Este trabalho foi realizado utilizando as instalações do Departamento de Engenharia Biomédica da Universidade Internacional da Flórida.

1. Setup Electrospinning Collector <ol><li> Corte o papel alumínio em uma peça retangular. </li><li> Dobre o pedaço retangular em uma tira retangular, e anexá-lo perpendicular a uma placa de metal plana com fita adesiva (Figura 1). Nota: O tamanho da esteira de fibras dependem do comprimento e da largura da tira. Assim, as dimensões da tira pode ser ajustada conforme necessário. </li></ol> 2. Solução polimérica Preparação <ol><li> Mistura de glicerol e ácido dodecanóico (ADD) em razão molar de 1:1, num copo de 120 ° C durante 100 horas para se obter polímero de DGP. </li><li> Dissolve-se o poli (óxido de etileno) (PEO) e de gelatina, em etanol a 65% com uma proporção de peso de 1.5:3:95.5 em um tubo de 15 ml, apertar a tampa e aquecer a mistura num forno a 60 ° C durante 1 hora com agitação até que se torna uma solução homogénea (solução basal). </li><li> Para electrospinning, misture o polímero PGD ea solução basal em 04:06 de peso. Nota: concentração PGD tem um big efeito sobre o diâmetro da fibra. 30% -50% por cento PGD é aceitável para a produção de fibras mais do que 5 cm com diâmetros de fibra de aumento. </li><li> Adicionar 0,1% de riboflavina para a solução polimérica e misturar bem. </li></ol> 3. Electrospinning <ol><li> Alimente a solução polimérica em uma seringa de 5 ml de série com um 18 G embotada agulha de aço inoxidável. </li><li> Insira a seringa em uma bomba de seringa. </li><li> Ligue o cabo ligado à terra de uma fonte de alimentação de alta tensão para a placa de metal e o chumbo carregada positivamente para a agulha. </li><li> Ajustar a distância entre a agulha e a tira de folha de alumínio de 15 cm. </li><li> Coloque a bomba de seringa em um ângulo de aproximadamente 15 ° com a horizontal para impedir a agregação das fibras na parte da frente da faixa. </li><li> Ligar a bomba de seringa e ajustar a taxa de fluxo da bomba de 0,6 mL / hora. </li><li> Ligue a fonte de alimentação de alta tensão e ajustar a tensão de operação de 14,6 kV. </li></ol> 4.Processamento de fibras <ol><li> Após a recolha está completa, expor a esteira de fibra para a luz UV, durante 60 minutos para a ligação cruzada. </li><li> Transferir a esteira de fibras a partir da tira de folha de alumínio de uma placa de Petri de 100 milímetros, e expô-la à luz UV durante mais 20 min para a esterilização. </li><li> Em uma cabine de segurança biológica, cortar a manta de fibra em peças redondas do mesmo tamanho com uma lâmina de bisturi e colocar os pedaços em uma placa de 24 poços. </li><li> Para o tratamento das células de pré-sementeira, imergir amostras de fibras em 1 ml de tampão fosfato salino (PBS) e incuba-se a 37 ° C durante a noite. </li><li> No dia seguinte, cuidadosamente aspirado PBS, adicionar 1 ml de meio de diferenciação (DMEM/F12, N2, e FGF2) (ver receita na tabela Materiais) a cada poço e incuba-se a 37 ° C durante 3 hr. </li><li> Meio de diferenciação aspirado cuidadosamente, adicionar 0,2 mL de matrigel a cada amostra de fibra e incubar a 37 ° C durante 30 min. Nota: A laminina também pode ser utilizado para o revestimento de fibra. Adicionar 0,2 mL de 20 ug / ml de lamininapara