Name: lentiviral mediated delivery of shrnas to hescs and npcs using low-cost cationic polymer polyethylenimine (pei)
Uploaded: 2022-05-24T15:00:00
Description: Watch this Scientific Journal Video about Lentiviral Mediated Delivery of shRNAs to hESCs and NPCs Using Low-cost Cationic Polymer Polyethylenimine PEI at JoVE.com

This work was supported by research grants from the United Arab Emirates University (UAEU), grant # 31R170 (Zayed Center for Health Sciences) and # 12R010 (UAEU-AUA grant). We thank Prof Randall Morse (Wadsworth Center, Albany, NY) for helping us to edit the manuscript for style and grammar.
All data are available upon request.

1. Transfection of HEK293T cells using either PEI or Lipofectamine 3000 reagent
<ol>
	<li>Culture HEK293T cells in DMEM + 10% FBS + 1x penicillin/streptomycin at 37 &#176;C in a humidified incubator with an atmosphere of 5% CO2 and 21% O2 until they are 90% confluent before seeding for transfection. Use a relatively low passage number of cells for high titer virus production (ideally less than P30).</li>
	<li>Seed 4 x 106 cells in 10 mL of complete growth medium in a 10...

<ol>
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D., Huang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonviral+is+superior+to+viral+gene+delivery.">Nonviral is superior to viral gene delivery.</a> Journal of Controlled Release. 123 (3), 181-183 (2007).</li><li>Mastrobattista, E., Bravo, S. A., vander Aa, M., Crommelin, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonviral+gene+delivery+systems:+From+simple+transfection+agents+to+artificial+viruses.">Nonviral gene delivery systems: From simple transfection agents to artificial viruses.</a> Drug Discovery Today. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-level+sustained+transgene+expression+in+human+embryonic+stem+cells+using+lentiviral+vectors.">High-level sustained transgene expression in human embryonic stem cells using lentiviral vectors.</a> Stem Cells. 21 (1), 111-117 (2003).</li><li>Gropp, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stable+genetic+modification+of+human+embryonic+stem+cells+by+lentiviral+vectors.">Stable genetic modification of human embryonic stem cells by lentiviral vectors.</a> Molecular Therapy. 7 (2), 281-287 (2003).</li><li>Tan, E., Chin, C. S. H., Lim, Z. F. S., Ng, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HEK293+cell+line+as+a+platform+to+produce+recombinant+proteins+and+viral+vectors.">HEK293 cell line as a platform to produce recombinant proteins and viral vectors.</a> Frontiers in Bioengineering and Biotechnology. 9, 796991 (2021).</li><li>Merten, O. W., Hebben, M., Bovolenta, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+lentiviral+vectors.">Production of lentiviral vectors.</a> Molecular Therapy: Methods &amp; Clinical Development. 3, 16017 (2016).</li><li>Lungwitz, U., Breunig, M., Blunk, T., G&#246;pferich, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polyethylenimine-based+nonviral+gene+delivery+systems.">Polyethylenimine-based nonviral gene delivery systems.</a> European Journal of Pharmaceutics and Biopharmaceutics. 60 (2), 247-266 (2005).</li><li>Parween, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Higher+O-GlcNAc+levels+are+associated+with+defects+in+progenitor+proliferation+and+premature+neuronal+differentiation+during+in-vitro+human+embryonic+cortical+neurogenesis.">Higher O-GlcNAc levels are associated with defects in progenitor proliferation and premature neuronal differentiation during in-vitro human embryonic cortical neurogenesis.</a> Frontiers in Cellular Neuroscience. 11, 415 (2017).</li><li>Weissinger, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+transfer+in+purified+human+hematopoietic+peripheral-blood+stem+cells+by+means+of+electroporation+without+prestimulation.">Gene transfer in purified human hematopoietic peripheral-blood stem cells by means of electroporation without prestimulation.</a> Journal of Laboratory and Clinical Medicine. 141 (2), 138-149 (2003).</li><li>Cui, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeting+transgene+expression+to+antigen-presenting+cells+derived+from+lentivirus-transduced+engrafting+human+hematopoietic+stem/progenitor+cells.">Targeting transgene expression to antigen-presenting cells derived from lentivirus-transduced engrafting human hematopoietic stem/progenitor cells.</a> Blood. 99 (2), 399-408 (2002).</li><li>Yu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Lentiviral+vectors+with+two+independent+internal+promoters+transfer+high-level+expression+of+multiple+transgenes+to+human+hematopoietic+stem-progenitor+cells.">Lentiviral vectors with two independent internal promoters transfer high-level expression of multiple transgenes to human hematopoietic stem-progenitor cells.</a> Molecular Therapy. 7 (6), 827-838 (2003).</li><li>Sweeney, N. P., Vink, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+impact+of+lentiviral+vector+genome+size+and+producer+cell+genomic+to+gag-pol+mRNA+ratios+on+packaging+efficiency+and+titre.">The impact of lentiviral vector genome size and producer cell genomic to gag-pol mRNA ratios on packaging efficiency and titre.</a> Molecular Therapy - Methods &amp; Clinical Development. 21, 574-584 (2021).</li></ol>

