>
			<td>V-0132</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Elastin</td>
			<td>Sigma</td>
			<td>E-6402</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Bioflex plate</td>
			<td>Flexcell International</td>
			<td>BF-3001U</td>
			<td>Uncoated</td>
		</tr>
		<tr>
			<td>Flexcell Strain Unit</td>
			<td>Flexcell International</td>
			<td>FX-5000</td>
			<td>&nbsp;</td>
		</tr>
	</tbody>
</table>

an experimental system to study mechanotransduction in fetal lung cells

Forças mecânicas geradas in utero pelos repetitivos movimentos como de respiração e pela distensão líquido são essenciais para o desenvolvimento do pulmão normal. Um componente-chave do desenvolvimento do pulmão é a diferenciação de células alveolares do tipo II epiteliais, a principal fonte de surfactante pulmonar. Estas células também participar na homeostase de fluido no lúmen alveolar, de defesa do hospedeiro, e reparação de lesão. Além disso, as células do pulmão distais do parênquima pode ser directamente exposta ao estiramento exagerada durante a ventilação mecânica após o nascimento. No entanto, os mecanismos precisos moleculares e celulares, através da qual as células do pulmão detectam estímulos mecânicos para influenciar o desenvolvimento do pulmão e para promover a lesão pulmonar não são completamente compreendidos. Aqui, nós proporcionar um método simples e de alta pureza para isolar células de tipo II e de fibroblastos a partir de pulmões de roedores fetais. Em seguida, nós descrevemos um sistema in vitro, A Unidade de Strain Flexcell, para proporcionar a estimulação mecânica para células fetais, simulando forças mecânicas emdesenvolvimento pulmonar fetal ou lesão pulmonar. Este sistema experimental fornece uma excelente ferramenta para investigar os mecanismos moleculares e celulares em células de pulmão de feto expostos a esticar. Usando essa abordagem, nosso laboratório identificou vários receptores e proteínas sinalizadoras que participam mecanotransdução no desenvolvimento do pulmão fetal e lesão pulmonar.

Watch this Scientific Journal Video about An Experimental System to Study Mechanotransduction in Fetal Lung Cells at JoVE.com

An Experimental System to Study Mechanotransduction in Fetal Lung Cells

Forças mecânicas desempenham um papel chave no desenvolvimento de pulmão e lesão pulmonar. Aqui, nós descrevemos um método para isolar roedores fetais de pulmão de células do tipo II epiteliais e fibroblastos e expô-los a estimulação mecânica utilizando um<em&gt; In vitro</em&gt; Sistema.

Um sistema experimental para estudar Mecanotransdução em células do pulmão fetal

Mechanical forces generated in utero by repetitive breathing-like movements and by fluid distension are critical for normal lung development. A key ...

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Research

JoVE Journal

Bioengineering

12.9K visualizações.  Alpert Medical School of Brown University. Forças mecânicas desempenham um papel chave no desenvolvimento de pulmão e lesão pulmonar. Aqui, nós descrevemos um método para isolar roedores fetais de pulmão de células do tipo II epiteliais e fibroblastos e expô-los a estimulação mecânica utilizando um In vitro Sistema.

Vídeo: An Experimental System to Study Mechanotransduction in Fetal Lung Cells

Axon Stretch Growth: The Mechanotransduction of Neuronal Growth

During pre-synaptic embryonic development, neuronal processes traverse short distances to reach their targets via growth cone. Over time, neuronal somata are separated from their axon terminals due to skeletal growth of the enlarging organism (Weiss 1941; Gray, Hukkanen et al. 1992). This mechanotransduction induces a secondary mode of neuronal growth capable of accommodating continual elongation of the axon (Bray 1984; Heidemann and Buxbaum 1994; Heidemann, Lamoureux et al. 1995; Pfister, Iwata et al. 2004).
Axon Stretch Growth (ASG) is conceivably a central factor in the maturation of short embryonic processes into the long nerves and white matter tracts characteristic of the adult nervous system. To study ASG in vitro, we engineered bioreactors to apply tension to the short axonal processes of neuronal cultures (Loverde, Ozoka et al. 2011). Here, we detail the methods we use to prepare bioreactors and conduct ASG. First, within each stretching lane of the bioreactor, neurons are plated upon a micro-manipulated towing substrate. Next, neurons regenerate their axonal processes, via growth cone extension, onto a stationary substrate. Finally, stretch growth is performed by towing the plated cell bodies away from the axon terminals adhered to the stationary substrate; recapitulating skeletal growth after growth cone extension.
Previous work has shown that ASG of embryonic rat dorsal root ganglia neurons are capable of unprecedented growth rates up to 10mm/day, reaching lengths of up to 10cm; while concurrently resulting in increased axonal diameters (Smith, Wolf et al. 2001; Pfister, Iwata et al. 2004; Pfister, Bonislawski et al. 2006; Pfister, Iwata et al. 2006; Smith 2009). This is in dramatic contrast to regenerative growth cone extension (in absence of mechanical stimuli) where growth rates average 1mm/day with successful regeneration limited to lengths of less than 3cm (Fu and Gordon 1997; Pfister, Gordon et al. 2011). Accordingly, further study of ASG may help to reveal dysregulated growth mechanisms that limit regeneration in the absence of mechanical stimuli.

