This study was supported by grants from the National Natural Science Fund for Distinguished Young Scholars (No. 31825011 to LY) and the National Natural Science Foundation of China (No. 31900643 to QH, No. 31900656 to ZW).

<ol>
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The authors have no conflicts of interest to disclose.

T cell-mediated immunity plays a crucial role in immune responses against tumors, with CTLs playing the leading role in eradicating cancerous cells. However, the origins of tumor antigen-specific CTLs within TME have not been elucidated30. The use of this tumor transplantation protocol has provided an important clue that intratumoral antigen-specific CD8+ T cells may not persist for a long time, despite the existence of stem-like TCF1+ progenitor CD8+ T cells. Nota...

An erratum was issued for:&#160;<a href="https://www.jove.com/t/62442">Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+&#160;T Cells in Mice</a>. The Protocol&#160;was&#160;updated.
Step 6.10 of the Protocol was updated from:
Administer penicillin every 8-12 h after the surgery for 3 days. Monitor the mouse&#39;s eating, drinking, moving, and the area operated on. Return the transplant recipient to the company of other animals only after it has fully recovered. 
NOTE: The administration of buprenorphine is suggested to prevent post-surgical pain [delete sentence]. The mouse typically recovers from the trauma of the surgery within 3 days. If the mouse is not back to normal feeding and mobility and shows any manifestations of infection, consult a veterinarian for interventions or euthanize it.
to:
Administer buprenorphine subcutaneously at a dose of 0.1 mg/kg body weight every 8 h three times after surgery to alleviate the pain. Monitor the mouse&#39;s eating, drinking, moving, and the area operated on. Return the transplant recipient to the company of other animals only after it has fully recovered. 
NOTE: The mouse typically recovers from the trauma of the surgery within 3 days. If the mouse is not back to normal feeding and mobility and shows any manifestations of infection, consult a veterinarian for interventions or euthanize it.

An erratum was issued for:&#160;<a href="https://www.jove.com/t/62442">Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+&#160;T Cells in Mice</a>. The Protocol&#160;was&#160;updated.

