This work was partially funded through the Richard Barber Foundation and a Thomas Rumble Fellowship (TJW).

1. água / óleo / água emulsão dupla Microsphere Produção <ol><li> Em primeiro lugar preparar a 2% e 0,5% w / v de solução de álcool polivinílico (PVA), em água desionizada. Mexa as soluções a 50 ° C até que claro, isso pode levar várias horas. Prepara-se uma solução de 2% v / v de álcool isopropílico em água desionizada. </li><li> Prepara-se uma solução aquosa de proteína hidrófila desejado. A tabela abaixo fornece formulações de exemplo. </li></ol><img alt="Tabela 1" src="/files/ftp_upload/51517/51517table1highres.jpg" /> Tabela 1:. Exemplo soluções de proteína As seguintes soluções de proteína foram encapsulados com sucesso e electrospun usando esse protocolo. Outras soluções de proteína hidrófilas podem ser utilizados conforme necessário. <ol start="3"><li> Colocar 40 ml da solução de PVA a 0,5% para um tubo de centrífuga de 50 ml e de lado. </li><li> Num tubo de centrífuga de 15 ml, dissolver 300 mg de 65:35poli (ácido láctico-co-glicólico) (PLGA), em 3 ml de diclorometano. Um misturador de vórtice pode ser usado para acelerar a dissolução de PLGA. </li><li> Combinar 200 mL de solução de proteína e 4 ul de solução de PVA a 2%. Despejar a mistura de proteína na solução de PLGA (passo 1.4). As soluções irão permanecer na maior parte separada. </li><li> Colocar o tubo em um copo de água com gelo. Usando um sonicador de varinha para ~ 10 Watts (RMS), agitar a solução durante alguns segundos (5-10) até uma emulsão branca cremosa uniforme é criado. </li><li> Verta a emulsão para dentro do tubo de 50 ml contendo 0,5% de PVA (fase 1.3). Misture a solução a alta velocidade num misturador vortex durante ~ 20 seg. A solução vai desenvolver uma aparência turva. </li><li> Transferir a emulsão para um copo de 200 ml e lugar numa placa de agitação a 350 rpm durante 2 min. Adicionar 50 ml de 2% de álcool isopropílico para o recipiente sobre a placa de agitação. Permitir que a mistura continue a agitar durante um período mínimo de 1 hora para permitir que o DCM evaporar-se e o PLGA a endurecer. </li><li> Transferência de tele microesfera solução em tubos de centrifugação. </li><li> Centrifugar a 425 xg por 3 min. As microesferas será coletado na parte inferior do tubo e aparecem em branco. Remova cuidadosamente o sobrenadante do tubo, acima das microesferas, e armazenar em um frasco de 500 ml. </li><li> Lavar as microesferas com água desionizada através do enchimento do tubo de três quartos cheio e agitando-a redistribuir as microesferas no líquido. </li><li> Repita os passos de 1,10 e 1,11 de quatro vezes. </li><li> Após a lavagem final, remover o sobrenadante e novamente lugar no frasco de 500 ml com as outras amostras. Congelar as microesferas recolhidas no tubo de centrífuga, em seguida, liofilizar durante pelo menos 24 horas. </li><li> Visualize as microesferas sob um microscópio de luz ou com um microscópio eletrônico de varredura. Microesferas não maiores que 60 um são para electrospinning eficaz. Se microesferas são muito grandes, sonicando ou vórtex vezes maior pode ser necessária no passo 1.6 ou 1.7. </li> &lt;li&gt; Guarde as microesferas secas em um freezer -20 ° C. </li><li> Opcional: Usar um ensaio de proteína, as instruções do fabricante, para testar a quantidade de proteína na garrafa de 500 ml a partir do passo 30 de 1,10. Isto é usado para calcular a percentagem de proteína encapsulada em microesferas, subtraindo a quantidade de solução a partir do que foi usado no processo de produção. </li></ol> Nota: Para visualizar a localização da proteína na microesfera adicionar Rodamina 2 ug / ml para a solução de PLGA 31 e encapsular uma proteína conjugada com FITC Figura 1 mostra um exemplo.. 2. Eletrofiação com Microesferas <ol><li> Antes da preparação de solução de electrospinning, criar uma solução 0,5% w / v do foto-iniciador, em água deionizada por dissolução a 37 ° C. Este processo pode demorar várias horas. </li><li> Criar um 2% w / v de metacrilado de ácido hialurónico (meha) (ver Burdick et al. De síntese), 29, 3%w / v de 900 kD de poli (óxido de etileno) (PEO) e 0,05% w / v solução de iniciador foto em água desionizada. <ol><li> Calcule a quantidade correta de MEHA e PEO para o volume desejado. Por exemplo, 10 ml de solução de electrospinning requer 200 mg de meha e 300 mg de PEO. </li><li> Dissolve-se o PEO em água deionizada a 90% do volume final desejado (9 ml, para este exemplo). Isto pode levar várias horas, numa placa de agitação aquecida ou banho de água a 37 ° C pode ser usado para acelerar o processo. </li><li> Em seguida adicione o meha e usar um misturador de vórtice de agitar a solução até estar límpida. Isso só vai levar alguns minutos. </li><li> Finalmente adicionar a solução