Los autores desean reconocer la Lynn y Mike Garvey Laboratorio de Imagen en el Instituto de Células Madre y Medicina Regenerativa, así como el Fondo de Washington nanofabricación de la Universidad de Washington. También reconocen el apoyo financiero del Instituto Nacional de Salud otorga DP2DK102258 (a YZ), y la formación otorga T32EB001650 (a SSK y MAR) y T32HL007312 (MAR).

<ol>
	<li>Rubanyi, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+endothelium+in+cardiovascular+homeostasis+and+diseases.">The role of endothelium in cardiovascular homeostasis and diseases.</a> J. Cardiovasc. Pharmacol. 22, 37-44 (1993).</li><li>van Hinsbergh, V. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+endothelium:+vascular+control+of+haemostasis.">The endothelium: vascular control of haemostasis.</a> Eur. J. Obstet. Gynecol. Reprod. Biol. 95 (2), 198-201 (2001).</li><li>Chiu, J. -. 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Los autores no tienen nada que revelar.

Microvasos de ingeniería son un modelo in vitro, donde están presentes y sintonizable características fisiológicas, tales como la geometría luminal, las fuerzas hidrodinámicas, y las interacciones multicelulares. Este tipo de plataforma es de gran alcance, ya que ofrece la posibilidad de modelar y estudiar el comportamiento del endotelio en una variedad de contextos en los que las condiciones de cultivo in vitro en puede ser igualada a la del microambiente en cuestión. Por ejemplo, los mecanismo...

La microvasculatura en cada órgano ayuda a definir el microambiente del tejido, mantener la homeostasis del tejido y regulan la inflamación, la permeabilidad, la trombosis, y la fibrinólisis 1,2. Endotelio microvascular, en particular, es la interfaz entre el flujo sanguíneo y el tejido circundante y por lo tanto juega un papel crítico en la modulación de la función del órgano vascular y en respuesta a estímulos tales como las fuerzas hidrodinámicas y citoquinas circulantes y hormonas 3 - 5. La comprensión de las interacciones detalladas entre el endotelio, la sangre y el microambiente tejido circundante es importante para el estudio de la biología vascular y progresión de la enfermedad. Sin embargo, los avances en el estudio de estas interacciones se ha visto obstaculizado por limitada en herramientas in vitro que no recapitulan en la estructura microvascular vivo y la función 6,7. Como resultado, el campo y el avance terapéutico se ha basado en gran medida en costoso y tiempo-el consumo de modelos animales que a menudo no traducir del éxito en seres humanos 8 - 10. Mientras que los modelos in vivo son de gran valor en el estudio de mecanismos de la enfermedad y funciones vasculares, que son complejas y a menudo carecen de un control preciso del individuo celular, bioquímica, y las señales biofísicas. Vasculatura en todo el cuerpo posee una estructura jerárquica madura en conjunción con lechos capilares expansivas, proporcionando la perfusión optimizado y el transporte de nutrientes al mismo tiempo 11. Inicialmente, las formas vasculatura como un plexo primitiva que reorganiza a una red jerárquica ramificada durante el desarrollo temprano 12,13. Aunque muchas de las señales implicadas en estos procesos se conocen bien 14 - 16, sigue siendo difícil de alcanzar, tales cómo el patrón vascular se determina 15. A su vez, la recapitulación de este proceso in vitro para diseñar redes vasculares organizados tiene abejan. Muchas plataformas difíciles existentes in vitro para modelar la vasculatura, por ejemplo, dos cultivos de células endoteliales dimensionales, carecen de características importantes tales como la proximidad multi-celular, tres geometría luminal dimensional, flujo, y de la matriz extracelular. Los ensayos de formación de tubos en 3D (hidrogeles de colágeno o fibrina) 17 - 19 o invasión ensayos de 20,21 se han utilizado para estudiar la función endotelial en 3D y sus interacciones con otras vasculares 17,22 celulares o tejidos tipos 23. Sin embargo, ensamblados lúmenes en estos ensayos carecen de interconectividad, el flujo hemodinámico, y la perfusión adecuada. Además, la propensión a la regresión vascular en estos ensayos de formación de tubo 24 impide que la cultura a largo plazo y la maduración que limita el grado de estudios funcionales que se pueden realizar. Por lo tanto, hay una necesidad creciente para diseñar plataformas in vitro de redes microvasculares que pueden modelar adecuadamente ESendotelial características y son capaces de cultivo a largo plazo. Una variedad de técnicas de ingeniería vasculares han surgido en los últimos años para aplicaciones médicas para reemplazar o vasos de derivación afectada en pacientes con enfermedad vascular. Vasos de gran diámetro fabricados con materiales sintéticos tales como tereftalato de polietileno (PET), y politetrafluoroetileno (PTFE) han tenido un considerable éxito terapéutico con la permeabilidad a largo plazo (promedio 95% la permeabilidad de más de 5 años) 25. Aunque de pequeño diámetro injertos sintéticos (&lt;6 mm) por lo general se enfrentan a complicaciones tales como hiperplasia de la íntima y trombopoyesis 26 - 28, ingeniería tisular injertos de pequeño diámetro hechos con material biológico han hecho progresos significativos 29,30. A pesar de los avances de este tipo, los vasos de ingeniería en la microescala han seguido siendo un reto. Para modelar adecuadamente la microvasculatura, es necesario para generar patrones de red complejas con sufciente resistencia mecánica para mantener la permeabilidad y con una composición de matriz que permite tanto la permeación de nutrientes para las células del parénquima y remodelación celular. Este protocolo presenta una novedosa red de vasos artificiales perfusable que imita un nativo in vivo con un ajuste ajustable y controlable microambiente el 31 de - de 34. El método descrito genera microvasos Diseñado con diámetros del orden de 100 micras. microvasos ingeniería se fabrican mediante la perfusión de las células endoteliales a través de un canal de microfluidos que está incrustado dentro del tipo I colágeno suave hidrogel. Este sistema tiene la capacidad de generar redes modelados con estructura luminal abierta, replicar las interacciones multicelulares, modular la composición de la matriz extracelular, y aplicar fuerzas hemodinámicas fisiológicamente relevantes.

