Die Finanzierung für dieses Projekt wurde von der California Institute for Regenerative Medicine zur Verfügung gestellt.

1. Lentivirus production, harvest, and freezing
<ol>
	<li>Consult your institutional safety official before beginning this protocol, and follow their recommended safety guidelines.</li>
	<li>Day 1. Start with healthy, rapidly growing 293T cells to produce virus. Plate the cells at 5 x 106 
	cells per 10 cm plate. Use antibiotic-free 293T medium (high-glucose DMEM with 10% FBS and 4 mM L-glutamine) for virus production.</li>
	<li>Day 2. In the late afternoon, transfect 293T cells as follows (numbers given are for one 10 cm plate). 
	Let all reagents warm up to room temperature. Pipette 375 &mu;l OptiMEM into a microcentrifuge tube, then add 25 &mu;l 
	Fugene HD. Do not allow undiluted Fugene to contact the surface of the tube.</li>
	<li>In a microcentrifuge tube, mix:
		<ul>
			<li>5 &mu;g transfer plasmid (Slc7a1, target vector, or fluorescent control vector)</li>
			<li>3.75 &mu;g packaging plasmid (pCMV-dR8.91 or psPax2)</li>
			<li>1.25 &mu;g envelope plasmid (pMD2.G for pantropic, pHCMV-EcoEnv for ecotropic)</li>
			<li>serum-free OptiMEM to 100 &mu;l</li>
		</ul>
	</li>
	<li>Combine the two tubes and incubate the mixture 20-30 minutes at room temperature.</li>
	<li>Change the medium on the 293T cells to 10 ml fresh antibiotic-free 293T medium. Add the Fugene/plasmid mix 
	drop-wise to the plate and incubate overnight at 37&deg;C, 5% CO2.</li>
	<li>Day 3. Change medium on the 293T cells to 10 ml fresh antibiotic-free 293T medium. Be gentle, 
	because 293T cells adhere only loosely and can slough off by media pipetted too forcefully onto the 
	monolayer. Incubate for two days in a humidified incubator for virus production.</li>
	<li>Day 5. Harvest virus and filter with a 0.45 mm low protein binding filter. Use immediately or dispense 
	into single-use aliquots and freeze at -80&deg;C. Frozen pantropic and ecotropic virus should be re-titered after it has 
	been stored for six months and one month, respectively.</li>
	<li>Titer the virus as follows, using cells that are relatively amenable to transduction. Transduce cells with fluorescent control virus overnight using serial dilutions (e.g. 1:10, 1:100, 1:1000) in fresh medium with 6 &mu;g/ml PB. Change to fresh medium the next day. Allow the cells two days after transduction to begin expressing the fluorescent protein, then determine the fraction of transduced cells by FACS. Calculate the titer in transforming units (TU) per ml, based on dilutions that yield &lt; 15% transduction to minimize multiple transduction events. 
	<img src="/files/ftp_upload/2822/2822eq1.jpg" alt="Equation 1" />
	</li>
</ol>
2. Transduction of human target cells with murine retrovirus receptor Slc7a1
<ol>
	<li>Select a multiplicity of infection (MOI) = 2 to ensure that most cells will be transduced. For target cells that are resistant to transduction such as HDFs, a higher MOI will be required; we dilute the viral supernatant only 1:2 to achieve transduction of a majority of the cells.</li>
	<li>Transduce target cells overnight with viral supernatant diluted in fresh culture medium with 6 &mu;g/ml PB, which increases transduction by enhancing electrostatic interaction between the virus and target cell.1 Ideally one should use a minimal volume of virus, such as 1 ml for a 35 mm plate, because diffusion is a limiting factor in transduction efficiency. </li>
	<li>Culture cells for at least 48 hours after removing virus before transducing them with ecotropic virus, in order to ensure sufficient expression of the Slc7a1 receptor.</li>
	<li>(Optional) It is possible to use blasticidin to select for stably transduced cells expressing Slc7a1, if desired. A blasticidin kill curve should be generated in advance to determine the lowest effective concentration, generally between 2 &#x2013; 10 &mu;g/ml, that kills all untransduced target cells in 7 days. About 2 days after removing the Slc7a1 virus, switch the transduced cells to medium containing blasticidin. Culture the cells in blasticidin-containing medium for 7 days, at which point all remaining cells will stably express the retrovirus receptor at which point they can be transduced with ecotropic virus as well as banked for future use as a stable Slc7a1-expressing line.</li>
</ol>
3. Polymer complex titration to determine toxicity
<ol>
	<li>Day 1. Plate cells at 5000 cells/well in a 96-well plate, allowing at least triplicate wells for each experimental group. Include untransduced cells in complete medium to provide a baseline value for healthy cells, as well as samples consisting of cells in serum-free medium to induce growth arrest as a control. In parallel, plate cells in an appropriate format (such as a 24-well plate) for microscopic or FACS-based analysis of transduction efficiency in each experimental condition.</li>
	<li>Day 2. Transduce cells in plates set up for both the MTT and FACS analyses with virus encoding GFP, at an MOI of 0.5 to transduce ~40% of target cells. Test varied concentrations of CS/PB (e.g. 50, 100, 200, 400, 600, and 800 mg/ml of each component), as well as 6 &mu;g/ml PB, to determine optimal amounts. Generate polymer complexes as described in Part 4, below.</li>
	<li>Day 3. Remove virus-containing medium and replace with fresh medium. Return the plates to a humidified incubator.</li>
	<li>Day 5. Analyze FACS plate to determine the transduction efficiency with each polymer concentration. </li>
	<li>Day 6. Remove the medium from all wells of the MTT plate and replace with 100 &mu;l MTT solution (1 mg/ml MTT in complete medium). Culture for three hours in a humidified incubator to allow MTT to be reduced in the mitochondria of metabolically active cells.</li>
	<li>Remove MTT solution and replace with 200 ml MTT solvent (0.1 N HCl, 0.1% Igepal CA-630 in isopropanol). </li>
	<li>Incubate for two hours at room temperature or until all of the purple MTT formazan precipitate is dissolved. Read the absorbance on a microplate reader at 570 nm, subtracting the background reading at 690 nm. </li>
	<li>Select the optimal polymer concentration that produces maximum enhancement of transduction, as determined by FACS, with minimal effect on metabolic activity, as determined by MTT. For HDFs, we selected 100 &mu;g/ml CS/PB based on the data shown in the Representative Results, below.</li>