The ability to genetically modify stem cells for study or clinical purposes is limited both by technology and the basic understanding of the biology of hESCs. Techniques that have shown significant potential in mouse ESCs, like lipofection and electroporation, are not highly efficient for hESCs, which are notoriously difficult for gene delivery by conventional methods20. This notion has led to not only the optimization of existing techniques but also the development of novel methods for increased ...

Human embryonic stem cells (hESCs) derived from the blastocyst inner cell mass are pluripotent and can be differentiated into different cell types depending upon external factors under in vitro conditions1,2. In order to fully harness the potential of hESCs, it is imperative to have rapid and reliable gene delivery methods for these cells. Conventionally, the techniques used can be broadly classified into two types: nonviral and viral gene delivery systems3,4. The more frequently used nonviral gene delivery systems are lipofection, electroporation, and nucleofection. Nonviral delivery systems are advantageous because of fewer insertion mutations and an overall decrease in immunogenicity5,6. However, these methods result in low transfection efficiency and a short duration of transient gene expression, which is a major limitation for long-term differentiation studies7. Electroporation results in better transfection efficiencies compared to lipofection; however, it results in more than 50% cell death8,9,10. Using nucleofection, the cell survival and transfection efficiency can be improved by combining lipofection and electroporation, but the approach needs cell-specific buffers and specialized equipment and, thus, becomes quite costly for scaled-up applications11,12.
In contrast, viral vectors have shown improved transfection efficiencies, as well as overall low cytotoxicity, following transduction. In addition, the genes delivered are stably expressed and, hence, make this method ideal for long-term studies13. Among the most commonly used viral vectors for gene delivery into hESCs are lentiviral vectors (LVS), which can give more than 80% transduction efficiency using high titer viral particles14,15. Lipofection and CaPO4 precipitation are amongst the most commonly used methods to transiently transfect HEK293T cells or its derivatives with gene transfer vectors along with packaging plasmids to yield lentiviral particles16. Although lipofection results in good transfection efficiency and low cytotoxicity, the technique is hampered by its cost, and scaling up to get high titer lentiviral particles would be very costly. CaPO4 precipitation results in relatively similar transfection efficiencies to those obtained using lipofection. Although cost-effective, CaPO4 precipitation results in significant cell death following transfections, which makes it difficult to standardize and to avoid batch-to-batch variations17. In this scenario, developing a method that gives high transfection efficiency, low cytotoxicity, and cost-effectiveness is crucial for the production of high titer lentiviral particles to be used in hESCs.
Polyethylenimine (PEI) is a cationic polymer that can transfect HEK293T cells at high efficiency without much cytotoxicity and has a negligible cost compared to lipofection-based methods18. In this situation, PEI can be used for scaled-up applications of high titer LVS production through the concentration of lentiviral particles from culture supernatants using various techniques. The presented article describes the use of PEI to transfect HEK293T cells and lentiviral vector concentration using ultracentrifugation through a sucrose cushion. Using this method, we regularly obtain titers well above 5 x 107 IU/mL with low batch-to-batch variations. The method is simple, straight-forward, and cost-effective for scaled-up applications for gene delivery to hESCs and hESCs-derived cells.