de iniciador foto 0,5% para preencher o volume restante 10% (1 ml para este exemplo). </li></ol></li><li> Adicionar microesferas na concentração desejada até 400 mg / ml. Misture a solução num misturador vortex até que as microesferas são distribuídas uniformemente na solução. </li><li> Transferir a solução para uma seringa e anexar um de 6 polegadas de calibre 18 blagulha ponta UNT. </li><li> Coloque a seringa em uma bomba de seringa e configurá-lo para dispensar a 1,2 ml / hr. </li><li> Tape uma camada de folha de alumínio na placa de coleção ou mandril. Isso permite fácil limpeza e armazenamento do andaime acabado. Um mandril rotativo é usado para criar fibras alinhadas. Uma placa plana ou mandril estacionário irá resultar em fibras dispostas aleatoriamente. </li><li> Conecte o fio terra a partir de uma fonte de alimentação de alta tensão para o aparelho de coleta. Ligue o fio positivo para a agulha. </li><li> Ajustar a superfície da bomba de seringa e de recolha de modo que não é de 15 cm entre a ponta da agulha e a superfície de recolha. </li><li> Iniciar o bombeamento de polímero, quando a solução é visível no final da seringa, ligar a fonte de tensão e ajuste a tensão de 24 kV. ATENÇÃO: Uma vez que a tensão é ligada não toque em qualquer parte metálica do sistema. Carga também podem saltar distâncias curtas a partir de partes eletrificadas para a pele. </li><li> Execute a solução até despessura andaime esired é alcançado. Quando completa desligar fonte de tensão e bomba de seringa. </li><li> Retire o papel alumínio com andaime anexado. Andaimes concluídas contendo proteína são armazenados num congelador de -20 ° C. </li></ol> 3. Protein Testing bioatividade <ol><li> Preparar meios de cultura de células. Adicionar 10% v / v de soro fetal bovino, 1% v / v de L-glutamina, e 1% v / v de Penicilina-Estreptomicina a meio de Eagle modificado por Dulbecco. </li><li> Selecione lamelas de vidro que se encaixam completamente dentro de um poço da placa. </li><li> Use 3 (Trimethoxysilyl) metacrilato de propilo para tratar as lamelas como descrito pelo fabricante. Metacrilaï¿½ï¿½o aumenta a adesão ao cadafalso as lamelas. </li><li> Anexar lamelas metacrilado para a área de cobrança da electrospinner com fita dupla face removível antes de eletrofiação. Girando sobre as lamelas facilita a manipulação e visualização. </li><li> Electrospin a espessura desejada, tal como descrito acima. </li><li> Aepois Eletrofiação remova cuidadosamente lamelas de mandril. Coloque o andaime lamínulas revestidas em uma câmara de nitrogênio claro e garantir que todo o oxigênio é removido. </li><li> Coloque a câmara de andaime e a menos de 10 mW / cm 2 de 365 nm de luz durante 15 minutos. Após reticulação lugar em dimensão apropriada poços. Certifique-se de que o lado do andaime está voltado para cima. </li><li> Coloque andaimes sob uma lâmpada germicida por 30 min para esterilizar. Se desejado fibronectina ou outra proteína é usado como um revestimento para melhorar a adesão das células. Siga as instruções do fabricante para andaimes casaco. </li><li> Colheita gânglios da raiz dorsal (DRG), como descrito anteriormente por Hollenbeck 32. Uma DRG serão necessários para cada andaime coberto lamela testado. </li><li> Coloque 100-200 mL de mídia em cada andaime na placa também. Com cuidado, coloque um em cada DRG andaime na gota de mídia. Para andaime de espessura podem ser necessários mais meios de comunicação; DRG precisam ser totalmente submersa e não Floating. </li><li> Incubar o andaime e DRG, a 37 ° C durante 4 horas para permitir que a célula aderir ao andaime. </li><li> Preencha os meios de comunicação para o nível apropriado para o bem e coloque de volta na incubadora. Continuar a incubação durante 4-6 dias. </li><li> Após o período de incubação remova cuidadosamente os meios de comunicação de cada poço e lavar cuidadosamente uma vez com PBS. Fixar as células durante 30 minutos, utilizando 4% w / v de paraformaldeído. </li><li> Células a mancha usando uma mancha de anticorpo para neurofilament. Isto irá permitir a visualização do crescimento de neurites para quantificação. DAPI também pode ser utilizado para visualizar os núcleos das células. Um exemplo de protocolo de coloração foi descrito por Sundararaghavan e colegas 14. </li><li> Visualizar as células utilizando um microscópio de fluorescência. <ol><li> Coloque poços na fase do microscópio. </li><li> Localize a massa celular usando as configurações de filtro e excitação para DAPI. </li><li> Uma vez que a célula está a mudar de filtro FITC para visualizar as neurites prolongadas. Ucantar a função de ponto no microscópio coletar e combinar o número de imagens necessárias para ver toda a estrutura. Repita o procedimento para DAPI, FITC e campo claro. </li></ol></li></ol>