</ol>
4. Ecotropic transduction with polymer complexation
<ol>
	<li>Prepare sterile-filtered stock solutions of PB and chondroitin sulfate at 20 mg/ml in water. Aliquot and store at -20&deg;C.</li>
	<li>Pipette viral supernatant into a microcentrifuge tube and dilute to the desired final concentration (e.g. MOI of 2) with fresh culture medium. Add equal volumes of PB and chondroitin sulfate (concentrations determined in step 3 above) in succession, flicking the tube to mix after each addition. The viral mixture will immediately become cloudy as precipitates form. Incubate the viral mixture at room temperature for 5 minutes to allow complex formation.</li>
	<li>Remove media from the receptor-expressing target cells, replace with the viral mix, and incubate overnight at 37&deg;C, 5% CO2. After removing the viral mix, wash the surface of the cells twice with PBS to aid in removing viral complexes. Complete removal is not necessary; we have observed no adverse effects on cell health from residual polymer complexes.</li>
</ol>
5. Verifying specificity of ecotropic transduction
<ol>
	<li>When producing ecotropic virus for the first time, it is prudent from a safety perspective to verify that the virus is unable to transduce unmodified human cells. Transduce human cells with ecotropic lentivirus at relatively high concentration (only a 1 to 2-fold dilution of viral supernatant in fresh medium) overnight with 6 &mu;g/ml PB or optimized CS/PB concentration. </li>
	<li>Remove virus-containing medium and replace with fresh medium. After incubating cells for 2 days, validate transgene expression by FACS using fluorescent vectors and/or by RT-PCR with transgene-specific primers.</li>
</ol>
6. Representative results:
Fig. 1A shows the lentivirus production process, and Fig. 1B shows transduction of human cells with ecotropic lentivirus, including pre-transduction with murine retrovirus receptor Slc7a1. For titering virus, we use a human rhabdomyosarcoma cell line stably transduced with Slc7a1 (Slc-hRMS). When using fluorescent control vectors to monitor transduction efficiency, we routinely achieve > 90% transduction efficiency of Slc-hRMS with ecotropic virus, as shown in Fig. 2A and 2B. Transduction rates of HDFs are generally lower because the cells have not been blasticidin-selected for receptor expression (Fig. 2C). Titers of ecotropic lentivirus are generally 10-20% of VSV-pseudotyped virus when measured on Slc-hRMS (Fig. 2D).
One freeze-thaw cycle reduces titer of ecotropic virus by 16 - 3%, equal to titer loss during a single freeze-thaw cycle of VSV-pseudotyped virus (p > 0.05). Contrary to previous reports,2 we observe no positive effect on virus titer from flash freezing in dry ice. Rather, we achieve higher post-thaw titers of either pseudotype by simply placing tubes of virus into a -80&deg;C freezer (data not shown). 
The MTT viability assay allows sensitive detection of growth arrest in target cells. Transduction with virus plus concentrations of CS/PB up to 800 &mu;g/ml has no effect on HDF metabolism (Fig. 3A). Exposure to CS/PB without virus also has no toxic effect on cells (data not shown). FACS analysis of HDFs transduced with virus plus various concentrations of CS/PB shows enhancement of transduction compared to PB alone (Fig. 3B). The maximum enhancement occurs at 100 &mu;g/ml CS/PB (Fig. 3C), several-fold lower than previously reported values.3 Thus, it is important to optimize conditions for any given target cell type.
Complexation with CS/PB enhances the observed titer roughly 3-fold in Slc-hRMS (Fig. 4A, p &lt; 0.01). In practice, this yields a greater effect on transduction efficiency at low virus concentrations than at higher concentrations (Fig. 4B), which is most likely due to multiply transduced cells and receptor saturation at higher virus concentrations.
Transduction with ecotropic virus is specific for cells expressing murine retrovirus receptor. When transducing unmodified human cells with ecotropic virus, we have not observed fluorescence greater than the untransduced background whether using PB or CS/PB, as shown in Fig. 5A. Microscopically, HDFs show no transduction in the absence of receptor (Fig. 5B) while pre-transduction with receptor results in fluorescent cells (Fig. 5C).
<img src="/files/ftp_upload/2822/2822fig1.jpg" alt="Figure 1" /> 
Figure 1. Schematic view of (A) the virus production process and (B) transduction of human cells with murine retrovirus receptor followed by ecotropic lentivirus.
<img src="/files/ftp_upload/2822/2822fig2.jpg" alt="Figure 2" /> 
Figure 2. High-efficiency transduction of human cells with ecotropic lentivirus encoding GFP. Cells were pre-transduced with murine retrovirus receptor Slc7a1. (A) Human rhabdomyosarcoma cell line blasticidin-selected for Slc7a1 (Slc-hRMS), transduced (blue) or untransduced (pink) with GFP. (B) Fluorescent micrograph of ecotropic-transduced Slc-hRMS (4X). (C) HDFs transduced (blue) and untransduced (pink) with ecotropic GFP lentivirus; cells were transduced with Slc7a1 two days prior to ecotropic transduction. (D) Titer of VSV-G pseudotyped and ecotropic lentivirus, measured on Slc-hRMS.
<img src="/files/ftp_upload/2822/2822fig3.jpg" alt="Figure 3" /> 
Figure 3. Optimizing chondroitin sulfate/polybrene (CS/PB) concentrations in human dermal fibroblasts. (A) Viability of HDFs measured by MTT assay after transduction in the presence of PB only or with varied concentrations of CS/PB. (B) Enhancement of transduction efficiency in HDFs by different concentrations of CS/PB, measured by FACS. (C) Quantification of transduction enhancement, showing that maximum transduction occurs at 100 &mu;g/ml CS/PB.
<img src="/files/ftp_upload/2822/2822fig4.jpg" alt="Figure 4" /> 
Figure 4. Effect of 400 &mu;g/ml CS/PB on transduction of Slc-hRMS with ecotropic lentivirus. (A) Titer enhancement, and (B) fold change in transduction rate compared to 6 &mu;g/ml polybrene alone.
<img src="/files/ftp_upload/2822/2822fig5.jpg" alt="Figure 5" /> 
Figure 5. Lack of ecotropic transduction of HDFs in the absence of murine retrovirus receptor Slc7a1. (A) FACS plot of BJ human fibroblasts, untransduced (pink) or transduced (blue) with ecotropic GFP lentivirus in both cases in the absence of receptor Slc7a1. BJ human fibroblasts transduced with ecotropic GFP lentivirus, without (B) and with (C) pre-transduction with receptor Slc7a1 (4X).

