We thank Alan B. Hoofring and Erina H. He for graphical assistance. This research was supported by the Intramural Research Program of the National Cancer Institute (ZIA BC010763) and the Intramural NCI Cancer Moonshot Initiative for Cell-based Cancer Immunotherapy.

1. Culturing Human iPSCs (hiPSCs) on Mouse Embryonic Fibroblasts (MEF)
NOTE: Alternative methods for culturing hiPSCs can also be used, including but not limited to: seeding onto a 6 well plate pre-coated with gelatin, a gelatinous protein mixture, recombinant laminin 511, or any other extracellular matrix used in hiPSC expansion, and cultured using defined media specially formulated for human pluripotent stem cell culture.
<ol>
	<li>Culturing MEF
	<ol>
		<li>Coat a 10 cm cell culture Petri dish with 4 mL of 0.1% gelatin and incubate for 30 min at 37 &#176;C.</li>
		<li>Thaw a vial of 4 x 106 irradiated MEF quickly into 10 mL of 37 &#176;C MEF media (DMEM + 10% FBS + 1x penicillin-streptomycin + 1x L-glutamine supplement). Centrifuge at 300 x g for 5 min at 4 &#176;C. Aspirate the supernatant and resuspend the cell pellet in 9 mL of MEF media.</li>
		<li>Remove the gelatin-coated dish from the incubator. Aspirate gelatin and add 7 mL of MEF media. Plate 3 mL of MEF suspension (from step 1.1.2) onto the gelatin-coated dish. Rock the dish side-to-side and front-to-back to ensure even distribution of MEF over the dish. Incubate at 37 &#176;C for 8-36 h.</li>
	</ol>
	</li>
	<li>Passaging hiPSC on MEF 
	NOTE: The data was generated using MART-1 iPSC derived from long-term cultured melanoma TIL, which specifically recognize MART-1 peptide in the context of HLA-A*02:01, as previously described18.&#160;
	<ol>
		<li>Passage hiPSCs when colonies are between 0.8 -&#160;1.2 mm in diameter. Prior to passaging, check hiPSC colonies in a stereo-microscope and remove any areas of differentiation from the culture using the plastic edge of a 200 &#181;L tip.</li>
		<li>Aspirate spent media and add 10 mL hiPSC media (human ES culture media [Table of Materials] + 10 ng/mL human basic fibroblast growth factor [hbFGF]) supplemented with 10 &#956;M ROCK inhibitor.</li>
		<li>Hold the cell culture dish in one hand and roll a disposable cell passaging tool across the entire dish in one direction. Apply enough pressure so that the entire roller blade touches the culture dish and maintain a uniform pressure during rolling action.</li>
		<li>Rotate the culture dish 90&#176; and repeat step 1.2.3. View the plate in the microscope to visually confirm proper cutting of the colonies, which should appear checkered. Detach cut colonies by gentle mechanical flushing using a 200 &#956;L pipette.&#160; 
		NOTE: Detachment of cut colonies by mechanical flushing must be done immediately after cutting colonies with the roller, because after 3 min the cut colonies will start to reattach to the dish, and it will become difficult to detach colonies of homogeneous size by flushing.</li>
		<li>Transfer 350 -&#160;600 clumps of cut colonies onto a new 10 cm dish of MEF (plated 8 -&#160;36 h prior to hiPSC passaging) with 10 mL of fresh hiPSC media supplemented with 10 &#956;M ROCK inhibitor. Incubate at 37 &#176;C. 
		NOTE: 600 clumps represents approximately 1.0 x 106 MART-1 iPSC and will yield 0.5-1.0 x 106 DP cells on day 35. However, expected numbers will vary depending on the potency of the starting cell line and culture conditions.</li>
		<li>The following day, aspirate spent media and add 10 mL of fresh hiPSC media. Change hiPSC media every 1-2 days depending on hiPSC growth rate.</li>
	</ol>
	</li>
</ol>
2. Preparation of OP9/DLL1 Cells for Co-culture with hiPSCs
<ol>
	<li>Culture OP9/DLL1 cells in OP9 media [&#945;-minimum essential medium (&#945;-MEM) + 20% fetal bovine serum (FBS) + 1x penicillin-streptomycin] at 37 &#176;C. When OP9/DLL1 cells reach confluency, aspirate media and wash once with 5 mL of 1x magnesium, calcium, and phenol red-free phosphate buffered saline (PBS).</li>
	<li>Aspirate PBS and add 2 mL of 0.05% Trypsin-EDTA.&#160; Incubate for 5 min at 37 &#176;C. Then, add 4 mL of OP9 media and mechanically dissociate the cell layer by pipetting to make a single-cell suspension.</li>
	<li>Transfer the cell suspension into a 50 mL conical tube through a 100 &#956;m cell strainer to avoid cell clumps. Centrifuge at 300 x g for 5 min at 4 &#176;C. Aspirate the supernatant and resuspend in 12 mL of OP9 media.&#160;</li>
	<li>Add 8 mL of OP9 media to each of six new 10 cm cell culture Petri dishes. Plate 2 mL of OP9/DLL1 cell suspension from step 2.3 onto each new 10 cm dish. Rock the dish side-to-side then front-to-back to ensure even distribution of OP9/DLL1 over the dish.</li>
	<li>Incubate at 37 &#176;C. Repeat passage every 2 -&#160;3 days when cells reach confluency. 
	NOTE: It is important to make enough frozen stock of OP9/DLL1 cells and thaw a new stock every 4-6 weeks.</li>
</ol>
3. In Vitro Differentiation of hiPSCs into CD8&#945;&#946;+ Single Positive (SP) T Cells
<ol>
	<li>Prepare gelatinized OP9/DLL1 dishes one week prior to co-culture with hiPSCs. To prepare 0.1% gelatin solution, add 5 mL of room temperature (RT) tissue-grade stock gelatin solution to 500 mL of PBS.
	<ol>
		<li>Coat 3 new 10 cm cell culture Petri dishes by adding 4 mL per dish of 0.1% gelatin.&#160; Incubate 30 min at 37 &#176;C.&#160;</li>
		<li>Aspirate gelatin and add 8 mL of OP9 media to each dish. Passage one confluent dish of OP9/DLL1 (as done in section 2 above) to three gelatin pre-coated dishes.</li>
	</ol>
	</li>
	<li>After 4 days, add 10 mL of OP9 media to each 10 cm dish of OP9/DLL1 on gelatin, for a total of 20 mL of media per dish.</li>
	<li>After 7 -&#160;8 days, begin the hiPSC co-culture on OP9/DLL1 confluent dishes (differentiation day 0).
	<ol>
		<li>Aspirate spent media from confluent 10 cm dish of hiPSCs on MEF. Add 10 mL of OP9 media. Cut and detach hiPSC colonies using a disposable cell passaging tool as done in steps 1.2.3 and 1.2.4.</li>
		<li>Transfer 350 -&#160;600 clumps of cut colonies onto a 10 cm pre-gelatinized OP9/DLL1 dish (step 3.1) with 10 mL of fresh OP9 media using a 200 &#956;L pipette. Rock the culture dish side-to-side then front-to-back to ensure even distribution of colonies. 