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			<td>2-Mercaptoethanol</td>
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			<td>38.5 mL, Sterile + Certified Free Open-Top Thinwall Ultra-Clear Tubes</td>
			<td>Beckman Coulter</td>
			<td>C14292</td>
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			<td>Accutase</td>
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			<td>7920</td>
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			<td>bFGF Recombinant human</td>
			<td>Invitrogen</td>
			<td>PHG0261</td>
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			<td>Bovine serum albumin FRAC V</td>
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			<td>Corning Matrigel Basement Membrane Matrix, LDEV-free</td>
			<td>Corning</td>
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			<td>Stem Cell Technologies</td>
			<td>72074</td>
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			<td>DMEM media</td>
			<td>Invitrogen</td>
			<td>11995073</td>
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			<td>DMEM Nutrient mix F12&#160;</td>
			<td>Invitrogen</td>
			<td>11320033</td>
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			<td>DPBS w/o: Ca and Mg</td>
			<td>PAN Biotech</td>
			<td>P04-36500</td>
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			<td>Fetal bovie serum</td>
			<td>Invitrogen</td>
			<td>10270106</td>
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			<td>GAPDH (14C10) Rabbit mAb Antibody</td>
			<td>CST</td>
			<td>2118S</td>
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			<td>Gentle Cell Dissociation Reagent</td>
			<td>Stem Cell Technologies</td>
			<td>7174</td>
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			<td>HyClone Non Essential Amino Acids (NEAA) 100X Solution</td>
			<td>GE healthcare</td>
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			<td>L Glutamine, 100X&#160;</td>
			<td>Invitrogen</td>
			<td>2924190090</td>
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			<td>L2HGDH Polyclonal antibody</td>
			<td>Proteintech</td>
			<td>15707-1-AP</td>
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			<td>L2HGDH shRNA</td>
			<td>Macrogen</td>
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			<td>Seq: CGCATTCTTCATGTGAGAAAT</td>
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			<td>Lipofectamine 3000 kit</td>
			<td>Thermo Fisher</td>
			<td>L3000001</td>
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			<td>mTesR1 complete media</td>
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			<td>85850</td>
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			<td>Neurobasal medium 1X CTS</td>
			<td>Invitrogen</td>
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			<td>Neuropan 2 Supplement 100x</td>
			<td>PAN Biotech</td>
			<td>P07-11050</td>
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			<td>Neuropan 27 Supplement 50x</td>
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			<td>P07-07200</td>
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			<td>Penicillin streptomycin SOL</td>
			<td>Invitrogen</td>
			<td>15140122</td>
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			<td>pLKO.1 TRC vector</td>
			<td>Addgene</td>
			<td>10878</td>
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			<td>pLL3.7 vector&#160;</td>
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			<td>Addgene</td>
			<td>12259</td>
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			<td>Polybrene infection reagent</td>
			<td>Sigma</td>
			<td>TR1003- G</td>
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			<td>Polyethylenimine, branched</td>
			<td>Sigma</td>
			<td>408727</td>
			<td></td>
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			<td>psPAX2.0</td>
			<td>Addgene</td>
			<td>12260</td>
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			<td>Purmorphamine</td>
			<td>Tocris</td>
			<td>4551/10</td>
			<td></td>
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			<td>Puromycin</td>
			<td>Invitrogen</td>
			<td>A1113802</td>
			<td></td>
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		<tr>
			<td>ROCK inhibitor Y-27632 
			dihydrochloride&#160;</td>
			<td>Tocris</td>
			<td>1254</td>
			<td></td>
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		<tr>
			<td>SB 431542</td>
			<td>Tocris</td>
			<td>1614/10</td>
			<td></td>
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			<td>Trypsin .05% EDTA&#160;</td>
			<td>Invitrogen</td>
			<td>25300062</td>
			<td></td>
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			<td>XAV 939</td>
			<td>Tocris</td>
			<td>3748/10</td>
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lentiviral mediated delivery of shrnas to hescs and npcs using low-cost cationic polymer polyethylenimine (pei)

The current protocol describes the use of lentiviral particles for the delivery of short hairpin RNAs (shRNAs) to both human embryonic stem cells (hESCs) as well as neural progenitor cells (NPCs) derived from hESCs at high efficiency. Lentiviral particles were generated by co-transfecting HEK293T cells using entry vectors (carrying shRNAs) along with packaging plasmids (pAX and pMD2.G) using the low-cost cationic polymer polyethylenimine (PEI). Viral particles were concentrated using ultracentrifugation, which resulted in average titers above 5 x 107. Both hESCs and NPCs could be infected at high efficiencies using these lentiviral particles, as shown by puromycin selection and stable expression in hESCs, as well as transient GFP expression in NPCs. Furthermore, western blot analysis showed a significant reduction in the expression of genes targeted by shRNAs. In addition, the cells retained their pluripotency as well as differentiation potential, as evidenced by their subsequent differentiation into different lineages of CNS. The current protocol deals with the delivery of shRNAs; however, the same approach could be used for the ectopic expression of cDNAs for overexpression studies.

Following gene transfer, high viability of hESCs is inevitably required. Despite the efforts and optimization of protocols to reduce cell death following electroporation of hESCs, more than 50% cell death is still observed after electroporation of these cells, along with low transfection efficiency20. Lentiviral mediated gene transfer not only results in high efficiency of gene transfer but also demonstrates high levels of cell viability following transduction. The results below present two approa...

Watch this Scientific Journal Video about Lentiviral Mediated Delivery of shRNAs to hESCs and NPCs Using Low-cost Cationic Polymer Polyethylenimine PEI at JoVE.com

Lentiviral Mediated Delivery of shRNAs to hESCs and NPCs Using Low-cost Cationic Polymer Polyethylenimine PEI

Using the low-cost cationic polymer polyethylenimine (PEI), we produced lentiviral particles for stable expression of shRNAs in H9 human embryonic stem cells (hESCs) and transiently transduced H9-derived neural progenitor cells (NPCs) at high efficiency.

Lentiviral Mediated Delivery of shRNAs to hESCs and NPCs Using Low-cost Cationic Polymer Polyethylenimine (PEI)

The current protocol describes the use of lentiviral particles for the delivery of short hairpin RNAs (shRNAs) to both human embryonic stem cells (hESCs) ...

Transfection of HEK293T cells must be performed at 90%confluency. Also, the use of a 0.45-micron low protein binding filter for lentiviral vector filtration and the use of a sucrose cushion for ultracentrifugation are essential. Begin by culturing HEK293T cells in DMEM medium containing 10%FBS and 1X penicillin streptomycin at 37 degrees Celsius in a humidified incubator with an atmosphere of 5%carbon dioxide and 21%oxygen until cells reach 90%confluency before seeding for transfection.Seed four times 10 to the six cells in 10 milliliters of complete growth medium in a 100-millimeter tissue culture plate and grow overnight in a humidified tissue culture incubator with an atmosphere of 5%carbon dioxide and 21%oxygen. For each transfection, dilute one milligram per milliliter of plasmid DNA stocks in one milliliter of serum-free DMEM media in 1.5-milliliter centrifuge tubes by following the ratio of entry and packaging plasmids as described in the text manuscript. Vortex the tube for 10 seconds and spin at 10, 000 times G for 30 seconds at room temperature to collect.Then, add 70 microliters of one milligram per milliliter stock solution of polymer polyethyleneimine, or PEI, to the tube. Again, vortex and briefly spin the tube. For lipofectamine-based transection, dilute the vectors in 500 microliters of serum-free DMEM media containing 45 microliters of reagent P supplied in the kit.Then, dilute 70 microliters of reagent L using 500 microliters of the same medium. Incubate both the tubes at room temperature for five minutes. Then, combine the contents of both tubes and incubate at room temperature for 20 minutes to allow complex formation.Next, add drop-wise one milliliter of DNA PEI or DNA lipofectamine complexes to the plate containing cells and incubate for six hours at 37 degrees Celsius with an atmosphere of 5%carbon dioxide and 21%oxygen. After incubation, replace the media with 10 milliliters of fresh complete growth media and return the plate to the incubator. After two days of transfection, collect the virus-containing media and overlay the cells with 10 milliliters of fresh complete growth media.Again, after three days of transfection, collect the virus-containing media and combine it with the media collected at the two-day time point. Centrifuge the viral supernatant at 2, 000 times G for 10 minutes at four degree Celsius to pellet cellular debris. Filter the supernatant using a 0.45-micron pore size low protein binding filter and store at four degrees Celsius until ready for ultracentrifugation.Sterilize the ultracentrifuge tubes'holding cups by washing with 70%ethanol for 10 minutes. Air dry, close, and place the cups at four degree Celsius. Add 36 milliliters at filtered media containing lentiviral particles to a sterile ultracentrifuge tube.Fill five milliliters of a sterile stripette with four milliliters of sterile 20%sucrose solution prepared in PBS and dispense it to the bottom of the tube containing lentiviral vectors, or LVS. Ensure that the sucrose solution should not be mixed with the media and makes a gradient at the bottom of the tube. Balance all the ultracentrifuge tubes using serum-free DMEM media, place the tubes in cold ultracentrifuge tube holding cups, and close the lids.Spin the tubes at 125, 000 times G for two hours at four degrees Celsius. After the spin, carefully discard the supernatant by inverting the contents of the tube in a container containing bleach without disturbing the pellet. Mark the pellet if visible.Place the ultracentrifuge tube in a 50-milliliter sterile tube and add 200 microliters of sterile DPBS at the top of the pellet. Place the tube at four degrees Celsius overnight. The following day, gently mix the content of a tube by pipetting up and down before spinning at 13, 000 times G in a tabletop centrifuge to pellet any debris.Transfer the supernatant to a new tube and aliquot the virus preparation. Finally, store the tubes at minus 80 degrees Celsius. After transfection, abundant GFP expression was observed in HEK293T cells.The expression of viral proteins resulted in syncytia formation of HEK293T cells where single cells are fused. Following infection, marked expression of GFP was also observed in viral-infected neural progenitor cells. LVS titer measurement between the low-cost PEI and lipofectamine 3000 reagent did not show any significant difference in viral titer.The viral titers for PLK 0.1-based vectors are shown here. Lentiviral transfected cells showed more than 80%cell viability as compared to non-transduced cells, while no cells survived the treatment. Western blot analysis showed abundant expression of L-2-hydroxyglutarate dehydrogenase in cells transduced with an empty vector backbone.However, no expression was observed in cells transduced with a vector carrying short hairpin RNAs. The main advantage of this technique is the use of low-cost cationic polymer polyethyleneimine to produce lentiviral particles by co-transfecting HEK293T cells using entry and packaging vectors.