a fibra e incubar à temperatura ambiente durante 3 hr. </li><li> Com cuidado, retire o excesso de matrigel de cada poço. Lavar com 2 ml de meio de diferenciação de uma vez. Nota: As amostras de fibras estão prontos para a cultura de células. </li></ol> 5. Sementeira celular em Fibras <ol><li> Adicionar 1 ml de Accutase para o prato de cultura de células MES e incubar durante 10 min a 37 ° C. </li><li> Após 10 min, as células MES são separadas do prato de cultura. Adicionar 4 ml de meio de diferenciação para a placa. Recolher as células MES flutuantes em um tubo de 15 ml e as células para cima e para baixo de pipeta para quebrar colónias (cerca de 15x). </li><li> Centrifugar a 400 xg durante 5 minutos e re-suspender as células em 4 ml de meio de diferenciação. </li><li> Contar as células usando um hemocitômetro. Transferir 200 ul da suspensão de células para um tubo de 15 ml e diluir 10x com meio de diferenciação. Transferir 15 uL da suspensão de células diluída a uma câmara na hemocitómetro com uma lamela no lugar. Contaras células no quadrado do centro a 1 mm e as quatro esquinas do hemocitómetro sob o microscópio. Nota: celular por ml = a contagem média por metro quadrado x fator de diluição x 10 4 </li><li> Colocar aproximadamente 5 x 10 4 células MES em cada poço. Gota lentamente a suspensão de células para o meio das amostras de fibras, em vez de correr para fora do lado do poço, para evitar que a solução de se drenar o tapete de fibra. </li><li> Adicionar 1 ml de meio de diferenciação em cada poço, e manter a placa numa incubadora a 37 ° C e 5% de CO2 para permitir que as células de fixação, o crescimento e diferenciação. </li><li> Aspirar o meio antigo em cada poço e substitua com 1 ml de meio de diferenciação fresco todos os dias. </li></ol> 6. Viabilidade celular <ol><li> Aspirar o meio antigo em cada poço. </li><li> Misture 1/10 de volume de Resazurina reagente de fluorescência com o meio de cultura e adicionar 1 ml para cada poço. </li><li> IncubComeram a 37 ° C e 5% de CO 2 durante 4 h, protegido da luz directa. </li><li> Depois de 4 horas, transferir 100 mL 3x do reagente de cada poço de uma placa de 96 poços, em seguida, as amostras estão prontas para ser medido em um espectrofotômetro de fluorescência usando configurações de filtro de 560EX nm/590EM. </li></ol> 7. PCR em Tempo Real <ol><li> Após 14 dias de cultura, adicionar tampão de lise às amostras e isolar o RNA total a partir das células nas amostras de fibras. </li><li> Use 4 ul de ARN total, para sintetizar ADNc em 20 uL de escalas de reacção de transcrição reversa. </li><li> Preparar a mistura de reacção de PCR em cada um dos tubos óptica: 10 ul Master Mix (2x), 0,2 ul de corante, 8 mL de água livre de nuclease, 1 ul de cDNA, e um iniciador pi (iniciadores utilizados neste estudo estão listados na Tabela 1). </li><li> Configure o programa de PCR: a. 95 ° C 02:20 min, um ciclo de b. 95 ° C 3 seg → 60 ° C 1 min, 40 ciclo c. 95 ° C 15 seg, um ciclo d. 60 ° C 1min, um ciclo de e. 95 ° C 15 seg, 1 ciclo. Escolha forma de C T comparativo para determinar os níveis de expressão gênica relativa. </li><li> Após PCR for concluído, analisar os resultados em tempo real PCR com software StepOne e exportar os resultados para o Excel. </li></ol>