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Rekombinante ecotropen gammaretrovirus auf Moloney Maus-Leukämie-Virus (MLV) und sein Rezeptor mSlc7a1 Basis sind gut untersucht und überall erhältlich, mit mehr als 20 Jahren verwendet worden, um Transgenen auf murine Zellen liefern. Ecotropen gammaretrovirus wurde auch in jüngerer Zeit, um Onkogene, menschliche Zellen zu liefern verwendet;. Im Rahmen der Reprogrammierung, die Verwendung von mSlc7a1 zu Generation amphotropen Virus beherbergen menschlichen Onkogene zu vermeiden, ist gut etabliert 4,5 Allerdings sieht Lentivirus erhebliche Vorteile gegenüber gammaretrovirus in transduzierenden feuerfesten Zellpopulationen, 6 einschließlich Primärzellen, die oft wünschenswert, Ziele für die Neuprogrammierung, weil die lentiviralen Präintegrationskomplexes ermöglicht Transduktion von nicht-teilenden Zellen. 7 Lentiviren haben mit Dutzenden von verschiedenen Pseudotypen, einschließlich MLV, in dem Bemühen, Virus Tropismus, Toxizität und andere Eigenschaften. 8 MLV-pseudotypisiert ecotropen Lentivirus wurde verwendet, um Zellen der Maus, 9 transduzieren, hat aber nur selten auf menschliche Zellen verwendet worden verändern produziert . 10 Wir schlagen daher die Verwendung von MLV-pseudotypisiert ecotropen Lentivirus als eine sichere, kostengünstige und hocheffiziente Fahrzeug bekannter oder vermuteter Onkogene, einschließlich der Reprogrammierung Faktoren, die menschliche Zellen zu liefern. Es ist wichtig zu beachten, dass dieses Protokoll nicht vollständig beseitigen die Notwendigkeit zu produzieren und zu nutzen pantropic Lentivirus, sondern trennt dieses Protokoll das Onkogen (s) aus dem pantropic Virus, isolierende Forscher vor möglichen Selbst-Impfung mit dem Krebs-verwandten Viren. Das Protein mSlc7a1 und seine menschliche Homolog hSlc7a1 sind ubiquitär Aminosäure-Transporter ohne bekannte Tumorigenität oder Fähigkeit, ein selektives Wachstum Vorteil Empfänger-Zellen übertragen, 11 machen mSlc7a1 von relativ geringem Risiko für den Einbau in amphotrope Virus exprimiert. Dieser zusätzliche Schritt kann besonders nützlich in Labors fehlen gewidmet Virus oder Gewebekultur Einrichtungen der erforderlichen Sicherheitsstufe. In manchen Situationen kann es möglich sein, vollständig zu eliminieren die Verwendung von pantropic Virus durch Transfektion der Slc7a1 Plasmid direkt in Zielzellen, jedoch sind viele Zellen, die nützliche Ziele dieser Technik werden auch feuerfeste der Transfektion. Als Alternative, die Fähigkeit zu isolieren Slc7a1-transduzierten Zellen durch Blasticidin Auswahl bedeutet, dass VSV-G pseudotypisiert Lentivirus einmal verwendet werden kann, um einen Bestand von Rezeptor-exprimierenden Zellen, nach denen ecotropen Virus routinemäßig eingesetzt werden können, um diese Zellen für viele transduzieren generieren Experimente. Forscher sollten immer nach ihrer institutionellen Sicherheit Richtlinien für die Arbeit mit einem Lentivirus, unabhängig von ihrer Tropismus. Titer ecotropen Virus mit diesem Protokoll erreicht werden moderat niedriger als VSV-pseudotypisiert Virus, in der Regel 10-20% des pantropic Virustiter, in Übereinstimmung mit früheren Studien. 9 Diese Titer in menschlichen Zellen wurden gemessen stabil transduzierten mit Slc7a1, so dass die unteren beobachtet Titer für ecotropen Virus kann teilweise durch vielseitige Ausdruck der Rezeptor-Gen in die Zielzellen. Dennoch sind die viralen Titer in unserem Protokoll erreicht mehr als ausreichend für die meisten Anwendungen und führen zu Transduktion der Mehrzahl der Zellen, in einigen Fällen&gt; 90% der Zellen. Centrifugation-basierte Techniken werden häufig verwendet, um virale Partikel zu konzentrieren. Allerdings erfordert Zentrifugation mehrere Stunden, erzeugt infektiöse Aerosole, und kann zu einem erheblichen Verlust der viralen Partikel führen. 12 Als Alternative Komplexierung mit CS / PB kann zur Transduktion ohne dass virale Tropismus zu verbessern. 3 Diese Methode ist schnell (5 Minuten ) und preisgünstig ($ 0,03 pro 10 ml-Virus), während etwa einer Verdreifachung der beobachteten Titer. Keine besondere Ausrüstung oder proprietären Reagenzien erforderlich sind, und wir beobachteten minimal akuten Toxizität nach der Exposition des HDF zu CS / PB, in Übereinstimmung mit früheren Arbeiten in anderen Zelllinien. 13 Ein potenzieller Nachteil dieses Protokolls ist, dass einige mikroskopisch sichtbare Polymer-Komplexe zu halten die Zellen für mehrere Tage in Kultur. Wir können nicht ausschließen, dass diese Komplexe, die zwar nicht offen toxisch auf die Zellen, können subtilere Effekte auf zellulärer Prozesse haben. Hier haben wir eine Methodik zur sicheren und effizienten Transduktion humaner Zellen mit onkogenen Faktoren beschrieben. Dieser Ansatz sollte von großem Nutzen für Forscher studieren Onkogene und Stammzellbiologie einschließlich iPS-Zellen sein.