Erratum: Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+ T Cells in Mice

CD8+ T cell-mediated immune response plays a pivotal role in controlling tumor growth. During tumorigenesis, naive CD8+ T cells get activated upon antigen recognition in an MHC class I-restricted manner and subsequently differentiate into effector cells and infiltrate into tumor mass1,2. However, within the tumor microenvironment (TME), prolonged antigen exposure, as well as immunosuppressive factors, drive infiltrated tumor-specific CD8+ T cells into a hyporesponsive state known as &#34;exhaustion&#34;3. Exhausted T cells (Tex) are distinct from effector or memory T cells generated in acute viral infection, both transcriptionally and epigenetically. These Tex cells are mainly characterized by the sustained and elevated expression of a series of inhibitory receptors as well as the hierarchical loss of effector functions. Further, the impaired proliferative capacity of exhausted CD8+ T cells results in decreasing numbers of tumor-specific T cells, such that the residual CD8+ T cells within the TME can barely provide sufficient protective immunity against tumor progression3. Thus, the maintenance or reinforcement of intratumoral antigen-specific CD8+ T cells is indispensable for tumor repression.
Moreover, immune checkpoint blockade (ICB) therapy is believed to reinvigorate Tex in tumors by increasing T cell infiltration and hence, T cell numbers and rejuvenating T cell functions to boost tumor repression. The widespread application of ICB treatment has changed the cancer therapy landscape, with a substantial subset of patients experiencing durable responses4,5,6. Nevertheless, the majority of patients and cancer types do not or only temporarily respond to ICB. Inadequate T cell infiltration in the TME has been postulated to be one of the underlying mechanisms accounting for ICB resistance7,8.
Several studies have demonstrated the heterogeneity of tumor-infiltrating CD8+ T cells (TILs) in both patients and mouse models9,10,11,12. It has been confirmed that a subset of CD8+ T cells expressing T cell factor-1 (TCF1) in a tumor mass exhibits stem cell-like properties, which could further give rise to terminally exhausted T cells and is responsible for the proliferation burst after ICB therapy12,13,14,15,16,17,18,19,20,21,22. However, it has been proved that only a small proportion of antigen-specific TCF1+CD8+ T cells exist in the TME and generate an expanded pool of differentiated progeny in response to ICB23,24,25,26. Whether the limited size of this population is enough to ensure the persistence of cytotoxic T lymphocytes (CTLs) to control tumor progression remains unknown, and whether there is replenishment from periphery tissues requires further investigation. Furthermore, recent research suggests the insufficient reinvigoration capacity of pre-existing tumor-specific T cells and the appearance of novel, previously non-existing clonotypes after anti-programmed cell death protein 1 treatment. This indicates that T cell response to checkpoint blockade may be due to the new influx of a distinct repertoire of T cell clones27. Together with the presence of bystander non-tumor-reactive cytotoxic T cell fraction in the TME, these findings prompted the establishment of a tumor allograft model to study the role of periphery-derived CD8+ T cells11.
Until now, several kinds of tumor implantation, as well as immune cell adoptive transfer, have been widely used in the field of tumor immunology28. TILs, peripheral blood mononuclear cells, and tumor-reactive immune cells originated from other tissues can be well-characterized using these methods. However, when studying the interactions between systemic and local antitumor immunity, these models appear inadequate to examine the interactions between immune cells derived from the periphery and the TME. Here, tumor tissues were transplanted from donors into tumor-matched recipient mice to precisely trace the influx of recipient-derived immune cells and observe the donor-derived cells in the TME concomitantly.