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			<td height="21" style="height:21px;width:459px;">Wafer Fabrication</td>
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			<td height="20" style="height:20px;">AutoGlow Plasma System</td>
			<td>AutoGlow</td>
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		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Headway Spin Coater</td>
			<td>Headway Research, Inc&#160;</td>
			<td colspan="2">PWM32 Spin Coater&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">ABM Contact Aligner</td>
			<td>AB-M</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Alpha Step Profilometer</td>
			<td>Tencor</td>
			<td>Alpha Step 200</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">SU-8 Developer</td>
			<td>Microchem</td>
			<td>Y020100</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">SU-8 Resist</td>
			<td>Microchem</td>
			<td>SU-8 2000</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">8&#34; silicon wafer</td>
			<td>Wafer World Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tabletop Micro Pattern Generator</td>
			<td>Heidelberg Instruments</td>
			<td>&#956;PG 101</td>
			<td>For generation of photomask</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Hot plate</td>
			<td>VWR</td>
			<td>97042-646</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ispropyl alcohol</td>
			<td>Avantor Performance Materials</td>
			<td>9088</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Petri dishes (120 x 120 mm, square)</td>
			<td>Sigma-Aldrich</td>
			<td>Z617679</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trichloro(3,3,3-trifluoropropyl)silane</td>
			<td>Sigma-Aldrich</td>
			<td>MKBG3805V</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Polydimethylsiloxane (PDMS) elastomer base and curing agent</td>
			<td>Dow Corning</td>
			<td>Sylgard 184</td>
			<td>Mixed at 10:1 (w/w)</td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Vacuum desiccator</td>
			<td>Sigma-Aldrich</td>
			<td>Z119024-1EA</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Oven</td>
			<td>VWR</td>
			<td>9120976</td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">Device Fabrication and Culture</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="17">
			<td height="17" style="height:17px;">poly(methyl methacrylate) (PMMA)</td>
			<td>Plexiglas</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Corona Treater</td>
			<td>Electro-Technic Products, Inc.</td>
			<td>BD-20</td>
			<td>Handheld device for plasma treatment of PMMA devices and PDMS molds</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Soldering Iron</td>
			<td>Weller&#160;</td>
			<td>WTCPS</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Stainless Steel Truss Head Slotted Machine Screw</td>
			<td>McMaster-Carr&#160;</td>
			<td>91785A096</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Stainless steel dowel pins</td>
			<td>McMaster-Carr&#160;</td>
			<td>93600A060</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tweezers&#160;</td>
			<td>Miltex</td>
			<td>24-572</td>
			<td>Any similar tweezers may be used</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Spatula (Micro Spoon)</td>
			<td>Electron Microscopy Services</td>
			<td>62410-01</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Screw driver</td>
			<td></td>
			<td></td>
			<td>Any flat head screwdriver may be used, autoclaved</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Glass coverslips (22 x 22 mm)</td>
			<td>Fisher Scientific</td>
			<td>12-542B</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Bleach</td>
			<td>Clorox</td>
			<td>4460030966</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Petri dishes (150 X 25mm)</td>
			<td>Corning</td>
			<td>430599</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Petri dishes (100 X 20 mm)</td>
			<td>Corning</td>
			<td>2909</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Cotton, cut into 1 cm x 3 cm pieces</td>
			<td></td>
			<td></td>
			<td>Autoclaved</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polyethyleneimine (PEI)</td>
			<td>Sigma-Aldrich</td>
			<td>P3143</td>
			<td>Dilute to 1% in cell culture grade water</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Glutaraldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>G6257</td>
			<td>Dilute to 0.1% in cell culture grade water</td>
		</tr>
		<tr height="26">
			<td height="26" style="height:26px;">Sterile H2O</td>
			<td></td>
			<td></td>
			<td>Autoclaved DI H2O</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Type I collagen, dissolved in 0.1% acetic acid</td>
			<td></td>
			<td></td>
			<td>Isolated from rat tails as described in Rajan et. al. 2006 (ref #37)</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1 mL syringe</td>