<table border="1"><tbody><tr><th> Name des Reagenzes </th><th> Firma </th><th> Katalog-Nummer </th><th> Kommentare </th></tr><tr><td> pLenti6/UbC/mSlc7a1 </td><td> Addgene </td><td> 17224 </td><td> Murine MLV-Rezeptor </td></tr><tr><td> pMD2.G </td><td> Addgene </td><td> 12259 </td><td> VSV-G Umschlag </td></tr><tr><td> pCMV-dR8.91 </td><td> D. Trono Labor 14 </td><td></td><td> Packaging-Plasmid (entspricht Plasmid psPax2 ist ab Addgene, Cat. Anzahl 12260) </td></tr><tr><td> pHCMV-EcoEnv </td><td> Addgene </td><td> 15802 </td><td> Ecotropen Umschlag </td></tr><tr><td> FUGW </td><td> Addgene </td><td> 14883 </td><td> GFP Kontroll-Plasmid </td></tr><tr><td> OptiMEM </td><td> Invitrogen </td><td> 31985 </td><td></td></tr><tr><td> Fugene HD </td><td> Roche </td><td> 04 709 705 001 </td><td></td></tr><tr><td> Hexadimethrinbromid (Polybrene) </td><td> Sigma-Aldrich </td><td> H9268 </td><td></td></tr><tr><td> Chondroitinsulfat Natriumsalz aus Haifischknorpel </td><td> Sigma-Aldrich </td><td> C4384 </td><td></td></tr><tr><td> Blasticidin S </td><td> Fischer </td><td> BP 2647100 </td><td></td></tr><tr><td> Methylthiazolyldiphenyl-Tetrazolium Bromid (MTT) </td><td> Sigma-Aldrich </td><td> M2128 </td><td></td></tr><tr><td> Igepal CA-630 </td><td> Sigma-Aldrich </td><td> I3021 </td><td></td></tr></tbody></table>

transduction of human cells with polymer-complexed ecotropic lentivirus for enhanced biosafety