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	<li>Migneco, F., Huang, Y. -. C., Birla, R. K., Hollister, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly+(glycerol-dodecanoate),+a+biodegradable+polyester+for+medical+devices+and+tissue+engineering+scaffolds.">Poly (glycerol-dodecanoate), a biodegradable polyester for medical devices and tissue engineering scaffolds.</a> Biomaterials. 30, 6479-6484 (2009).</li><li>Reneker, D. H., Yarin, A. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrospinning+jets+and+polymer+nanofibers.">Electrospinning jets and polymer nanofibers.</a> Polymer. 49, 2387-2425 (2008).</li><li>Wang, Y., Ameer, G. A., Sheppard, B. 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As limitações de coletores simples ou as complexidades de colecionadores que são usados ​​atualmente para eletrofiação aumentar a restrição de se obter o comprimento desejado e tamanho do tapete de fibra para algumas aplicações rotativas. Além disso, a transferência de fibras do coletor de terra para o prato de cultura ou outros substratos é um desafio 5. Neste relatório, um coletor recém-concebido, feito, simplesmente anexando uma tira de folha de alumínio para o coletor de castigo, foi ca...

Eletrofiação é um dos métodos de processamento eficazes para produzir suportes de fibra de tamanho micro-a-nanómetro. O princípio básico de electrospinning envolve um cone de Taylor de uma solução que é realizada ao nível do orifício de uma agulha através da aplicação de alta tensão entre a ponta da agulha e de um colector ligado à terra. Quando a repulsão electrostática na solução vence a tensão superficial, um jacto de fluido carregado é ejectado para fora da ponta da agulha, se desloca através do ar com a evaporação do solvente, e é, finalmente depositada sobre o colector ligado à terra. A bomba de seringa fornece um fluxo contínuo de uma solução que emerge da fieira e, portanto, múltiplas cópias das fibras electrospun pode ser fabricado dentro de um curto período de tempo. Durante o curso de deixar a fieira de chegar ao colector, o jacto carregada sofrer estiramento e batimento de acordo com uma série de parâmetros, que incluem a viscosidade e tensão superficial da solução polimérica, os electrostatic força na solução, ea interação do campo elétrico externo, etc 2. No processo de electrospinning, um colector serve como um substrato condutor em que as fibras de micro-a-nanométrica pode ser depositado. Neste estudo, um novo tipo de colector de fibras foi concebido para obter mantas de fibra com a dimensão desejada (comprimento x largura). Tradicionalmente, a folha de alumínio é usado como um colector, mas é difícil de transferir as fibras a partir da superfície plana a um outro substrato. A dificuldade de colher um tapete de fibra intacta de um colecionador tradicional deveu-se principalmente ao fato de que as fibras electrospun anexar fortemente à superfície do coletor. Portanto, nós modificamos o coletor dobrando um pedaço de papel alumínio em uma tira retangular e anexá-lo perpendicular a uma placa de metal plana. As fibras são electrospun esticado em toda a área entre a ponta da tira e a placa de metal, que pode ser facilmente transferida para outro substrate. Interesse em polímeros elastoméricos termicamente reticuladas está crescendo rapidamente por causa do trabalho pioneiro do grupo de Robert Langer, que introduziu poli (sebaçato glicerol) (PGS), um poliéster que é análoga à borracha vulcanizada, em 2002 3. Semelhante ao PGS, temos desenvolvido com sucesso poli (glicerol-dodecanoato) (PGD) por condensação térmica do glicerol e ácido dodecanodioíco e demonstrou a sua propriedade única memória de forma 1. Ao contrário rígida poli materiais sintéticos (hidroxil-butirato) ou poli (L-lactido) (módulos de Young de 250 MPa e 660 MPa, respectivamente), o PGD exibe propriedade elastomérica como a borracha, com um módulo de Young de 1,08 MPa, quando a temperatura estiver acima de 37 ° C, que é um jogo perto do nervo periférico in-situ (0,45 MPa). Além disso, o PGD é biodegradável e o tempo de degradação, podem ser afinadas variando a proporção de glicerol e ácido dodecanóico. Ácido dodecanodioíco é um sub de doze carbonoposição com dois grupos carboxílicos terminais, HOOC (CH2) 10 COOH. Ácidos dicarboxílicos pares numeradas como ácido sebácico e o ácido dodecanodióico pode ser metabolizado a acetil-CoA e introduzir o ácido tricarboxílico (TCA) / ciclo (ácido cítrico). O produto metabólico de ácidos dicarboxílicos, succinil-CoA, é um precursor gluconeogenetic e intermédia do ciclo de TCA 4. Assim, alguns estudos sugerem que poderiam ser utilizados como um substrato de combustível alternativo para nutrição entérica e parentérica, especialmente nas condições patológicas. Além disso, o PGD exibe memória de forma única por causa da sua temperatura de transição de vidro é de 31 ° C, portanto, apresenta propriedades mecânicas diferentes, à temperatura ambiente e à temperatura do corpo. Em suma, a PGD é biodegradável, biocompatível, exibindo propriedades elásticas únicas com propriedades mecânicas semelhantes aos tecidos nervosos; por conseguinte, é um material adequado para aplicações de engenharia de tecidos nervosos. Neste protocolo, o electrospunfibras longas que abrangem uma grande área de depósito foram fabricados através do coletor recém-projetado do PGD. Os andaimes de fibras pode suportar o crescimento e diferenciação de células-tronco pluripotentes.