		NOTE: Alternatively, pre-formed hiPSC embryoid bodies (EBs) or small clump suspension may be used.&#160; However, the use of a disposable cell passaging tool or EB formation system is preferred to produce hiPSC clumps of uniform size.</li>
	</ol>
	</li>
	<li>On day 1, aspirate spent media and replace with 20 mL of fresh OP9 media. hiPSC clumps co-cultured on OP9/DLL1 for 1 day will appear as small round monolayer colonies (Figure 1).</li>
	<li>On day 5, aspirate 10 mL of spent media and add 10 mL of fresh OP9 media. hiPSC colonies will begin to differentiate into primitive mesoderm, which is characterized by a multilayered dark center.</li>
	<li>On day 9, aspirate 10 mL of spent media and add 10 mL of fresh OP9 media. At this point, multilayered center structures will evolve into dome-like shapes, and a peripheral network-like area will start to become evident.</li>
	<li>On day 13, harvest hematopoietic progenitor cells (HPCs) (Figure 1). hiPSC-derived structures on day 13 are characterized by a dark central organoid surrounded by a network of dome-like areas, representative of hematopoietic zones (HZs) previously reported to enclose human embryonic stem cell-derived hematopoietic progenitors21. 
	NOTE: The presence of the dome-like structures indicates a successful process even in the absence of dark centers. The inability to produce HPCs may be due to poor quality of OP9/DLL1, quality of FBS lot, confluency of iPSC clumps seeded onto OP9/DLL1 (350-600 clumps is optimal), and/or variations in potency of iPSC lines to produce hematopoietic precursors.
	<ol>
		<li>Aspirate spent media and wash 1x with 5 mL of 1x phenol red-free Hanks&#39;&#160;balanced salt solution modified with calcium and magnesium (HBSS).&#160;</li>
		<li>Aspirate HBSS and add 250 &#956;L of 5000 Units/mL collagenase IV in 10 mL of HBSS. Incubate at 37 &#176;C for 45 min. Aspirate HBSS with collagenase IV and wash once with 5 mL of PBS.</li>
		<li>Aspirate PBS and add 5 mL of 0.25% Trypsin-EDTA. Incubate at 37 &#176;C for 20 min. Then, add 4 mL of OP9 media and dissociate the cell layer by pipetting to make a single-cell suspension.</li>
		<li>Transfer the cell suspension into a 50 mL conical tube through a 100 &#956;m cell strainer.&#160; Centrifuge at 300 x g for 5 min at 4 &#176;C. Aspirate the supernatant and resuspend in 10 mL of OP9 media.&#160;</li>
		<li>Plate cell suspension onto a new gelatinized 10 cm cell-culture Petri dish (see steps 3.1.1 and 3.1.2). Incubate at 37 &#176;C for 45 min. Then, collect non-adherent cells by gentle pipetting.</li>
		<li>Transfer collected cell suspension into a 50 mL conical tube through a 100 &#956;m cell strainer.&#160; Centrifuge at 300 x g for 5 min at 4 &#176;C. Aspirate the supernatant and resuspend in 10 mL of differentiation media [OP9 media with 5 ng/mL human stem cell factor (hSCF), 5 ng/mL human Flt3 ligand (hFLT3L), and 5 ng/mL human interleukin 7 (hIL-7)].</li>
		<li>Plate the cell suspension onto a new 10 cm OP9/DLL1 confluent dish.&#160;</li>
	</ol>
	</li>
	<li>On day 16, passage the cells.&#160;
	<ol>
		<li>Mechanically detach non-adherent cells by gentle pipetting and filter through a 100 &#956;m cell strainer. Centrifuge at 300 x g for 5 min at 4 &#176;C. Aspirate the supernatant and resuspend in 10 mL differentiation media.</li>
		<li>Plate the cell suspension onto a new 10 cm OP9/DLL1 confluent dish.&#160;</li>
	</ol>
	</li>
	<li>Continue passaging non-adherent cells every 5-7 days thereafter by repeating step 3.8.</li>
	<li>On day 35, enrich CD4+CD8+ double positive (DP) population and stimulate to produce CD8&#945;&#946;+ SP T cells (Figure 2).
	<ol>
		<li>Mechanically detach non-adherent cells by gentle pipetting and filter through a 100 &#956;m cell strainer to remove cell clumps. Enrich CD4+ cell population by CD4 magnetic bead isolation according to the manufacturer&#8217;s protocol. 
		NOTE: The rationale for using CD4 magnetic beads is to remove CD4-CD8- DN cells from the culture, as these have been demonstrated to cause direct killing of CD4+CD8+ DP cells after stimulation22.</li>
		<li>Count live CD4 enriched cells using a Neubauer hemocytometer and Trypan blue dye.&#160; Suspend in OP9 media at total concentration 0.5 x 106 cells/mL. Aliquot 1 mL of the cell suspension (0.5 x 106 cells) into each well of a tissue culture flat bottom 24 well plate of confluent OP9/DLL1.</li>
		<li>Add 100 IU human interleukin 2 (hIL-2), 5 ng/mL hIL-7, 500 ng/mL anti-human CD3 antibody, and 2 &#956;g/mL anti-human CD28 antibody, then culture at 37 &#176;C.</li>
		<li>On day 4 -&#160;7 after stimulation, collect cells for molecular analysis (Figure 3) or co-culture with peptide-pulsed antigen presenting cells (APCs).</li>
	</ol>
	</li>
</ol>
4. Measuring Antigen Specificity of hiPSC Derived CD8&#945;&#946;+ SP T Cells
NOTE: The type of APCs to be used for this experiement is dependent on the MHC restriction of hiPSC-derived T cells. Here, T2 cell line is used, which is a hybrid of T and B lymphoblastoid cell lines. T2 cells express HLA-A*02:0123, which is recognized by JKF6 cells from which MART1-iPSC was derived18. This T2 cell line can be expanded in RPMI 1640 + 20% FBS + 1x penicillin-streptomycin and is passaged when cells reach a density of 5 x 105 cells/mL.
<ol>
	<li>Count live HLA-A*02:01+ T-B hybrid lymphoblastoid T2 cells using a Neubauer hemocytometer and Trypan blue dye. Incubate APCs in 24 well tissue culture plate with 1 &#956;g/mL MART-1 peptide for 2 h at 37 &#176;C. &#160; 
	NOTE: Optimal peptide concentration is variable, depending on cell line and antigen specificity.</li>
	<li>Collect APCs and wash 2x with 10 mL of PBS to remove any extra peptide.</li>
	<li>Count APCs and suspend at 2 &#8211; 5 x 105 cells/mL in OP9 media with 100 IU IL-2 and 5 ng/mL IL-7. Aliquot 100 &#956;L of cell suspension (2-5 x 104 cells) into each well of an ultra-low attachment U bottom 96 well plate or directly into a pre-coated ELISpot plate.</li>
	<li>Sort hiPSC-derived CD8&#945;&#946;+ SP T cells (1 week after anti-human CD3/CD28 antibody stimulation) using a cell sorter and suspend at 1 x 106 cells/mL in OP9 media with 100 IU IL-2 and 5 ng/mL IL-7. Aliquot 100 &#956;L of cell suspension (1 x 105 cells) into each well of APCs and culture for 16 -&#160;20 h at 37 &#176;C.</li>
	<li>After 16 -&#160;20 h, analyze the cytokine secretion profile by ELISpot assay per the manufacturer&#39;s protocol (Figure 4).</li>
</ol>