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Research

JoVE Journal

Biology

From MEFs to Matrigel I: Passaging hESCs in the Presence of MEFs

This video demonstrates how to grow human embryonic stem cells (hESCs) on mouse embryonic fibroblast (MEF) feeder cells.


This video demonstrates how to grow human embryonic stem cells (hESCs) on mouse embryonic fibroblast (MEF) feeder cells. Part 1 of 3.

This video demonstrates how to grow human embryonic stem cells (hESCs) on mouse embryonic fibroblast (MEF) feeder cells.
...

From MEFs to Matrigel 2: Splitting hESCs from MEFs onto Matrigel

This video demonstrates how to grow human embryonic stem cells (hESCs) on mouse embryonic fibroblast (MEF) feeder cells, how to passage hESCs from MEF plates to feeder cell-free Matrigel plates.


This video demonstrates how to maintain the growth of human embryonic stem cells (hESCs) in feeder cell-free conditions and how to continuously passage hESCs in feeder cell-free conditions. Confirmation of hESC pluripotency grown in feeder cell-free conditions by immunofluorescence microscopy is also demonstrated. Part 2 of 3.

This video demonstrates how to grow human embryonic stem cells (hESCs) on mouse embryonic fibroblast (MEF) feeder cells, how to passage hESCs from MEF ...

From MEFs to Matrigel 3: Passaging hESCs from Matrigel onto Matrigel

This video demonstrates how to maintain the growth of human embryonic stem cells (hESCs) in feeder cell-free conditions and how to continuously passage hESCs in feeder cell-free conditions. Confirmation of hESC pluripotency grown in feeder cell-free conditions by immunofluorescence microscopy is also demonstrated.

This video demonstrates how to maintain the growth of human embryonic stem cells (hESCs) in feeder cell-free conditions and how to continuously passage hESCs in feeder cell-free conditions. Confirmation of hESC pluripotency grown in feeder cell-free conditions by immunofluorescence microscopy is also demonstrated. Part 3 of 3.

This video demonstrates how to maintain the growth of human embryonic stem cells (hESCs) in feeder cell-free conditions and how to continuously passage ...

Lentiviral-mediated Knockdown During Ex Vivo Erythropoiesis of Human Hematopoietic Stem Cells

Erythropoiesis is a commonly used model system to study cell differentiation. During erythropoiesis, pluripotent adult human hematopoietic stem cells (HSCs) differentiate into oligopotent progenitors, committed precursors and mature red blood cells 1. This process is regulated for a large part at the level of gene expression, whereby specific transcription factors activate lineage-specific genes while concomitantly repressing genes that are specific to other cell types 2. Studies on transcription factors regulating erythropoiesis are often performed using human and murine cell lines that represent, to some extent, erythroid cells at given stages of differentiation 3-5. However transformed cell lines can only partially mimic erythroid cells and most importantly they do not allow one to comprehensibly study the dynamic changes that occur as cells progress through many stages towards their final erythroid fate. Therefore, a current challenge remains the development of a protocol to obtain relatively homogenous populations of primary HSCs and erythroid cells at various stages of differentiation in quantities that are sufficient to perform genomics and proteomics experiments.
Here we describe an ex vivo cell culture protocol to induce erythroid differentiation from human hematopoietic stem/progenitor cells that have been isolated from either cord blood, bone marrow, or adult peripheral blood mobilized with G-CSF (leukapheresis). This culture system, initially developed by the Douay laboratory 6, uses cytokines and co-culture on mesenchymal cells to mimic the bone marrow microenvironment. Using this ex vivo differentiation protocol, we observe a strong amplification of erythroid progenitors, an induction of differentiation exclusively towards the erythroid lineage and a complete maturation to the stage of enucleated red blood cells. Thus, this system provides an opportunity to study the molecular mechanism of transcriptional regulation as hematopoietic stem cells progress along the erythroid lineage. 
Studying erythropoiesis at the transcriptional level also requires the ability to over-express or knockdown specific factors in primary erythroid cells. For this purpose, we use a lentivirus-mediated gene delivery system that allows for the efficient infection of both dividing and non-dividing cells 7. Here we show that we are able to efficiently knockdown the transcription factor TAL1 in primary human erythroid cells. In addition, GFP expression demonstrates an efficiency of lentiviral infection close to 90%. Thus, our protocol provides a highly useful system for characterization of the regulatory network of transcription factors that control erythropoiesis.

Lentiviral-mediated Knockdown During Ex Vivo Erythropoiesis of Human Hematopoietic Stem Cells

An ex vivo protocol to generate mature human red blood cells from hematopoietic stem/progenitors is described. Additionally we describe an efficient lentiviral-delivery method to knockdown the transcription factor TAL1 in primary erythroid cells. The efficiency of lentivirus mediated gene delivery is demonstrated using GFP expressing viruses.

Erythropoiesis is a commonly used model system to study cell differentiation. During erythropoiesis, pluripotent adult human hematopoietic stem cells ...

Generation of Human Induced Pluripotent Stem Cells from Peripheral Blood Using the STEMCCA Lentiviral Vector

Through the ectopic expression of four transcription factors, Oct4, Klf4, Sox2 and cMyc, human somatic cells can be converted to a pluripotent state, generating so-called induced pluripotent stem cells (iPSCs)1-4. Patient-specific iPSCs lack the ethical concerns that surround embryonic stem cells (ESCs) and would bypass possible immune rejection. Thus, iPSCs have attracted considerable attention for disease modeling studies, the screening of pharmacological compounds, and regenerative therapies5.
We have shown the generation of transgene-free human iPSCs from patients with different lung diseases using a single excisable polycistronic lentiviral Stem Cell Cassette (STEMCCA) encoding the Yamanaka factors6. These iPSC lines were generated from skin fibroblasts, the most common cell type used for reprogramming. Normally, obtaining fibroblasts requires a skin punch biopsy followed by expansion of the cells in culture for a few passages. Importantly, a number of groups have reported the reprogramming of human peripheral blood cells into iPSCs7-9. In one study, a Tet inducible version of the STEMCCA vector was employed9, which required the blood cells to be simultaneously infected with a constitutively active lentivirus encoding the reverse tetracycline transactivator. In contrast to fibroblasts, peripheral blood cells can be collected via minimally invasive procedures, greatly reducing the discomfort and distress of the patient. A simple and effective protocol for reprogramming blood cells using a constitutive single excisable vector may accelerate the application of iPSC technology by making it accessible to a broader research community. Furthermore, reprogramming of peripheral blood cells allows for the generation of iPSCs from individuals in which skin biopsies should be avoided (i.e. aberrant scarring) or due to pre-existing disease conditions preventing access to punch biopsies.
Here we demonstrate a protocol for the generation of human iPSCs from peripheral blood mononuclear cells (PBMCs) using a single floxed-excisable lentiviral vector constitutively expressing the 4 factors. Freshly collected or thawed PBMCs are expanded for 9 days as described10,11 in medium containing ascorbic acid, SCF, IGF-1, IL-3 and EPO before being transduced with the STEMCCA lentivirus. Cells are then plated onto MEFs and ESC-like colonies can be visualized two weeks after infection. Finally, selected clones are expanded and tested for the expression of the pluripotency markers SSEA-4, Tra-1-60 and Tra-1-81. This protocol is simple, robust and highly consistent, providing a reliable methodology for the generation of human iPSCs from readily accessible 4 ml of blood.

Here we show a simple and effective protocol for the generation of human iPSCs from 3-4 ml of peripheral blood using a single lentiviral reprogramming vector. Reprogramming of readily available blood cells promises to accelerate the utilization of iPSC technology by making it accessible to a broader research community.

Through the ectopic expression of four transcription factors, Oct4, Klf4, Sox2 and cMyc, human somatic cells can be converted to a pluripotent state, ...

Long-term Silencing of Intersectin-1s in Mouse Lungs by Repeated Delivery of a Specific siRNA via Cationic Liposomes. Evaluation of Knockdown Effects by Electron Microscopy

Previous studies showed that knockdown of ITSN-1s (KDITSN), an endocytic protein involved in regulating lung vascular permeability and endothelial cells (ECs) survival, induced apoptotic cell death, a major obstacle in developing a cell culture system with prolonged ITSN-1s inhibition1. Using cationic liposomes as carriers, we explored the silencing of ITSN-1s gene in mouse lungs by systemic administration of siRNA targeting ITSN-1 gene (siRNAITSN). Cationic liposomes offer several advantages for siRNA delivery: safe with repeated dosing, nonimmunogenic, nontoxic, and easy to produce2. Liposomes performance and biological activity depend on their size, charge, lipid composition, stability, dose and route of administration3Here, efficient and specific KDITSN in mouse lungs has been obtained using a cholesterol and dimethyl dioctadecyl ammonium bromide combination. Intravenous delivery of siRNAITSN/cationic liposome complexes transiently knocked down ITSN-1s protein and mRNA in mouse lungs at day 3, which recovered after additional 3 days. Taking advantage of the cationic liposomes as a repeatable safe carrier, the study extended for 24 days. Thus, retro-orbital treatment with freshly generated complexes was administered every 3rd day, inducing sustained KDITSN throughout the study4. Mouse tissues collected at several time points post-siRNAITSN were subjected to electron microscopy (EM) analyses to evaluate the effects of chronic KDITSN, in lung endothelium. High-resolution EM imaging allowed us to evaluate the morphological changes caused by KDITSN in the lung vascular bed (i.e. disruption of the endothelial barrier, decreased number of caveolae and upregulation of alternative transport pathways), characteristics non-detectable by light microscopy. Overall these findings established an important role of ITSN-1s in the ECs function and lung homeostasis, while illustrating the effectiveness of siRNA-liposomes delivery in vivo.

Repeated retro-orbital injections of cationic liposomes/siRNA/ITSN-1s complexes in mice, every 72 hours for 24 days, efficiently deliver the siRNA duplex to the mouse lung microvasculature reducing ITSN-1s mRNA and protein expression by 75%. This technique is highly reproducible in an animal model, has no adverse effects and avoids fatalities.

Previous  studies showed that knockdown of ITSN-1s (KDITSN), an endocytic  protein involved in regulating lung vascular permeability and endothelial cells ...

Using Coculture to Detect Chemically Mediated Interspecies Interactions

In nature, bacteria rarely exist in isolation; they are instead surrounded by a diverse array of other microorganisms that alter the local environment by secreting metabolites. These metabolites have the potential to modulate the physiology and differentiation of their microbial neighbors and are likely important factors in the establishment and maintenance of complex microbial communities. We have developed a fluorescence-based coculture screen to identify such chemically mediated microbial interactions. The screen involves combining a fluorescent transcriptional reporter strain with environmental microbes on solid media and allowing the colonies to grow in coculture. The fluorescent transcriptional reporter is designed so that the chosen bacterial strain fluoresces when it is expressing a particular phenotype of interest (i.e. biofilm formation, sporulation, virulence factor production, etc.) Screening is performed under growth conditions where this phenotype is not expressed (and therefore the reporter strain is typically nonfluorescent). When an environmental microbe secretes a metabolite that activates this phenotype, it diffuses through the agar and activates the fluorescent reporter construct. This allows the inducing-metabolite-producing microbe to be detected: they are the nonfluorescent colonies most proximal to the fluorescent colonies. Thus, this screen allows the identification of environmental microbes that produce diffusible metabolites that activate a particular physiological response in a reporter strain. This publication discusses how to: a) select appropriate coculture screening conditions, b) prepare the reporter and environmental microbes for screening, c) perform the coculture screen, d) isolate putative inducing organisms, and e) confirm their activity in a secondary screen. We developed this method to screen for soil organisms that activate biofilm matrix-production in Bacillus subtilis; however, we also discuss considerations for applying this approach to other genetically tractable bacteria.

Bacteria produce secreted compounds that have the potential to affect the physiology of their microbial neighbors. Here we describe a coculture screen that allows detection of such chemically mediated interspecies interactions by mixing soil microbes with fluorescent transcriptional reporter strains of Bacillus subtilis on solid media.

