This work was supported by NIH R21CA162259, NIH R01CA209829, NIH P20 MD006988, NIH 2R25 GM060507, a Hyundai Hope on Wheels Scholar Hope Grant, the Department of Pathology and Human Anatomy, the Department of Basic Sciences, and the Center for Health Disparities and Molecular Medicine at Loma Linda University School of Medicine and by a Grant to Promote Collaborative and Translational Research from Loma Linda University (KJP). The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Studies were conducted in accordance with Loma Linda University&#39;s Institutional Animal Care and Use Committee (IACUC) and Institutional Review Board (IRB) approved protocols and according to all federal guidelines.
CAUTION: PDX and human tissues should be handled in accordance with safety procedures to prevent the transmission of blood borne pathogens.
1. Culture and Expansion of Cytokine-Transduced Stromal Cells
NOTE: Each time stroma ...

<ol>
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W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Murine+and+human+IL-7+activate+STAT5+and+induce+proliferation+of+normal+human+pro-B+cells.">Murine and human IL-7 activate STAT5 and induce proliferation of normal human pro-B cells.</a> J Immunol. 175 (11), 7325-7331 (2005).</li><li>Milford, T. 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=TSLP+or+IL-7+provide+an+IL-7Ralpha+signal+that+is+critical+for+human+B+lymphopoiesis.">TSLP or IL-7 provide an IL-7Ralpha signal that is critical for human B lymphopoiesis.</a> Eur J Immunol. 46 (9), 2155-2161 (2016).</li><li>Reche, P. 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=Human+thymic+stromal+lymphopoietin+preferentially+stimulates+myeloid+cells.">Human thymic stromal lymphopoietin preferentially stimulates myeloid cells.</a> J Immunol. 167 (1), 336-343 (2001).</li><li>Francis, O. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+xenograft+model+to+study+the+role+of+TSLP-induced+CRLF2+signals+in+normal+and+malignant+human+B+lymphopoiesis.">A novel xenograft model to study the role of TSLP-induced CRLF2 signals in normal and malignant human B lymphopoiesis.</a> Haematologica. 101 (4), 417-426 (2016).</li><li>Willinger, T., Rongvaux, A., Strowig, T., Manz, M. G., Flavell, R. 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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=Aberrant+STAT5+and+PI3K/mTOR+pathway+signaling+occurs+in+human+CRLF2-rearranged+B-precursor+acute+lymphoblastic+leukemia.">Aberrant STAT5 and PI3K/mTOR pathway signaling occurs in human CRLF2-rearranged B-precursor acute lymphoblastic leukemia.</a> Blood. 120 (4), 833-842 (2012).</li><li>Kalaitzidis, D., Neel, B. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Flow-cytometric+phosphoprotein+analysis+reveals+agonist+and+temporal+differences+in+responses+of+murine+hematopoietic+stem/progenitor+cells.">Flow-cytometric phosphoprotein analysis reveals agonist and temporal differences in responses of murine hematopoietic stem/progenitor cells.</a> PLoS One. 3 (11), (2008).</li><li>Machholz, E., Mulder, G., Ruiz, C., Corning, B. 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This manuscript describes a simple, quick, and relatively cost effective method for engineering PDX to express exogenous human cytokine. The strategy described here is based on weekly intraperitoneal injections of a stromal cell line transduced to express the human cytokine, TSLP. Prior to performing the methods described here, stroma engineered to express high levels of the cytokine of interest (TSLP) and similarly engineered control stroma were generated. In the protocols presented here, stroma are expanded in culture ...

Patient-derived xenografts (PDX) are a powerful in vivo model for studying the production of normal and malignant hematopoietic cells in a &#39;native&#39; mammalian environment. Most often, PDX are produced by injecting or transplanting human cells into immune deficient mice. The production of PDX using normal human hematopoietic stem cells allows in vivo studies of normal human blood and immune cell development. PDX produced from leukemia or other cancer cells make it possible to study oncogenic mechanisms and to identify effective therapies in context of the range of genetic landscapes and mutations present in the human population.1 Consequently, PDX are the current gold standard for translational biomedical research to identify effective therapies and an important tool for understanding mechanisms of cancer progression. PDX models are an essential tool to aid research into health disparities diseases due to specific genetic lesions, or any disease in which the variations of a patient&#39;s genetic landscape can substantially contribute to oncogenesis and treatment outcome.
