Este trabajo se llevó a cabo utilizando las instalaciones del Departamento de Ingeniería Biomédica de la Universidad Internacional de la Florida.

1. Configuración Electrohilado Collector <ol><li> Cortar el papel de aluminio en una pieza rectangular. </li><li> Doble la pieza rectangular en una tira rectangular, y adjuntarlo perpendicular a una placa metálica plana con cinta (Figura 1). Nota: El tamaño de la estera de fibras depende de la longitud y la anchura de la tira. Por lo tanto, las dimensiones de la tira se pueden ajustar según sea necesario. </li></ol> 2. Polimérico Preparación de la Solución <ol><li> Mezclar glicerol y ácido dodecanodioico (DDA) en una relación molar 1:1 en un vaso de precipitados a 120 ° C durante 100 h para obtener polímero de PGD. </li><li> Disolver poli (óxido de etileno) (PEO) y gelatina en etanol 65% con una relación en peso de 1.5:3:95.5 en un tubo de 15 ml, apretar la tapa y calentar la mezcla en un horno a 60 ° C durante 1 hora con agitación hasta que se convierte en una solución homogénea (solución basal). </li><li> Para electrospinning, mezclar el polímero PGD y la solución basal en 04:06 relación de pesos. Nota: La concentración PGD tiene un big efecto sobre diámetro de la fibra. 30% -50% por ciento PGD es aceptable para producir fibras de más de 5 cm con mayores diámetros de las fibras. </li><li> Añadir 0,1% de riboflavina a la solución polimérica y mezclar bien. </li></ol> 3. Electrohilado <ol><li> Alimentar a la solución polimérica en una jeringa estándar de 5 ml con una aguja de 18 G romos de acero inoxidable. </li><li> Inserte la jeringa en una bomba de jeringa. </li><li> Una el plomo a tierra de una fuente de alimentación de alta tensión a la placa metálica y el cable de carga positiva a la aguja. </li><li> Ajustar la distancia entre la aguja y la tira de papel de aluminio a 15 cm. </li><li> Coloque la bomba de jeringa en un ángulo de aproximadamente 15 ° con la horizontal para evitar la agregación de las fibras en la parte delantera de la tira. </li><li> Encienda la bomba de jeringa y ajustar la velocidad de flujo de la bomba a 0,6 ml / h. </li><li> Encienda la fuente de alimentación de alta tensión y ajustar la tensión de funcionamiento a 14,6 kV. </li></ol> 4.Procesamiento de Fibra <ol><li> Después de la colección es completa, exponer la esterilla de fibra a luz UV durante 60 min para la reticulación. </li><li> Transfiera la estera de fibra de la tira de papel de aluminio para un 100 mm placa de Petri, y exponerlo a la luz UV durante otros 20 minutos para la esterilización. </li><li> En un gabinete de bioseguridad, corte la estera de fibra en pedazos redondos del mismo tamaño, con una hoja de bisturí y colocar las piezas en una placa de 24 pocillos. </li><li> Para celda de tratamiento de pre-siembra, sumerja las muestras de fibra en 1 ml de tampón fosfato salino (PBS) y se incuba a 37 ° C durante la noche. </li><li> Al día siguiente, aspirado PBS con cuidado, añadir 1 ml de medio de diferenciación (DMEM/F12, N2, y FGF2) (vea la receta en la tabla de materiales) a cada pocillo y se incuba a 37 ° C durante 3 horas. </li><li> Medio de diferenciación Aspirar cuidadosamente, añadir 0,2 ml de Matrigel a cada muestra de fibra y se incuba a 37 ° C durante 30 min. Nota: La laminina también puede ser utilizado para el recubrimiento de fibra. Añadir 0,2 ml de 20 mg / ml de