			<td>BD</td>
			<td>309659</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">10 mL syringe</td>
			<td>BD</td>
			<td>309604</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">15 mL conical tubes</td>
			<td>Corning</td>
			<td>352097</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">30 mL conical tubes</td>
			<td>Corning</td>
			<td>352098</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">M199 10X Media&#160;</td>
			<td>Life Technologies</td>
			<td>11825-015</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1N NaOH (sterile)</td>
			<td>Sigma-Aldrich</td>
			<td>415413</td>
			<td>Dilute to 1N in cell culture grade water</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">HUVECs&#160;</td>
			<td>Lonza</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Endothelial growth media</td>
			<td>Lonza</td>
			<td>CC-3124</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trypsin</td>
			<td>Corning</td>
			<td>25-052-CI</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fetal bovine serum (FBS)</td>
			<td>Thermofisher Scientific</td>
			<td>10082147</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dextran from Leuconostoc spp. (70kDa)</td>
			<td>Sigma-Aldrich</td>
			<td>31390</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Phosphate Buffered Saline (PBS)</td>
			<td>Corning</td>
			<td>21-031-CV</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Hemocytometer</td>
			<td>Hausser Scientific Co.</td>
			<td>3200</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Gel loading tips</td>
			<td>VWR</td>
			<td>37001-152</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">18G Blunt Fill Needle</td>
			<td>BD&#160;</td>
			<td>305180</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">20G Stainless Steel Dispensing Needle</td>
			<td>McMaster-Carr</td>
			<td>75165A123</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tygon 1/32&#8221; ID, 3/32&#34; OD Silicon Tubing</td>
			<td>Cole-Parmer</td>
			<td>EW-95702-00</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">1/16&#34; Tube-to-tube Coupling</td>
			<td>McMaster-Carr</td>
			<td>5116K165</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">90&#176; Elbow Connectors, Tube-to-Tube</td>
			<td>McMaster-Carr</td>
			<td>5121K901</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Luer Lock Coupling (Female, 1/16&#34; ID)</td>
			<td>McMaster-Carr</td>
			<td>51525K211</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Plastic Forceps, with Jaw Grips</td>
			<td>Electron Microscopy Services</td>
			<td>72971</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Dual Syringe Pump</td>
			<td>Harvard Apparatus</td>
			<td>70-4505</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">5 mL Polystyrene Round-bottom tube</td>
			<td>Fisher Scientific</td>
			<td>14-959-2A</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Device Analysis</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Formaldehyde</td>
			<td>Sigma-Aldrich</td>
			<td>F8775</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Bovine Serum Albumin</td>
			<td>Sigma-Aldrich</td>
			<td>A8806-5G</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>T-9284</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Rabbit anti-hCD31</td>
			<td>Abcam</td>
			<td>ab32457</td>
			<td>1:25 working dilution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">FITC conjugated anti-von Willebrand Factor antibody</td>
			<td>Abcam</td>
			<td>ab8822</td>
			<td>1:100 working dilution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Goat anti-rabbit 568 secondary antibody</td>
			<td>Thermofisher Scientific</td>
			<td>A-11011</td>
			<td>1:100 working dilution</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Hoescht</td>
			<td>Thermofisher Scientific</td>
			<td>H1399</td>
			<td>Resuspended in DMSO</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Sodium cacodylate&#160;</td>
			<td>Sigma-Aldrich</td>
			<td>C0250</td>
			<td>To make 0.2M cacodylate buffer</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ethanol</td>
			<td>VWR International</td>
			<td>BDH1164-4LP</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">40kDa FITC-conjugated Dextran</td>
			<td>Sigma-Aldrich</td>
			<td>FD40S&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Additional Culture Reagents&#160;</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">CHIR-99021</td>
			<td>Selleck Chem</td>
			<td>S2924</td>
			<td>Small molecule GSK-3 inhibitor</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Human recombinant VEGF</td>
			<td>Peprotech</td>
			<td>100-20</td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Human recombinant bFGF</td>
			<td>Peprotech</td>
			<td>AF-100-18B</td>
			<td></td>
		</tr>
	</tbody>
</table>