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J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+dual+compartment+diffusion+chamber+for+studying+axonal+chemotaxis+in+3D+collagen.">A dual compartment diffusion chamber for studying axonal chemotaxis in 3D collagen.</a> Journal of Neuroscience Methods. 215, 53-59 (2013).</li><li>Madduri, S., di Summa, P., Papalo&#239;zos, M., Kalbermatten, D., Gander, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+controlled+co-delivery+of+synergistic+neurotrophic+factors+on+early+nerve+regeneration+in+rats.">Effect of controlled co-delivery of synergistic neurotrophic factors on early nerve regeneration in rats.</a> Biomaterials. 31, 8402-8409 (2010).</li><li>Xu, X., 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=Polyphosphoester+microspheres+for+sustained+release+of+biologically+active+nerve+growth+factor.">Polyphosphoester microspheres for sustained release of biologically active nerve growth factor.</a> Biomaterials. 23, 3765-3772 (2002).</li><li>Yan, Q., Yin, Y., Li, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Use+new+PLGL-RGD-NGF+nerve+conduits+for+promoting+peripheral+nerve+regeneration.">Use new PLGL-RGD-NGF nerve conduits for promoting peripheral nerve regeneration.</a> Biomed Eng Online. 11, (2012).</li><li>Gungor-Ozkerim, P. S., Balkan, T., Kose, G. T., Sarac, A. S., Kok, F. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Incorporation+of+growth+factor+loaded+microspheres+into+polymeric+electrospun+nanofibers+for+tissue+engineering+applications.">Incorporation of growth factor loaded microspheres into polymeric electrospun nanofibers for tissue engineering applications.</a> J Biomed Mater Res A. , (2013).</li><li>Li, X., 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=Encapsulation+of+proteins+in+poly(L-lactide-co-caprolactone)+fibers+by+emulsion+electrospinning.">Encapsulation of proteins in poly(L-lactide-co-caprolactone) fibers by emulsion electrospinning.</a> Colloids Surf B Biointerfaces. 75, 418-424 (2010).</li><li>Wang, C. -. Y., 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+effect+of+aligned+core-shell+nanofibres+delivering+NGF+on+the+promotion+of+sciatic+nerve+regeneration.">The effect of aligned core-shell nanofibres delivering NGF on the promotion of sciatic nerve regeneration.</a> J Biomater Sci Polym Ed. 23, 167-184 (2012).</li><li>Liu, J. -. J., Wang, C. -. Y., Wang, J. -. G., Ruan, H. -. J., Fan, C. -. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Peripheral+nerve+regeneration+using+composite+poly(lactic+acid-caprolactone)/nerve+growth+factor+conduits+prepared+by+coaxial+electrospinning.">Peripheral nerve regeneration using composite poly(lactic acid-caprolactone)/nerve growth factor conduits prepared by coaxial electrospinning.</a> J Biomed Mater Res A. 96, 13-20 (2011).</li></ol>