In this study, a murine syngeneic model of melanoma was established with the B16F10-OVA melanoma cell line, which stably expresses the surrogate neoantigen ovalbumin. TCR transgenic OT-I mice, in which over 90% of CD8+ T cells specifically recognize the OVA-derived peptide OVA257-264 (SIINFEKL) bound to the class I MHC molecule H2-Kb, enable the study of antigen-specific T cell responses developed in the B16F10-OVA tumor model. Combining this model with tumor transplantation, the immune responses of tumor-inherent and periphery-originated antigen-specific CD8+ T cells were compared to reveal a dynamic transition between these two populations. Collectively, this experimental design has provided another approach to precisely investigate the immune responses of CD8+ T cells in the TME, which sheds new light on the dynamics of tumor-specific T cell immune responses in the TME.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>0.22 &#956;m filter</td>
			<td>Millipore</td>
			<td>SLGPR33RB</td>
			<td></td>
		</tr>
		<tr>
			<td>1 mL tuberculin syringe</td>
			<td>KDL</td>
			<td>BB000925</td>
			<td></td>
		</tr>
		<tr>
			<td>1.5 mL centrifuge tube</td>
			<td>KIRGEN</td>
			<td>KG2211</td>
			<td></td>
		</tr>
		<tr>
			<td>100 U insulin syringe</td>
			<td>BD Biosciences</td>
			<td>320310</td>
			<td></td>
		</tr>
		<tr>
			<td>15 mL conical tube</td>
			<td>BEAVER</td>
			<td>43008</td>
			<td></td>
		</tr>
		<tr>
			<td>2,2,2-Tribromoethanol (Avertin)</td>
			<td>Sigma</td>
			<td>T48402-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>2-Methyl-2-butanol</td>
			<td>Sigma</td>
			<td>240486-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>70 &#956;m nylon cell strainer</td>
			<td>BD Falcon</td>
			<td>352350</td>
			<td></td>
		</tr>
		<tr>
			<td>APC anti-mouse CD45.1</td>
			<td>BioLegend</td>
			<td>110714</td>
			<td>Clone:A20</td>
		</tr>
		<tr>
			<td>B16F10-OVA cell line</td>
			<td>bluefbio</td>
			<td>BFN607200447</td>
			<td></td>
		</tr>
		<tr>
			<td>BSA-V (bovine serum albumin)</td>
			<td>Bioss</td>
			<td>bs-0292P</td>
			<td></td>
		</tr>
		<tr>
			<td>BV421 Mouse Anti-Mouse CD45.2</td>
			<td>BD Horizon</td>
			<td>562895</td>
			<td>Clone:104</td>
		</tr>
		<tr>
			<td>cell culture dish</td>
			<td>BEAVER</td>
			<td>43701/43702/43703</td>
			<td></td>
		</tr>
		<tr>
			<td>centrifuge</td>
			<td>Eppendorf</td>
			<td>5810R-A462/5424R</td>
			<td></td>
		</tr>
		<tr>
			<td>cyclophosphamide</td>
			<td>Sigma</td>
			<td>C0768-25G</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Modified Eagle Medium</td>
			<td>Gibco</td>
			<td>C11995500BT</td>
			<td></td>
		</tr>
		<tr>
			<td>EasySep Mouse CD8+ T Cell Isolation Kit</td>
			<td>Stemcell Technologies</td>
			<td>19853</td>
			<td></td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma</td>
			<td>EDS-500g</td>
			<td></td>
		</tr>
		<tr>
			<td>FACS tubes</td>
			<td>BD Falcon</td>
			<td>352052</td>
			<td></td>
		</tr>
		<tr>
			<td>fetal bovine serum</td>
			<td>Gibco</td>
			<td>10270-106</td>
			<td></td>
		</tr>
		<tr>
			<td>flow cytometer</td>
			<td>BD</td>
			<td>FACSCanto II</td>
			<td></td>
		</tr>
		<tr>
			<td>hemocytometer</td>
			<td>PorLab Scientific</td>
			<td>HM330</td>
			<td></td>
		</tr>
		<tr>
			<td>isoflurane</td>
			<td>RWD life science</td>
			<td>R510-22-16</td>
			<td></td>
		</tr>
		<tr>
			<td>KHCO3</td>
			<td>Sangon Biotech</td>
			<td>A501195-0500</td>
			<td></td>
		</tr>
		<tr>
			<td>LIVE/DEAD Fixable Near-IR Dead Cell Stain Kit, for 633 or 635 nm excitation</td>
			<td>Life Technologies</td>
			<td>L10199</td>
			<td></td>
		</tr>
		<tr>
			<td>needle carrier</td>
			<td>RWD Life Science</td>
			<td>F31034-14</td>
			<td></td>
		</tr>
		<tr>
			<td>NH4Cl</td>
			<td>Sangon Biotech</td>
			<td>A501569-0500</td>
			<td></td>
		</tr>
		<tr>
			<td>paraformaldehyde</td>
			<td>Beyotime</td>
			<td>P0099-500ml</td>
			<td></td>
		</tr>
		<tr>
			<td>PE anti-mouse TCR V&#945;2</td>
			<td>BioLegend</td>
			<td>127808</td>
			<td>Clone:B20.1</td>
		</tr>
		<tr>
			<td>Pen Strep Glutamine (100x)</td>
			<td>Gibco</td>
			<td>10378-016</td>
			<td></td>
		</tr>
		<tr>
			<td>PerCP/Cy5.5 anti-mouse CD8a</td>
			<td>BioLegend</td>
			<td>100734</td>
			<td>Clone:53-6.7</td>
		</tr>
		<tr>
			<td>RPMI-1640</td>
			<td>Sigma</td>
			<td>R8758-500ML</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium azide</td>
			<td>Sigma</td>
			<td>S2002</td>
			<td></td>
		</tr>
		<tr>
			<td>surgical forceps</td>
			<td>RWD Life Science</td>
			<td>F12005-10</td>
			<td></td>
		</tr>
		<tr>
			<td>surgical scissors</td>
			<td>RWD Life Science</td>
			<td>S12003-09</td>
			<td></td>
		</tr>
		<tr>
			<td>suture thread</td>
			<td>RWD Life Science</td>
			<td>F34004-30</td>
			<td></td>
		</tr>
		<tr>
			<td>trypsin-EDTA</td>
			<td>Sigma</td>
			<td>T4049-100ml</td>
			<td></td>
		</tr>
	</tbody>
</table>

tumor transplantation for assessing the dynamics of tumor-infiltrating cd8+ t cells in mice

T cell-mediated immunity plays a crucial role in immune responses against tumors, with cytotoxic T lymphocytes (CTLs) playing the leading role in eradicating cancerous cells. However, the origins and replenishment of tumor antigen-specific CD8+ T cells within the tumor microenvironment (TME) remain obscure. This protocol employs the B16F10-OVA melanoma cell line, which stably expresses the surrogate neoantigen, ovalbumin (OVA), and TCR transgenic OT-I mice, in which over 90% of CD8+ T cells specifically recognize the OVA-derived peptide OVA257-264 (SIINFEKL) bound to the class I major histocompatibility complex (MHC) molecule H2-Kb. These features enable the study of antigen-specific T cell responses during tumorigenesis.
Combining this model with tumor transplantation surgery, tumor tissues from donors were transplanted into tumor-matched syngeneic recipient mice to precisely trace the influx of recipient-derived immune cells into transplanted donor tissues, allowing the analysis of the immune responses of tumor-inherent and periphery-originated antigen-specific CD8+ T cells. A dynamic transition was found to occur between these two populations. Collectively, this experimental design has provided another approach to precisely investigate the immune responses of CD8+ T cells in TME, which will shed new light on tumor immunology.

The schematic of this protocol is shown in Figure 1. Eight days after tumor inoculation, CD45.1+ and CD45.1+CD45.2+ OT-I cells were injected into B16F10-OVA tumor-bearing C57BL/6 mice. The tumor was surgically dissected from CD45.1+ OT-I cell-implanted mice (donor) on day 8 post-transfer and transplanted into tumor-matched CD45.1+CD45.2+ OT-I cell-implanted mice (recipient) in the dorsal flank on the same side as the implanted...

Watch this Scientific Journal Video about Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+ T Cells in Mice at JoVE.com

Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+ T Cells in Mice

Here, we present a tumor transplantation protocol for the characterization of tumor-inherent and periphery-derived tumor-infiltrated lymphocytes in a mouse tumor model. Specific tracing of the influx of recipient-derived immune cells with flow cytometry reveals the dynamics of the phenotypic and functional changes of these cells during antitumor immune responses.

Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+ T Cells in Mice

T cell-mediated immunity plays a crucial role in immune responses against tumors, with cytotoxic T lymphocytes (CTLs) playing the leading role in ...

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Research

JoVE Journal

Cancer Research

6.2K Views.  Third Military Medical University. Here, we present a tumor transplantation protocol for the characterization of tumor-inherent and periphery-derived tumor-infiltrated lymphocytes in a mouse tumor model. Specific tracing of the influx of recipient-derived immune cells with flow cytometry reveals the dynamics of the phenotypic and functional changes of these cells during antitumor immune responses.

Video: Tumor Transplantation for Assessing the Dynamics of Tumor-Infiltrating CD8+ T Cells in Mice

Ex Vivo Imaging of Resident CD8 T Lymphocytes in Human Lung Tumor Slices Using Confocal Microscopy

CD8 T cell are key players in the fight against cancer. In order for CD8 T cells to kill tumor cells they need to enter into the tumor, migrate within the tumor microenvironment and respond adequately to tumor antigens. The recent development of improved imaging approaches, such as 2-photon microscopy, and the use of powerful mouse tumor models have shed light on some of the mechanisms that regulate anti-tumor T cell activities. Whereas such systems have provided valuable insights, they do not always predict human responses. In human, our knowledge in the field mainly comes from a description of fixed tumor samples from human patients, as well as in vitro studies. However, in vitro models lack the complex three-dimensional tumor milieu and, therefore, are incomplete approximations of in vivo T cell activities. Fresh slices made from explanted tissue represent a complex multi-cellular tumor environment that can act as an important link between co-cultured studies and animal models. Originally set up in murine lymph nodes1 and previously described in a JoVE article2, this approach has now been transposed to human tumors to examine the dynamics of both plated3&#160;as well as resident&#160;T cells4.
Here, a protocol for the preparation of human lung tumor slices, immunostaining of resident CD8 T and tumor cells, and tracking of CD8 T lymphocytes within the tumor microenvironment using confocal microscopy is described. This system is uniquely placed to screen for novel immunotherapy agents favoring T cell migration in tumors.

Ex Vivo Imaging of Resident CD8 T Lymphocytes in Human Lung Tumor Slices Using Confocal Microscopy

This protocol describes a method to image resident tumor-infiltrating CD8 T cells labeled with fluorescently coupled antibodies within human lung tumor slices. This technique permits real-time analyses of CD8 T cell migration using confocal microscopy.

CD8 T cell are key players in the fight against cancer. In order for CD8 T cells to kill tumor cells they need to enter into the tumor, migrate within the ...

Real Time Detection of In Vitro Tumor Cell Apoptosis Induced by CD8+ T Cells to Study Immune Suppressive Functions of Tumor-infiltrating Myeloid Cells

Potentiation of the tumor-killing ability of CD8+ T cells in tumors, along with their efficient tumor infiltration, is a key element of successful immunotherapies. Several studies have indicated that tumor infiltrating myeloid cells (e.g., myeloid-derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs)) suppress cytotoxicity of CD8+ T cells in the tumor microenvironment, and that targeting these regulatory myeloid cells can improve immunotherapies. Here, we present an in vitro assay system to evaluate immune suppressive effects of monocytic-MDSCs and TAMs on the tumor-killing ability of CD8+ T cells. To this end, we first cultured na&#239;ve splenic CD8+ T cells with anti-CD3/CD28 activating antibodies in the presence or absence of suppressor cells, and then co-cultured the pre-activated T cells with target cancer cells in the presence of a fluorogenic caspase-3 substrate. Fluorescence from the substrate in cancer cells was detected by real-time fluorescence microscopy as an indicator of T-cell induced tumor cell apoptosis. In this assay, we can successfully detect the increase of tumor cell apoptosis by CD8+ T cells and its suppression by pre-culture with TAMs or MDSCs. This functional assay is useful for investigating CD8+ T cell suppression mechanisms by regulatory myeloid cells and identifying druggable targets to overcome it via high throughput screening.

Real Time Detection of In Vitro Tumor Cell Apoptosis Induced by CD8+ T Cells to Study Immune Suppressive Functions of Tumor-infiltrating Myeloid Cells

We describe here a protocol to investigate cytotoxicity of pre-activated CD8+ T cells against cancer cells by detecting apoptotic cancer cells via real-time microscopy. This protocol can investigate mechanisms behind myeloid cell-induced T cell suppression and evaluate compounds aimed at replenishing T cells via blockade of immune suppressive myeloid cells.

Potentiation of the tumor-killing ability of CD8+ T cells in tumors, along with their efficient tumor infiltration, is a key element of successful ...

In Vitro Tumor Cell Rechallenge For Predictive Evaluation of Chimeric Antigen Receptor T Cell Antitumor Function

The field of chimeric antigen receptor (CAR) T cell therapy is rapidly advancing with improvements in CAR design, gene-engineering approaches and manufacturing optimizations. One challenge for these development efforts, however, has been the establishment of in vitro assays that can robustly inform selection of the optimal CAR T cell products for in vivo therapeutic success. Standard in vitro tumor-lysis assays often fail to reflect the true antitumor potential of the CAR T cells due to the relatively short co-culture time and high T cell to tumor ratio. Here, we describe an in vitro co-culture method to evaluate CAR T cell recursive killing potential at high tumor cell loads. In this assay, long-term cytotoxic function and proliferative capacity of CAR T cells is examined in vitro over 7 days with additional tumor targets administered to the co-culture every other day. This assay can be coupled with profiling T cell activation, exhaustion and memory phenotypes. Using this assay, we have successfully distinguished the functional and phenotypic differences between CD4+ and CD8+ CAR T cells against glioblastoma (GBM) cells, reflecting their differential in vivo antitumor activity in orthotopic xenograft models. This method provides a facile approach to assess CAR T cell potency and to elucidate the functional variations across different CAR T cell products.

Here, we describe an in vitro co-culture method to recursively challenge tumor-targeted T cells, which allows for phenotypic and functional analysis of antitumor T cell activity.

The field of chimeric antigen receptor (CAR) T cell therapy is rapidly advancing with improvements in CAR design, gene-engineering approaches and ...

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.

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 ...