<table border="0" cellpadding="0" cellspacing="0" width="729">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Glycerol</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:119px;">G7757</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Dodecanedioic acid</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:119px;">D1009</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Gelatin</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:119px;">D1890</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Poly (ehtylene oxide) (PEO)</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:119px;">182028</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Riboflavin</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:119px;">132350250</td>
			<td style="width:167px;">0.10%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Mouse embryonic stem cells</td>
			<td style="width:175px;">GlobalStem</td>
			<td style="width:119px;">GSC-5002</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Matrigel</td>
			<td style="width:175px;">Becton Dickinson</td>
			<td style="width:119px;">356234</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">DMEM/F12</td>
			<td style="width:175px;">Thermo Scientific</td>
			<td style="width:119px;">SH30272.02</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">N2 supplement&#160;</td>
			<td style="width:175px;">Invitrogen</td>
			<td style="width:119px;">17502048</td>
			<td style="width:167px;">1%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">FGF2</td>
			<td style="width:175px;">Stemgent</td>
			<td style="width:119px;">03-0002</td>
			<td style="width:167px;">10ng/ml</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Accutase</td>
			<td style="width:175px;">Invitrogen</td>
			<td style="width:119px;">A11105-01</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Phosphate buffered saline (PBS)</td>
			<td style="width:175px;">Invitrogen</td>
			<td style="width:119px;">10010-031&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Resazurin fluorescence dye&#160;</td>
			<td style="width:175px;">Sigma-Aldrich</td>
			<td style="width:119px;">62758-13-8&#160;</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">SV Total RNA Isolation System</td>
			<td style="width:175px;">Promega</td>
			<td style="width:119px;">Z3100</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">GoScript Reverse Transcription System</td>
			<td style="width:175px;">Promega</td>
			<td style="width:119px;">A5000</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">GoTaq&#129; qPCR Master Mix</td>
			<td style="width:175px;">Promega</td>
			<td style="width:119px;">A6001</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Syringe pump&#160;</td>
			<td style="width:175px;">Fisher scientific</td>
			<td style="width:119px;">14-831-200</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="33">
			<td height="33" style="height:33px;width:268px;">High voltage power source&#160;</td>
			<td style="width:175px;">Spellman High Voltage Electronics Corporation</td>
			<td style="width:119px;"></td>
			<td style="width:167px;">SL30</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">UV light</td>
			<td style="width:175px;">Philips</td>
			<td style="width:119px;">308643</td>
			<td style="width:167px;">15W/G15T8</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Synergy HT Multi-Mode Microplate Reader</td>
			<td style="width:175px;">BioTek</td>
			<td style="width:119px;"></td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">Perkin Elmer GeneAmp PCR System 9600</td>
			<td style="width:175px;">Perkin Elmer</td>
			<td style="width:119px;">8488</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:268px;">StepOne Real-time PCR System</td>
			<td style="width:175px;">Applied Biosystems</td>
			<td style="width:119px;">4376357</td>
			<td style="width:167px;"></td>
		</tr>
	</tbody>
</table>

electrospun fibrous scaffolds of poly(glycerol-dodecanedioate) for engineering neural tissues from mouse embryonic stem cells