A unique tissue engineering method was developed to elongate numerous nerve fibers in culture by recapitulating axon stretch growth; a form of nervous system growth whereby nerves elongate in conjunction with growth of the enlarging body.

Axon Crescimento Stretch: O Mecanotransdução do Crescimento Neuronal

During pre-synaptic embryonic development, neuronal processes traverse short distances to reach their targets via growth cone. Over time, neuronal somata ...

Bioengenharia

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

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

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

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

Projeto de um biorreator de pressão cíclica para o Ex Vivo Estudo de válvulas cardíacas Aórtica

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

Constructing a Low-budget Laser Axotomy System to Study Axon Regeneration in C. elegans

Laser axotomy followed by time-lapse microscopy is a sensitive assay for axon regeneration phenotypes in C. elegans1. The main difficulty of this assay is the perceived cost ($25-100K) and technical expertise required for implementing a laser ablation system2,3. However, solid-state pulse lasers of modest costs (&lt;$10K) can provide robust performance for laser ablation in transparent preparations where target axons are "close" to the tissue surface. Construction and alignment of a system can be accomplished in a day. The optical path provided by light from the focused condenser to the ablation laser provides a convenient alignment guide. An intermediate module with all optics removed can be dedicated to the ablation laser and assures that no optical elements need be moved during a laser ablation session. A dichroic in the intermediate module allows simultaneous imaging and laser ablation. Centering the laser beam to the outgoing beam from the focused microscope condenser lens guides the initial alignment of the system. A variety of lenses are used to condition and expand the laser beam to fill the back aperture of the chosen objective lens. Final alignment and testing is performed with a front surface mirrored glass slide target. Laser power is adjusted to give a minimum size ablation spot (&lt;1um). The ablation spot is centered with fine adjustments of the last kinematically mounted mirror to cross hairs fixed in the imaging window. Laser power for axotomy will be approximately 10X higher than needed for the minimum ablation spot on the target slide (this may vary with the target you use). Worms can be immobilized for laser axotomy and time-lapse imaging by mounting on agarose pads (or in microfluidic chambers4). Agarose pads are easily made with 10% agarose in balanced saline melted in a microwave. A drop of molten agarose is placed on a glass slide and flattened with another glass slide into a pad approximately 200 um thick (a single layer of time tape on adjacent slides is used as a spacer). A "Sharpie" cap is used to cut out a uniformed diameter circular pad of 13mm. Anesthetic (1ul Muscimol 20mM) and Microspheres (Chris Fang-Yen personal communication) (1ul 2.65% Polystyrene 0.1 um in water) are added to the center of the pad followed by 3-5 worms oriented so they are lying on their left sides. A glass coverslip is applied and then Vaseline is used to seal the coverslip and prevent evaporation of the sample.

Constructing a Low-budget Laser Axotomy System to Study Axon Regeneration in C. elegans

Laser axotomy followed by time-lapse imaging is a sensitive way to assay the effects of mutations in C. elegans on axon regeneration. A high quality, but inexpensive, laser ablation system can be easily added to most microscopes. Time lapse imaging over 15 hours requires careful immobilization of the worm.

Construção de um baixo orçamento Laser Sistema axotomia para estudar a regeneração do axônio em C. elegans</em

Laser axotomy followed by time-lapse microscopy is a sensitive assay for axon regeneration phenotypes in C. elegans1.  The main difficulty of this assay ...

Luminescence Resonance Energy Transfer to Study Conformational Changes in Membrane Proteins Expressed in Mammalian Cells

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range of 10-100 &#197;. By measuring the distances under various ligated conditions, conformational changes of the protein can be easily assessed. With LRET, a lanthanide, most often chelated terbium, is used as the donor fluorophore, affording advantages such as a longer donor-only emission lifetime, the flexibility to use multiple acceptor fluorophores, and the opportunity to detect sensitized acceptor emission as an easy way to measure energy transfer without the risk of also detecting donor-only signal. Here, we describe a method to use LRET on membrane proteins expressed and assayed on the surface of intact mammalian cells. We introduce a protease cleavage site between the LRET fluorophore pair. After obtaining the original LRET signal, cleavage at that site removes the specific LRET signal from the protein of interest allowing us to quantitatively subtract the background signal that remains after cleavage. This method allows for more physiologically relevant measurements to be made without the need for purification of protein.