lamininaa la fibra y se incuba a temperatura ambiente durante 3 h. </li><li> Eliminar cuidadosamente el exceso matrigel de cada pocillo. Enjuague con 2 ml de medio de diferenciación una vez. Nota: Las muestras de fibra están listos para el cultivo celular. </li></ol> 5. Siembra de células en fibras <ol><li> Añadir 1 ml de Accutase a la placa de cultivo celular MES y se incuba durante 10 min a 37 ° C. </li><li> Después de 10 min, las células TEr se separan de la placa de cultivo. Añadir 4 ml de medio de diferenciación a la placa. Recoger las células TEr flotantes en un tubo de 15 ml y las células de la pipeta hacia arriba y abajo para romper colonias (aproximadamente 15x). </li><li> Centrifugar a 400 xg durante 5 min y volver a suspender las células en 4 ml de medio de diferenciación. </li><li> Contar las células utilizando un hemocitómetro. Transferir 200 l de la suspensión celular en un tubo de 15 ml y diluir 10 veces con medio de diferenciación. Transferir 15 l de la suspensión celular diluida a una cámara en el hemocitómetro con un cubre en su lugar. Contarlas células en la plaza del centro de 1 mm y las cuatro esquinas del hemocitómetro bajo el microscopio. Nota: la célula por ml = el recuento promedio por metro cuadrado x el factor de dilución x 10 4 </li><li> Coloque aproximadamente 5 x 10 4 células TEr en cada pocillo. Lentamente gota la suspensión celular en el medio de las muestras de fibra, en vez de deslizarse a un lado del pozo, para evitar que la solución se drene fuera de la estera de fibra. </li><li> Añadir 1 ml de medio de diferenciación a cada pocillo, y mantener la placa en una incubadora a 37 ° C y 5% de CO 2 para permitir la unión de células, el crecimiento y la diferenciación. </li><li> Aspirar el viejo medio de cada pocillo y sustituir con 1 ml de medio de diferenciación fresca cada dos días. </li></ol> 6. Viabilidad de las células <ol><li> Aspirar el viejo medio de cada pocillo. </li><li> Mezclar 1/10 volumen de resazurina reactivo de fluorescencia con medio de cultivo y añadir 1 ml a cada pocillo. </li><li> IncubComimos en 37 ° C y 5% de CO 2 durante 4 horas, protegido de la luz directa. </li><li> Después de 4 horas, la transferencia de 100 l 3x del reactivo de cada pocillo a una placa de 96 pocillos, y luego las muestras están listas para ser medido en un espectrofotómetro de fluorescencia utilizando los ajustes de filtro 560EX nm/590EM. </li></ol> 7. En tiempo real PCR <ol><li> Después de 14 días de cultivo, añadir tampón de lisis a las muestras y aislar ARN total de las células en las muestras de fibra. </li><li> Utilice 4 l de ARN total para sintetizar cDNA en 20 escalas de reacción mu l mediante transcripción inversa. </li><li> Preparar la mezcla de PCR reacción en cada tubo óptico: 10 l de mezcla maestra (2x), 0,2 l de colorante, 8 l agua libre de nucleasa, 1 l de ADNc, y 1 l de cebadores (primers utilizados en este estudio se enumeran en la Tabla 1). </li><li> Configure el programa de PCR: a. 95 ° C 2:20 min, 1 ciclo b. 95 ° C 3 seg → 60 ° C 1 min, 40 ciclos c. 95 ° C 15 seg, 1 ciclo d. 60 ° C 1min, 1 ciclo e. 95 ° C 15 seg, 1 ciclo. Elija comparativo C T método para determinar los niveles de expresión génica relativa. </li><li> Después de la PCR está terminado, analizar los resultados en tiempo real de PCR con el software StepOne y exportar los resultados a Excel. </li></ol>