The authors have nothing to disclose.

Muitos estudos têm mostrado que as células nervosas pode ser dirigido por sinais topográficos (alinhamento de fibra) e sinais químicos (fatores de crescimento) 1,2,10,11,35. Eletrofiação é um método fácil para criar fibras alinhadas. Factores de crescimento de estimular o crescimento do nervo, mas de modo a incluir os em condutas nervosas (NC), é necessário um método para libertação sustentada. Para criar um sistema mais robusto com as duas pistas, estes dois sinais devem ser combinados. Vários...

Um dos desafios em curso em engenharia de tecido neural é a criação de um canal do nervo (NC) que imita a matriz extracelular, onde os nervos crescem naturalmente. A pesquisa mostrou que as células respondem a vários fatores em seu ambiente, incluindo mecânica, topográfica, adesivo e sinais químicos 1-3. Um dos principais desafios nesta área é determinar a combinação adequada de sinais e fabricação de um sistema que pode manter pistas por um longo período para apoiar o crescimento de células 4. Neurónios periféricos são conhecidos a preferir um substrato macio, ser dirigido por fibras alinhadas, e responder ao factor de crescimento do nervo (NGF) 5-7. CNs que pode fornecer pistas químicas durante semanas têm sido mostrados para proporcionar uma melhor recuperação funcional mais próximo ao de enxertos, o padrão ouro atual para o reparo do nervo 8,9. Materiais e métodos de produção Vários pode ser usado para produzir mecânica e topográficoal deixas 10-13. Sinais mecânicos são inerentes ao material escolhido, fazendo com que a seleção do material apropriado para a aplicação crítica 1,13. Os métodos de produção para controlar sinais topográficos incluem a separação das fases, a auto-montagem e eletrofiação 1,13. Para aplicações em microescala, microfluídica, photopatterning, gravar, lixívias sal, ou espumas de gás também pode ser usado 14-17. Electrospinning surgiu como a forma mais popular para engenheiro substratos fibrosos para cultura de tecidos, devido à sua flexibilidade e facilidade de produção 13,18-23. Nanofibras electrospun são fabricados pela aplicação de uma alta tensão de uma solução de polímero fazendo-a afastar-se e estender-se através de um curto intervalo de descarga 24. Um andaime alinhado pode ser criado através da recolha das fibras num mandril rotativo ligado à terra e não alinhados andaimes são recolhidos numa placa fixa 25. Adesão de sinalização pode ser conseguida através do revestimento do engenho andaime fibrosoh fibronectina ou conjugação de um péptido de aderência, tal como RGD, para o HA antes electrospinning 26. Sinais químicos, tais como fatores de crescimento, são as mais difíceis de manter por longos períodos, porque eles precisam de uma fonte de liberação controlada. Muitos sistemas foram tentou adicionar liberação controlada de redes fibrosas electrospun com níveis variados de sucesso. Estes métodos incluem electrospinning mistura, emulsão electrospinning, shell electrospinning núcleo e conjugação de proteínas 27. Além disso, electrospinning é tradicionalmente realizada num solvente volátil, o que pode afectar a viabilidade da proteína de 28, mantendo assim a bioactividade da proteína deve ser considerada. Esta abordagem trata especificamente combinando, sinais químicos e adesivos mecânicos, topográficos para criar um andaime ajustável para o crescimento do nervo periférico. Mecânica de andaime é precisamente controlada pela sínteseÁcido Hialurônico metacrilado (HA). Os locais metacrilaï¿½ï¿½o são usados ​​para anexar fotos crosslinkers reativos. O material reticulado não é solúvel em água e é exclusivamente discriminado por enzimas 29. A quantidade de reticulação altera a taxa de degradação, mecânica e outras propriedades físicas do material. Usando HA com 30% metacrilaï¿½ï¿½o, que tem um módulo de elasticidade de aproximadamente 500 Pa, cria um substrato macio que está perto das mecânica nativas de tecido neural e é tipicamente preferido pelos neurónios 26,29. Electrospinning sobre um mandril rotativo é usado para criar fibras alinhadas para um taco topográfico. Usando electrospinning juntamente com microesferas fornece sinais químicos no interior da armação ao longo de períodos prolongados. Para suportar o crescimento de neurites microesferas contendo NGF são utilizadas para criar o sinal químico. Ao contrário da maioria materiais electrospun HA é solúvel em água de modo que o NGF não encontrar solventes agressivos durante a produção. Para adicionar um sinal de adesivo, o scaffold é revestido com fibronectina. O sistema completo contém todos os quatro tipos de sinais acima descritos: fibras macias (mecânicos) alinhadas (topográficas) com NGF libertando microesferas (química) revestidos com fibronectina (adesivo). Produção e ensaio do presente sistema é descrito neste protocolo. O processo começa com a produção de microesferas com um água-em-óleo-em-água de emulsão dupla. A emulsão é estabilizada com um agente tensioactivo, álcool polivinílico (PVA). A fase aquosa interna contém a proteína. Como é adicionada à fase de óleo, contendo o material de revestimento de PLGA dissolvido em diclorometano (DCM), o agente tensioactivo cria uma barreira entre as fases que protegem a proteína a partir de DCM. Esta emulsão é de outra fase dispersos em água contendo PVA para criar a superfície externa das microesferas. A emulsão estável é agitada para permitir que o DCM evapore. Depois de enxaguar e liofilização você é deixado com a microesferas cont secoaining a proteína. Após as microesferas são concluídas eles estão prontos para ser electrospun em andaimes. Primeiro você preparar a solução electrospinning. A viscosidade da solução é crítico para a formação de fibras adequado. Soluções de puro HA não atender a esse requisito; PEO é adicionado como um polímero de suporte para permitir electrospinning. As microesferas são adicionadas à solução e electrospun resultando num andaime fibroso com microesferas distribuídas por toda parte. Uma vez que a produção é completa, a proteína deve ser testada para verificar a sua viabilidade. Para fazer isso, uma célula primária que responde a NGF pode ser utilizada. Este protocolo utiliza Dorsal Root Ganglia (DRG) 8-10 dias de idade, os embriões de galinha. Os feixes de células são semeadas em scaffolds contendo microesferas cheias de NGF aqueles que estão vazios ou. Se o NGF é ainda viável você deve ver um maior crescimento neurite nas NGF contendo andaimes. Se o NGF não é mais viável que vainão promover neurites para ampliar e deverá ser semelhante ao controle. O procedimento exacto aqui descrito é focada em suporte neural, no entanto, com modificações simples para o material, o método de electrospinning, e proteínas do sistema pode ser optimizado para vários tipos de células e tecidos.