Para aplicações de engenharia de tecidos, a preparação de scaffolds biodegradáveis ​​e biocompatíveis é a tarefa mais desejável, mas desafiador. Entre os vários métodos de fabricação, electrospinning é o mais atractivo, devido à sua simplicidade e versatilidade. Além disso, nanofibras electrospun imitar o tamanho da matriz extracelular natural, assegurando um apoio adicional para a sobrevivência e crescimento das células. Este estudo mostrou a viabilidade da fabricação de fibras longas, abrangendo uma área maior depósito de um polímero biodegradável e biocompatível romance chamado poli (glicerol-dodecanoato) (PGD) 1, usando um coletor recém-projetado para electrospinning. PGD ​​exibe propriedades elásticas originais com propriedades mecânicas semelhantes às dos tecidos nervosos, assim, ele é adequado para aplicações de engenharia de tecidos neurais. A síntese e fabricação set-up para fazer materiais fibrosos andaimes era simples, altamente reprodutível e barato. Em biocompatibilidadeteste, as células derivadas de células estaminais embrionárias de ratinho podia aderir e crescer nas fibras PGD electrospun. Em resumo, este protocolo fornecido um método de fabricação versátil para fabricação de fibras PGD electrospun para suportar o crescimento de células da linhagem neurais derivadas do rato de células-tronco embrionárias.

Os principais componentes do electrospinning são mostrados na Figura 1. Uma esteira de fibras de tamanho grande foi tipicamente obtida através da tira perpendicularmente ligada folha de alumínio e uma chapa de metal plana. Figura 2 mostra o desenho do colector e o tapete de fibra de electrospinning. A largura e o comprimento pode ser ajustado para diferentes aplicações. O comprimento da fibra feito com polímeros de PGD e mistura solução basal é de até 10 cm. A morfologia das f...

Watch this Scientific Journal Video about Electrospun Fibrous Scaffolds of Polyglycerol-dodecanedioate for Engineering Neural Tissues From Mouse Embryonic Stem Cells at JoVE.com

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

Síntese e fabricação de fibras longas electrospun abrangendo uma área maior depósito através de um coletor recém-concebido a partir de um polímero biodegradável romance chamado poli (glicerol-dodecanoato) (PGD) foi relatado. As fibras eram capazes de suportar o crescimento de células derivadas de células-tronco pluripotentes.

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 ...

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Research

JoVE Journal

Bioengineering

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

10.8K visualizações.  Florida International University.  Síntese e fabricação de fibras longas electrospun abrangendo uma área maior depósito através de um coletor recém-concebido a partir de um polímero biodegradável romance chamado poli (glicerol-dodecanoato) (PGD) foi relatado. As fibras eram capazes de suportar o crescimento de células derivadas de células-tronco pluripotentes. 

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

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 ...