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No hay conflictos de interés declarado.

Las limitaciones de los colectores simples o las complejidades de los colectores que se utilizan actualmente para electrospinning aumentar la restricción de obtener la longitud deseada y el tamaño de la estera de fibra para algunas aplicaciones de rotación. Además, la transferencia de fibras desde el colector de tierra a la placa de cultivo o de otros sustratos es un desafío 5. En este informe, un coleccionista de nuevo diseño, hecho simplemente uniendo una tira de papel de aluminio para el colector a t...

Electrospinning es uno de los métodos de procesamiento eficaces para producir andamios de fibra de tamaño micro-a nanómetros. El principio básico de electrospinning implica un cono de Taylor de la solución que se mantiene en el orificio de una aguja, mediante la aplicación de alto voltaje entre la punta de la aguja y un colector a tierra. Cuando la repulsión electrostática en la solución supera la tensión superficial, un chorro de fluido cargado se expulsa fuera de la punta de la aguja, viaja por el aire con la evaporación del disolvente, y finalmente se deposita en el colector conectado a tierra. La bomba de jeringa proporciona un flujo continuo de la solución que emerge de la hilera y por lo tanto múltiples copias de las fibras electrohiladas se puede fabricar dentro de un corto período de tiempo. Durante el curso de salir de la hilera para llegar al colector, el chorro cargada someterse a estiramiento y batir según un número de parámetros que incluyen la viscosidad y la tensión superficial de la solución polimérica, los electrostáticamentefuerza de C en la solución, y la interacción del campo eléctrico externo, etc 2. En el proceso de electrospinning, un colector sirve como un sustrato conductor, donde las fibras micro-a nanómetros podrían ser depositados. En este estudio, un nuevo tipo de colector de fibras fue diseñado para obtener esteras de fibra con el tamaño deseado (longitud x anchura). Tradicionalmente, el papel de aluminio se utiliza como un colector pero es difícil de transferir las fibras de la superficie plana a otro sustrato. La dificultad de la recolección de una manta de fibra intacta de un coleccionista tradicional se debió principalmente al hecho de que las fibras se adhieren fuertemente electrohiladas a la superficie del colector. Por lo tanto, hemos modificado el colector doblando un pedazo de papel de aluminio en una tira rectangular y lo conecta perpendicularmente a una placa metálica plana. Las fibras electrohiladas se estiran a través del área entre la punta de la tira y la placa de metal, que se puede transferir fácilmente a otro sustrato dee. El interés en los polímeros elastoméricos reticulados térmicamente está creciendo rápidamente debido a la labor pionera del grupo de Robert Langer, quien presentó poli (sebacato de glicerol) (PGS), un poliéster que es análogo al caucho vulcanizado en 2002 3. Similar a PGS, hemos desarrollado con éxito poli (glicerol-dodecanoato) (PGD) por condensación térmica de glicerol y ácido dodecanodioico y demostraron su única propiedad con memoria de forma 1. A diferencia de más rígido materiales sintéticos de poli (butirato de hidroxilo) o poli (L-lactida) (módulos de Young de 250 MPa y 660 MPa, respectivamente), PGD exhibe la propiedad de elastómero como el caucho, con un módulo de Young de 1,08 MPa cuando la temperatura está por encima de 37 ° C, que es una coincidencia cercana a la de los nervios periféricos in situ (0,45 MPa). Además, PGD es biodegradable y el tiempo de degradación puede ser ajustado por la variación de la proporción de glicerol y ácido dodecanodioico. Ácido dodecanodioico es un sub doce de carbonopostura con dos grupos carboxílicos terminales, HOOC (CH2) 10 COOH. Ácidos dicarboxílicos con número par, como el ácido sebácico y ácido dodecanodioico pueden ser metabolizados a acetil-CoA y entrar en el de los ácidos tricarboxílicos (TCA) / ciclo (ácido cítrico). El producto metabólico de los ácidos dicarboxílicos, succinil-CoA reductasa, es un precursor gluconeogenética y el intermedio de ciclo TCA 4. Por lo tanto, algunos estudios sugieren que podrían ser utilizados como un sustrato de combustible alternativo para la nutrición enteral y parenteral, especialmente en las condiciones patológicas. Además, el DGP presenta memoria de forma única, ya que su temperatura de transición vítrea es de 31 ° C, por lo tanto, muestra propiedades mecánicas distintas a temperatura ambiente y a la temperatura corporal. En suma, PGD es biodegradable, biocompatible, que presenta propiedades elásticas únicas con propiedades mecánicas similares a los tejidos nerviosos; Por lo tanto, es un material adecuado para aplicaciones de ingeniería de tejido nervioso. En este protocolo, el electrospunfibras largas que cubren un área de gran depósito fueron fabricados por el captador de nuevo diseño de PGD. Los andamios de fibra pueden apoyar el crecimiento de células madre pluripotentes de ratón y la diferenciación.

<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 aplicaciones de ingeniería de tejidos, la preparación de estructuras biodegradables y biocompatibles es la tarea más deseable pero desafiante. Entre los diversos métodos de fabricación, de electrospinning es la más atractiva debido a su simplicidad y versatilidad. Además, las nanofibras electrohiladas imitan el tamaño de la matriz extracelular natural, garantizando un apoyo adicional para la supervivencia y el crecimiento celular. Este estudio demostró la viabilidad de la fabricación de fibras largas que abarcan un área de depósito más grande para un nuevo polímero biodegradable y biocompatible llamado poli (glicerol-dodecanoato) (DGP) 1 mediante el uso de un colector de nuevo diseño para electrospinning. PGD ​​exhibe propiedades elásticas únicas con propiedades mecánicas similares a los tejidos nerviosos, por lo que es adecuado para aplicaciones de ingeniería de tejidos neuronales. La síntesis y fabricación de puesta a punto para la fabricación de materiales de andamios fibrosos era simple, altamente reproducible y de bajo costo. En biocompatibilidadlas pruebas, las células derivadas de células madre embrionarias de ratón podrían adherirse y crecer en las fibras de PGD electrospun. En resumen, este protocolo proporciona un método de fabricación versátil para la fabricación de fibras electrohiladas PGD para apoyar el crecimiento de las células madre embrionarias de ratón derivados de células de linaje neural.