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I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hematoendothelial+differentiation+of+human+embryonic+stem+cells.">Hematoendothelial differentiation of human embryonic stem cells.</a> Current Protocols in Cell Biology. , (2007).</li><li>Vizcardo, R., 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=Generation+of+Tumor+Antigen-Specific+iPSC-Derived+Thymic+Emigrants+Using+a+3D+Thymic+Culture+System.">Generation of Tumor Antigen-Specific iPSC-Derived Thymic Emigrants Using a 3D Thymic Culture System.</a> Cell Reports. 22 (12), 3175-3190 (2018).</li><li>McNicol, A. 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=CD8alpha/alpha+homodimers+fail+to+function+as+co-receptor+for+a+CD8-dependent+TCR.">CD8alpha/alpha homodimers fail to function as co-receptor for a CD8-dependent TCR.</a> European Journal of Immunology. 37 (6), 1634-1641 (2007).</li><li>Themeli, M., Riviere, I., Sadelain, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=New+cell+sources+for+T+cell+engineering+and+adoptive+immunotherapy.">New cell sources for T cell engineering and adoptive immunotherapy.</a> Cell Stem Cell. 16 (4), 357-366 (2015).</li><li>Minagawa, 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=Enhancing+T+Cell+Receptor+Stability+in+Rejuvenated+iPSC-Derived+T+Cells+Improves+Their+Use+in+Cancer+Immunotherapy.">Enhancing T Cell Receptor Stability in Rejuvenated iPSC-Derived T Cells Improves Their Use in Cancer Immunotherapy.</a> Cell Stem Cell. 23 (6), 850-858 (2018).</li><li>Montel-Hagen, 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=Organoid-Induced+Differentiation+of+Conventional+T+Cells+from+Human+Pluripotent+Stem+Cells.">Organoid-Induced Differentiation of Conventional T Cells from Human Pluripotent Stem Cells.</a> Cell Stem Cell. 24 (3), 376-389 (2019).</li><li>Takada, K., Kondo, K., Takahama, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+Peptides+That+Promote+Positive+Selection+in+the+Thymus.">Generation of Peptides That Promote Positive Selection in the Thymus.</a> Journal of Immunology. 198 (6), 2215-2222 (2017).</li><li>Takada, K., 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=TCR+affinity+for+thymoproteasome-dependent+positively+selecting+peptides+conditions+antigen+responsiveness+in+CD8(+)+T+cells.">TCR affinity for thymoproteasome-dependent positively selecting peptides conditions antigen responsiveness in CD8(+) T cells.</a> Nature Immunology. 16 (10), 1069-1076 (2015).</li><li>Vizcardo, R., 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+Three-dimensional+Thymic+Culture+System+to+Generate+Murine+Induced+Pluripotent+Stem+Cell-derived+Tumor+Antigen-specific+Thymic+Emigrants.">A Three-dimensional Thymic Culture System to Generate Murine Induced Pluripotent Stem Cell-derived Tumor Antigen-specific Thymic Emigrants.</a> JoVE. , e58672 (2019).</li></ol>

The authors have no disclosures.

The co-culture of OP9 murine stromal cells is a well-established system for in vitro generation of lymphocytes (i.e., NK, B, and T cells) from HSPCs and pluripotent stem cells. Notch signaling is required to induce T lineage commitment and can be accomplished by the ectopic expression of Notch ligand DLL1 or DLL4, which have comparable efficacy for T cell generation1. Therefore, the OP9/DLL1 co-culture system has become a widely used method for producing T cells in vitro.&#160; Furthermore, this method is applicable for use with several types and sources of human cells, including cord blood, bone marrow HSPCs and ESCs.&#160; However, the generation of T cells from these sources is limited either by insufficient retrieval of source cells or by inefficient differentiation to T cells1. Additionally, a T cell product with a single TCR recombination cannot be generated from these open repertoire sources. By using regenerative medicine techniques, namely induced pluripotent stem cell (iPSC) technology, it may be possible to produce massive numbers of antigen-specific T cells for use in cell-based therapeutics15.&#160;
hiPSCs are similar to pluripotent ESCs in their capacity for self-renewal, limitless expansion, and potential to differentiate to any type of somatic cell in the body; however, they lack the ethical concerns surrounding the use of products of embryonic origin for clinical applications. Moreover, hiPSCs can be produced from any somatic cell, allowing the development of cell products for personalized medicine. In previous reports, hiPSCs have been produced from human T cells using whole peripheral mononuclear cells, CD3+ cells, or isolated cytotoxic T lymphocytes (CTLs) as a source18,19,22,26. When hiPSCs are generated from a T cell source (T-iPSCs), the original TCR gene rearrangement is inherited. Therefore, patient T-iPSC derived T cells may provide a model for personalized ACT treatment by targeting a patient&#8217;s distinct cancer antigens.
The differentiation of human pluripotent stem cells into T lineage cells is divided into two steps: the generation of hematopoietic progenitor cells (HPCs)27 and their further differentiation into T lineage cells21. Both steps can be accomplished using the OP9/DLL1 co-culture system. Importantly, the quality of OP9/DLL1 feeder cells is critical to the success of T cell differentiation. Since OP9/DLL1 cells are not an immortalized homogenous cell line, the quality of the FBS and culture conditions are critical to maintaining their expansion without losing the ability to support hiPSC differentiation. Therefore, it is recommended to pre-evaluate the lot of FBS and passage consistently when cell-to-cell cytoplasmic contact begins to occur, in order to prevent cell differentiation and senescence. One point to take into consideration is that cell-to-cell contact can appear indistinguishable from the background depending on the phase contrast and magnification of the microscope. In our experience, most OP9/DLL1 dishes will appear to be 80% confluent when ready to passage.
It has been shown that the redifferentiated T lineage cells generated from T-iPSCs by OP9/DLL1 co-culture can produce CD8+ SP T cells upon stimulation18,19. However, regenerated CD8+ SP T cells acquire the innate-like CD8&#945;&#945; homodimer22,28, which is an ineffective co-receptor for TCR signaling29. &#160;Additionally, these regenerated CD8+ SP T cells have shown strong TCR-independent cytotoxicity, making these cells unfavorable for clinical use30. This protocol describes a recent method involving stimulation of purified CD4+CD8+ DP cells to generate CD8&#945;&#946;+ SP T cells with a more conventional phenotype and improved antigen-specific cytotoxicity22. Although the loss of antigen specificity due to secondary TCR&#945; allelic rearrangement occurs in the DP stage after prolonged long-term culture, this can be overcome by genome editing in T-iPSCs31.&#160; In our experience, hiPSC-derived DP cells start to appear on day 30 -&#160;35 of culture, and these newly generated DP cells have not yet undergone secondary TCR&#945; rearrangement. Therefore, most DP cells on day 35 retain antigen specificity and can be used to generate antigen-specific CD8&#945;&#946;+ SP T cells. &#160;
Prior to human anti-CD3 and anti-CD28 stimulation on day 35, CD4-CD8- DN cells must be removed from the culture, as these have been demonstrated to cause direct killing of CD4+CD8+ DP cells after stimulation22. Using CD4 magnetic bead enrichment (step 3.10) will enrich for both DP and CD4+CD8- intermediate single positive (ISP) cells1, which we have been shown to have no negative effects22. Alternatively, fluorescence-activated cell sorting by flow cytometry can be performed to isolate DP cells. However, magnetic bead separation is preferred as it avoids the mechanical stress induced by flow cytometry.
The generation of CD8&#945;&#946;+ SP T cells from human pluripotent stem cells without activation-mediated agonist selection has subsequently been demonstrated by the use of 3D murine stromal cell culture32. However, physiological positive selection is dependent on the interaction of TCR with self-peptide-MHC complexes, which are uniquely processed and presented by thymic cortical epithelial cells33. Furthermore, TCR affinity for selection peptides has been shown to determine the subsequent functional capabilities of mature CD8&#945;&#946;+ SP T cells34.&#160; Currently, there is no evidence to suggest that a Notch stromal cell-based co-culture system can provide the defined selection peptide and MHC complex required for physiological positive selection.
It has been previously reported in a murine model that T lineage cells generated from tumor antigen-specific T cell-derived hiPSCs using OP9/DLL1 alone fail to experience conventional maturation. However, iPSC-derived immature T cells generated by the OP9/DLL1 system can mature into na&#239;ve-like T cells by further physiological thymic education in a 3D culture system 28,35. Therefore, the protocol presented here to produce iPSC-derived immature T cells generated by the OP9/DLL1 system is vital for further attempts to generate real human tumor antigen-specific post-thymic T cells capable of long-term persistence in vivo with efficiency to treat established vascularized tumors.