Bioengenharia

Preparation of 3D Fibrin Scaffolds for Stem Cell Culture Applications

Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. Culturing stem cells inside of 3D biomaterial scaffolds provides a way to accurately mimic these microenvironments, providing an advantage over traditional 2D culture methods using polystyrene as well as a method for engineering replacement tissues 2. While 2D tissue culture polystrene has been used for the majority of cell culture experiments, 3D biomaterial scaffolds can more closely replicate the microenvironments found in vivo by enabling more accurate establishment of cell polarity in the environment and possessing biochemical and mechanical properties similar to soft tissue.3 A variety of naturally derived and synthetic biomaterial scaffolds have been investigated as 3D environments for supporting stem cell growth. While synthetic scaffolds can be synthesized to have a greater range of mechanical and chemical properties and often have greater reproducibility, natural biomaterials are often composed of proteins and polysaccharides found in the extracelluar matrix and as a result contain binding sites for cell adhesion and readily support cell culture. Fibrin scaffolds, produced by polymerizing the protein fibrinogen obtained from plasma, have been widely investigated for a variety of tissue engineering applications both in vitro and in vivo 4. Such scaffolds can be modified using a variety of methods to incorporate controlled release systems for delivering therapeutic factors 5. Previous work has shown that such scaffolds can be used to successfully culture embryonic stem cells and this scaffold-based culture system can be used to screen the effects of various growth factors on the differentiation of the stem cells seeded inside 6,7.
 This protocol details the process of polymerizing fibrin scaffolds from fibrinogen solutions using the enzymatic activity of thrombin. The process takes 2 days to complete, including an overnight dialysis step for the fibrinogen solution to remove citrates that inhibit polymerization. These detailed methods rely on fibrinogen concentrations determined to be optimal for embryonic and induced pluripotent stem cell culture. Other groups have further investigated fibrin scaffolds for a wide range of cell types and applications - demonstrating the versatility of this approach 8-12.

This work details the preparation of 3D fibrin scaffolds for culturing and differentiating plutipotent stem cells. Such scaffolds can be used to screen the effects of various biological compounds on stem cell behavior as well as modified to contain drug delivery systems.

Preparação de fibrina Andaimes 3D para aplicações de cultura de células-tronco

Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. Culturing stem cells ...

Postproduction Processing of Electrospun Fibres for Tissue Engineering

Electrospinning is a commonly used and versatile method to produce scaffolds (often biodegradable) for 3D tissue engineering.1, 2, 3 Many tissues in vivo undergo biaxial distension to varying extents such as skin, bladder, pelvic floor and even the hard palate as children grow. In producing scaffolds for these purposes there is a need to develop scaffolds of appropriate biomechanical properties (whether achieved without or with cells) and which are sterile for clinical use. The focus of this paper is not how to establish basic electrospinning parameters (as there is extensive literature on electrospinning) but on how to modify spun scaffolds post production to make them fit for tissue engineering purposes - here thickness, mechanical properties and sterilisation (required for clinical use) are considered and we also describe how cells can be cultured on scaffolds and subjected to biaxial strain to condition them for specific applications.
Electrospinning tends to produce thin sheets; as the electrospinning collector becomes coated with insulating fibres it becomes a poor conductor such that fibres no longer deposit on it. Hence we describe approaches to produce thicker structures by heat or vapour annealing increasing the strength of scaffolds but not necessarily the elasticity. Sequential spinning of scaffolds of different polymers to achieve complex scaffolds is also described. Sterilisation methodologies can adversely affect strength and elasticity of scaffolds. We compare three methods for their effects on the biomechanical properties on electrospun scaffolds of poly lactic-co-glycolic acid (PLGA).
Imaging of cells on scaffolds and assessment of production of extracellular matrix (ECM) proteins by cells on scaffolds is described. Culturing cells on scaffolds in vitro can improve scaffold strength and elasticity but the tissue engineering literature shows that cells often fail to produce appropriate ECM when cultured under static conditions. There are few commercial systems available that allow one to culture cells on scaffolds under dynamic conditioning regimes - one example is the Bose Electroforce 3100 which can be used to exert a conditioning programme on cells in scaffolds held using mechanical grips within a media filled chamber.4 An approach to a budget cell culture bioreactor for controlled distortion in 2 dimensions is described. We show that cells can be induced to produce elastin under these conditions. Finally assessment of the biomechanical properties of processed scaffolds cultured with or without cells is described.

Electrospun scaffolds can be processed post production for tissue engineering applications. Here we describe methods for spinning complex scaffolds (by consecutive spinning), for making thicker scaffolds (by multi-layering using heat or vapour annealing), for achieving sterility (aseptic production or sterilisation post production) and for achieving appropriate biomechanical properties.

Processamento de pós-produção de Fibras electrospun para Engenharia de Tecidos

Electrospinning is a commonly used and versatile method to produce  scaffolds (often biodegradable) for 3D tissue engineering.1, 2, 3 Many tissues in vivo ...