We describe here an improved Luminescence Resonance Energy Transfer (LRET) method where we introduce a protease cleavage site between the donor and acceptor fluorophore sites. This modification allows us to obtain specific LRET signals arising from membrane proteins of interest, allowing for the study of membrane proteins without protein purification.

Luminescência Ressonância transferência de energia para estudar mudanças conformacionais na membrana proteínas expressas em células de mamíferos

Luminescence Resonance Energy Transfer, or LRET, is a powerful technique used to measure distances between two sites in proteins within the distance range ...

Electrotaxis Studies of Lung Cancer Cells using a Multichannel Dual-electric-field Microfluidic Chip

The behavior of directional cell migration under a direct current electric-field (dcEF) is referred to as electrotaxis. The significant role of physiological dcEF in guiding cell movement during embryo development, cell differentiation, and wound healing has been demonstrated in many studies. By applying microfluidic chips to an electrotaxis assay, the investigation process is shortened and experimental errors are minimized. In recent years, microfluidic devices made of polymeric substances (e.g., polymethylmethacrylate, PMMA, or acrylic) or polydimethylsiloxane (PDMS) have been widely used in studying the responses of cells to electrical stimulation. However, unlike the numerous steps required to fabricate a PDMS device, the simple and rapid construction of the acrylic micro&#64258;uidic chip makes it suitable for both device prototyping and production. Yet none of the reported devices facilitate the efficient study of the simultaneous chemical and dcEF effects on cells. In this report, we describe our design and fabrication of an acrylic-based multichannel dual-electric-field (MDF) chip to investigate the concurrent effect of chemical and electrical stimulation on lung cancer cells. The MDF chip provides eight combinations of electrical/chemical stimulations in a single test. The chip not only greatly shortens the required experimental time but also increases accuracy in electrotaxis studies.

Many microfluidic devices have been developed for use in the study of electrotaxis. Yet, none of these chips allows the efficient study of the simultaneous chemical and electric-field (EF) effects on cells. We developed a polymethylmethacrylate-based device that offers better-controlled coexisting EF and chemical stimulation for use in electrotaxis research.

Electrotaxis Estudos de pulmão células de câncer usando um Multichannel Dual-elétrico-campo Microfluidic Chip

The behavior of directional cell migration under a direct current electric-field (dcEF) is referred to as electrotaxis. The significant role of ...

Generation of ESC-derived Mouse Airway Epithelial Cells Using Decellularized Lung Scaffolds

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and cell-matrix interactions. Due to this complexity, recapitulation of lung development in vitro to promote differentiation of stem cells to lung epithelial cells has been challenging. In this protocol, decellularized lung scaffolds are used to mimic the 3-dimensional environment of the lung and generate stem cell-derived airway epithelial cells. Mouse embryonic stem cell are first differentiated to the endoderm lineage using an embryoid body (EB) culture method with activin A. Endoderm cells are then seeded onto decellularized scaffolds and cultured at air-liquid interface for up to 21 days. This technique promotes differentiation of seeded cells to functional airway epithelial cells (ciliated cells, club cells, and basal cells) without additional growth factor supplementation. This culture setup is defined, serum-free, inexpensive, and reproducible. Although there is limited contamination from non-lung endoderm lineages in culture, this protocol only generates airway epithelial populations and does not give rise to alveolar epithelial cells. Airway epithelia generated with this protocol can be used to study cell-matrix interactions during lung organogenesis and for disease modeling or drug-discovery platforms of airway-related pathologies such as cystic fibrosis.

This protocol efficiently directs mouse embryonic stem cell-derived definitive endoderm to mature airway epithelial cells. This differentiation technique uses 3-dimensional decellularized lung scaffolds to direct lung lineage specification, in a defined, serum-free culture setting.

Geração de células de camundongo Airway epiteliais derivados de ESC Usando descelularizado Lung Scaffolds

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and ...

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

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

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

Um protocolo Experimental para avaliar o desempenho de novas sondas de ultrassom baseado na tecnologia CMUT na aplicação de imagens do cérebro