micropatterning and assembly of 3d microvessels

En plataformas in vitro para estudiar las células endoteliales y la biología vascular se limitan en gran medida a la cultura de células endoteliales 2D, el flujo cámaras con polímero o sustratos a base de vidrio, y ensayos de formación de tubo a base de hidrogel. Estos ensayos, mientras informativa, no se recapitulan la geometría del lumen, la matriz extracelular adecuada, y la proximidad multicelular, que juegan un papel clave en la modulación de la función vascular. Este manuscrito describe un método de moldeo por inyección para generar vasos diseñado con diámetros del orden de 100 micras. Los microvasos se fabrican mediante la siembra de células endoteliales en un canal microfluídico incrustado dentro de un tipo nativo I colágeno hidrogel. Mediante la incorporación de las células del parénquima dentro de la matriz de colágeno antes de la formación de canal, microambientes específicos de tejido pueden ser modeladas y estudiadas. modulaciones adicionales de propiedades y medios hidrodinámico composición permiten el control de la función vascular compleja dentro del microambiente deseada.Esta plataforma permite el estudio de la contratación perivascular de células, las interacciones sangre-endotelio, respuesta de flujo, y las interacciones de tejido microvascular. microvasos ingeniería ofrecen la posibilidad de aislar la influencia de los componentes individuales de un nicho vascular y precisamente controlan sus químicos, biológicos, mecánicos y propiedades para estudiar la biología vascular tanto en la salud y la enfermedad.

La plataforma recipiente ingeniería crea microvasculatura funcional incrustado dentro de un tipo natural de colágeno I de la matriz y permite el control ajustado del medio ambiente celular, biofísicas y bioquímicas in vitro. Para fabricar los microvasos de ingeniería, las células endoteliales de la vena umbilical humana (HUVECs) se sometieron a perfusión a través de la red de microfluidos colágeno embebido en donde se unen para formar un lumen de patentes y el endotelio...

Watch this Scientific Journal Video about Micropatterning and Assembly of 3D Microvessels at JoVE.com

Micropatterning and Assembly of 3D Microvessels

Este manuscrito presenta un método de moldeo por inyección para diseñar microvasos que recapitular las propiedades fisiológicas de endotelio. El proceso basado en microfluidos crea redes vasculares 3D patente con condiciones tailorable, tales como gradientes bioquímicos de flujo, composición celular, la geometría, y. Se describe el proceso de fabricación y los ejemplos de posibles aplicaciones.

Micropatterning y Montaje de Microvasos 3D

In vitro platforms to study endothelial cells and vascular biology are largely limited to 2D endothelial cell culture, flow chambers with polymer or glass ...

micropatterning-and-assembly-of-3d-microvessels

Research

JoVE Journal

Bioengineering

11.6K vistas.  University of Washington.  Este manuscrito presenta un método de moldeo por inyección para diseñar microvasos que recapitular las propiedades fisiológicas de endotelio. El proceso basado en microfluidos crea redes vasculares 3D patente con condiciones tailorable, tales como gradientes bioquímicos de flujo, composición celular, la geometría, y. Se describe el proceso de fabricación y los ejemplos de posibles aplicaciones. 

Video: Micropatterning and Assembly of 3D Microvessels

ECM Protein Nanofibers and Nanostructures Engineered Using Surface-initiated Assembly

The extracellular matrix (ECM) in tissues is synthesized and assembled by cells to form a 3D fibrillar, protein network with tightly regulated fiber diameter, composition and organization. In addition to providing structural support, the physical and chemical properties of the ECM play an important role in multiple cellular processes including adhesion, differentiation, and apoptosis. In vivo, the ECM is assembled by exposing cryptic self-assembly (fibrillogenesis) sites within proteins. This process varies for different proteins, but fibronectin (FN) fibrillogenesis is well-characterized and serves as a model system for cell-mediated ECM assembly. Specifically, cells use integrin receptors on the cell membrane to bind FN dimers and actomyosin-generated contractile forces to unfold and expose binding sites for assembly into insoluble fibers. This receptor-mediated process enables cells to assemble and organize the ECM from the cellular to tissue scales. Here, we present a method termed surface-initiated assembly (SIA), which recapitulates cell-mediated matrix assembly using protein-surface interactions to unfold ECM proteins and assemble them into insoluble fibers. First, ECM proteins are adsorbed onto a hydrophobic polydimethylsiloxane (PDMS) surface where they partially denature (unfold) and expose cryptic binding domains. The unfolded proteins are then transferred in well-defined micro- and nanopatterns through microcontact printing onto a thermally responsive poly(N-isopropylacrylamide) (PIPAAm) surface. Thermally-triggered dissolution of the PIPAAm leads to final assembly and release of insoluble ECM protein nanofibers and nanostructures with well-defined geometries. Complex architectures are possible by engineering defined patterns on the PDMS stamps used for microcontact printing. In addition to FN, the SIA process can be used with laminin, fibrinogen and collagens type I and IV to create multi-component ECM nanostructures. Thus, SIA can be used to engineer ECM protein-based materials with precise control over the protein composition, fiber geometry and scaffold architecture in order to recapitulate the structure and composition of the ECM in vivo.

A method to obtain nanofibers and complex nanostructures from single or multiple extracellular matrix proteins is described. This method uses protein-surface interactions to create free-standing protein-based materials with tunable composition and architecture for use in a variety of tissue engineering and biotechnology applications.

Las nanofibras ECM proteínas y Uso Asamblea Superficie iniciadas Nanoestructuras Engineered

The extracellular matrix (ECM) in tissues is synthesized and assembled by cells to form a 3D fibrillar, protein network with tightly regulated fiber ...

Investigación

Bioingeniería

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Historically, most cellular processes have been studied in only 2 dimensions. While these studies have been informative about general cell signaling mechanisms, they neglect important cellular cues received from the structural and mechanical properties of the local microenvironment and extracellular matrix (ECM). To understand how cells interact within a physiological ECM, it is important to study them in the context of 3 dimensional assays. Cell migration, cell differentiation, and cell proliferation are only a few processes that have been shown to be impacted by local changes in the mechanical properties of a 3-dimensional ECM. Collagen I, a core fibrillar component of the ECM, is more than a simple structural element of a tissue. Under normal conditions, mechanical cues from the collagen network direct morphogenesis and maintain cellular structures. In diseased microenvironments, such as the tumor microenvironment, the collagen network is often dramatically remodeled, demonstrating altered composition, enhanced deposition and altered fiber organization. In breast cancer, the degree of fiber alignment is important, as an increase in aligned fibers perpendicular to the tumor boundary has been correlated to poorer patient prognosis1. Aligned collagen matrices result in increased dissemination of tumor cells via persistent migration2,3. The following is a simple protocol for embedding cells within a 3-dimensional, fibrillar collagen hydrogel. This protocol is readily adaptable to many platforms, and can reproducibly generate both aligned and random collagen matrices for investigation of cell migration, cell division, and other cellular processes in a tunable, 3-dimensional, physiological microenvironment.

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Collagen is a core component of the ECM, and provides essential cues for several cellular processes ranging from migration to differentiation and proliferation. Provided here is a protocol for embedding cells within 3D collagen hydrogels, and a more advanced technique for generating randomized or aligned collagen matrices using PDMS microchannels.

Preparación de geles de colágeno en 3D y microcanales para el estudio de las interacciones 3D<em&gt; En Vivo</em

Historically, most cellular processes have been studied in only 2 dimensions.  While these studies have been informative about general cell signaling ...