Stamm-und Tumor-Zellbiologie Studien erfordern häufig virale Transduktion humaner Zellen mit bekannter oder vermuteter Onkogene, Erhöhung wichtigen Fragen der Sicherheit für das Laborpersonal. Pantropic Lentiviren, wie die häufig verwendeten VSV-G Pseudotyp, sind ein wertvolles Werkzeug zur Untersuchung der Genfunktion, weil sie vielen Zelltypen, einschließlich nicht-teilenden Zellen transduzieren. Allerdings können Forscher wollen Produktions-und Zentrifugation pantropic Viren kodieren Onkogene durch höhere Sicherheitsstufe Umgang mit Anforderungen und Fragen der Sicherheit zu vermeiden. Mehrere starke Onkogene, einschließlich c-Myc und SV40 large T-Antigen, sind bekannt, die Produktion von induzierten pluripotenten Stammzellen (IPSC) zu verbessern. Alle anderen bekannten iPSC-induzierenden genetischen Veränderungen (Oct4, Sox2, Klf4, NANOG, LIN28 und p53 Verlust der Funktion) auch Links zu Krebs, so dass sie relativ hoher Sicherheit betreffen, sowie. Während diese im Zusammenhang mit Krebs Viren nützlich beim Studium der Reprogrammierung und Pluripotenz sind, müssen sie sicher verwendet werden. Um diese Fragen der biologischen Sicherheit, zeigen wir eine Methode zur Transduktion humaner Zellen mit ecotropen Lentivirus, mit zusätzlichem Schwerpunkt auf reduzierte Kosten und eine bequeme Handhabung. Wir haben ecotropen Lentivirus mit einer ausreichend hohen Titer produziert, um mehr als 90% der transduzieren-Rezeptor-exprimierenden menschlichen Zellen mit dem Virus, der Validierung der Wirksamkeit dieses Ansatzes. Lentivirus ist oft durch Ultrazentrifugation konzentriert, allerdings dauert dieser Vorgang mehrere Stunden und kann Aerosole Infektionskrankheiten des Menschen biomedizinische Forscher produzieren. Als Alternative, virale Partikel können mehr sicher auf Zellen werden durch Komplexierung mit Chondroitinsulfat und Polybren (CS / PB) sedimentiert. Diese Technik erhöht die funktionelle virale Titer von bis zu 3-fach in den Zellen stabil exprimieren Mäuse-Retrovirus-Rezeptor, mit vernachlässigbaren zusätzlichen Zeit-und Kosten. Transduktion von humanen dermalen Fibroblasten (HDF) ist maximal erweitert mit CS / PB-Konzentrationen etwa 4-fach niedriger als der optimale Wert zuvor für Krebszelllinien gemeldet, was darauf hindeutet, dass Polymer-Konzentration für die Zielzelle Art der Verzinsung sollte titriert werden. Deshalb beschreiben die Verwendung von methylthiazolyldiphenyl-Tetrazolium Bromid (MTT) zum Testen auf Polymer-Toxizität in einem neuen Zelltyp. Wir beobachten, entspricht Lebensfähigkeit der HDF nach einer viralen Transduktion entweder mit Polymer-Komplexierung oder der Standard-Dosierung von Polybren (PB, 6 pg / ml), was darauf hinweist minimal akute Toxizität. In diesem Protokoll, beschreiben wir die Verwendung von ecotropen Lentivirus für die Überexpression von Onkogenen in menschlichen Zellen, wodurch die biologische Sicherheit Risiken und die Erhöhung der Transduktion Rate. Wir zeigen auch die Verwendung von Polymer-Komplexierung Transduktion zu verbessern und gleichzeitig die Vermeidung aerosolbildende Zentrifugation von Viruspartikeln.

Watch this Scientific Journal Video about Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety at JoVE.com

Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety

Lentiviren sind eine wertvolle Recherche-Tool für die Erkundung der Genfunktion, aber Forscher möge Produktion von pantropic Lentivirus Kodierung bekannten oder vermuteten Onkogene zu vermeiden. Als Alternative stellen wir ein sicheres Protokoll für die Verwendung von ecotropen Lentivirus auf menschliche Zellen geändert, um die ecotropen Rezeptor mSlc7a1 auszudrücken.

Transduktion humaner Zellen mit Polymer-Komplex ecotropen Lentivirus für Enhanced Biosafety

Stem and tumor cell biology studies often require viral transduction of human cells with known or suspected oncogenes, raising major safety issues for ...

transduction-human-cells-with-polymer-complexed-ecotropic-lentivirus

Research

JoVE Journal

Biology

15.1K Aufrufe.  University of California, Davis. Lentiviren sind eine wertvolle Recherche-Tool für die Erkundung der Genfunktion, aber Forscher möge Produktion von pantropic Lentivirus Kodierung bekannten oder vermuteten Onkogene zu vermeiden. Als Alternative stellen wir ein sicheres Protokoll für die Verwendung von ecotropen Lentivirus auf menschliche Zellen geändert, um die ecotropen Rezeptor mSlc7a1 auszudrücken.

Serie: Transduction of Human Cells with Polymer-complexed Ecotropic Lentivirus for Enhanced Biosafety