In addition to physiological advantages, T cells have many potential therapeutic applications. The generation and expansion of T cells in vitro can be used for disease modeling and therapeutic validation as well as a source of treatment for hereditary and acquired immunodeficiency states (i.e., viral immunodeficiencies and lymphodepletion secondary to chemotherapy or transplantation) and for the eradication of cancer. This latter quality has led to the development of adoptive T cell transfer (ACT) for the treatment of patients with advanced cancer1.&#160;
ACT consists of resecting a patient&#8217;s tumor, extracting tumor-infiltrating lymphocytes (TILs), expanding TILs ex vivo, then reinfusing the expanded cells into the patient2. It has been shown to be an effective treatment modality for some patients with metastatic cancer. &#160;Unfortunately, not all patients respond to this therapy. Previous reports have shown that the differentiation state of transferred cells3,4,5,6,7,8,9, use of large numbers of highly enriched cancer antigen-specific T cells10, and persistence of T cells after transfer11,12 are all correlated with more durable responses13,14. Therefore, when ACT fails to elicit an anti-tumor response, it may in part be due to a low yield of cancer antigen-specific T cells, inefficient ex vivo expansion leading to the exhaustion and loss of reactive clones, or lack of persistence after transfer4. It has been postulated that these obstacles may be overcome by the generation of large numbers of less differentiated cancer antigen-specific T cells in vitro15,16.&#160;
Hematopoietic stem/progenitor cells (HSPCs) are a conventional source for in vitro T cell generation, although this method is limited by the small number of cells able to be recovered from a single donor1. Embryonic stem cells (ESCs) have also been shown to produce T cells but with low yield17, making it inefficient for clinical applications. Furthermore, since T lineage cells experience stochastic genetic recombination of their T cell receptors (TCRs) in early developmental stages, it is not possible to use HSPCs or ESCs to generate a pure population of antigen-specific T cells without further genomic modifications like TCR gene transduction.
One approach to overcome these caveats is to reprogram TILs to human induced pluripotent stem cells (hiPSCs), which may provide a limitless source for in vitro T cell generation. It has been shown that cancer antigen-specific TILs can be reprogrammed into hiPSCs and re-differentiated to T cell lineage, which retains the same T cell receptor (TCR) gene rearrangement as the original T cell18,19.&#160; This detail is important for ACT because individual patient tumors have unique mutational profiles, and very few cancer antigens have been shown to be shared among patients20. Therefore, using cancer antigen-specific TILs as a source for in vitro generation of hiPSC-derived T cells may provide a new strategy for the personalized treatment of patients with metastatic cancer.
Presented here in detail is a protocol for differentiating hiPSC-derived T lineage cells into functional antigen-specific CD8&#945;&#946;+ single positive (SP) T cells using OP9/DLL1 co-culture system. This method is a powerful tool for in vitro T cell differentiation of hiPSCs, hematopoietic progenitors, and embryonic stem cells, as well as their further applications in regenerative medicine and cell-based therapies.