Generation of Orthotopic Pancreatic Tumors and Ex vivo Characterization of Tumor-Infiltrating T Cell Cytotoxicity

In vivo models of pancreatic cancer provide invaluable tools for studying disease dynamics, immune infiltration and new therapeutic strategies. The orthotopic murine model can be performed on large cohorts of immunocompetent mice simultaneously, is relatively inexpensive and preserves the cognate tissue microenvironment. The quantification of T cell infiltration and cytotoxic activity within orthotopic tumors provides a useful indicator of an antitumoral response.
This protocol describes the methodology for surgical generation of orthotopic pancreatic tumors by injection of a low number of syngeneic tumor cells resuspended in 5 &#181;L basement membrane directly into the pancreas. Mice bearing orthotopic tumors take approximately 30 days to reach endpoint, at which point tumors can be harvested and processed for characterization of tumor-infiltrating T cell activity. Rapid enzymatic digestion using collagenase and DNase allows a single-cell suspension to be extracted from tumors. The viability and cell surface markers of immune cells extracted from the tumor are preserved; therefore, it is appropriate for multiple downstream applications, including flow-assisted cell sorting of immune cells for culture or RNA extraction, flow cytometry analysis of immune cell populations. Here, we describe the ex vivo stimulation of T cell populations for intracellular cytokine quantification (IFN&#947; and TNF&#945;) and degranulation activity (CD107a) as a measure of overall cytotoxicity. Whole-tumor digests were stimulated with phorbol myristate acetate and ionomycin for 5 h, in the presence of anti-CD107a antibody in order to upregulate cytokine production and degranulation. The addition of brefeldin A and monensin for the final 4 h was performed to block extracellular transport and maximize cytokine detection. Extra- and intra-cellular staining of cells was then performed for flow cytometry analysis, where the proportion of IFN&#947;+, TNF&#945;+ and CD107a+ CD4+ and CD8+ T cells was quantified.
This method provides a starting base to perform comprehensive analysis of the tumor microenvironment.

Generation of Orthotopic Pancreatic Tumors and Ex vivo Characterization of Tumor-Infiltrating T Cell Cytotoxicity

This protocol describes the surgical generation of orthotopic pancreatic tumors and the rapid digestion of freshly isolated murine pancreatic tumors. Following digestion, viable immune cell populations can be used for further downstream analysis, including ex vivo stimulation of T cells for intracellular cytokine detection by flow cytometry.

In vivo models of pancreatic cancer provide invaluable tools for studying disease dynamics, immune infiltration and new therapeutic strategies. The ...

In Vivo Immunogenicity Screening of Tumor-Derived Extracellular Vesicles by Flow Cytometry of Splenic T Cells

Immunogenic cell death of tumors, caused by chemotherapy or irradiation, can trigger tumor-specific T cell responses by releasing danger-associated molecular patterns and inducing the production of type I interferon. Immunotherapies, including checkpoint inhibition, primarily rely on preexisting tumor-specific T cells to unfold a therapeutic effect. Thus, synergistic therapeutic approaches that exploit immunogenic cell death as an intrinsic anti-cancer vaccine may improve their responsiveness. However, the spectrum of immunogenic factors released by cells under therapy-induced stress remains incompletely characterized, especially regarding extracellular vesicles (EVs). EVs, nano-scale membranous particles emitted from virtually all cells, are considered to facilitate intercellular communication and, in cancer, have been shown to mediate cross-priming against tumor antigens. To assess the immunogenic effect of EVs derived from tumors under various conditions, adaptable, scalable, and valid methods are sought-for. Therefore, herein a relatively easy and robust approach is presented to assess EVs' in vivo immunogenicity. The protocol is based on flow cytometry analysis of splenic T cells after in vivo immunization of mice with EVs, isolated by precipitation-based assays from tumor cell cultures under therapy or steady-state conditions. For example, this work shows that oxaliplatin exposure of B16-OVA murine melanoma cells resulted in the release of immunogenic EVs that can mediate the activation of tumor-reactive cytotoxic T cells. Hence, screening of EVs via in vivo immunization and flow cytometry identifies conditions under which immunogenic EVs can emerge. Identifying conditions of immunogenic EV release provides an essential prerequisite to testing EVs' therapeutic efficacy against cancer and exploring the underlying molecular mechanisms to ultimately unveil new insights into EVs' role in cancer immunology.

In Vivo Immunogenicity Screening of Tumor-Derived Extracellular Vesicles by Flow Cytometry of Splenic T Cells

This manuscript describes how to assess in vivo immunogenicity of tumor cell-derived extracellular vesicles (EVs) using flow cytometry. EVs derived from tumors undergoing treatment-induced immunogenic cell death seem particularly relevant in tumor immunosurveillance. This protocol exemplifies the assessment of oxaliplatin-induced immunostimulatory tumor EVs but can be adapted to various settings.

Immunogenic cell death of tumors, caused by chemotherapy or irradiation, can trigger tumor-specific T cell responses by releasing danger-associated ...

Intra-Peritoneal Transplantation for Generating Acute Myeloid Leukemia in Mice

There is an unmet need for novel therapies to treat acute myeloid leukemia (AML) and the associated relapse that involves persistent leukemia stem cells (LSCs). An experimental AML rodent model to test therapies based on successfully transplanting these cells via retro-orbital injections in recipient mice is fraught with challenges. The aim of this study was to develop an easy, reliable, and consistent method to generate a robust murine model of AML using an intra-peritoneal route. In the present protocol, bone marrow cells were transduced with a retrovirus expressing human MLL-AF9 fusion oncoprotein. The efficiency of lineage negative (Lin-) and Lin-Sca-1+c-Kit+ (LSK) populations as donor LSCs in the development of primary AML was tested, and intra-peritoneal injection was adopted as a new method to generate AML. Comparison between intra-peritoneal and retro-orbital injections was done in serial transplantations to compare and contrast the two methods. Both Lin- and LSK&#160;cells transduced with human MLL-AF9 virus engrafted well in the bone marrow and spleen of recipients, leading to a full-blown AML. The intra-peritoneal injection of donor cells established AML in recipients upon serial transplantation, and the infiltration of AML cells was detected in the blood, bone marrow, spleen, and liver of recipients by flow cytometry, qPCR, and histological analyses. Thus, intra-peritoneal injection is an efficient method of AML induction using serial transplantation of donor leukemic cells.

Here, intra-peritoneal injection of leukemia cells is utilized to establish and propagate acute myeloid leukemia (AML) in mice. This new method is effective in the serial transplantation of AML cells and can serve as an alternative for those who may experience difficulties and inconsistencies with intravenous injection in mice.

There is an unmet need for novel therapies to treat acute myeloid leukemia (AML) and the associated relapse that involves persistent leukemia stem cells ...

Prognostic Significance of Immune Cell Infiltration in Hepatocellular Carcinoma

Mast Cells in the Microenvironment of Hepatocellular Carcinoma Confer Favorable Prognosis: A Retrospective Study using QuPath Image Analysis Software

The insights provided by in-situ detection of immune cells within hepatocellular carcinoma (HCC) might present information on patient outcomes. Studies investigating the expression and localization of immune cells within tumor tissues are associated with several challenges, including a lack of precise annotation for tumor regions and random selection of microscopic fields of view. QuPath is an open-source, user-friendly software that could meet the growing need for digital pathology in whole-slide image (WSI) analysis.
The infiltration of HCC and adjacent tissues by CD1a+ immature dendritic cells (iDCs), CD117+ mast cells, and NKp46+ natural killer cells (NKs) cells was assessed immunohistochemically in representative specimens of 67 patients with HCC who underwent curative resection. The area fraction (AF) of positively stained cells was assessed automatically in WSIs using QuPath in the tumor center (TC), inner margin (IM), outer margin (OM), and peritumor (PT) area. The prognostic significance of immune cells was evaluated for time to recurrence (TTR), disease-free survival (DFS), and overall survival (OS).
The AF of mast cells was significantly greater than the AF of NKs, and the AF of iDCs was significantly lower compared to NKs in each region of interest. High AFs of mast cells in the IM and PT areas were associated with longer DFS. In addition, high AF of mast cells in IM was associated with longer OS.
Computer-assisted analysis using this software is a suitable tool for obtaining prognostic information for tumor-infiltrating immune cells (iDCs, mast cells, and NKs) in different regions of HCC after resection. Mast cells displayed the greatest AF in all regions of interest (ROIs). Mast cells in the peritumor region and IM showed a positive prognostic significance.

Author Spotlight: Investigating Immune Cell Dynamics in the Tumor Microenvironment &#8212; Challenges and Innovations in Cancer Prognosis

The presence of mast cells in the inner margin and peritumor areas of hepatocellular carcinoma after resection confers a favorable prognosis. This study endorses QuPath image analysis software as a promising platform that could meet the need for reproducibility, consistency, and accuracy in digital pathology.

The insights provided by in-situ detection of immune cells within hepatocellular carcinoma (HCC) might present information on patient outcomes. Studies ...

Flow Cytometry-Based Monitoring of Cancer-Immunity Cycle 

Co-Culture In Vitro Systems to Reproduce the Cancer-Immunity Cycle

Fundamental cancer research and the development of effective counterattack therapies both rely on experimental studies detailing the interactions between cancer and immune cells, the so-called cancer-immunity cycle. In vitro co-culture systems combined with multiparametric flow cytometry (mFC) and tumor-on-a-chip microfluidic devices (ToCs) enable simple, fast, and reliable monitoring and characterization of each step of the cancer-immunity cycle and lead to the identification of the mechanisms responsible for tipping the balance between cancer immunosurveillance and immunoevasion. A thorough understanding of the dynamic interplays between cancer and immune cells provides critical insights to outsmart tumors and will accelerate the pace of therapeutic personalization and optimization in patients. Specifically, here we detail a straightforward mFC- and ToC-assisted protocol for unraveling the dynamic complexities of each step of the cancer-immunity cycle in murine cancer cell lines and mouse-derived immune cells and focus on immunosurveillance. Considering the time- and cost-related features of this protocol, it is certainly feasible on a large scale. Moreover, with minor variations, this protocol can be both adapted to human cancer cell lines and human peripheral-blood-derived immune cells and combined with genetic and/or pharmacologic inhibition of specific pathways in order to identify biomarkers of immune response.

Monitoring the Cancer-Immunity Cycle and Exploring Tumor Microenvironment Dynamics

Here, we detail a simple, fast, and reliable multiparametric flow cytometry- and tumor-on-a-chip-assisted protocol to monitor and characterize the steps constituting the cancer-immunity cycle. Indeed, a thorough understanding of the interplays between cancer and immune cells provides critical insights to outsmart tumors and guide clinical care.

Fundamental cancer research and the development of effective counterattack therapies both rely on experimental studies detailing the interactions between ...

Utilizing Larval Zebrafish for Efficient In Vivo Tumor Studies

A Simple, Rapid, and Effective Method for Tumor Xenotransplantation Analysis in Transparent Zebrafish Embryos

In vivo studies of tumor behavior are a staple of cancer research; however, the use of mice presents significant challenges in cost and time. Here, we present larval zebrafish as a transplant model that has numerous advantages over murine models, including ease of handling, low expense, and short experimental duration. Moreover, the absence of an adaptive immune system during larval stages obviates the need to generate and use immunodeficient strains. While established protocols for xenotransplantation in zebrafish embryos exist, we present here an improved method involving embryo staging for faster transfer, survival analysis, and the use of flow cytometry to assess disease burden. Embryos are staged to facilitate rapid cell injection into the yolk of the larvae and cell marking to monitor the consistency of the injected cell bolus. After injection, embryo survival analysis is assessed up to 7 days post injection (dpi). Finally, disease burden is also assessed by marking transferred cells with a fluorescent protein and analysis by flow cytometry. Flow cytometry is enabled by a standardized method of preparing cell suspensions from zebrafish embryos, which could also be used in establishing the primary culture of zebrafish cells. In summary, the procedure described here allows a more rapid assessment of the behavior of tumor cells in vivo with larger numbers of animals per study arm and in a more cost-effective manner.

Author Spotlight: Advancing Cancer Therapeutics Using Tumor Xenotransplantation in Zebrafish

We describe a protocol for xenotransplantation into the yolk of transparent zebrafish embryos that is optimized by a simple, rapid staging method. Post-injection analyses include survival and assessing the disease burden of xenotransplanted cells by flow cytometry.

In vivo studies of tumor behavior are a staple of cancer research; however, the use of mice presents significant challenges in cost and time. Here, we ...