Propagation of Human Embryonic Stem (ES) Cells

Propagation of Human Embryonic Stem ES Cells

Yeah, so I'm Lauren Deon. I'm in charge of the Human Amgen stem cell co facility at MGH. Yeah, so I'm Lauren, I'm in charge of the Human AM stem cell co facility at MGH.So I've been working with human Amgen stem cells for years now since I was a postdoc in George De Lab before, from four, four years. And so right now we have two cell lines, H one and H nine, which are both from Y cell. And so the way we are expanding or maintaining these cells in culture is by, at least the way we are splitting these cells is by using collagenous.So what I usually do is for the first few passage after throwing the cells, I use a technical, the picking colonies. So in this case, I can check under the microscope which colonies are good and differentiate and nice shape, and I will collect only these colonies and I will cut them in few pieces and put them back in, in a fresh flat. And the, the colonies that look kind of differentiate it are just left them alone.The other way to pass the cells is by using trypsin. So I don't use this technique here. I think collagenase is a little bit safer because human being stem cells don't like to be individualized or they don't like to be alone.So if you do trypsin, if you use trypsin for a little bit too long, if you use it for like three to four minutes, which is the way we use strips in for other type of cells, human stem cells will be individualized and most of them will die or just differentiate or will not attach to the myth. So the idea is you have to keep the cells as clumps. You don't want them to be alone in the in, in the flask.So using collagenase, the advantage is to keep cells as plants. Using chipsy, you just select for cells that will survive this very, very harsh process of g opsonization. So these cells are usually very highly proliferative.So you get, you can adapt your cells to this tripsin process. The problem is that you have cells that they behave differently, they go much faster. And one risk is that you can get some commercial abnormality to, to this, to this very high division process.So you say that ization can cause selection of cells in culture for most proliferative cells.Right. More ative and probably also higher survival rates than other cells. So after proliferation, basically culture after proliferation in tripsin, after several passages become a different culture, these different properties.So it's, it's hard to figure out if they are exactly identical. If you do the test, the usual test, let's say you check markers, regular markers of end differentiated cells like OC four, nano one 60 SC four C, C3, all this molecule might still be expressed. If you do TER formation, this cells might still differentiate and be formed like al like normal cells.If you look at the karyotype, you might have some abnormality, but you might still have a normal karyotype. The, the, the selective advantage might be due to just a mutation that you cannot see by doing a karyotype. So the fact that they grow much faster is by itself I think a little bit worser.And if we want to use these cells for transplantation at some point, I would definitely not use this type of cells.Okay. So would you like to tell me what are the main technical problems with using this technique for, for passages of cells? So using S, yes.It's just a little bit longer and also it's, since the cells are not going as fast, it's just much longer to get a high number of cells to do some experiment. So it's just less convenient I would say. Would you like to tell me about few words about the goals of your experiment?How do you use CS cells? Okay, so my main project here is to get endothelial cells from human AB stem cells. And the idea is to be able to make blood.And we are working a lot with tissue bioengineering labs and one of their goal is to make tissue in vitro. But one of the limitation to this is the lack of blood vessels going through this tissues. So if we can bring endothelial cells or put endothelial cells in this tissue, we would have better growth of this tissue.So the idea few sources of cells are known for endothelial cells like cold blood or pressure blood, but it would be interesting to have another source of cells like human years. And the advantage is since human years can be expanded and most infinitely, you could modify these cells, make some inducible system and be able to use it. Then in your final product, your material cells, in this case.

Vermehrung von humanen embryonalen Stammzellen (ES-Zellen)

Forschung

Biologie

Detection of Protein Ubiquitination

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of three enzymes. They include ubiquitin-activating enzyme E1, ubiquitin-conjugating enzyme E2, and ubiquitin ligase E3. Unlike to E1 and E2, E3 ubiquitin ligases display substrate specificity. On the other hand, numerous deubiquitylating enzymes have roles in processing polyubiquitinated proteins. Ubiquitination can result in change of protein stability, cellular localization, and biological activity. Mutations of genes involved in the ubiquitination/deubiquitination pathway or altered ubiquitin system function are associated with many different human diseases such as various types of cancer, neurodegeneration, and metabolic disorders. The detection of altered or normal ubiquitination of target proteins may provide a better understanding on the pathogenesis of these diseases. &nbsp;Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro. These protocols are also useful to detect other ubiquitin-like small molecule modification such as sumolyation and neddylation.

Ubiquitination is a key posttranslational modification carried out by a set of three enzymes. Mutations of genes involved in this modification are associated with many different human diseases. Here, we describe protocols to detect protein ubiquitination in cultured cells in vivo and test tubes in vitro.

Detektion von Protein Ubiquitination

Ubiquitination, the covalent attachment of the polypeptide ubiquitin to target proteins, is a key posttranslational modification carried out by a set of ...

Generation of Induced Pluripotent Stem Cells by Reprogramming Mouse Embryonic Fibroblasts with a Four Transcription Factor, Doxycycline Inducible Lentiviral Transduction System

Using a defined set of transcription factors and cell culture conditions, Yamanaka and colleagues demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc, and Klf4 is capable of inducing pluripotency in mouse fibroblasts.1 Subsequent reports have demonstrated the utility of the doxycycline (DOX) inducible lentiviral delivery system for the generation of both primary and secondary iPS cells from a variety of other adult mouse somatic cell types.2,3
Induced pluripotent stem (iPS) cells are similar to embryonic stem (ES) cells in morphology, proliferation and ability to induce teratoma formation. Both types of cell can be used as the pluripotent starting material for the generation of differentiated cells or tissues in regenerative medicine.4-6 iPS cells also have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction.
Here we demonstrate the protocol for reprogramming mouse embryonic fibroblast (MEF) cells with the Stemgent DOX Inducible Mouse TF Lentivirus Set. We also demonstrate that the Stemgent DOX Inducible Mouse TF Lentivirus Set is capable of expressing each of the four transcription factors upon transduction into MEFs thereby inducing a pluripotent stem cell state that displays the pluripotency markers characteristic of ES cells.

The Stemgent Dox Inducible Mouse TF Lentivirus Set can reprogram mouse embryonic fibroblasts (MEFs) to induced pluripotent stem (iPS) cells. Here we demonstrate the protocol for DOX-inducible expression of mouse reprogramming transcription factors Oct4, Sox2, Klf4 and c-Myc to generate iPS colonies that express common mES pluripotency markers.

Erzeugung von induzierten pluripotenten Stammzellen durch Reprogrammierung embryonalen Maus-Fibroblasten mit einem Vier Transcription Factor, induzierbare Doxycycline Lentivirale Transduktionssystems

Using a defined set of transcription factors and cell culture conditions, Yamanaka and colleagues demonstrated that retrovirus-mediated delivery and ...