<table><tbody><tr><td>10 cm dish</td><td>Corning, Inc.&amp;nbsp;</td><td>353003</td><td></td></tr><tr><td>Anti-CD3, human</td><td>BD Biosciences</td><td>Cat# 561812, RRID:AB_1089628</td><td></td></tr><tr><td>Anti-CD34, human</td><td>BD Biosciences</td><td>Cat# 348791, RRID:AB_400381</td><td></td></tr><tr><td>Anti-CD4, human</td><td>Biolegend</td><td>Cat# 344612, RRID:AB_2028479</td><td></td></tr><tr><td>Anti-CD43, human</td><td>BD Biosciences</td><td>Cat# 560198, RRID:AB_1645460</td><td></td></tr><tr><td>Anti-CD7, human</td><td>BD Biosciences</td><td>Cat# 555361, RRID:AB_395764</td><td></td></tr><tr><td>Anti-CD8a, human</td><td>BD Biosciences</td><td>Cat# 555369, RRID:AB_398595</td><td></td></tr><tr><td>Anti-CD8b, human</td><td>BD Biosciences</td><td>Cat# 641057, RRID:AB_1645747</td><td></td></tr><tr><td>Anti-TCRb, human</td><td>BD Biosciences</td><td>Cat# 555548, RRID:AB_395932</td><td></td></tr><tr><td>CD28 human monoclonal antibody (15E8), pure functional grade</td><td>Miltenyl Biotec</td><td>130-093-375</td><td></td></tr><tr><td>CD3 human monoclonal antibody (OKT3), pure functional grade</td><td>Miltenyl Biotec</td><td>130-093-387</td><td></td></tr><tr><td>CD4 Microbeads, human</td><td>Miltenyl Biotec</td><td>130-045-101</td><td></td></tr><tr><td>Cell strainer 100 um</td><td>Fisher Scientific</td><td>22-363-549</td><td></td></tr><tr><td>Fetal Bovine Serum (FBS)</td><td>Gemini</td><td>100-500</td><td></td></tr><tr><td>Flt-3 ligand</td><td>R&amp;amp;D Systems</td><td>427-FL</td><td></td></tr><tr><td>Gelatin Solution 2%&amp;nbsp;</td><td>SIGMA-Aldritch</td><td>G1393-100ML</td><td></td></tr><tr><td>GlutaMAX (100X)</td><td>Thermo Fisher Scientific</td><td>35050-061</td><td>L-Glutamine supplement</td></tr><tr><td>HBSS Mg+Ca+ Phenol-Red Free</td><td>Gibco</td><td>14025-092</td><td></td></tr><tr><td>Interleukin-2</td><td>R&amp;amp;D Systems</td><td>202-IL</td><td></td></tr><tr><td>Interleukin-7</td><td>R&amp;amp;D Systems</td><td>407-ML</td><td></td></tr><tr><td>iTAG MHC Tetramer HLA-A*0201 Mart1 Tetramer -ELAGIGILTV</td><td>MBL</td><td>Cat#TB-0009-2</td><td></td></tr><tr><td>Mart1-hiPSC</td><td>Vizcardo et al., Cell Stem Cell 2013</td><td>RIKEN-IMS</td><td></td></tr><tr><td>Melan-A, MART 1 (26-35)</td><td>InnoPep</td><td>3146-0100</td><td></td></tr><tr><td>MEM Non-Essential Amino Acids Solution</td><td>Gibco</td><td>11140050</td><td></td></tr><tr><td>&amp;alpha;MEM powder</td><td>Gibco</td><td>61100061</td><td></td></tr><tr><td>Mouse Embryonic Fibroblasts (MEF)</td><td>Thermo Fisher Scientific</td><td>C57BL/6 MEF MITC-TREATED 4M EACH; A34962</td><td></td></tr><tr><td>OP9/N-DLL1</td><td>Riken Bioresource center</td><td>Cat# RCB2927; RRID:CVCL_B220</td><td>OP9/DLL1</td></tr><tr><td>Penicillin/streptomycin</td><td>Thermo Fisher Scientific</td><td>15140-122</td><td></td></tr><tr><td>Phosphate buffered saline pH 7.4 (1x)</td><td>Thermo Fisher Scientific</td><td>10010-023</td><td></td></tr><tr><td>Primate ES Cell Medium</td><td>Reprocell</td><td>RCHEMD001</td><td>Human ESC Culture Media</td></tr><tr><td>Rhok inhibitor (Y-27632 dihydrochloride)</td><td>Tocris</td><td>1254</td><td></td></tr><tr><td>RPMI 1640</td><td>Gibco</td><td>11875093</td><td></td></tr><tr><td>Stem Cell Factor (SCF)</td><td>R&amp;amp;D Systems</td><td>455-MC</td><td></td></tr><tr><td>StemPro</td><td>EZPassage</td><td>23181-010</td><td></td></tr><tr><td>T2-tumor</td><td>ATCC</td><td>T2 (174 x CEM.T2) (ATCC&amp;reg; CRL-1992&amp;trade;)&amp;nbsp;</td><td></td></tr><tr><td>Trypsin-EDTA (0.05%), phenol red&amp;nbsp;</td><td>Thermo Fisher Scientific</td><td>25300-062</td><td></td></tr><tr><td>Trypsin-EDTA (0.25%), phenol red&amp;nbsp;</td><td>Thermo Fisher Scientific</td><td>25200-072</td><td></td></tr><tr><td>U Bottom 96 well plate</td><td>Corning, Inc.&amp;nbsp;</td><td>3799</td><td></td></tr></tbody></table>

using human induced pluripotent stem cells for the generation of tumor antigen-specific t cells

The generation and expansion of functional T cells in vitro can lead to a broad range of clinical applications. One such use is for the treatment of patients with advanced cancer. Adoptive T cell transfer (ACT) of highly enriched tumor antigen-specific T cells has been shown to cause durable regression of metastatic cancer in some patients. However, during expansion, these cells may become exhausted or senescent, limiting their effector function and persistence in vivo. Induced pluripotent stem cell (iPSC) technology may overcome these obstacles by leading to in vitro generation of large numbers of less differentiated tumor antigen-specific T cells. Human iPSC (hiPSC) have the capacity to differentiate into any type of somatic cell, including lymphocytes, which retain the original T cell receptor (TCR) genomic rearrangement when a T cell is used as a starting cell. Therefore, reprogramming of human tumor antigen-specific T cells to hiPSC followed by redifferentiation to T cell lineage has the potential to produce rejuvenated tumor antigen-specific T cells. Described here is a method for generating tumor antigen-specific CD8&#945;&#946;+ single positive (SP) T cells from hiPSC using OP9/DLL1 co-culture system. This method is a powerful tool for in vitro T cell lineage generation and will facilitate the development of in vitro derived T cells for use in regenerative medicine and cell-based therapies.