<table border="0" cellpadding="0" cellspacing="0" width="906">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">DAPI</td>
			<td style="width:208px;">Invitrogen</td>
			<td style="width:139px;">D1306</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Irgacure 2959</td>
			<td style="width:208px;">BASF</td>
			<td style="width:139px;">24650-42-8</td>
			<td style="width:291px;">Protect from light</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">PEO 900 kDa</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td align="right" style="width:139px;">189456</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:269px;">Methacryloxethyl thiocarbamoyl rhodamine B</td>
			<td style="width:208px;">Polysciences, Inc.</td>
			<td style="width:139px;">23591-100</td>
			<td style="width:291px;">Prepare stock solution in DMSO</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Syringe Pump</td>
			<td style="width:208px;">KD Scientific</td>
			<td style="width:139px;">KDS100</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Power Source</td>
			<td style="width:208px;">Gamma High Voltage</td>
			<td style="width:139px;">ES30P-5W</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Motor</td>
			<td style="width:208px;">Triem Electric Motors, Inc</td>
			<td style="width:139px;">0132022-15</td>
			<td style="width:291px;">Must attach to a custom built mandrel</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Tachometer</td>
			<td style="width:208px;">Network Tool Warehouse</td>
			<td style="width:139px;">ESI-330</td>
			<td style="width:291px;">Use to monitor mandrel speed</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:269px;">Omnicure UV Spot Cure System with collimating adapter</td>
			<td style="width:208px;">EXFO</td>
			<td style="width:139px;">S1000</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Needles</td>
			<td style="width:208px;">Fisher Scientific</td>
			<td style="width:139px;">14-825-16H</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Coverslips</td>
			<td style="width:208px;">Fisher Scientific</td>
			<td style="width:139px;">12-545-81</td>
			<td style="width:291px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Polyvinyl Alcohol</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td style="width:139px;">P8136-250G</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Isoporopyl Alcohol</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td style="width:139px;">I9030-500mL</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Bovine Serum Albumin (BSA)</td>
			<td style="width:208px;">Fisher Scientific</td>
			<td style="width:139px;">BP9703-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">BSA-FITC</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td style="width:139px;">080M7400</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">&#946;-Nerve Growth Factor (NGF)</td>
			<td style="width:208px;">R&#38;D Systems</td>
			<td style="width:139px;">1156-NG</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">65:35 Poly-Lactic-Glycolic-Acid (PLGA)</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td align="right" style="width:139px;">1001554270</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Dichloromethane</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td style="width:139px;">34856-2L</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Coomassie (Bradford) Protein Assay</td>
			<td style="width:208px;">Thermo Scientific</td>
			<td align="right" style="width:139px;">1856209</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">3-(Trimethoxysilyl)propyl methacrylate</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td align="right" style="width:139px;">1001558456</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Fibronectin</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td style="width:139px;">F2006</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">DMEM</td>
			<td style="width:208px;">Lonza</td>
			<td style="width:139px;">12-604F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">FBS</td>
			<td style="width:208px;">Atlanta Biologicals</td>
			<td style="width:139px;">S11150</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">PBS</td>
			<td style="width:208px;">Hyclone</td>
			<td style="width:139px;">SH30256.01</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Glutamine</td>
			<td style="width:208px;">Fisher Scientific</td>
			<td>G7513</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Pen-Strep</td>
			<td style="width:208px;">Sigma-Aldrich</td>
			<td style="width:139px;">P4333</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:269px;">Paraformaldehyde</td>
			<td style="width:208px;">Alfa Aesar</td>
			<td style="width:139px;">A11313&#160;</td>
			<td></td>
		</tr>
	</tbody>
</table>

electrospinning growth factor releasing microspheres into fibrous scaffolds

This procedure describes a method to fabricate a multifaceted substrate to direct nerve cell growth. This system incorporates mechanical, topographical, adhesive and chemical signals. Mechanical properties are controlled by the type of material used to fabricate the electrospun fibers. In this protocol we use 30% methacrylated Hyaluronic Acid (HA), which has a tensile modulus of ~500 Pa, to produce a soft fibrous scaffold. Electrospinning on to a rotating mandrel produces aligned fibers to create a topographical cue. Adhesion is achieved by coating the scaffold with fibronectin. The primary challenge addressed herein is providing a chemical signal throughout the depth of the scaffold for extended periods. This procedure describes fabricating&#160;poly(lactic-co-glycolic acid) (PLGA) microspheres that contain Nerve Growth Factor (NGF) and directly impregnating the scaffold with these microspheres during the electrospinning process. Due to the harsh production environment, including high sheer forces and electrical charges, protein viability is measured after production. The system provides protein release for over 60 days and has been shown to promote primary nerve cell growth.

Microesferas de 50 ± 14 m de diâmetro com um encapsulamento de proteínas superior a 85% têm sido consistentemente produzidos e electrospun em andaimes. Tamanho foi determinada pela imagem amostras de microesferas de três lotes de produção separadas. As imagens capturadas onde num microscópio óptico e comprimentos de onde medida utilizando software de laboratório comercial. Figura 1 mostra um histograma da distribuição de tamanho. Taxa de encapsulação também foi testado a partir de três l...

Watch this Scientific Journal Video about Electrospinning Growth Factor Releasing Microspheres into Fibrous Scaffolds at JoVE.com

Electrospinning Growth Factor Releasing Microspheres into Fibrous Scaffolds

This protocol combines electrospinning and microspheres to develop tissue engineered scaffolds to direct neurons. Nerve growth factor was encapsulated within PLGA microspheres and electrospun into Hyaluronic Acid (HA) fibrous scaffolds. The protein bioactivity was tested by seeding the scaffolds with primary chick Dorsal Root Ganglia and culturing for 4-6 days.

Electrospinning Fator de Crescimento Releasing Microesferas em fibrosa Andaimes

This procedure describes a method to fabricate a multifaceted substrate to direct nerve cell growth.  This system incorporates mechanical, topographical, ...

electrospinning-growth-factor-releasing-microspheres-into-fibrous

Research

JoVE Journal

Bioengineering

12.2K visualizações.  Wayne State University. This protocol combines electrospinning and microspheres to develop tissue engineered scaffolds to direct neurons. Nerve growth factor was encapsulated within PLGA microspheres and electrospun into Hyaluronic Acid (HA) fibrous scaffolds. The protein bioactivity was tested by seeding the scaffolds with primary chick Dorsal Root Ganglia and culturing for 4-6 days.