Lentivirus Production

RNA interference (RNAi) is a system of gene silencing in living cells. In RNAi, genes homologous in sequence to short interfering RNAs (siRNA) are silenced at the post-transcriptional state. Short hairpin RNAs, precursors to siRNA, can be expressed using lentivirus, allowing for RNAi in a variety of cell types. Lentiviruses, such as the Human Immunodeficiency Virus, are capable to infecting both dividing and non-dividing cells. We will describe a procedure which to package lentiviruses. Packaging refers to the preparation of competent virus from DNA vectors. Lentiviral vector production systems are based on a 'split' system, where the natural viral genome has been split into individual helper plasmid constructs. This splitting of the different viral elements into four separate vectors diminishes the risk of creating a replication-capable virus by adventitious recombination of the lentiviral genome. Here, a vector containing the shRNA of interest and three packaging vectors (p-VSVG, pRSV, pMDL) are transiently transfected into human 293 cells. After at least a 48-hour incubation period, the virus containing supernatant is harvested and concentrated. Finally, virus titer is determined by reporter (fluorescent) expression with a flow cytometer.

To make lentiviruses, DNA vectors are transfected into human 293 cells. After harvest and concentrating the supernatant, virus titer is determined by fluorescence expression with a flow cytometer.

Lentivirus Produktion

RNA interference (RNAi) is a system of gene silencing in living cells. In RNAi, genes homologous in sequence to short interfering RNAs (siRNA) are ...

Generation of Induced Pluripotent Stem Cells by Reprogramming Human Fibroblasts with the Stemgent Human TF Lentivirus Set

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing the pluripotent state in mouse fibroblasts.1 The same group also reported the successful reprogramming of human somatic cells into induced pluripotent stem (iPS) cells using human versions of the same transcription factors delivered by retroviral vectors.2 Additionally, James Thomson et al. reported that the lentivirus-mediated co-expression of another set of factors (Oct4, Sox2, Nanog and Lin28) was capable of reprogramming human somatic cells into iPS cells.3
iPS cells are similar to ES cells in morphology, proliferation and the ability to differentiate into all tissue types of the body. Human iPS cells have a distinct advantage over ES cells as they exhibit key properties of ES cells without the ethical dilemma of embryo destruction. The generation of patient-specific iPS cells circumvents an important roadblock to personalized regenerative medicine therapies by eliminating the potential for immune rejection of non-autologous transplanted cells.
Here we demonstrate the protocol for reprogramming human fibroblast cells using the Stemgent Human TF Lentivirus Set. We also show that cells reprogrammed with this set begin to show iPS morphology four days post-transduction. Using the Stemolecule Y27632, we selected for iPS cells and observed correct morphology after three sequential rounds of colony picking and passaging. We also demonstrate that after reprogramming cells displayed the pluripotency marker AP, surface markers TRA-1-81, TRA-1-60, SSEA-4, and SSEA-3, and nuclear markers Oct4, Sox2 and Nanog.

We demonstrate the protocol for the generation of induced pluripotent stem cells from human somatic cells using lentivirus-mediated delivery of the human factors Oct4, Sox2, Nanog, and Lin28. Pluripotency was confirmed by morphology and the presence of embryonic stem (ES) cell-specific markers.

Erzeugung von induzierten pluripotenten Stammzellen durch Reprogrammierung menschlichen Fibroblasten mit dem Stemgent Menschliche TF Lentivirus Set

In 2006, Yamanaka and colleagues first demonstrated that retrovirus-mediated delivery and expression of Oct4, Sox2, c-Myc and Klf4 is capable of inducing ...

Differentiation of Embryonic Stem Cells into Oligodendrocyte Precursors

Oligodendrocytes are the myelinating cells of the central nervous system. For regenerative cell therapy in demyelinating diseases, there is significant interest in deriving a pure population of lineage-committed oligodendrocyte precursor cells (OPCs) for transplantation. OPCs are characterized by the activity of the transcription factor Olig2 and surface expression of a proteoglycan NG2. Using the GFP-Olig2 (G-Olig2) mouse embryonic stem cell (mESC) reporter line, we optimized conditions for the differentiation of mESCs into GFP+Olig2+NG2+ OPCs. In our protocol, we first describe the generation of embryoid bodies (EBs) from mESCs. Second, we describe treatment of mESC-derived EBs with small molecules: (1) retinoic acid (RA) and (2) a sonic hedgehog (Shh) agonist purmorphamine (Pur) under defined culture conditions to direct EB differentiation into the oligodendroglial lineage. By this approach, OPCs can be obtained with high efficiency (&gt;80%) in a time period of 30 days. Cells derived from mESCs in this protocol are phenotypically similar to OPCs derived from primary tissue culture. The mESC-derived OPCs do not show the spiking property described for a subpopulation of brain OPCs in situ. To study this electrophysiological property, we describe the generation of spiking mESC-derived OPCs by ectopically expressing NaV1.2 subunit. The spiking and nonspiking cells obtained from this protocol will help advance functional studies on the two subpopulations of OPCs.

We describe a small molecule-based protocol for differentiation of mouse embryonic stem cells into oligodendrocyte precursor cells (OPCs). This protocol generates Olig2+NG2+ OPCs with high efficiency by 30 days of differentiation. We also describe a method to generate "spiking" OPCs that can fire action potentials.

Differenzierung von embryonalen Stammzellen in Oligodendrozyten Precursors

Oligodendrocytes are the myelinating cells of the central nervous system. For regenerative cell therapy in demyelinating diseases, there is significant ...