Automated Robotic Liquid Handling Assembly of Modular DNA Devices

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; represented by &#34;devices&#34; created as combinations of individual genetic components. However, manual assembly of such large numbers of devices is time-intensive, error-prone, and costly. The increasing sophistication and scale of synthetic biology research necessitates an efficient, reproducible way to accommodate large-scale, complex, and high throughput device construction.
Here, a DNA assembly protocol using the Type-IIS restriction endonuclease based Modular Cloning (MoClo) technique is automated on two liquid-handling robotic platforms. Automated liquid-handling robots require careful, often times tedious optimization of pipetting parameters for liquids of different viscosities (e.g. enzymes, DNA, water, buffers), as well as explicit programming to ensure correct aspiration and dispensing of DNA parts and reagents. This makes manual script writing for complex assemblies just as problematic as manual DNA assembly, and necessitates a software tool that can automate script generation. To this end, we have developed a web-based software tool, http://mocloassembly.com, for generating combinatorial DNA device libraries from basic DNA parts uploaded as Genbank files. We provide access to the tool, and an export file from our liquid handler software which includes optimized liquid classes, labware parameters, and deck layout. All DNA parts used are available through Addgene, and their digital maps can be accessed via the Boston University BDC ICE Registry. Together, these elements provide a foundation for other organizations to automate modular cloning experiments and similar protocols.
The automated DNA assembly workflow presented here enables the repeatable, automated, high-throughput production of DNA devices, and reduces the risk of human error arising from repetitive manual pipetting. Sequencing data show the automated DNA assembly reactions generated from this workflow are ~95% correct and require as little as 4% as much hands-on time, compared to manual reaction preparation.

Here, an automated workflow to perform modular DNA &#34;device&#34; assembly using a modular cloning DNA assembly method on liquid-handling robots is presented. The protocol uses an intuitive software tool for generating liquid handler picklists for combinatorial DNA device library generation, which we demonstrate using two liquid handling platforms.

Automatizado de montaje robotizada manipulación líquido de dispositivos modulares de la DNA

Recent advances in modular DNA assembly techniques have enabled synthetic biologists to test significantly more of the available &#34;design space&#34; ...

Synthesis of Cationized Magnetoferritin for Ultra-fast Magnetization of Cells

Many important biomedical applications, such as cell imaging and remote manipulation, can be achieved by labeling cells with superparamagnetic iron oxide nanoparticles (SPIONs). Achieving sufficient cellular uptake of SPIONs is a challenge that has traditionally been met by exposing cells to elevated concentrations of SPIONs or by prolonging exposure times (up to 72 hr). However, these strategies are likely to mediate toxicity. Here, we present the synthesis of the protein-based SPION magnetoferritin as well as a facile surface functionalization protocol that enables rapid cell magnetization using low exposure concentrations. The SPION core of magnetoferritin consists of cobalt-doped iron oxide with an average particle diameter of 8.2 nm mineralized inside the cavity of horse spleen apo-ferritin. Chemical cationization of magnetoferritin produced a novel, highly membrane-active SPION that magnetized human mesenchymal stem cells (hMSCs) using incubation times as short as one minute and iron concentrations as lows as 0.2 mM.

A protocol for the synthesis and cationization of cobalt-doped magnetoferritin is presented, as well as a method to rapidly magnetize stem cells with cationized magnetoferritin.

Síntesis de cationizada Magnetoferritin para la magnetización ultra-rápido de las células

Many important biomedical applications, such as cell imaging and remote manipulation, can be achieved by labeling cells with superparamagnetic iron oxide ...

Assembly and Tracking of Microbial Community Development within a Microwell Array Platform

The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial distribution and activities of community members. We have developed a microwell array platform that can be used to rapidly assemble and track thousands of bacterial communities in parallel. This protocol highlights the utility of the platform and describes its use for optically monitoring the development of simple, two-member communities within an ensemble of arrays within the platform. This demonstration uses two mutants of Pseudomonas aeruginosa, part of a series of mutants developed to study Type VI secretion pathogenicity. Chromosomal inserts of either mCherry or GFP genes facilitate the constitutive expression of fluorescent proteins with distinct emission wavelengths that can be used to monitor community member abundance and location within each microwell. This protocol describes a detailed method for assembling mixtures of bacteria into the wells of the array and using time-lapse fluorescence imaging and quantitative image analysis to measure the relative growth of each member population over time. The seeding and assembly of the microwell platform, the imaging procedures necessary for the quantitative analysis of microbial communities within the array, and the methods that can be used to reveal interactions between microbial species area all discussed.

The development of microbial communities depends on a combination of factors, including environmental architecture, member abundance, traits, and interactions. This protocol describes a synthetic, microfabricated environment for the simultaneous tracking of thousands of communities contained in femtoliter wells, where key factors such as niche size and confinement can be approximated.

Montaje y Seguimiento de Desarrollo Comunitario Microbiano dentro de una Plataforma de Matriz de Micropedulos

The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial ...