Vídeo: Electrospinning Growth Factor Releasing Microspheres into Fibrous Scaffolds

Electrospinning Fundamentals: Optimizing Solution and Apparatus Parameters

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. Electrospinning is a process in which a charged polymer jet is collected on a grounded collector; a rapidly rotating collector results in aligned nanofibers while stationary collectors result in randomly oriented fiber mats. The polymer jet is formed when an applied electrostatic charge overcomes the surface tension of the solution. There is a minimum concentration for a given polymer, termed the critical entanglement concentration, below which a stable jet cannot be achieved and no nanofibers will form - although nanoparticles may be achieved (electrospray). A stable jet has two domains, a streaming segment and a whipping segment. While the whipping jet is usually invisible to the naked eye, the streaming segment is often visible under appropriate lighting conditions. Observing the length, thickness, consistency and movement of the stream is useful to predict the alignment and morphology of the nanofibers being formed. A short, non-uniform, inconsistent, and/or oscillating stream is indicative of a variety of problems, including poor fiber alignment, beading, splattering, and curlicue or wavy patterns. The stream can be optimized by adjusting the composition of the solution and the configuration of the electrospinning apparatus, thus optimizing the alignment and morphology of the fibers being produced. In this protocol, we present a procedure for setting up a basic electrospinning apparatus, empirically approximating the critical entanglement concentration of a polymer solution and optimizing the electrospinning process. In addition, we discuss some common problems and troubleshooting techniques.

Electrospinning techniques can create a variety of nanofibrous scaffolds for tissue engineering or other applications. We describe here a procedure to optimize the parameters of the electrospinning solution and apparatus to obtain fibers with the desired morphology and alignment. Common problems and troubleshooting techniques are also presented.

Fundamentos eletrofiação: Solução de Otimização e Parâmetros Aparelho

Electrospun nanofiber scaffolds have been shown to accelerate the maturation, improve the growth, and direct the migration of cells in vitro. ...

Bioengenharia

Elastomeric PGS Scaffolds in Arterial Tissue Engineering

Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and increasing obesity1. Currently, bypass surgery using autologous vessels, allografts, and synthetic grafts are known as a commonly used for arterial substitutes2. However, these grafts have limited applications when an inner diameter of arteries is less than 6 mm due to low availability, thrombotic complications, compliance mismatch, and late intimal hyperplasia3,4. To overcome these limitations, tissue engineering has been successfully applied as a promising alternative to develop small-diameter arterial constructs that are nonthrombogenic, robust, and compliant. Several previous studies have developed small-diameter arterial constructs with tri-lamellar structure, excellent mechanical properties and burst pressure comparable to native arteries5,6. While high tensile strength and burst pressure by increasing collagen production from a rigid material or cell sheet scaffold, these constructs still had low elastin production and compliance, which is a major problem to cause graft failure after implantation. Considering these issues, we hypothesized that an elastometric biomaterial combined with mechanical conditioning would provide elasticity and conduct mechanical signals more efficiently to vascular cells, which increase extracellular matrix production and support cellular orientation.
The objective of this report is to introduce a fabrication technique of porous tubular scaffolds and a dynamic mechanical conditioning for applying them to arterial tissue engineering. We used a biodegradable elastomer, poly (glycerol sebacate) (PGS)7 for fabricating porous tubular scaffolds from the salt fusion method. Adult primary baboon smooth muscle cells (SMCs) were seeded on the lumen of scaffolds, which cultured in our designed pulsatile flow bioreactor for 3 weeks. PGS scaffolds had consistent thickness and randomly distributed macro- and micro-pores. Mechanical conditioning from pulsatile flow bioreactor supported SMC orientation and enhanced ECM production in scaffolds. These results suggest that elastomeric scaffolds and mechanical conditioning of bioreactor culture may be a promising method for arterial tissue engineering.

Elastomeric PGS scaffolds with vascular smooth muscle cells cultured in a pulsatile flow bioreactor may lead to promising small-diameter arterial constructs with native ECM production in a relatively short culture period.

PGS elastomérico Andaimes em Engenharia de Tecidos Arterial

Cardiovascular disease is one of the leading cause of mortality in the US and especially, coronary artery disease increases with an aging population and ...

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 ...

Therapeutic Gene Delivery and Transfection in Human Pancreatic Cancer Cells using Epidermal Growth Factor Receptor-targeted Gelatin Nanoparticles

More than 32,000 patients are diagnosed with pancreatic cancer in the United States per year and the disease is associated with very high mortality 1. Urgent need exists to develop novel clinically-translatable therapeutic strategies that can improve on the dismal survival statistics of pancreatic cancer patients. Although gene therapy in cancer has shown a tremendous promise, the major challenge is in the development of safe and effective delivery system, which can lead to sustained transgene expression. 
Gelatin is one of the most versatile natural biopolymer, widely used in food and pharmaceutical products. Previous studies from our laboratory have shown that type B gelatin could physical encapsulate DNA, which preserved the supercoiled structure of the plasmid and improved transfection efficiency upon intracellular delivery. By thiolation of gelatin, the sulfhydryl groups could be introduced into the polymer and would form disulfide bond within nanoparticles, which stabilizes the whole complex and once disulfide bond is broken due to the presence of glutathione in cytosol, payload would be released 2-5. Poly(ethylene glycol) (PEG)-modified GENS, when administered into the systemic circulation, provides long-circulation times and preferentially targets to the tumor mass due to the hyper-permeability of the neovasculature by the enhanced permeability and retention effect 6. Studies have shown over-expression of the epidermal growth factor receptor (EGFR) on Panc-1 human pancreatic adenocarcinoma cells 7. In order to actively target pancreatic cancer cell line, EGFR specific peptide was conjugated on the particle surface through a PEG spacer.8
Most anti-tumor gene therapies are focused on administration of the tumor suppressor genes, such as wild-type p53 (wt-p53), to restore the pro-apoptotic function in the cells 9. The p53 mechanism functions as a critical signaling pathway in cell growth, which regulates apoptosis, cell cycle arrest, metabolism and other processes 10. In pancreatic cancer, most cells have mutations in p53 protein, causing the loss of apoptotic activity. With the introduction of wt-p53, the apoptosis could be repaired and further triggers cell death in cancer cells 11. 
Based on the above rationale, we have designed EGFR targeting peptide-modified thiolated gelatin nanoparticles for wt-p53 gene delivery and evaluated delivery efficiency and transfection in Panc-1 cells.