After 13 days hiPSCs co-culturing with OP9/DLL1, CD34+CD43+ hematopoietic progenitor cells appeared (Figure 1). After an additional 22 days of culture on non-gelatinized OP9/DLL1 in the presence of hSCF, hFLT3L, and hIL-7, hematopoietic progenitors differentiated into CD3+CD7+CD4+CD8+ double-positive (DP) T lineage cells, the majority of which expressed TCR specific to the MART-1 epitope (tetramer) (Figure 2).
It has previously been shown that CD8+ SP T cells can be induced from CD4+CD8+ DP T cells by TCR signaling via agonist peptide or antibody-driven TCR stimulation24,25. Therefore, on day 35 of culture, hiPSC-derived CD4+CD8+ DP T cells were stimulated with anti-human CD3 and anti-human CD28 antibodies in the presence of hIL-7 and hIL-2.&#160; Four days after stimulation, the number of CD3+CD8&#945;&#946;+ SP cells increased dramatically and remained specific for the MART-1 epitope, confirming the preservation of their inherited antigen-specificity (Figure 3).&#160;
To determine the functional properties of hiPSC-derived CD8&#945;&#946;+ SP T cells, antigen-dependent activation and secretion of interferon gamma (IFN-&#947;) was analyzed. After stimulation with anti-human CD3 and anti-human CD28 antibodies for 1 week, hiPSC-derived CD8&#945;&#946;+ SP T cells were isolated using a cell sorter and co-cultured with T2 cell line expressing HLA-A*02:01 with or without cognate MART1 peptide for 16 -&#160;20 h. The ELISpot assay revealed that hiPSC-derived CD8&#945;&#946;+ SP T cells secrete higher amounts of IFN-&#947; compared with CD8&#945;&#945;+ SP T cells, when cultured in the presence of MART-1 peptide. IFN-&#947; expression was null for T cells and APCs alone, demonstrating that human T-iPSC-derived T cells are antigen-specific and functional (Figure 4).
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/59997/59997fig1.jpg" /> 
Figure 1: Generation of hiPSC-derived hematopoietic progenitor cells. (A) Schematic overview of the differentiation of hiPSCs to hematopoietic lineage using OP9/DLL1 co-culture. (B) Appearance of hiPSC-derived structures on days 1 (top left), 3 (top right), 7 (bottom left), and 13 (bottom right). Scale bars = 100 &#181;m. (C) Flow cytometric analysis of hiPSC derived CD34+CD43+ hematopoietic progenitor cells on day 13. Data are representative of six independent experiments (n = 1 to 2). <a href="https://www.jove.com/files/ftp_upload/59997/59997fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/59997/59997fig2.jpg" /> 
Figure 2: hiPSC differentiation into Mart1+ CD4+CD8&#945;&#946;+ DP T cells. (A) Schematic overview of the differentiation of hiPSC-derived hematopoietic lineage to immature T cells using OP9/DLL1 co-culture. (B) Flow cytometric analysis of CD4 vs. CD8&#945;, CD3 vs. CD8&#946;, and MART-1 tetramer expression in hiPSC-derived T cells on day 35. Gated on lymphocytes, single cells, PI negative. Data are representative of three independent experiments (n = 3 -&#160;8). <a href="https://www.jove.com/files/ftp_upload/59997/59997fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/59997/59997fig3.jpg" /> 
Figure 3: Induction of CD8&#945;&#946;+ SP T cell phenotype. Flow cytometric analysis of CD4- hiPSC-derived T cells 4 days after human anti-CD3 and human anti-CD28 antibody-driven stimulation. Gated on lymphocytes, single cells, PI negative (n = 4). &#160; <a href="https://www.jove.com/files/ftp_upload/59997/59997fig3large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/59997/59997fig4.jpg" /> 
Figure 4: Antigen specificity of hiPSC-derived CD8&#945;&#946;+ SP T cells. IFN-&#947; secretion by ELISpot assay of hiPSC-derived CD8&#945;&#946;+ SP, CD8&#945;&#945;+ SP, and bulk T cells after 20 h co-culture with or without T2 cells pulsed (or not) with MART-1 peptide. <a href="https://www.jove.com/files/ftp_upload/59997/59997fig4large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Using Human Induced Pluripotent Stem Cells for the Generation of Tumor Antigen-specific T Cells at JoVE.com

Using Human Induced Pluripotent Stem Cells for the Generation of Tumor Antigen-specific T Cells

This article describes a method to generate functional tumor antigen-specific induced pluripotent stem cell-derived CD8&#945;&#946;+ single positive T cells using OP9/DLL1 co-culture system.

The generation and expansion of functional T cells in vitro can lead to a broad range of clinical applications. One such use is for the treatment of ...

using-human-induced-pluripotent-stem-cells-for-generation-tumor

Research

JoVE Journal

Cancer Research

10.3K Views.  National Cancer Institute, NIH. This article describes a method to generate functional tumor antigen-specific induced pluripotent stem cell-derived CD8αβ+ single positive T cells using OP9/DLL1 co-culture system.

Video: Using Human Induced Pluripotent Stem Cells for the Generation of Tumor Antigen-specific T Cells

Generation of Induced Pluripotent Stem Cells from Human Peripheral T Cells Using Sendai Virus in Feeder-free Conditions

Recently, iPSCs have attracted attention as a new source of cells for regenerative therapies. Although the initial method for generating iPSCs relied on dermal fibroblasts obtained by invasive biopsy and retroviral genomic insertion of transgenes, there have been many efforts to avoid these disadvantages. Human peripheral T cells are a unique cell source for generating iPSCs. iPSCs derived from T cells contain rearrangements of the T cell receptor (TCR) genes and are a source of antigen-specific T cells. Additionally, T cell receptor rearrangement in the genome has the potential to label individual cell lines and distinguish between transplanted and donor cells. For safe clinical application of iPSCs, it is important to minimize the risk of exposing newly generated iPSCs to harmful agents. Although fetal bovine serum and feeder cells have been essential for pluripotent stem cell culture, it is preferable to remove them from the culture system to reduce the risk of unpredictable pathogenicity. To address this, we have established a protocol for generating iPSCs from human peripheral T cells using Sendai virus to reduce the risk of exposing iPSCs to undefined pathogens. Although handling Sendai virus requires equipment with the appropriate biosafety level, Sendai virus infects activated T cells without genome insertion, yet with high efficiency. In this protocol, we demonstrate the generation of iPSCs from human peripheral T cells in feeder-free conditions using a combination of activated T cell culture and Sendai virus.

This protocol describes how to generate induced pluripotent stem cells (iPSCs) from human peripheral T cells in feeder-free conditions using a combination of matrigel and Sendai virus vectors containing reprogramming factors.

Recently, iPSCs have attracted attention as a new source of cells for regenerative therapies. Although the initial method for generating iPSCs relied on ...

Developmental Biology

Teratoma Generation in the Testis Capsule

Pluripotent stem cells (PSCs) have the unique characteristic that they can differentiate into cells from all three germ layers. This makes them a potentially valuable tool for the treatment of many different diseases. With the advent of induced pluripotent stem cells (iPSCs) and continuing research with human embryonic stem cells (hESCs) there is a need for assays that can demonstrate that a particular cell line is pluripotent. Germline transmission has been the gold standard for demonstrating the pluripotence of mouse embryonic stem cell (mESC) lines1,2,3. Using this assay, researchers can show that a mESC line can make all cell types in the embryo including germ cells4. With the generation of human ESC lines5,6, the appropriate assay to prove pluripotence of these cells was unclear since human ESCs cannot be tested for germline transmission. As a surrogate, the teratoma assay is currently used to demonstrate the pluripotency of human pluripotent stem cells (hPSCs)7,8,9. Though this assay has recently come under scrutiny and new technologies are being actively explored, the teratoma assay is the current gold standard7. In this assay, the cells in question are injected into an immune compromised mouse. If the cells are pluripotent, a teratoma will eventually develop and sections of the tumor will show tissues from all 3 germ layers10. In the teratoma assay, hPSCs can be injected into different areas of the mouse. The most common injection sites include the testis capsule, the kidney capsule, the liver; or into the leg either subcutaneously or intramuscularly11. Here we describe a robust protocol for the generation of teratomas from hPSCs using the testis capsule as the site for tumor growth.

Human pluripotent stem cells (hPSCs) have the potential to treat a myriad of different diseases. The utility of these cells lies in the fact that they can differentiate into any cell type in the body. Here we describe the teratoma assay, which is used to demonstrate the pluripotence of hPSCs.

Pluripotent stem cells (PSCs) have the unique characteristic that they can differentiate into cells from all three germ layers.  This makes them a ...