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

DNA Nanotubes as a Versatile Tool to Study Semiflexible Polymers

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of flexible polymers nor of rigid rods. Underlying filaments remain outstretched due to their non-vanishing backbone stiffness, which is quantified via the persistence length (lp), but they are also subject to strong thermal fluctuations. Their finite bending stiffness leads to unique, non-trivial collective mechanics of bulk networks, enabling the formation of stable scaffolds at low volume fractions while providing large mesh sizes. This underlying principle is prevalent in nature (e.g., in cells or tissues), minimizing the high molecular content and thereby facilitating diffusive or active transport. Due to their biological implications and potential technological applications in biocompatible hydrogels, semiflexible polymers have been subject to considerable study. However, comprehensible investigations remained challenging since they relied on natural polymers, such as actin filaments, which are not freely tunable. Despite these limitations and due to the lack of synthetic, mechanically tunable, and semiflexible polymers, actin filaments were established as the common model system. A major limitation is that the central quantity lp cannot be freely tuned to study its impact on macroscopic bulk structures. This limitation was resolved by employing structurally programmable DNA nanotubes, enabling controlled alteration of the filament stiffness. They are formed through tile-based designs, where a discrete set of partially complementary strands hybridize in a ring structure with a discrete circumference. These rings feature sticky ends, enabling the effective polymerization into filaments several microns in length, and display similar polymerization kinetics as natural biopolymers. Due to their programmable mechanics, these tubes are versatile, novel tools to study the impact of lp on the single-molecule as well as the bulk scale. In contrast to actin filaments, they remain stable over weeks, without notable degeneration, and their handling is comparably straightforward.

Semiflexible polymers display unique mechanical properties that are extensively applied by living systems. However, systematic studies on biopolymers are limited since properties such as polymer rigidity are inaccessible. This manuscript describes how this limitation is circumvented by programmable DNA nanotubes, enabling experimental studies on the impact of filament rigidity.

Nanotubos de DNA como uma ferramenta versátil para estudar semiflexível polímeros

Mechanical properties of complex, polymer-based soft matter, such as cells or biopolymer networks, can be understood in neither the classical frame of ...

An Orbital Shaking Culture of Mammalian Cells in O-shaped Vessels to Produce Uniform Aggregates

Suspension cultures of mammalian cell aggregates are required for various applications in medical and biotechnological fields. The disposable bag-based method is one of the simplest techniques for the mass production of cellular aggregates, but it does not protect the cultures against over-aggregation, which occurs when they gather at the bottom center of the culture vessel. To solve this problem, we developed an O-shaped dish and an O-shaped bag, neither of which contains a central region. Aggregates grown in either O-shaped culture vessel were noticeably more uniform in size than aggregates grown in conventional vessels. Histological analyses showed that aggregates in conventional culture dishes contained necrotic cores most likely caused by a poor oxygen supply. In contrast, aggregates that were grown in the O-shaped bag, even those with similar diameters to aggregates in conventional culture dishes, did not show necrotic cores. These results suggest that the O-shaped bag provides sufficient oxygen to the aggregates due to the oxygen permeability of the bag material. We, therefore, propose that this novel gas-permeable O-shaped culture bag is suitable for the mass production of uniform aggregates that are necessary in various biotechnological fields.

Here we present a protocol for using O-shaped vessels, specialized for suspension cultures of cellular aggregates, with orbital shaking. The HEK293 cells grown in this bag form more homogeneous aggregates than those grown in conventional culture vessels.

Um Orbital agitando a cultura de células de mamíferos em vasos em forma do produzir agregados uniformes

Suspension cultures of mammalian cell aggregates are required for various applications in medical and biotechnological fields. The disposable bag-based ...

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

Organ engineering is a novel strategy to generate liver organ substitutes that can potentially be used in transplantation. Recently, in vivo liver engineering, including in vivo organ decellularization followed by repopulation, has emerged as a promising approach over ex vivo liver engineering. However, postoperative survival was not achieved. The aim of this study is to develop a novel surgical technique of in vivo selective liver lobe perfusion in rats as a prerequisite for in vivo liver engineering. We generate a circuit bypass only through the left lateral lobe. Then, the left lateral lobe is perfused with heparinized saline. The experiment is performed with 4 groups (n = 3 rats per group) based on different perfusion times of 20 min, 2 h, 3 h, and 4 h. Survival, as well as the macroscopically visible change of color and the histologically determined absence of blood cells in the portal triad and the sinusoids, is taken as an indicator for a successful model establishment. After selective perfusion of the left lateral lobe, we observe that the left lateral lobe, indeed, turned from red to faint yellow. In a histological assessment, no blood cells are visible in the branch of the portal vein, the central vein, and the sinusoids. The left lateral lobe turns red after reopening the blocked vessels. 12/12 rats survived the procedure for more than one week. We are the first to report a surgical model for in vivo single liver lobe perfusion with a long survival period of more than one week. In contrast to the previously published report, the most important advantage of the technique presented here is that perfusion of 70% of the liver is maintained throughout the whole procedure. The establishment of this technique provides a foundation for in vivo partial liver engineering in rats, including decellularization and recellularization.

A Novel Surgical Technique As a Foundation for In Vivo Partial Liver Engineering in Rat

We establish a novel surgical technique for an in vivo single liver lobe perfusion model in rat as a prerequisite for further studying in vivo partial liver engineering in the future.