In nature, bacteria rarely exist in isolation; they are instead surrounded by a diverse array of other microorganisms that alter the local environment by ...

Generation of Myospheres From hESCs by Epigenetic Reprogramming

Generation of a homogeneous and abundant population of skeletal muscle cells from human embryonic stem cells (hESCs) is a requirement for cell-based therapies and for a "disease in a dish" model of human neuromuscular diseases. Major hurdles, such as low abundance and heterogeneity of the population of interest, as well as a lack of protocols for the formation of three-dimensional contractile structures, have limited the applications of stem cells for neuromuscular disorders. We have designed a protocol that overcomes these limits by ectopic introduction of defined factors in hESCs - the muscle determination factor MyoD and SWI/SNF chromatin remodeling complex component BAF60C - that are able to reprogram hESCs into skeletal muscle cells. Here we describe the protocol established to generate hESC-derived myoblasts and promote their clustering into tridimensional miniaturized structures (myospheres) that functionally mimic miniaturized skeletal muscles7.

Here, we describe a protocol based on epigenetic reprogramming of human embryonic stem cells (hESCs) toward generating a homogeneous population of skeletal muscle progenitors that under permissive culture conditions form three-dimensional clusters of contractile myofibers (myospheres), which recapitulate biological features of human skeletal muscles.

Generation of a homogeneous and abundant population of skeletal muscle cells from human embryonic stem cells (hESCs) is a requirement for cell-based ...

Live Cell Imaging of Primary Rat Neonatal Cardiomyocytes Following Adenoviral and Lentiviral Transduction Using Confocal Spinning Disk Microscopy

Primary rat neonatal cardiomyocytes are useful in basic in vitro cardiovascular research because they can be easily isolated in large numbers in a single procedure. Due to advances in microscope technology it is relatively easy to capture live cell images for the purpose of investigating cellular events in real time with minimal concern regarding phototoxicity to the cells. This protocol describes how to take live cell timelapse images of primary rat neonatal cardiomyocytes using a confocal spinning disk microscope following lentiviral and adenoviral transduction to modulate properties of the cell. The application of two different types of viruses makes it easier to achieve an appropriate transduction rate and expression levels for two different genes. Well focused live cell images can be obtained using the microscope&#8217;s autofocus system, which maintains stable focus for long time periods. Applying this method, the functions of exogenously engineered proteins expressed in cultured primary cells can be analyzed. Additionally, this system can be used to examine the functions of genes through the use of siRNAs as well as of chemical modulators.

This protocol describes a method of live cell imaging using primary rat neonatal cardiomyocytes following lentiviral and adenoviral transduction using confocal spinning disk microscopy. This enables detailed observations of cellular processes in living cardiomyocytes.

Primary rat neonatal cardiomyocytes are useful in basic in vitro cardiovascular research because they can be easily isolated in large numbers in a single ...

A Protocol for Lentiviral Transduction and Downstream Analysis of Intestinal Organoids

Intestinal crypt-villus structures termed organoids, can be kept in sustained culture three dimensionally when supplemented with the appropriate growth factors. Since organoids are highly similar to the original tissue in terms of homeostatic stem cell differentiation, cell polarity and presence of all terminally differentiated cell types known to the adult intestinal epithelium, they serve as an essential resource in experimental research on the epithelium. The possibility to express transgenes or interfering RNA using lentiviral or retroviral vectors in organoids has increased opportunities for functional analysis of the intestinal epithelium and intestinal stem cells, surpassing traditional mouse transgenics in speed and cost. In the current video protocol we show how to utilize transduction of small intestinal organoids with lentiviral vectors illustrated by use of doxycylin inducible transgenes, or IPTG inducible short hairpin RNA for overexpression or gene knockdown. Furthermore, considering organoid culture yields minute cell counts that may even be reduced by experimental treatment, we explain how to process organoids for downstream analysis aimed at quantitative RT-PCR, RNA-microarray and immunohistochemistry. Techniques that enable transgene expression and gene knock down in intestinal organoids contribute to the research potential that these intestinal epithelial structures hold, establishing organoid culture as a new standard in cell culture.

In this video protocol we give a step by step explanation of lentiviral transduction in organoids of primary intestinal epithelium and of processing and downstream analysis of these cultures by quantitative RT-PCR, RNA-microarray and immunohistochemistry.

Intestinal crypt-villus structures termed organoids, can be kept in sustained culture three dimensionally when supplemented with the appropriate growth ...