Los componentes principales de la electrospinning se muestran en la Figura 1. Una gran estera de fibras de tamaño se obtuvo típicamente a través de la tira de papel de aluminio perpendicularmente adjunto y una placa de metal plana. Figura 2 muestra el diseño de colector y la estera de fibra de electrospinning. La anchura y la longitud se pueden ajustar para diferentes aplicaciones. La longitud de la fibra hecho con polímero de PGD y mezcla de solución basal es de hasta 10 cm. La m...

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

Se informó de síntesis y fabricación de fibras electrohiladas largos que abarcan un área de depósito más grande a través de un colector de nuevo diseño de un nuevo polímero biodegradable llamado poli (glicerol-dodecanoato) (PGD). Las fibras fueron capaces de apoyar el crecimiento de células derivadas de células madre pluripotentes de ratón.

Electrospun fibroso Andamios de poli (glicerol-dodecanodioato) de Ingeniería Neural Los tejidos de las células madre embrionarias de ratón

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

electrospun-fibrous-scaffolds-polyglycerol-dodecanedioate-for

Research

JoVE Journal

Bioengineering

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

10.8K vistas.  Florida International University.  Se informó de síntesis y fabricación de fibras electrohiladas largos que abarcan un área de depósito más grande a través de un colector de nuevo diseño de un nuevo polímero biodegradable llamado poli (glicerol-dodecanoato) (PGD). Las fibras fueron capaces de apoyar el crecimiento de células derivadas de células madre pluripotentes de ratón. 

Video: 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 andamios en ingeniería de tejidos arteriales

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

Investigación

Bioingeniería

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.

Preparación de fibrina Andamios 3D para Aplicaciones madre para cultivo celular

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.

Postproducción de procesamiento de las Fibras electrospun de Ingeniería de Tejidos

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.

Los tejidos de ingeniería músculo esquelético de células mioblastos murinos progenitoras y aplicación de estimulación eléctrica

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 ...

Development, Expansion, and In vivo Monitoring of Human NK Cells from Human Embryonic Stem Cells (hESCs) and Induced Pluripotent Stem Cells (iPSCs)

We present a method for deriving natural killer (NK) cells from undifferentiated hESCs and iPSCs using a feeder-free approach. This method gives rise to high levels of NK cells after 4 weeks culture and can undergo further 2-log expansion with artificial antigen presenting cells. hESC- and iPSC-derived NK cells developed in this system have a mature phenotype and function. The production of large numbers of genetically modifiable NK cells is applicable for both basic mechanistic as well as anti-tumor studies. Expression of firefly luciferase in hESC-derived NK cells allows a non-invasive approach to follow NK cell engraftment, distribution, and function. We also describe a dual-imaging scheme that allows separate monitoring of two different cell populations to more distinctly characterize their interactions in vivo. This method of derivation, expansion, and dual in vivo imaging provides a reliable approach for producing NK cells and their evaluation which is necessary to improve current NK cell adoptive therapies.

Development, Expansion, and In vivo Monitoring of Human NK Cells from Human Embryonic Stem Cells hESCs and Induced Pluripotent Stem Cells iPSCs

This protocol describes the development, expansion, and in vivo imaging of NK cells derived from hESCs and iPSCs.

Desarrollo, la expansión y<em&gt; En vivo</em&gt; Monitoreo de las células NK humanas a partir de células madre embrionarias humanas (hESCs) y y células madre pluripotentes inducidas (iPSCs)

We present a method for deriving natural killer (NK) cells from undifferentiated hESCs and iPSCs using a feeder-free approach. This method gives rise 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.

Factor de Crecimiento de electrospinning Liberar microesferas en Fibrosa andamios

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.

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

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.

Optimización de unión de las células madre mesenquimales humanas en poli (ε-caprolactona) electrohiladas Hilos

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 andamios con gradaciones en Organización de fibra

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.

Generación de células epiteliales de las vías respiratorias del ratón ESC-Obtenido usando Descelularizado pulmón andamios

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

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.

Dos métodos de descelularización de tejidos vegetales para aplicaciones de ingeniería de tejidos

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