Medicine

Generation of Induced Pluripotent Stem Cells from Human Melanoma Tumor-infiltrating Lymphocytes

Adoptive transfer of ex vivo expanded autologous tumor-infiltrating lymphocytes (TILs) can mediate durable and complete responses in significant subsets of patients with metastatic melanoma. Major obstacles of this approach are the reduced viability of transferred T cells, caused by telomere shortening, and the limited number of TILs obtained from patients. Less-differentiated T cells with long telomeres would be an ideal T cell subset for adoptive T cell therapy;however, generating large numbers of these less-differentiated T cells is problematic. This limitation of adoptive T cell therapy can be theoretically overcome by using induced pluripotent stem cells (iPSCs) that self-renew, maintain pluripotency, have elongated telomeres, and provide an unlimited source of autologous T cells for immunotherapy. Here, we present a protocol to generate iPSCs using Sendai virus vectors for the transduction of reprogramming factors into TILs. This protocol generates fully reprogrammed, vector-free clones. These TIL-derived iPSCs might be able to generate less-differentiated patient- and tumor-specific T cells for adoptive T cell therapy.

The goal of this protocol is to show the protocol for reprogramming melanoma tumor-infiltrating lymphocytes into induced pluripotent stem cells.

Adoptive transfer of ex vivo expanded autologous tumor-infiltrating lymphocytes (TILs) can mediate durable and complete responses in significant subsets ...

A Three-dimensional Thymic Culture System to Generate Murine Induced Pluripotent Stem Cell-derived Tumor Antigen-specific Thymic Emigrants

The inheritance of pre-rearranged T cell receptors (TCRs) and their epigenetic rejuvenation make induced pluripotent stem cell (iPSC)-derived T cells a promising source for adoptive T cell therapy (ACT). However, classical in vitro methods for producing regenerated T cells from iPSC result in either innate-like or terminally differentiated T cells, which are phenotypically and functionally distinct from na&#239;ve T cells. Recently, a novel three-dimensional (3D) thymic culture system was developed to generate a homogenous subset of CD8&#945;&#946;+ antigen-specific T cells with a na&#239;ve T cell-like functional phenotype, including the capacity for proliferation, memory formation, and tumor suppression in vivo. This protocol avoids aberrant developmental fates, allowing for the generation of clinically relevant iPSC-derived T cells, designated as iPSC-derived thymic emigrants (iTE), while also providing a potent tool to elucidate the subsequent functions necessary for T cell maturation after thymic selection.

This article describes a novel method to generate tumor antigen-specific induced pluripotent stem cell-derived thymic emigrants (iTE) by a three-dimensional (3D) thymic culture system. iTE are a homogenous subset of T cells closely related to na&#239;ve T cells with the capacity for proliferation, memory formation, and tumor suppression.

The inheritance of pre-rearranged T cell receptors (TCRs) and their epigenetic rejuvenation make induced pluripotent stem cell (iPSC)-derived T cells a ...

Directed Differentiation of Induced Pluripotent Stem Cells towards T Lymphocytes

Adoptive cell transfer (ACT) of antigen-specific CD8+ cytotoxic T lymphocytes (CTLs) is a promising treatment for a variety of malignancies 1. CTLs can recognize malignant cells by interacting tumor antigens with the T cell receptors (TCR), and release cytotoxins as well as cytokines to kill malignant cells. It is known that less-differentiated and central-memory-like (termed highly reactive) CTLs are the optimal population for ACT-based immunotherapy, because these CTLs have a high proliferative potential, are less prone to apoptosis than more differentiated cells and have a higher ability to respond to homeostatic cytokines 2-7. However, due to difficulties in obtaining a high number of such CTLs from patients, there is an urgent need to find a new approach to generate highly reactive Ag-specific CTLs for successful ACT-based therapies.
TCR transduction of the self-renewable stem cells for immune reconstitution has a therapeutic potential for the treatment of diseases 8-10. However, the approach to obtain embryonic stem cells (ESCs) from patients is not feasible. Although the use of hematopoietic stem cells (HSCs) for therapeutic purposes has been widely applied in clinic 11-13, HSCs have reduced differentiation and proliferative capacities, and HSCs are difficult to expand in in vitro cell culture 14-16. Recent iPS cell technology and the development of an in vitro system for gene delivery are capable of generating iPS cells from patients without any surgical approach. In addition, like ESCs, iPS cells possess indefinite proliferative capacity in vitro, and have been shown to differentiate into hematopoietic cells. Thus, iPS cells have greater potential to be used in ACT-based immunotherapy compared to ESCs or HSCs.
Here, we present methods for the generation of T lymphocytes from iPS cells in vitro, and in vivo programming of antigen-specific CTLs from iPS cells for promoting cancer immune surveillance. Stimulation in vitro with a Notch ligand drives T cell differentiation from iPS cells, and TCR gene transduction results in iPS cells differentiating into antigen-specific T cells in vivo, which prevents tumor growth. Thus, we demonstrate antigen-specific T cell differentiation from iPS cells. Our studies provide a potentially more efficient approach for generating antigen-specific CTLs for ACT-based therapies and facilitate the development of therapeutic strategies for diseases.

Generation of T lymphocytes from induced pluripotent stem (iPS) cells gives an alternative approach of using embryonic stem cells for T cell-based immunotherapy. The method shows that by utilizing either in vitro or in vivo induction system, iPS cells are able to differentiate into both conventional and antigen-specific T lymphocytes.

Adoptive cell transfer (ACT) of antigen-specific CD8+  cytotoxic T lymphocytes (CTLs) is a promising treatment for a variety of  malignancies 1. CTLs can  ...

Immunology and Infection

Using the BLT Humanized Mouse as a Stem Cell based Gene Therapy Tumor Model

Small animal models such as mice have been extensively used to study human disease and to develop new therapeutic interventions. Despite the wealth of information gained from these studies, the unique characteristics of mouse immunity as well as the species specificity of viral diseases such as human immunodeficiency virus (HIV) infection led to the development of humanized mouse models. The earlier models involved the use of C. B 17 scid/scid mice and the transplantation of human fetal thymus and fetal liver termed thy/liv (SCID-hu) 1, 2 or the adoptive transfer of human peripheral blood leukocytes (SCID-huPBL) 3. Both models were mainly utilized for the study of HIV infection.
One of the main limitations of both of these models was the lack of stable reconstitution of human immune cells in the periphery to make them a more physiologically relevant model to study HIV disease. To this end, the BLT humanized mouse model was developed. BLT stands for bone marrow/liver/thymus. In this model, 6 to 8 week old NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) immunocompromised mice receive the thy/liv implant as in the SCID-hu mouse model only to be followed by a second human hematopoietic stem cell transplant 4. The advantage of this system is the full reconstitution of the human immune system in the periphery. This model has been used to study HIV infection and latency 5-8.
We have generated a modified version of this model in which we use genetically modified human hematopoietic stem cells (hHSC) to construct the thy/liv implant followed by injection of transduced autologous hHSC 7, 9. This approach results in the generation of genetically modified lineages. More importantly, we adapted this system to examine the potential of generating functional cytotoxic T cells (CTL) expressing a melanoma specific T cell receptor. Using this model we were able to assess the functionality of our transgenic CTL utilizing live positron emission tomography (PET) imaging to determine tumor regression (9).
The goal of this protocol is to describe the process of generating these transgenic mice and assessing in vivo efficacy using live PET imaging. As a note, since we use human tissues and lentiviral vectors, our facilities conform to CDC NIH guidelines for Biosafety Level 2 (BSL2) with special precautions (BSL2+). In addition, the NSG mice are severely immunocompromised thus, their housing and maintenance must conform to the highest health standards (<a href="http://jaxmice.jax.org/research/immunology/005557-housing.html" target="_blank">http://jaxmice.jax.org/research/immunology/005557-housing.html</a>).

