Die Autoren möchten die Lynn und Mike Garvey Imaging Labor am Institut für Stammzell und Regenerative Medizin, sowie die Washington Nanofabrication Einrichtung an der Universität von Washington zu bestätigen. Sie erkennen auch die finanzielle Unterstützung des National Institute of Health gewährt DP2DK102258 (zu YZ) und die Ausbildung gewährt T32EB001650 (bis SSK und MAR) und T32HL007312 (MAR).

<ol>
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Die Autoren haben nichts zu offenbaren.

Engineered microvessels sind ein in vitro - Modell , wo physiologische Eigenschaften wie luminalen Geometrie, hydrodynamischen Kräfte und mehrzelligen Wechselwirkungen vorhanden und abstimmbaren sind. Diese Art von Plattform ist in leistungsstark , dass es bietet die Möglichkeit , endothelial Verhalten in einer Vielzahl von Kontexten zu modellieren und zu studieren , wo die in vitro Kulturbedingungen können zu der der Mikroumgebung in Frage abgestimmt werden. Zum Beispiel werden die Antriebsmechanis...

Die Mikrovaskulatur in jedem Organ hilft , die Gewebemikroumgebung definieren, Gewebe - Homöostase und Entzündung regulieren, Permeabilität, Thrombose und Fibrinolyse 1,2 aufrechtzuerhalten. Mikrovaskulären Endothel, insbesondere ist die Schnittstelle zwischen der Blutströmung und dem umgebenden Gewebe und somit eine kritische Rolle spielt Gefäß- und Organfunktion in Reaktion auf Reize wie hydrodynamischen Kräfte in Modulieren und zirkulierende Cytokine und Hormone 3 bis 5. Das Verständnis der detaillierten Wechselwirkungen zwischen dem Endothel, Blut, und das umgebende Gewebe Mikroumgebung ist für die Untersuchung der Gefäßbiologie und Fortschreiten der Krankheit wichtig. Allerdings sind die Fortschritte , diese Interaktionen in das Studium wurde durch in - vitro - Tools beschränkt behindert , die in vivo mikrovaskulären Struktur rekapitulieren nicht und Funktion 6,7. Als Ergebnis hat sich das Feld und therapeutischen Fortschritt stark auf kostspielige und zeit verlassenraubend Tiermodelle , die oft nicht zum Erfolg beim Menschen 8 zu übersetzen - 10. Während in vivo - Modellen bei der Untersuchung von Krankheitsmechanismen und vaskuläre Funktionen sind von unschätzbarem Wert, sind sie komplex und fehlt oft eine genaue Kontrolle der einzelnen zellulären, biochemischen und biophysikalischen Signale. Gefäßsystem im ganzen Körper verfügt über eine breite hierarchische Struktur in Verbindung mit expansive kapillaren Betten, optimierte Perfusion und Nährstofftransport gleichzeitig 11 bereitstellt. Zunächst Gefäßformen als primitive Plexus , die 12,13 während der frühen Entwicklung zu einem hierarchisch verzweigten Netzwerk reorganisiert. Obwohl viele der in diesen Prozessen beteiligt sind Signale gut 14 verstanden werden - 16, bleibt es schwer , wie solche Gefäßmuster 15 bestimmt wird. Im Gegenzug diesen Prozess in vitro zu rekapitulieren organisierten Gefäßnetze zu konstruieren hat Bienen schwierig. Viele existierende in vitro Plattformen Vaskulatur, wie zweidimensionale Endothelzellkulturen zu modellieren, fehlen wichtige Eigenschaften wie mehrzelligen Nähe dreidimensionale luminalen Geometrie, Durchfluss- und extrazellulären Matrix. Rohrbildungstests in 3D Hydrogele (Collagen oder Fibrin) 17-19 oder Invasionsassays 20,21 verwendet wurden 23 Endothelfunktion in 3D und ihre Wechselwirkungen mit anderen vaskulären 17,22 oder Gewebezelltypen zu untersuchen. Allerdings montiert Lumen in diesen Tests fehlt Verbunds, der hämodynamischen Strömungs und entsprechende Perfusion. Darüber hinaus verhindert die Neigung zur Gefäß Regression in diesen Rohrbildungstests 24 Langzeitkultur und Reifung , die den Grad der funktionellen Studien begrenzt, die durchgeführt werden können. Somit gibt es einen wachsenden Bedarf in vitro Plattformen der mikrovaskulären Netzwerke zu konstruieren , die in geeigneter Weise modellieren endothelial Eigenschaften und sind in der Lage Langzeitkultur. Eine Vielzahl von vaskulären Engineering-Techniken haben in den letzten Jahren für medizinische Anwendungen entstanden bei Patienten mit Gefäßerkrankung zu ersetzen oder zu umgehen betroffenen Schiffe. Mit großem Durchmesser Gefäße aus synthetischen Materialien, wie Polyethylenterephthalat (PET), und Polytetrafluorethylen (ePTFE) , haben erhebliche therapeutische Erfolge mit Langzeitdurchgängigkeit (durchschnittlich 95% Durchgängigkeit über 5 Jahre) 25 hatte. Obwohl mit kleinem Durchmesser synthetische Transplantate (&lt;6 mm) in der Regel Komplikationen konfrontiert wie Intimahyperplasie und Thrombopoese 26 - 28, Gewebe mit kleinem Durchmesser Transplantate mit biologischen Material entwickelt haben erhebliche Fortschritte gemacht 29,30. Trotz Fortschritten dieser Art entwickelt, Schiffe, die auf der Mikroskala haben eine Herausforderung geblieben. Um adäquat microvasculature zu modellieren, ist es notwendig, komplexe Netzwerkstrukturen mit suf zu erzeugenreichend mechanische Festigkeit Durchgängigkeit und mit einer Matrix-Zusammensetzung zu erhalten, die für die parenchymalen Zellen und Zellumbau für beide Nahrungsmittelpermeation ermöglicht. Dieses Protokoll stellt einen neuartigen künstlichen perfundierbaren Gefäßnetz , das eine native in vivo nachahmt mit einem abstimmbaren und steuerbaren Mikroumgebung schaffen 31-34. Das beschriebene Verfahren erzeugt Engineered microvessels mit einem Durchmesser in der Größenordnung von 100 &amp; mgr; m. Ausgeführt microvessels werden hergestellt durch Perfusion Endothelzellen durch einen mikrofluidischen Kanal, der in weichen Typ eingebettet ist I-Hydrogel-Kollagen. Dieses System hat die Fähigkeit, gemusterten Netzwerke mit offenen Struktur luminalen erzeugen, replizieren multi-zellulären Interaktionen modulieren extrazellulären Matrixzusammensetzung und gelten physiologisch relevanten hämodynamischen Kräften.