Bioprinting of Cartilage and Skin Tissue Analogs Utilizing a Novel Passive Mixing Unit Technique for Bioink Precellularization

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both cartilage and skin analogs were fabricated after bioink pre-cellularization utilizing a novel passive mixing unit technique. This technique was developed with the aim to simplify the steps involved in the mixing of a cell suspension into a highly viscous bioink. The resolution of filaments deposited through bioprinting necessitates the assurance of uniformity in cell distribution prior to printing to avoid the deposition of regions without cells or retention of large cell clumps that can clog the needle. We demonstrate the ability to rapidly blend a cell suspension with a bioink prior to bioprinting of both cartilage and skin analogs. Both tissue analogs could be cultured for up to 4 weeks. Histological analysis demonstrated both cell viability and deposition of tissue specific extracellular matrix (ECM) markers such as glycosaminoglycans (GAGs) and collagen I respectively.

Cartilage and skin analogs were bioprinted using a nanocellulose-alginate based bioink. The bioinks were cellularized prior to printing via a single step passive mixing unit. The constructs were demonstrated to be uniformly cellularized, have high viability, and exhibit favorable markers of differentiation.

Bioprinting de cartílago y piel análogos de tejido utilizando un pasivo novela mezcla de unidad técnica de Bioink Precellularization

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both ...

Fabrication of Custom Agarose Wells for Cell Seeding and Tissue Ring Self-assembly Using 3D-Printed Molds

Engineered tissues are being used clinically for tissue repair and replacement, and are being developed as tools for drug screening and human disease modeling. Self-assembled tissues offer advantages over scaffold-based tissue engineering, such as enhanced matrix deposition, strength, and function. However, there are few available methods for fabricating 3D tissues without seeding cells on or within a supporting scaffold. Previously, we developed a system for fabricating self-assembled tissue rings by seeding cells into non-adhesive agarose wells. A polydimethylsiloxane (PDMS) negative was first cast in a machined polycarbonate mold, and then agarose was gelled in the PDMS negative to create ring-shaped cell seeding wells. However, the versatility of this approach was limited by the resolution of the tools available for machining the polycarbonate mold. Here, we demonstrate that 3D-printed plastic can be used as an alternative to machined polycarbonate for fabricating PDMS negatives. The 3D-printed mold and revised mold design is simpler to use, inexpensive to produce, and requires significantly less agarose and PDMS per cell seeding well. We have demonstrated that the resulting agarose wells can be used to create self-assembled tissue rings with customized diameters from a variety of different cell types. Rings can then be used for mechanical, functional, and histological analysis, or for fabricating larger and more complex tubular tissues.

This protocol describes a platform for fabricating self-assembled tissue rings in variable sizes using a customized 3D-printed plastic mold. PDMS negatives are cured in the 3D-printed mold; then agarose is cast in the cured PDMS negatives. Cells are seeded into the resulting agarose wells where they aggregate into tissue rings.

Fabricación de pozos de agarosa personalizado para la siembra de células y tejido anillo autoensamblaje con moldes impresa en 3D

Engineered tissues are being used clinically for tissue repair and replacement, and are being developed as tools for drug screening and human disease ...

Assembly and Characterization of Biomolecular Memristors Consisting of Ion Channel-doped Lipid Membranes

The ability to recreate synaptic functionalities in synthetic circuit elements is essential for neuromorphic computing systems that seek to emulate the cognitive powers of the brain with comparable efficiency and density. To date, silicon-based three-terminal transistors and two-terminal memristors have been widely used in neuromorphic circuits, in large part due to their ability to co-locate information processing and memory. Yet these devices cannot achieve the interconnectivity and complexity of the brain because they are power-hungry, fail to mimic key synaptic functionalities, and suffer from high noise and high switching voltages. To overcome these limitations, we have developed and characterized a biomolecular memristor that mimics the composition, structure, and switching characteristics of biological synapses. Here, we describe the process of assembling and characterizing biomolecular memristors consisting of a 5 nm-thick lipid bilayer formed between lipid-functionalized water droplets in oil and doped with voltage-activated alamethicin peptides. While similar assembly protocols have been used to investigate biophysical properties of droplet-supported lipid membranes and membrane-bound ion channels, this article focuses on key modifications of the droplet interface bilayer method essential for achieving consistent memristor performance. Specifically, we describe the liposome preparation process and the incorporation of alamethicin peptides in lipid bilayer membranes, and the appropriate concentrations of each constituent as well as their impact on the overall response of the memristors. We also detail the characterization process of biomolecular memristors, including measurement and analysis of memristive current-voltage relationships obtained via cyclic voltammetry, as well as short-term plasticity and learning in response to step-wise voltage pulse trains.

Soft, low-power, biomolecular memristors leverage similar composition, structure, and switching mechanisms of bio-synapses. Presented here is a protocol to assemble and characterize biomolecular memristors obtained from insulating lipid bilayers formed between water droplets in oil. The incorporation of voltage-activated alamethicin peptides results in memristive ionic conductance across the membrane.

Montaje y caracterización de memristores Biomolecular consisten en membranas lipídicas dopado canal iónico

The ability to recreate synaptic functionalities in synthetic circuit elements is essential for neuromorphic computing systems that seek to emulate the ...

Protocols of 3D Bioprinting of Gelatin Methacryloyl Hydrogel Based Bioinks

Gelatin methacryloyl (GelMA) has become a popular biomaterial in the field of bioprinting. The derivation of this material is gelatin, which is hydrolyzed from mammal collagen. Thus, the arginine-glycine-aspartic acid (RGD) sequences and target motifs of matrix metalloproteinase (MMP) remain on the molecular chains, which help achieve cell attachment and degradation. Furthermore, formation properties of GelMA are versatile. The methacrylamide groups allow a material to become rapidly crosslinked under light irradiation in the presence of a photoinitiator. Therefore, it makes great sense to establish suitable methods for synthesizing three-dimensional (3D) structures with this promising material. However, its low viscosity restricts GelMA's printability. Presented here are methods to carry out 3D bioprinting of GelMA hydrogels, namely the fabrication of GelMA microspheres, GelMA fibers, GelMA complex structures, and GelMA-based microfluidic chips. The resulting structures and biocompatibility of the materials as well as the printing methods are discussed. It is believed that this protocol may serve as a bridge between previously applied biomaterials and GelMA as well as contribute to the establishment of GelMA-based 3D architectures for biomedical applications.

Presented here is a method for the 3D bioprinting of gelatin methacryloyl.

Protocolos de Bioimpresión 3D de Bioinks basados en Gelatin Methacryloyl Hydrogel

Gelatin methacryloyl (GelMA) has become a popular biomaterial in the field of bioprinting. The derivation of this material is gelatin, which is hydrolyzed ...

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer

The droplet interface bilayer (DIB) method for assembling lipid bilayers (i.e., DIBs) between lipid-coated aqueous droplets in oil offers key benefits versus other methods: DIBs are stable and often long-lasting, bilayer area can be reversibly tuned, leaflet asymmetry is readily controlled via droplet compositions, and tissue-like networks of bilayers can be obtained by adjoining many droplets. Forming DIBs requires spontaneous assembly of lipids into high density lipid monolayers at the surfaces of the droplets. While this occurs readily at room temperature for common synthetic lipids, a sufficient monolayer or stable bilayer fails to form at similar conditions for lipids with melting points above room temperature, including some cellular lipid extracts. This behavior has likely limited the compositions&#8212;and perhaps the biological relevance&#8212;of DIBs in model membrane studies. To address this problem, an experimental protocol is presented to carefully heat the oil reservoir hosting DIB droplets and characterize the effects of temperature on the lipid membrane. Specifically, this protocol shows how to use a thermally conductive aluminum fixture and resistive heating elements controlled by a feedback loop to prescribe elevated temperatures, which improves monolayer assembly and bilayer formation for a wider set of lipid types. Structural characteristics of the membrane, as well as the thermotropic phase transitions of the lipids comprising the bilayer, are quantified by measuring the changes in electrical capacitance of the DIB. Together, this procedure can aid in evaluating biophysical phenomena in model membranes over various temperatures, including determining an effective melting temperature (TM) for multi-component lipid mixtures. This capability will thus allow for closer replication of natural phase transitions in model membranes and encourage the formation and use of model membranes from a wider swath of membrane constituents, including those that better capture the heterogeneity of their cellular counterparts.

This protocol details the use of a feedback temperature-controlled heating system to promote lipid monolayer assembly and droplet interface bilayer formation for lipids with elevated melting temperatures, and capacitance measurements to characterize temperature-driven changes in the membrane.

Montaje con temperatura controlada y caracterización de una bicapa de interfaz de gota

The droplet interface bilayer (DIB) method for assembling lipid bilayers (i.e., DIBs) between lipid-coated aqueous droplets in oil offers key benefits ...