Mouse-human PDX models are possible because many mouse cytokines adequately mimic their human analogs in activating the cytokine receptors of human cells while they are inside the mouse. For example, interleukin-7 (IL-7) provides a critical signal for human B cell development.2 In this case, mouse IL-7 has sufficient homology with human IL-7 that the mouse cytokine stimulates signaling pathways in human B cell precursors.2,3,4 However, this is not the case for thymic stromal lymphopoietin (TSLP),5,6 which among other cytokines (IL-3, granulocyte-macrophage colony stimulating factor (GM-CSF), stem cell factor (SCF),7 is important for the production of normal and malignant human hematopoietic cells. When mouse and human cytokines show low homology the mouse cytokines do not activate their respective receptors on human cells. To overcome this obstacle, a number of strategies have been used to engineer expression of human cytokines in PDX mice. These include injection of recombinant human cytokines, hydrodynamic injection of DNA, lentiviral expression, transgenic expression and knockin gene replacement.7 This report describes a method for engineering PDX to produce human cytokine via stromal-mediated cytokine delivery (Figure 1).
In the method demonstrated here, PDX mice are engineered to express the human cytokine, TSLP, or to serve as cytokine-negative controls. TSLP-expressing PDX are achieved by weekly intraperitoneal injections of stromal cells that have been transduced to express high levels of human TSLP. Cytokine-negative PDX &#34;control&#34; mice are similarly engineered; though control stroma are transduced with a control vector. This method achieves normal physiological levels of human TSLP in PDX mice injected with the TSLP+ stroma. No detectable TSLP is observed in PDX mice receiving the cytokine-negative stroma. We selected the human stromal cell line HS-27A for our studies because it grows robustly in culture and shows very low level of cytokine production that does not support proliferation of isolated progenitor cells in cocultures.8 For human TSLP expression, stroma were transduced with an advanced generation self-inactivating lentiviral vector derived from a previously described backbone,9 and includes the cPPT/cts element and the woodchuck hepatitis post-transcriptional regulatory element (WPRE) to increase transgene expression. The human TSLP gene was constructed into this vector under the control of the elongation factor-1 (EF-1) alpha promoter to achieve robust, constitutive, and long-term expression.
The engineering of this human-cytokine enhanced PDX model consists of 4 major steps. First, transduced stroma are expanded in vitro and assessed by enzyme-linked immunosorbent assay (ELISA) for stable, high level cytokine production. Second, the activity of human cytokine produced by the transduced stromal cells (and lack of cytokine activity from control stroma) is verified using phospho-flow cytometry. Cell lines known to be responsive to cytokine of interest (in this instance,TSLP) are incubated with stromal cell supernatant and assayed for cytokine-induced phosphorylation. Third, mice are injected with transduced human stroma and then mouse plasma is assessed by ELISA for levels of human cytokine on a weekly basis. Fourth, human hematopoietic cells are transplanted and the in vivo functional effects of the human cytokine is evaluated on a known target (e.g. cell population).
<img alt="Figure 1" src="/files/ftp_upload/55384/55384fig1.jpg" /> 
Figure 1: PDX Model Engineered to Produce Exogenous Human Cytokine in Mice. (1A) Design experiment and obtain transduced human stromal cells (1B) Obtain human cells (hematopoietic stem cells, leukemia cells, etc.) to generate PDX (patient-derived xenograft) mice. (2A) Inject engineered stroma and (2B) transplant human cells into immune deficient mice according experimental schedule. (3A-B) Monitor cytokine concentrations in the stroma supernatant and the mouse plasma by ELISA. (4) Harvest human cells and assess the in vivo functional effects of the human cytokine present in the PDX. <a href="http://cloudflare.jove.com/files/ftp_upload/55384/55384fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Delivery of human cytokine via stromal cells offers both advantages and disadvantages when compared to other methods of delivering/producing human cytokines in PDX mice.7 Compared to injection of recombinant human cytokine, stroma-mediated delivery is generally less expensive (cost of stromal cell culture is less than cost of recombinant cytokine) and less labor intensive (one injection per week versus multiple injections per week). The issue of short cytokine half-life is also mitigated since stroma continually produce the exogenous cytokine. Delivery of cytokine via hydrodynamic injection of DNA may be less expensive than delivery via stroma. However, it is similarly transient and may require more technical skill than the simple weekly intraperitoneal injection required for stroma-mediated delivery. Lentiviral gene expression in the mouse may provide a less transient method of cytokine delivery; however, in our hands physiological TSLP levels were not achieved. Additionally, this method is labor intensive, requiring continuous production of lentiviral vector. Transgenic or knock-in mice offer stable long-term expression of cytokine and can be engineered for tissue specific expression, which can be an advantage. On the other hand, the transgenic expression of the human cytokine gene on the immune deficient mouse background required for PDX mice, necessitates an immense investment of resources before the value of the model has been established. Furthermore, transgenic models do not generally allow for the option of varying the timing of cytokine initiation or level of in vivo cytokine production. These can be achieved with stroma-mediated delivery by simply changing the time point for initiation of stromal cell injection or the dose of stromal cells injected.