The generation and characterization of tumor specific T cells using humanized mice is described here. Human thymic tissue and genetically modified human hematopoietic stem cells are transplanted into immunocompromised mice. This results in the reconstitution of an engineered human immune system allowing for in vivo examination of anti-tumor immune responses.

Small animal models such as mice have been extensively used to study human  disease and to develop new therapeutic interventions. Despite the wealth of  ...

Generation of Human Alloantigen-specific T Cells from Peripheral Blood

The study of human T lymphocyte biology often involves examination of responses to activating ligands. T cells recognize and respond to processed peptide antigens presented by MHC (human ortholog HLA) molecules through the T cell receptor (TCR) in a highly sensitive and specific manner. While the primary function of T cells is to mediate protective immune responses to foreign antigens presented by self-MHC, T cells respond robustly to antigenic differences in allogeneic tissues. T cell responses to alloantigens can be described as either direct or indirect alloreactivity. In alloreactivity, the T cell responds through highly specific recognition of both the presented peptide and the MHC molecule. The robust oligoclonal response of T cells to allogeneic stimulation reflects the large number of potentially stimulatory alloantigens present in allogeneic tissues. While the breadth of alloreactive T cell responses is an important factor in initiating and mediating the pathology associated with biologically-relevant alloreactive responses such as graft versus host disease and allograft rejection, it can preclude analysis of T cell responses to allogeneic ligands. To this end, this protocol describes a method for generating alloreactive T cells from naive human peripheral blood leukocytes (PBL) that respond to known peptide-MHC (pMHC) alloantigens. The protocol applies pMHC multimer labeling, magnetic bead enrichment and flow cytometry to single cell in vitro culture methods for the generation of alloantigen-specific T cell clones. This enables studies of the biochemistry and function of T cells responding to allogeneic stimulation.

This article describes a method for the generation and propagation of human T cell clones that specifically respond to a defined alloantigen. This protocol can be adapted for cloning human T cells specific for a variety of peptide-MHC ligands.

The study of human T lymphocyte biology often involves examination of responses to activating ligands. T cells recognize and respond to processed peptide ...

Development of Stem Cell-derived Antigen-specific Regulatory T Cells Against Autoimmunity

Autoimmune diseases arise due to the loss of immunological self-tolerance. Regulatory T cells (Tregs) are important mediators of immunologic self-tolerance. Tregs represent about 5 - 10% of the mature CD4+ T cell subpopulation in mice and humans, with about 1 - 2% of those Tregs circulating in the peripheral blood. Induced pluripotent stem cells (iPSCs) can be differentiated into functional Tregs, which have a potential to be used for cell-based therapies of autoimmune diseases. Here, we present a method to develop antigen (Ag)-specific Tregs from iPSCs (i.e., iPSC-Tregs). The method is based on incorporating the transcription factor FoxP3 and an Ag-specific T cell receptor (TCR) into iPSCs and then differentiating on OP9 stromal cells expressing Notch ligands delta-like (DL) 1 and DL4. Following in vitro differentiation, the iPSC-Tregs express CD4, CD8, CD3, CD25, FoxP3, and Ag-specific TCR and are able to respond to Ag stimulation. This method has been successfully applied to cell-based therapy of autoimmune arthritis in a murine model. Adoptive transfer of these Ag-specific iPSC-Tregs into Ag-induced arthritis (AIA)-bearing mice has the ability to reduce joint inflammation and swelling and to prevent bone loss.

We present here a method to develop functional antigen (Ag)-specific regulatory T cells (Tregs) from induced pluripotent stem cells (iPSCs) for immunotherapy of autoimmune arthritis in a murine model.

Autoimmune diseases arise due to the loss of immunological self-tolerance. Regulatory T cells (Tregs) are important mediators of immunologic ...

Stem Cell-Derived Viral Ag-Specific T Lymphocytes Suppress HBV Replication in Mice

Hepatitis B virus (HBV) infection is a global health issue. With over 350 million people affected worldwide, HBV infection remains the leading cause of liver cancer. This is a major concern, especially in developing countries. Failure of the immune system to mount an effective response against HBV leads to chronic infection. Although HBV vaccine is present and novel antiviral medicines are being created, eradication of virus-reservoir cells remains a major health topic. Described here is a method for the generation of viral antigen (Ag) -specific CD8+ cytotoxic T lymphocytes (CTLs) derived from induced pluripotent stem cells (iPSCs) (i.e., iPSC-CTLs), which have the ability to suppress HBV replication. HBV replication is efficiently induced in mice through hydrodynamic injection of an HBV expression plasmid, pAAV/HBV1.2, into the liver. Then, HBV surface Ag-specific mouse iPSC-CTLs are adoptively transferred, which greatly suppresses HBV replication in the liver and blood as well as prevents HBV surface Ag expression in hepatocytes. This method demonstrates HBV replication in mice after hydrodynamic injection and that stem cell-derived viral Ag-specific CTLs can suppress HBV replication. This protocol provides a useful method for HBV immunotherapy.

Presented here is a protocol for the effective suppression of hepatitis B virus (HBV) replication in mice by utilizing adoptive cell transfer (ACT) of stem cell-derived viral antigen (Ag)-specific T lymphocytes. This procedure may be adapted for potential ACT-based immunotherapy of HBV infection.

Hepatitis B virus (HBV) infection is a global health issue. With over 350 million people affected worldwide, HBV infection remains the leading cause of ...

Three-Dimensional Thymic Culture System to Generate iPSC-Derived Thymic Emigrants

Source: Vizcardo, R., et al. <a href="https://app.jove.com/v/58672">A Three-dimensional Thymic Culture System to Generate Murine Induced Pluripotent Stem Cell-derived Tumor Antigen-specific Thymic Emigrants.</a> J. Vis. Exp. (2019).
This video demonstrates a protocol for generating functional antigen-specific T cells from iPSC-derived immature T cells using a three-dimensional thymic culture system. Co-culturing the iPSC-derived immature T cells with endogenous lymphocyte-depleted mice fetal thymic lobes resulted in successful maturation of the T cells to form CD8&#945;&#946;+ MHC class I+ iPSC-derived thymic emigrants (iTEs).

Trójwymiarowy system hodowli grasicy do generowania emigrantów grasicy pochodzących od iPSC

Source: Vizcardo, R., et al. A Three-dimensional Thymic Culture System to Generate Murine Induced Pluripotent Stem Cell-derived Tumor Antigen-specific ...