Type B gelatin-based engineered nanovectors system (GENS) was developed for systemic gene delivery and transfection in the treatment of pancreatic cancer. By modification with epidermal growth factor receptor (EGFR) specific peptide on the surface of nanparticles, they could target on EGFR receptor and release plasmid under reducing environment, such as high intracellular glutathione concentrations.

Entrega de genes e Transfection em células pancreáticas humanas Cancer usando Fator de Crescimento Epidérmico Receptor-alvo à base de gelatina Nanovectors Engineered

More than 32,000 patients are diagnosed with pancreatic cancer in the United States per year and the disease is associated with very high mortality 1. ...

Electrospun Fibrous Scaffolds of Poly(glycerol-dodecanedioate) for Engineering Neural Tissues From Mouse Embryonic Stem Cells

For tissue engineering applications, the preparation of biodegradable and biocompatible scaffolds is the most desirable but challenging task. &#160;Among the various fabrication methods, electrospinning is the most attractive one due to its simplicity and versatility. Additionally, electrospun nanofibers mimic the size of natural extracellular matrix ensuring additional support for cell survival and growth. This study showed the viability of the fabrication of long fibers spanning a larger deposit area for a novel biodegradable and biocompatible polymer named&#160;poly(glycerol-dodecanoate) (PGD)1 by using a newly designed collector for electrospinning. PGD exhibits unique elastic properties with similar mechanical properties to nerve tissues, thus it is suitable for neural tissue engineering applications. The synthesis and fabrication set-up for making fibrous scaffolding materials was simple, highly reproducible, and inexpensive. In biocompatibility testing, cells derived from mouse embryonic stem cells could adhere to and grow on the electrospun PGD fibers. In summary, this protocol provided a versatile fabrication method for making PGD electrospun fibers to support the growth of mouse embryonic stem cell derived neural lineage cells.

Electrospun Fibrous Scaffolds of Polyglycerol-dodecanedioate for Engineering Neural Tissues From Mouse Embryonic Stem Cells

Synthesis and fabrication of electrospun long fibers spanning a larger deposit area via a newly designed collector from a novel biodegradable polymer named poly(glycerol-dodecanoate) (PGD) was reported. The fibers were able to support the growth of cells derived from mouse pluripotent stem cells.

Electrospun fibrosa Andaimes de Poli (glicerol-dodecanedioate) para Engenharia Neural tecidos de rato as células estaminais embrionárias

For tissue engineering applications, the preparation of biodegradable and biocompatible scaffolds is the most desirable but challenging task. &#160;Among ...

Studying the Stoichiometry of Epidermal Growth Factor Receptor in Intact Cells using Correlative Microscopy

This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative fluorescence microscopy and environmental scanning electron microscopy (ESEM) of whole cells in hydrated state. Fluorescent quantum dots (QDs) were coupled to EGFR via a two-step labeling protocol, providing an efficient and specific protein labeling, while avoiding label-induced clustering of the receptor. Fluorescence microscopy provided overview images of the cellular locations of the EGFR. The scanning transmission electron microscopy (STEM) detector was used to detect the QD labels with nanoscale resolution. The resulting correlative images provide data of the cellular EGFR distribution, and the stoichiometry at the single molecular level in the natural context of the hydrated intact cell. ESEM-STEM images revealed the receptor to be present as monomer, as homodimer, and in small clusters. Labeling with two different QDs, i.e.,&#160;one emitting at 655 nm and at 800 revealed similar characteristic results.

This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative light- and electron microscopy of whole cells in hydrated state. The label contained fluorescent quantum dots. The protocol can be used to study the stoichiometry of EGFR at the single molecule level.

Estudando a estequiometria do Receptor do Factor de Crescimento Epidérmico em células intactas utilizando Microscopia Correlativo

This protocol describes the labeling of epidermal growth factor receptor (EGFR) on COS7 fibroblast cells, and subsequent correlative fluorescence ...

Polyelectrolyte Complex for Heparin Binding Domain Osteogenic Growth Factor Delivery

During reconstructive bone surgeries, supraphysiological amounts of growth factors are empirically loaded onto scaffolds to promote successful bone fusion. Large doses of highly potent biological agents are required due to growth factor instability as a result of rapid enzymatic degradation as well as carrier inefficiencies in localizing sufficient amounts of growth factor at implant sites. Hence, strategies that prolong the stability of growth factors such as BMP-2/NELL-1, and control their release could actually lower their efficacious dose and thus reduce the need for larger doses during future bone regeneration surgeries. This in turn will reduce side effects and growth factor costs. Self-assembled PECs have been fabricated to provide better control of BMP-2/NELL-1 delivery via heparin binding and further potentiate growth factor bioactivity by enhancing in vivo stability. Here we illustrate the simplicity of PEC fabrication which aids in the delivery of a variety of growth factors during reconstructive bone surgeries.