Engineering Skeletal Muscle Tissues from Murine Myoblast Progenitor Cells and Application of Electrical Stimulation

Engineered muscle tissues can be used for several different purposes, which include the production of tissues for use as a disease model in vitro, e.g. to study pressure ulcers, for regenerative medicine and as a meat alternative 1. The first reported 3D muscle constructs have been made many years ago and pioneers in the field are Vandenburgh and colleagues 2,3. Advances made in muscle tissue engineering are not only the result from the vast gain in knowledge of biochemical factors, stem cells and progenitor cells, but are in particular based on insights gained by researchers that physical factors play essential roles in the control of cell behavior and tissue development. State-of-the-art engineered muscle constructs currently consist of cell-populated hydrogel constructs. In our lab these generally consist of murine myoblast progenitor cells, isolated from murine hind limb muscles or a murine myoblast cell line C2C12, mixed with a mixture of collagen/Matrigel and plated between two anchoring points, mimicking the muscle ligaments. Other cells may be considered as well, e.g. alternative cell lines such as L6 rat myoblasts 4, neonatal muscle derived progenitor cells 5, cells derived from adult muscle tissues from other species such as human 6 or even induced pluripotent stem cells (iPS cells) 7. Cell contractility causes alignment of the cells along the long axis of the construct 8,9 and differentiation of the muscle progenitor cells after approximately one week of culture. Moreover, the application of electrical stimulation can enhance the process of differentiation to some extent 8. Because of its limited size (8 x 2 x 0.5 mm) the complete tissue can be analyzed using confocal microscopy to monitor e.g. viability, differentiation and cell alignment. Depending on the specific application the requirements for the engineered muscle tissue will vary; e.g. use for regenerative medicine requires the up scaling of tissue size and vascularization, while to serve as a meat alternative translation to other species is necessary.

Engineered muscle tissue has great potential in regenerative medicine, as disease model and also as an alternative source for meat. Here we describe the engineering of a muscle construct, in this case from mouse myoblast progenitor cells, and the stimulation by electrical pulses.

Os tecidos músculo esquelético de engenharia a partir de células progenitoras mioblastos murinos e Aplicação da estimulação elétrica

Engineered muscle tissues can be used for several different purposes, which include the production of tissues for use as a disease model in vitro, e.g. to ...

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.

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, ...

Optimizing Attachment of Human Mesenchymal Stem Cells on Poly(&#949;-caprolactone) Electrospun Yarns

Research into biomaterials and tissue engineering often includes cell-based in vitro investigations, which require initial knowledge of the starting cell number. While researchers commonly reference their seeding density this does not necessarily indicate the actual number of cells that have adhered to the material in question. This is particularly the case for materials, or scaffolds, that do not cover the base of standard cell culture well plates. This study investigates the initial attachment of human mesenchymal stem cells seeded at a known number onto electrospun poly(&#949;-caprolactone) yarn after 4 hr in culture. Electrospun yarns were held within several different set-ups, including bioreactor vessels rotating at 9 rpm, cell culture inserts positioned in low binding well plates and polytetrafluoroethylene (PTFE) troughs placed within petri dishes. The latter two were subjected to either static conditions or positioned on a shaker plate (30 rpm). After 4 hr incubation at 37&#160;oC, 5% CO2, the location of seeded cells was determined by cell DNA assay. Scaffolds were removed from their containers and placed in lysis buffer. The media fraction was similarly removed and centrifuged &#8211; the supernatant discarded and pellet broken up with lysis buffer. Lysis buffer was added to each receptacle, or well, and scraped to free any cells that may be present. The cell DNA assay determined the percentage of cells present within the scaffold, media and well fractions. Cell attachment was low for all experimental set-ups, with greatest attachment (30%) for yarns held within cell culture inserts and subjected to shaking motion. This study raises awareness to the actual number of cells attaching to scaffolds irrespective of the stated cell seeding density.

This article describes a range of set-ups for seeding human mesenchymal stem cells onto materials, in this case electrospun yarns, that do not cover the base of standard culture well plates in order to maximize and quantify the number of cells that initially attach compared to the known seeding density.

Otimizando Penhora de mesenquimais humanas Células-Tronco em Poly (ε-caprolactona) electrospun Yarns

Research into biomaterials and tissue engineering often includes cell-based in vitro investigations, which require initial knowledge of the starting cell ...

Electrospun Nanofiber Scaffolds with Gradations in Fiber Organization

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion.

Here, we present a protocol to fabricate electrospun nanofiber scaffolds with gradated organization of fibers and explore their applications in regulating cell morphology/orientation. Gradients with regard to physical and chemical properties of the nanofiber scaffolds offer a wide variety of applications in the biomedical field.

Electrospun nanofibras Andaimes com gradações de Organização Fiber

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible ...

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 ...

Microfluidic Bioprinting for Engineering Vascularized Tissues and Organoids

Engineering vascularized tissue constructs and organoids has been historically challenging. Here we describe a novel method based on microfluidic bioprinting to generate a scaffold with multilayer interlacing hydrogel microfibers. To achieve smooth bioprinting, a core-sheath microfluidic printhead containing a composite bioink formulation extruded from the core flow and the crosslinking solution carried by the sheath flow, was designed and fitted onto the bioprinter. By blending gelatin methacryloyl (GelMA) with alginate, a polysaccharide that undergoes instantaneous ionic crosslinking in the presence of select divalent ions, followed by a secondary photocrosslinking of the GelMA component to achieve permanent stabilization, a microfibrous scaffold could be obtained using this bioprinting strategy. Importantly, the endothelial cells encapsulated inside the bioprinted microfibers can form the lumen-like structures resembling the vasculature over the course of culture for 16 days. The endothelialized microfibrous scaffold may be further used as a vascular bed to construct a vascularized tissue through subsequent seeding of the secondary cell type into the interstitial space of the microfibers. Microfluidic bioprinting provides a generalized strategy in convenient engineering of vascularized tissues at high fidelity.

We provide a generalized protocol based on a microfluidic bioprinting strategy for engineering a microfibrous vascular bed, where a secondary cell type could be further seeded into the interstitial space of this microfibrous structure to generate vascularized tissues and organoids.

Vascularizado de microfluidic Bioprinting para a engenharia de tecidos e Organoids

Engineering vascularized tissue constructs and organoids has been historically challenging. Here we describe a novel method based on microfluidic ...

Two Methods for Decellularization of Plant Tissues for Tissue Engineering Applications

The autologous, synthetic, and animal-derived grafts currently used as scaffolds for tissue replacement have limitations due to low availability, poor biocompatibility, and cost. Plant tissues have favorable characteristics that make them uniquely suited for use as scaffolds, such as high surface area, excellent water transport and retention, interconnected porosity, preexisting vascular networks, and a wide range of mechanical properties. Two successful methods of plant decellularization for tissue engineering applications are described here. The first method is based on detergent baths to remove cellular matter, which is similar to previously established methods used to clear mammalian tissues. The second is a detergent-free method adapted from a protocol that isolates leaf vasculature and involves the use of a heated bleach and salt bath to clear the leaves and stems. Both methods yield scaffolds with comparable mechanical properties and low cellular metabolic impact, thus allowing the user to select the protocol which better suits their intended application.

Here we present, and contrast two protocols used to decellularize plant tissues: a detergent-based approach and a detergent-free approach. Both methods leave behind the extracellular matrix of the plant tissues used, which can then be utilized as scaffolds for tissue engineering applications.

Dois métodos para Decellularization de tecidos vegetais para aplicações de engenharia de tecidos

The autologous, synthetic, and animal-derived grafts currently used as scaffolds for tissue replacement have limitations due to low availability, poor ...