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			<td height="21" style="height:21px;width:459px;">Wafer Fabrication</td>
			<td style="width:225px;"></td>
			<td style="width:140px;"></td>
			<td style="width:540px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">AutoGlow Plasma System</td>
			<td>AutoGlow</td>
			<td></td>
			<td></td>
		</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

In - vitro - Plattformen Endothelzellen und Gefäßbiologie zu studieren , um 2D - endothelialen Zellkultur, Strömungskammern mit Polymer oder Glas basierenden Substraten und Hydrogel-basierte Rohrbildungstests weitgehend begrenzt sind. Diese Tests, während informativ, nicht rekapitulieren nicht Lumen Geometrie, richtige extrazellulären Matrix und mehrzelligen Nähe, die bei der Modulation der Gefäßfunktion eine Schlüsselrolle spielen. Dieses Manuskript beschreibt ein Spritzgussverfahren Engineered Gefäße mit einem Durchmesser in der Größenordnung von 100 &amp; mgr; m zu erzeugen. Microvessels werden durch Impfen Endothelzellen in einem mikrofluidischen Kanal innerhalb einer nativen Typ-I-Kollagen-Hydrogel eingebettet hergestellt. Durch die Integration von Bildung Parenchymzellen in der Kollagenmatrix vor dem Kanal können spezifische Gewebe-Mikroumgebungen modelliert und untersucht werden. Zusätzliche Modulationen der hydrodynamischen Eigenschaften und Medienzusammensetzung ermöglichen Steuerung von komplexen Gefäßfunktion innerhalb des gewünschten Mikro.Diese Plattform ermöglicht die Studie von perivaskulären Zellrekrutierung, Blut-Endothel-Interaktionen, Flussantwort und Gewebe-mikrovaskulären Wechselwirkungen. Ausgeführt microvessels bieten die Möglichkeit, den Einfluss von einzelnen Komponenten eines vaskulären Nische zu isolieren und zu steuern, genau seine chemischen, mechanischen und biologischen Eigenschaften der Gefäßbiologie sowohl in Gesundheit und Krankheit zu studieren.

Die konstruierte Schiff Plattform schafft funktionelle microvasculature in einem natürlichem Kollagen Typ I Matrix eingebettet und ermöglicht eine strenge Kontrolle der zellulären, biophysikalische und biochemische Umgebung in vitro. Engineered microvessels, humane Nabelschnurvenen-Endothelzellen (HUVECs) herzustellen sind durch die kollagen eingebettet mikrofluidischen Netzwerk durchbluteten, wo sie legen ein Patent Lumen und konfluenten Endothel zu bilden. Wie in 1A...

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

Micropatterning and Assembly of 3D Microvessels

Dieses Manuskript stellt ein Spritzgussverfahren microvessels zu entwickeln, die physiologischen Eigenschaften des Endothels rekapitulieren. Die Mikrofluidik-basierten Prozess erstellt Patent 3D Gefäßnetze mit tailor Bedingungen, wie Durchfluss, zelluläre Zusammensetzung, Geometrie und biochemische Steigungen. Das Herstellungsverfahren und Beispiele für mögliche Anwendungen beschrieben.

Mikrostrukturierung und Montage von 3D-Micro-Ader

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

Universidad de Cartagena UDEC

Research

JoVE Journal

Bioengineering

11.7K Aufrufe.  University of Washington.  Dieses Manuskript stellt ein Spritzgussverfahren microvessels zu entwickeln, die physiologischen Eigenschaften des Endothels rekapitulieren. Die Mikrofluidik-basierten Prozess erstellt Patent 3D Gefäßnetze mit tailor Bedingungen, wie Durchfluss, zelluläre Zusammensetzung, Geometrie und biochemische Steigungen. Das Herstellungsverfahren und Beispiele für mögliche Anwendungen beschrieben. 

Serie: 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.

ECM-Protein-Nanofasern und Nanostrukturen Engineered Mit Oberflächen initiierte Versammlung

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

Forschung

Biotechnik

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.

Herstellung von 3D-Kollagen-Gel und Mikrokanäle für das Studium der 3D-Interaktionen<em&gt; In 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.

Automatisierte Roboter Liquid Handling Versammlung Modular DNA-Geräte

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.

Synthese von kationisiertem Magnetoferritin für ultraschnelle Magnetisierungs von Zellen

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.

Zusammenbau und Verfolgung der mikrobiellen Gemeinschaftsentwicklung innerhalb einer Microwell Array Plattform

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 von Knorpel und Haut-Gewebe-Analoga nutzen eine neuartige Passive Einheit Mischtechnik für 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.

Herstellung von benutzerdefinierten Agarose Brunnen für die Aussaat von Zelle und Gewebe Ring Selbstmontage mit 3D-Druck Formen

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.

Montage und Charakterisierung der biomolekularen Memristors bestehend aus Ionenkanal-dotierte Lipidmembranen

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.

Protokolle des 3D-Bioprintings von Gelatine Methacryloyl Hydrogel-basierten Bioinks

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.

Temperaturgesteuerte Montage und Charakterisierung eines Droplet Interface Bilayers

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