The stromal-cell mediated cytokine delivery method detailed here was used to develop PDX for evaluating the role of TSLP in normal human B cell development4,6 and high risk B-cell acute lymphoblastic leukemia.6 This method provides an alternative cytokine delivery method for use in generating similar models with human cytokines other than TSLP. This model can also be useful for generating preliminary data that can help determine whether the value of a cytokine transgenic or cytokine knock-in PDX model would be worthy of the substantial time and money investment.

<table border="0" cellpadding="0" cellspacing="0" width="1101">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Wet lab reagents&#160;</td>
			<td style="width:212px;"></td>
			<td style="width:136px;"></td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">T-25 Nunc Cell Culture Treated EasYFlasks, 7 mL capacity,&#160; 25cm&#178; culture area</td>
			<td style="width:212px;">Thermo Scientific / Fisher</td>
			<td style="width:136px;">156367</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">T-75 Falcon Tissue Culture Treated Flask, 250 mL capacity, 75 cm&#178; culture area &#38; vented cap</td>
			<td style="width:212px;">Corning Inc. / Fisher</td>
			<td style="width:136px;">353136</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">T-150 Falcon Tissue Culture Treated Flask, 600 mL capacity, 150 cm&#178; culture area &#38; vented cap</td>
			<td style="width:212px;">Corning Inc. / Fisher</td>
			<td style="width:136px;">355001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">10 mL serological pipettes</td>
			<td style="width:212px;">Falcon</td>
			<td style="width:136px;">357551</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">15 mL&#160; polypropylene conical tubes</td>
			<td style="width:212px;">Fisher</td>
			<td style="width:136px;">05-539-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">5 mL round-bottom polystyrene tubes</td>
			<td style="width:212px;">Falcon</td>
			<td style="width:136px;">352054</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">50 mL polypropylene conical tubes</td>
			<td style="width:212px;">Falcon</td>
			<td style="width:136px;">352098</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">2.0 mL cryogenic vials, externally threaded</td>
			<td style="width:212px;">Corning Inc. / Fisher</td>
			<td style="width:136px;">4230659</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">1 mL pipette tips</td>
			<td style="width:212px;">Fisher</td>
			<td style="width:136px;">2707509</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">200 &#956;L pipette tips&#160;</td>
			<td style="width:212px;">Denville Scientific</td>
			<td style="width:136px;">P3020-CPS</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">10 &#956;L pipette tips</td>
			<td style="width:212px;">Denville Scientific</td>
			<td style="width:136px;">P-1096-CP</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Sterile Disposable Filter Units with SFCA Membrane, Nalgene Rapid-Flow</td>
			<td style="width:212px;">Fisher</td>
			<td style="width:136px;">09-740-28D</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:665px;">2N H2SO4&#160;</td>
			<td style="width:212px;">BioLegend</td>
			<td style="width:136px;">423001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Dulbecco&#8217;s phosphate-buffered saline (PBS) without calicium and magnesium, 1&#215;</td>
			<td style="width:212px;">Corning cellgro/ Mediatech</td>
			<td style="width:136px;">21-031-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Human TSLP ELISA Max Deluxe Set</td>
			<td style="width:212px;">BioLegend</td>
			<td style="width:136px;">434204</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">3% Acetic Acid with Methylene Blue</td>
			<td style="width:212px;">Stemcell Technologies</td>
			<td style="width:136px;">7060</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Trypan Blue&#160;</td>
			<td style="width:212px;">Corning</td>
			<td style="width:136px;">25-900-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#34;Trypsin&#34; 1x 0.25% Trypsin 2.21 mM EDTA in HBSS</td>
			<td style="width:212px;">ThermoFisher</td>
			<td style="width:136px;">25-053</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">TWEEN 20 BioXtra</td>
			<td style="width:212px;">Sigma-Aldrich</td>
			<td style="width:136px;">P-7949</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#8220;R10&#8221; cell culture medium, % of total volume (makes 565 mL)</td>
			<td style="width:212px;">-</td>
			<td style="width:136px;">-</td>
			<td style="width:88px;">Lab Recipe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">RPMI, 88.5% (500 mL)&#160;</td>
			<td style="width:212px;">Mediatech</td>
			<td style="width:136px;">10-040-CV&#160;&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">FBS, 9.9% (56 mL)&#160;</td>
			<td style="width:212px;">Mediatech</td>
			<td style="width:136px;">35-011-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">L-Glutamine, 0.99% (5.6 mL)&#160;</td>
			<td style="width:212px;">Mediatech</td>
			<td style="width:136px;">25-005-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Penicillin-Streptomycin, 0.50% (2.8 mL)&#160;</td>
			<td style="width:212px;">Mediatech</td>
			<td style="width:136px;">30-002-Cl</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">2-Mercaptoethanol, 0.10% (560 &#181;L)&#160;</td>
			<td style="width:212px;">MP</td>
			<td style="width:136px;">190242</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#8220;R20&#8221; cell culture medium, % of total volume (makes 195 mL)</td>