Self-assembled polyelectrolyte complexes (PEC) fabricated from heparin and protamine were deposited on alginate beads to entrap and regulate the release of osteogenic growth factors. This delivery strategy enables a 20-fold reduction of BMP-2 dose in spinal fusion applications. This article illustrates the benefits and fabrication of PECs.

Complexo polielectrólito de ligação à heparina de entrega osteogénica Factor de Crescimento Domínio

During reconstructive bone surgeries, supraphysiological amounts of growth factors are empirically loaded onto scaffolds to promote successful bone ...

Preparation and Characterization of Novel HDL-mimicking Nanoparticles for Nerve Growth Factor Encapsulation

The objective of this article is to introduce preparation and characterization methods for nerve growth factor (NGF)-loaded, high-density, lipoprotein (HDL)-mimicking nanoparticles (NPs). HDLs are endogenous NPs and have been explored as vehicles for the delivery of therapeutic agents. Various methods have been developed to prepare HDL-mimicking NPs. However, they are generally complicated, time consuming, and difficult for industrial scale-up. In this study, one-step homogenization was used to mix the excipients and form the prototype NPs. NGF is a water-soluble protein of 26 kDa. To facilitate the encapsulation of NGF into the lipid environment of HDL-mimicking NPs, protamine USP was used to form an ion-pair complex with NGF to neutralize the charges on the NGF surface. The NGF/protamine complex was then introduced into the prototype NPs. Apolipoprotein A-I was finally coated on the surface of the NPs. NGF HDL-mimicking NPs showed preferable properties in terms of particle size, size distribution, entrapment efficiency, in vitro release, bioactivity, and biodistribution. With the careful design and exploration of homogenization in HDL-mimicking NPs, the procedure was greatly simplified, and the NPs were made scalable. Moreover, various challenges, such as separating unloaded NGF from the NPs, conducting reliable in vitro release studies, and measuring the bioactivity of the NPs, were overcome.

Simple homogenization was used to prepare novel, high-density, lipoprotein-mimicking nanoparticles to encapsulate nerve growth factor. Challenges, detailed protocols for nanoparticle preparation, in vitro characterization, and in vivo studies are described in this article.

Preparação e caracterização de novas nanopartículas simuladoras de HDL para encapsulação de fatores de crescimento nervoso

The objective of this article is to introduce preparation and characterization methods for nerve growth factor (NGF)-loaded, high-density, lipoprotein ...

Melt Electrospinning Writing of Three-dimensional Poly(&#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology with great potential for biomedical applications. The technique facilitates the direct deposition of biocompatible polymer fibers to fabricate well-ordered scaffolds in the sub-micron to micro scale range. The establishment of a stable, viscoelastic, polymer jet between a spinneret and a collector is achieved using an applied voltage and can be direct-written. A significant benefit of a typical porous scaffold is a high surface-to-volume ratio which provides increased effective adhesion sites for cell attachment and growth. Controlling the printing process by fine-tuning the system parameters enables high reproducibility in the quality of the printed scaffolds. It also provides a flexible manufacturing platform for users to tailor the morphological structures of the scaffolds to their specific requirements. For this purpose, we present a protocol to obtain different fiber diameters using melt electrospinning writing (MEW) with a guided amendment of the parameters, including flow rate, voltage and collection speed. Furthermore, we demonstrate how to optimize the jet, discuss often experienced technical challenges, explain troubleshooting techniques and showcase a wide range of printable scaffold architectures.

Melt Electrospinning Writing of Three-dimensional Poly(&amp;#949;-caprolactone) Scaffolds with Controllable Morphologies for Tissue Engineering Applications

This protocol serves as a comprehensive guideline to fabricate scaffolds via electrospinning with polymer melts in a direct writing mode. We systematically outline the process and define the appropriate parameter settings for achieving targeted scaffold architectures.

Derreter a eletrofiação escrita de andaimes Poly(ε-caprolactone) tridimensional com morfologias controláveis para aplicações de engenharia de tecidos

This tutorial reflects on the fundamental principles and guidelines for electrospinning writing with polymer melts, an additive manufacturing technology ...

Fabrication of Decellularized Cartilage-derived Matrix Scaffolds

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage research has focused on the development of regenerative scaffolds. This article describes the development of scaffolds that are completely derived from natural cartilage extracellular matrix, coming from an equine donor. Potential applications of the scaffolds include producing allografts for cartilage repair, serving as a scaffold for osteochondral tissue engineering, and providing in vitro models to study tissue formation. By decellularizing the tissue, the donor cells are removed, but many of the natural bioactive cues are thought to be retained. The main advantage of using such a natural scaffold in comparison to a synthetically produced scaffold is that no further functionalization of polymers is required to drive osteochondral tissue regeneration. The cartilage-derived matrix scaffolds can be used for bone and cartilage tissue regeneration in both in vivo and in vitro settings.

Decellularized cartilage-derived scaffolds can be used as a scaffold to guide cartilage repair and as a means to regenerate osteochondral tissue. This paper describes the decellularization process in detail and provides suggestions to use these scaffolds in in vitro settings.

Fabricação de matriz de cartilagem-derivado Decellularized andaimes

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage ...