This work was supported through grants from K12CA090628 (SSK), the National Comprehensive Cancer Network (SSK), the Mayo Clinic Center for Individualized Medicine (SSK), the Predolin Foundation (SSK), the Mayo Clinic Office of Translation to Practice (SSK), and the Mayo Clinic Medical Scientist Training Program Robert L. Howell Physician-Scientist Scholarship (RMS).

This protocol follows the guidelines of Mayo Clinic&#39;s Institutional Review Board (IRB) and Institutional Biosafety Committee (IBC).
1. CART19 cell production
<ol>
	<li>T cell isolation, stimulation, and ex-vivo culture
	<ol>
		<li>Carry out all cell culture work in a cell culture hood utilizing appropriate personal protective equipment. Harvest peripheral blood mononuclear cells (PBMCs) from de-identified normal donor blood cones collected during apheresis as these are known to be a viab...

<ol>
	<li>Kenderian, S. S., Ruella, M., Gill, S., Kalos, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chimeric+antigen+receptor+T-cell+therapy+to+target+hematologic+malignancies.">Chimeric antigen receptor T-cell therapy to target hematologic malignancies.</a> Cancer Research. 74 (22), 6383-6389 (2014).</li><li>Lim, W. A., June, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Principles+of+Engineering+Immune+Cells+to+Treat+Cancer.">The Principles of Engineering Immune Cells to Treat Cancer.</a> Cell. 168 (4), 724-740 (2017).</li><li>Neelapu, S. 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=Axicabtagene+Ciloleucel+CAR+T-Cell+Therapy+in+Refractory+Large+B-Cell+Lymphoma.">Axicabtagene Ciloleucel CAR T-Cell Therapy in Refractory Large B-Cell Lymphoma.</a> The New England Journal of Medicine. 377 (26), 2531-2544 (2017).</li><li>Maude, S. L., 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=Tisagenlecleucel+in+Children+and+Young+Adults+with+B-Cell+Lymphoblastic+Leukemia.">Tisagenlecleucel in Children and Young Adults with B-Cell Lymphoblastic Leukemia.</a> The New England Journal of Medicine. 378 (5), 439-448 (2018).</li><li>Schuster, S. J., 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=Chimeric+Antigen+Receptor+T+Cells+in+Refractory+B-Cell+Lymphomas.">Chimeric Antigen Receptor T Cells in Refractory B-Cell Lymphomas.</a> The New England Journal of Medicine. 377 (26), 2545-2554 (2017).</li><li>Grupp, S. A., 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=Chimeric+antigen+receptor-modified+T+cells+for+acute+lymphoid+leukemia.">Chimeric antigen receptor-modified T cells for acute lymphoid leukemia.</a> The New England Journal of Medicine. 368 (16), 1509-1518 (2013).</li><li>Porter, D. L., Levine, B. L., Kalos, M., Bagg, A., June, C. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chimeric+antigen+receptor-modified+T+cells+in+chronic+lymphoid+leukemia.">Chimeric antigen receptor-modified T cells in chronic lymphoid leukemia.</a> The New England Journal of Medicine. 365 (8), 725-733 (2011).</li><li>Gust, J., 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=Endothelial+Activation+and+Blood-Brain+Barrier+Disruption+in+Neurotoxicity+after+Adoptive+Immunotherapy+with+CD19+CAR-T+Cells.">Endothelial Activation and Blood-Brain Barrier Disruption in Neurotoxicity after Adoptive Immunotherapy with CD19 CAR-T Cells.</a> Cancer Discovery. 7 (12), 1404-1419 (2017).</li><li>Fitzgerald, J. C., 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=Cytokine+Release+Syndrome+After+Chimeric+Antigen+Receptor+T+Cell+Therapy+for+Acute+Lymphoblastic+Leukemia.">Cytokine Release Syndrome After Chimeric Antigen Receptor T Cell Therapy for Acute Lymphoblastic Leukemia.</a> Critical Care Medicine. 45 (2), e124-e131 (2017).</li><li>Liu, X., Zhao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CRISPR/Cas9+genome+editing:+Fueling+the+revolution+in+cancer+immunotherapy.">CRISPR/Cas9 genome editing: Fueling the revolution in cancer immunotherapy.</a> Current Research in Translational Medicine. 66 (2), 39-42 (2018).</li><li>Ren, J., Zhao, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Advancing+chimeric+antigen+receptor+T+cell+therapy+with+CRISPR/Cas9.">Advancing chimeric antigen receptor T cell therapy with CRISPR/Cas9.</a> Protein Cell. 8 (9), 634-643 (2017).</li><li>Sterner, R. 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=GM-CSF+inhibition+reduces+cytokine+release+syndrome+and+neuroinflammation+but+enhances+CAR-T+cell+function+in+xenografts.">GM-CSF inhibition reduces cytokine release syndrome and neuroinflammation but enhances CAR-T cell function in xenografts.</a> Blood. , (2018).</li><li>Dietz, A. B., 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=A+novel+source+of+viable+peripheral+blood+mononuclear+cells+from+leukoreduction+system+chambers.">A novel source of viable peripheral blood mononuclear cells from leukoreduction system chambers.</a> Transfusion. 46 (12), 2083-2089 (2006).</li><li>Sanjana, N. E., Shalem, O., Zhang, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+vectors+and+genome-wide+libraries+for+CRISPR+screening.">Improved vectors and genome-wide libraries for CRISPR screening.</a> Nature Methods. 11 (8), 783-784 (2014).</li><li>Brinkman, E. K., Chen, T., Amendola, M., van Steensel, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Easy+quantitative+assessment+of+genome+editing+by+sequence+trace+decomposition.">Easy quantitative assessment of genome editing by sequence trace decomposition.</a> Nucleic Acids Research. 42 (22), e168 (2014).</li></ol>

SSK is an inventor on patents in the field of CAR T-cell therapy that are licensed to Novartis (under an agreement between Mayo Clinic, University of Pennsylvania, and Novartis). These studies were funded in part by a grant from Humanigen (SSK). RMS, MJC, RS, and SSK are inventors on patents related to this work. The laboratory (SSK) receives funding from Tolero, Humanigen, Kite, Lentigen, Morphosys, and Actinium.

In this report, we describe a methodology to utilize CRISPR/Cas9 technology to induce secondary modifications in CAR-T cells. Specifically, this&#160;is demonstrated using lentiviral transduction with a viral vector that contains gRNA targeting the gene of interest and Cas9 to generate GM-CSFk/o CART19 cells. We had previously shown that GM-CSF neutralization ameliorates CRS and NT in a xenograft model.12&#160;As previously described, GM-CSFk/o CAR-T cells allow for the inhib...

Chimeric antigen receptor T (CAR-T) cell therapy exhibits great promise in the treatment of cancer.1,2&#160;Two CAR-T cell therapies targeting CD19 (CART19) were recently approved in the United Stated and in Europe for the use in B cell malignancies after demonstrating striking results in multicenter clinical trials.3,4,5&#160;Barriers to more widespread use of CAR-T cells are limited activity in solid tumors and associated toxicities including cytokine release syndrome (CRS) and neurotoxicity (NT).3,5,6,7,8,9&#160;To enhance the therapeutic index of CAR-T cell therapy, genome engineering tools such as zinc finger nucleases, TALENs, and CRISPR are employed to further modify CAR-T cells in an attempt to generate less toxic or more effective CAR-T cells.10,11
In this article, we describe a method to generate CRISPR/Cas9 edited CAR-T cells. The specific goal of this method is to genetically modify CAR-T cells during CAR-T cell manufacturing via CRISPR/Cas9 to generate less toxic or more effective CAR-T cells. The rationale for developing this methodology is built on lessons learned from clinical experience of CAR-T cell therapy, which indicates an urgent need for novel strategies to increase the therapeutic window of CAR-T cell therapy and to extend the application into other tumors and is supported by the recent advances in synthetic biology allowing multiple modifications of CAR-T cells that have started to enter the clinic. While several genome engineering tools are being developed and applied in different settings, such as zinc finger nucleases, TALENs, and CRISPR, our methodology describes CRISPR/Cas9 modification of CAR-T cells.10,11&#160;CRISPR/Cas9 is an RNA-based bacterial defense mechanism that is designed to eliminate foreign DNA. CRISPR relies on endonucleases to cleave a target sequence identified through a guide RNA (gRNA). CRISPR editing of CAR-T cells offers several advantages over other genome engineering tools. These include precision of the gRNA sequence, simplicity to design a gRNA targeting the gene of interest, high gene editing efficiency, and the ability to target multiple genes since multiple gRNAs can be used at the same time.
Specifically in the methods described here, we used a lentivirus encoding CRISPR guide RNA and Cas9 to disrupt a gene during CAR transduction of T cells. In selecting an appropriate technique to edit CAR-T cells, we suggest the technique described here is an efficient mechanism to generate research grade CAR-T cells, but because the long term effect of permanent integration of Cas9 into the genome is unknown, we propose this methodology to develop proof of concept research grade CAR-T cells but not for producing good manufacturing practice grade CAR-T cells.
In particular, here we describe the generation of granulocyte macrophage colony stimulating factor (GM-CSF) knockout CAR-T cells targeting human CD19. These CAR-T cells were generated by transduction with lentiviral particles encoding a guide RNA specific to GM-CSF (gene name CSF2) and Cas9. We previously found that GM-CSF neutralization ameliorates CRS and NT in a xenograft model.12&#160;GM-CSFk/o CAR-T cells allow for the inhibition of GM-CSF during the manufacturing process, effectively reducing production of GM-CSF while enhancing CAR-T cell anti-tumor activity and survival in vivo compared to wildtype CAR-T cells.12&#160;Thus, here we provide a methodology to generate CRISPR/Cas9 edited CAR-T cells.

<table border="0" cellpadding="0" cellspacing="0" style="width:1377px;" width="1377">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">CD3 Monoclonal Antibody (OKT3), PE, eBioscience</td>
			<td style="width:217px;">Invitrogen</td>
			<td style="width:123px;">12-0037-42</td>
			<td style="width:480px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CD3 Monoclonal Antibody (UCHT1), APC, eBioscience</td>
			<td>Invitrogen</td>
			<td style="width:123px;">17-0038-42</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Choice Taq Blue Mastermix</td>
			<td>Denville Scientific</td>
			<td style="width:123px;">C775Y51</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">CTS (Cell Therapy Systems) Dynabeads CD3/CD28</td>
			<td>Gibco</td>
			<td style="width:123px;">40203D</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">CytoFLEX System B4-R2-V2</td>
			<td style="width:217px;">Beckman Coulter</td>
			<td style="width:123px;">C10343</td>
			<td>flow cytometer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">dimethyl sulfoxide</td>
			<td style="width:217px;">Millipore Sigma</td>
			<td style="width:123px;">D2650-100ML</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Dulbecco&#39;s Phosphate-Buffered Saline</td>
			<td style="width:217px;">Gibco</td>
			<td style="width:123px;">14190-144&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Dynabeads MPC-S (Magnetic Particle Concentrator)</td>
			<td>Applied Biosystems</td>
			<td style="width:123px;">A13346</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Easy 50 EasySep Magnet</td>
			<td>STEMCELL Technologies</td>
			<td style="width:123px;">18002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EasySep Human T Cell Isolation Kit&#160;</td>
			<td>STEMCELL Technologies</td>
			<td style="width:123px;">17951</td>
			<td>negative selection magnetic beads; 17951RF includes tips and buffer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Fetal bovine serum</td>
			<td style="width:217px;">Millipore Sigma</td>
			<td style="width:123px;">F8067</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FITC Mouse Anti-Human CD107a&#160;</td>
			<td>BD Pharmingen</td>
			<td style="width:123px;">555800</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Fixation Medium (Medium A)</td>
			<td style="width:217px;">Invitrogen</td>
			<td style="width:123px;">GAS001S100</td>
			<td></td>
		</tr>
		<tr height="104">
			<td height="104" style="height:104px;width:557px;">GenCRISPR gRNA Construct: Name: CSF2 
			CRISPR guide RNA 1; Species: Human, Vector: 
			pLentiCRISPR v2; Resistance: Ampicillin; Copy number: 
			High; Plasmid preparation: Standard delivery: 4 &#956;g (Free 
			of charge)</td>
			<td style="width:217px;">GenScript</td>
			<td style="width:123px;">N/A</td>
			<td>custom order</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Goat anti-Mouse IgG (H+L) Cross-Adsorbed Secondary Antibody, Alexa Fluor 647</td>
			<td>Invitrogen</td>
			<td style="width:123px;">A-21235</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">https://tide.nki.nl.</td>
			<td style="width:217px;">Desktop Genetics</td>
			<td style="width:123px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Human AB Serum; Male Donors; type AB; US</td>
			<td>Corning</td>
			<td style="width:123px;">35-060-CI</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">IFN gamma Monoclonal Antibody (4S.B3), APC-eFluor 780, eBioscience</td>
			<td>Invitrogen</td>
			<td style="width:123px;">47-7319-42</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lipofectamine 3000 Transfection Reagent</td>
			<td>Invitrogen</td>
			<td style="width:123px;">L3000075</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">LIVE/DEAD Fixable Aqua Dead Cell Stain Kit, for 405 nm excitation</td>
			<td>Invitrogen</td>
			<td style="width:123px;">L34966</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Lymphoprep</td>
			<td>STEMCELL Technologies</td>
			<td style="width:123px;">07851</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Monensin Solution, 1000X</td>
			<td>BioLegend</td>
			<td style="width:123px;">420701</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse Anti-Human CD28 Clone CD28.2</td>
			<td>BD Pharmingen</td>
			<td style="width:123px;">559770</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse Anti-Human CD49d Clone 9F10</td>
			<td>BD Pharmingen</td>
			<td style="width:123px;">561892</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Mouse Anti-Human MIP-1&#946; PE-Cy7</td>
			<td>BD Pharmingen</td>
			<td style="width:123px;">560687</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Mr. Frosty Freezing Container</td>
			<td style="width:217px;">Thermo Scientific</td>
			<td style="width:123px;">5100-0001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">NALM6, clone G5&#160;</td>
			<td>ATCC</td>
			<td style="width:123px;">CRL-3273</td>
			<td>acute lymphoblastic leukemia cell line</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Nuclease Free Water</td>
			<td>Promega</td>
			<td style="width:123px;">P119C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Olympus Vacuum Filter Systems, 500 mL, PES Membrane, 0.22uM, sterile</td>
			<td>Genesee Scientific</td>
			<td style="width:123px;">25-227</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Olympus Vacuum Filter Systems, 500 mL, PES Membrane, 0.45uM, sterile</td>
			<td>Genesee Scientific</td>
			<td style="width:123px;">25-228</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Opti-MEM I Reduced-Serum Medium (1X), Liquid</td>
			<td style="width:217px;">Gibco</td>
			<td style="width:123px;">31985-070</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PE-CF594 Mouse Anti-Human IL-2</td>
			<td>BD Horizon</td>
			<td style="width:123px;">562384</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin-Streptomycin-Glutamine (100X), Liquid</td>
			<td>Gibco</td>
			<td style="width:123px;">10378-016</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Permeabilization Medium (Medium B)</td>
			<td style="width:217px;">Invitrogen</td>
			<td style="width:123px;">GAS002S100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">PureLink Genomic DNA Mini Kit</td>
			<td>Invitrogen</td>
			<td style="width:123px;">K182001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Puromycin Dihydrochloride</td>
			<td>MP Biomedicals, Inc.</td>
			<td style="width:123px;">0210055210</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">QIAquick Gel Extraction Kit</td>
			<td>QIAGEN</td>
			<td style="width:123px;">28704</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rat Anti-Human GM-CSF BV421</td>
			<td>BD Horizon</td>
			<td style="width:123px;">562930</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">RoboSep-S</td>
			<td style="width:217px;">STEMCELL Technologies</td>
			<td style="width:123px;">21000</td>
			<td>Fully Automated Cell Separator</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SepMate-50 (IVD)</td>
			<td>STEMCELL Technologies</td>
			<td style="width:123px;">85450</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:557px;">Sodium Azide, 5% (w/v)</td>
			<td style="width:217px;">Ricca Chemical</td>
			<td style="width:123px;">7144.8-16</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">X-VIVO 15 Serum-free Hematopoietic Cell Medium</td>
			<td>Lonza</td>
			<td style="width:123px;">04-418Q</td>
			<td></td>
		</tr>
	</tbody>
</table>

using crispr/cas9 to knock out gm-csf in car-t cells

Chimeric antigen receptor T (CAR-T) cell therapy is a cutting edge and potentially revolutionary new treatment option for cancer. However, there are significant limitations to its widespread use in the treatment of cancer. These limitations include the development of unique toxicities such as cytokine release syndrome (CRS) and neurotoxicity (NT) and limited expansion, effector functions, and anti-tumor activity in solid tumors. One strategy to enhance CAR-T efficacy and/or control toxicities of CAR-T cells is to edit the genome of the CAR-T cells themselves during CAR-T cell manufacturing. Here, we describe the use of CRISPR/Cas9 gene editing in CAR-T cells via transduction with a lentiviral construct containing a guide RNA to granulocyte macrophage colony-stimulating factor (GM-CSF) and Cas9. As an example, we describe CRISPR/Cas9 mediated knockout of GM-CSF. We have shown that these GM-CSFk/o CAR-T cells effectively produce less GM-CSF while maintaining critical T cell function and result in enhanced anti-tumor activity in vivo compared to wild type CAR-T cells.

Figure 1&#160;shows reduction of GM-CSF in GM-CSFk/o CART19 cells. To verify that the genome of the T cells was altered to knockout GM-CSF, TIDE sequencing was used in the GM-CSFk/o CART19 cells (Figure 1A). CAR-T cell surface staining verifies that the T cells successfully express the CAR surface receptor in vitro by gating on live CD3+ cells (Figure 1B). Intracellular staining...

Watch this Scientific Journal Video about Using CRISPR/Cas9 to Knock Out GM-CSF in CAR-T Cells at JoVE.com

Using CRISPR/Cas9 to Knock Out GM-CSF in CAR-T Cells

Here, we present a protocol to genetically edit CAR-T cells via a CRISPR/Cas9 system.

Chimeric antigen receptor T (CAR-T) cell therapy is a cutting edge and potentially revolutionary new treatment option for cancer. However, there are ...

Our protocol describes the genetic modification of CAR-T cell during their manufacturing via the CRISPR technology to generate more effective and less toxic product. An advantage of this technique is that CAR-T cell production and genetic manipulation can both occur in one cell with good efficiency. Demonstrating the procedure will be Rosalie Sterner, an MD PhD student, Michelle Cox, a technologist and a graduate student, and Reona Sakemura, a postdoctorate fellow, from my laboratory.After isolating T-cells from harvested peripheral blood mononuclear cells, start culturing them by first preparing T-cell medium and then sterilizing it by filtering it through a 0.45 micrometer sterile vacuum filter and then with a 0.22 micrometer sterile vacuum filter. On the day of T-cell stimulation or day zero, prior to stimulation, wash CD3/CD28 beads by placing the required volume of beads in a sterile 1.5 milliliter microcentrifuge tube and resuspending in one milliliter of TCM. Place the tube in contact with a magnet for one minute.Then aspirate the TCM and resuspend in one milliliter of fresh TCM to wash the beads again and repeat for a total of three washes. And finally, resuspend the beads in one milliliter of TCM. After counting the T-cells, transfer the beads to the T-cells at a ratio of three to one beads to cells.Then dilute the cells to a final concentration of one million cells per milliliter and incubate at 37 degrees Celsius, 5%CO2 for 24 hours. After acquiring a CART19 construct in a lentiviral vector, perform lentiviral production by first incubating lentiviral plasmid, packaging vector, envelope vector, precomplexing reagent, transfection reagent, and transfection medium at room temperature for 30 minutes. Carry out lentiviral work using BSL2+precautions including cell culture hoods, personal protective equipment, and disinfection of used materials with bleach before disposal.After incubation, add these transfection reagents to the 293 T-cells that have reached 70 to 90%confluency and culture the transfected cells at 37 degrees Celsius and 5%CO2. At 24 and 48 hours after transfection, harvest, centrifuge, filter and concentrate virus-containing supernatant by ultracentrifugation and freeze at minus 80 degrees Celsius for future use. On day one, gently resuspend T-cells that have been stimulated at one million cells per milliliter on day zero in order to break up the rosettes of cells.Under appropriate BSL2+precautions, add fresh or frozen harvested virus to the simulated T-cells at a multiplicity of infection of 3.0. Continue to incubate the transduced T-cells at 37 degrees Celsius, 5%CO2. On days three and five, count CAR-T cells and add fresh pre-warmed TCM to the culture to maintain a CAR-T cell concentration of one million cells per milliliter.Six days after simulation, remove beads from the transduced T-cells by first harvesting and resuspending the cells. Transfer the cells in 50 milliliter conical tubes and place the tubes in a magnet for one minute. After collecting the CAR-T cell-containing supernatant and discarding the beads, place the cells back in culture at a concentration of one million cells per milliliter in a culture flask.Use a sample of cells for flow cytometry to assess surface expression of the CARs. Incubate the rest to resume expansion and then harvest and cryo-preserve the cells at day eight as described in the manuscript. To disrupt the granulocyte macrophage colony stimulating factor, utilize a guide RNA as described in the manuscript.Incubate transfection reagents at room temperature for 30 minutes. After incubation, add them to the 293 T-cells that have reached 70 to 90%confluency and culture the transfected cells at 37 degrees Celsius, 5%CO2 to produce a lentivirus. At 24 and 48 hours, harvest and concentrate virus-containing supernatant by ultracentrifugation in 50 milliliter ultracentrifuge tubes and freeze at minus 80 degrees Celsius for future use.Then on day one, gently resuspend the T-cells to break up rosettes. In a BSL2+approved laboratory, to generate CAR-T cells, add CAR19 lentivirus and GMCSF-targeting CRISPR lentivirus to the simulated T-cells. On day three and day five for successfully transduced lentiCRISPR-edited T-cells carrying puromycin resistance, treat cells with puromycin dihydrochloride at a concentration of one microgram of puromycin per milliliter.Tide sequencing was used to confirm a GM-CSF reduction in GM-CSF knockout CART19 cells with a disruption efficiency of approximately 71%Flow plots of CAR-T cell surface staining gated on live CD3-positive cells show that both wild-type CART19 and GM-CSF knockout CART19 successfully and in a similar fashion express the CAR surface receptor in vitro. On the other hand, intracellular staining of GM-CSF by flow cytometry also gated on live CD3-positive cells demonstrates decreased expression of GM-CSF in the knockout cells compared to wild-type CART19 cells confirming functional success of the knockout. Particular care should be taken during the transduction steps of this procedure as they are the most critical to the development of genetically modified CAR-T cells.The methodology described can potentially be applied to a variety of genes to modify CAR-T cells via CRISPR/CAS9 to help generate a less toxic and more effective product. CRISPR/CAS9 technology provides the strategies to directly target the genome of CAR-T cells to engineer solutions to current clinical shortcomings.

using-crisprcas9-to-knock-out-gm-csf-in-car-t-cells

Research

JoVE Journal

Cancer Research

10.9K Views.  Mayo Clinic College of Medicine and Science. Our protocol describes the genetic modification of CAR-T cell during their manufacturing via the CRISPR technology to generate more effective and less toxic product. An advantage of this technique is that CAR-T cell production and genetic manipulation can both occur in one cell with good efficiency. Demonstrating the procedure will be Rosalie Sterner, an MD PhD student, Michelle Cox, a technologist and a graduate student, and Reona Sakemura, a postdoctorate fellow, from my laboratory.A...