Proteomic Sample Preparation from Formalin Fixed and Paraffin Embedded Tissue

Preserved clinical material is a unique source for proteomic investigation of human disorders. Here we describe an optimized protocol allowing large scale quantitative analysis of formalin fixed and paraffin embedded (FFPE) tissue. The procedure comprises four distinct steps. The first one is the preparation of sections from the FFPE material and microdissection of cells of interest. In the second step the isolated cells are lysed and processed using 'filter aided sample preparation' (FASP) technique. In this step, proteins are depleted from reagents used for the sample lysis and are digested in two-steps using endoproteinase LysC and trypsin. 
After each digestion, the peptides are collected in separate fractions and their content is determined using a highly sensitive fluorescence measurement. Finally, the peptides are fractionated on 'pipette-tip' microcolumns. The LysC-peptides are separated into 4 fractions whereas the tryptic peptides are separated into 2 fractions. In this way prepared samples allow analysis of proteomes from minute amounts of material to a depth of 10,000 proteins. Thus, the described workflow is a powerful technique for studying diseases in a system-wide-fashion as well as for identification of potential biomarkers and drug targets.

Archival formalin fixed and paraffin embedded (FFPE) clinical samples are valuable material for investigation of diseases. Here we demonstrate a sample preparation workflow allowing in-depth proteomic analysis of microdissected FFPE tissue.

Proteomik Probenvorbereitung von Formalin fixiert und in Paraffin eingebetteten Gewebe

Preserved clinical material is a unique source for proteomic investigation of human disorders. Here we describe an optimized protocol allowing large scale ...

Efficient Production and Purification of Recombinant Murine Kindlin-3 from Insect Cells for Biophysical Studies

Kindlins are essential coactivators, with talin, of the cell surface receptors&#160;integrins and also participate in integrin outside-in signalling, and the control of gene transcription in the cell nucleus. The kindlins are ~75 kDa multidomain proteins and bind to an NPxY motif and upstream T/S cluster of the integrin &#946;-subunit cytoplasmic tail. The hematopoietically-important kindlin isoform, kindlin-3, is critical for platelet aggregation during thrombus formation, leukocyte rolling in response to infection and inflammation and osteoclast podocyte formation in bone resorption. Kindlin-3&#39;s role in these processes has resulted in extensive cellular and physiological studies. However, there is a need for an efficient method of acquiring high quality milligram quantities of the protein for further studies. We have developed a protocol, here described, for the efficient expression and purification of recombinant murine kindlin-3 by use of a baculovirus-driven expression system in Sf9 cells yielding sufficient amounts of high purity full-length protein to allow its biophysical characterization. The same approach could be taken in the study of the other mammalian kindlin isoforms.

Kindlins are fundamental to cell adhesion through integrins but studies of them have been hampered by the difficulty encountered in expressing them recombinantly in bacterial hosts. We describe here methods for their efficient production in baculovirus-infected insect cells.

Effizienten Herstellung und Reinigung von rekombinantem murinem Kindlin-3 von Insektenzellen für biophysikalische Studien

Kindlins are essential coactivators, with talin, of the cell surface receptors&#160;integrins and also participate in integrin outside-in signalling, and ...

Efficient Generation Human Induced Pluripotent Stem Cells from Human Somatic Cells with Sendai-virus

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs include modeling pathogenesis of human genetic diseases, autologous cell therapy after gene correction, and personalized drug screening by providing a source of patient-specific and symptom relevant cells. However, there are several hurdles to overcome, such as eliminating the remaining reprogramming factor transgene expression after human iPSCs production. More importantly, residual transgene expression in undifferentiated human iPSCs could hamper proper differentiations and misguide the interpretation of disease-relevant in vitro phenotypes. With this reason, integration-free and/or transgene-free human iPSCs have been developed using several methods, such as adenovirus, the piggyBac system, minicircle vector, episomal vectors, direct protein delivery and synthesized mRNA. However, efficiency of reprogramming using integration-free methods is quite low in most cases.
Here, we present a method to isolate human iPSCs by using Sendai-virus (RNA virus) based reprogramming system. This reprogramming method shows consistent results and high efficiency in cost-effective manner.

Here, we present our established method to reprogram human somatic cells into transgene-free human iPSCs with Sendai virus, which shows consistent outcome and enhanced efficiency.

Effiziente Erzeugung Menschen induzierten pluripotenten Stammzellen aus menschlichen Körperzellen mit Sendai-Virus

A few years ago, the establishment of human induced pluripotent stem cells (iPSCs) ushered in a new era in biomedicine. Potential uses of human iPSCs ...

Zinc-finger Nuclease Enhanced Gene Targeting in Human Embryonic Stem Cells

One major limitation with current human embryonic stem cell (ESC) differentiation protocols is the generation of heterogeneous cell populations.&#160;These cultures contain the cells of interest, but are also contaminated with undifferentiated ESCs, non-neural derivatives and other neuronal subtypes.&#160; This limits their use in in vitro and in vivo applications, such as in vitro modeling for drug discovery or cell replacement therapy. To help overcome this, reporter cell lines, which offer a means to visualize, track and isolate cells of interest, can be engineered.&#160;However, to achieve this in human embryonic stem cells via conventional homologous recombination is extremely inefficient.&#160;This protocol describes targeting of the Pituitary homeobox 3 (PITX3) locus in human embryonic stem cells using custom designed zinc-finger nucleases, which introduce site-specific double-strand DNA breaks, together with a PITX3-EGFP-specific DNA donor vector. Following the generation of the PITX3 reporter cell line, it can then be differentiated using published protocols for use in studies such as in vitro Parkinson&#8217;s disease modeling or cell replacement therapy.

Reporter cell lines offer a means to visualize, track and isolate cells of interest from heterogeneous populations.&#160;However, gene-targeting using conventional homologous recombination in human embryonic stem cells is extremely inefficient. Herein, we describe targeting CNS midbrain specific transcription factor PITX3 locus with EGFP using zinc-finger nuclease enhanced homologous recombination.