			<td style="width:212px;">-</td>
			<td style="width:136px;">-</td>
			<td style="width:88px;">Lab Recipe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#160;&#160;&#160;&#160; RPMI, 76.84% (150&#160; mL)</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">see above</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#160;&#160;&#160;&#160; FBS, 20.49% (40 mL)</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">see above</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#160;&#160;&#160;&#160; 2mM L-glutamine, 1.02% (2 mL)</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">see above</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#160;&#160;&#160;&#160; 1mM Na pyruvate, 1.02% (2 mL )</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">see above</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#160;&#160;&#160;&#160; Penicillin-Streptomycin,&#160; 0.51% (1 mL)</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">see above</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#160;&#160;&#160;&#160; 2-Mercaptoethanol, 0.10% (0.1 M),&#160; 0.10% (200 &#181;L)</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">see above</td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#8220;Freezing medium&#8221;, % of total volume</td>
			<td style="width:212px;">-</td>
			<td style="width:136px;">-</td>
			<td style="width:88px;">Lab Recipe</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#8220;R10&#8221; medium, 45%</td>
			<td style="width:212px;">see &#34;R10&#34; recipe</td>
			<td style="width:136px;">-</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">FBS, 20%</td>
			<td style="width:212px;">see above</td>
			<td style="width:136px;">35-011-CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">DMSO, 10%</td>
			<td style="width:212px;">Corning</td>
			<td style="width:136px;">25-950-CQC</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:665px;">D(-)(+)-Trehalose dihydrate, 5%</td>
			<td style="width:212px;">Fisher Scientific</td>
			<td style="width:136px;">BP2687-100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Name</td>
			<td style="width:212px;">Company</td>
			<td style="width:136px;">Catolog Number</td>
			<td style="width:88px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Biologics&#160;</td>
			<td style="width:212px;"></td>
			<td style="width:136px;"></td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#34;HS-27&#34; HS-27A human stroma line</td>
			<td style="width:212px;">ATCC</td>
			<td>CRL-2496</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#34;CALL-4&#34; MHH-CALL-4 cell line, human B cell precursor leukemia</td>
			<td style="width:212px;">DSMZ</td>
			<td style="width:136px;">ACC 337</td>
			<td></td>
		</tr>
		<tr height="24">
			<td height="24" style="height:24px;width:665px;">&#8220;NSG mice&#8221; NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ, male or female, age 6 &#8211; 8 weeks</td>
			<td style="width:212px;">JAX Mice&#160;</td>
			<td style="width:136px;"># 005557</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">MUTZ-5 cell line, human B cell precursor leukemia</td>
			<td style="width:212px;">DSMZ</td>
			<td style="width:136px;">ACC 490</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:665px;">Recombinant Human TSLP protein</td>
			<td style="width:212px;">R&#38;D Systems</td>
			<td style="width:136px;">1398-TS-010</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Name</td>
			<td style="width:212px;">Company</td>
			<td style="width:136px;">Catolog Number</td>
			<td style="width:88px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Flow cytomery antibodies (clone)*</td>
			<td style="width:212px;"></td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Anti-mouse CD45 FITC (30F11)</td>
			<td>Miltenyi Biotec</td>
			<td>130-102-778</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">CD127 PE (MB15-18C9) (alternate name is IL-7R&#945;)</td>
			<td>Miltenyi Biotec</td>
			<td>130-098-094</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">CD34 APC (8G12)</td>
			<td>BD Biosciences</td>
			<td>340667</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">CD45 PE-Cy7&#160; (HI30)</td>
			<td>eBioscience</td>
			<td>25-0459</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">&#34;FVD&#34; Fixable viability dye&#160; eFluor 780&#160;</td>
			<td>eBioscience</td>
			<td>65-0865</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Ig &#954; light chain FITC&#160; (G20-193)</td>
			<td style="width:212px;">BD Pharmingen</td>
			<td>555791</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Ig &#955; light chain FITC (JDC-12)</td>
			<td style="width:212px;">BD Pharmingen</td>
			<td>561379</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">IgD PE (IA6-2)</td>
			<td style="width:212px;">BioLegend</td>
			<td>348203</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">IgM PE-Cy5 (G20-127)</td>
			<td>BD Biosciences</td>
			<td>551079</td>
			<td></td>
		</tr>
		<tr height="22">
			<td height="22" style="height:22px;width:665px;">pSTAT5 PE,&#160; mouse anti-STAT5 (pY694)</td>
			<td style="width:212px;">BD PhosphoFlow</td>
			<td>612567</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Name</td>
			<td style="width:212px;">Company</td>
			<td style="width:136px;">Catolog Number</td>
			<td style="width:88px;">Comments</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Other materials &#38; equipment&#160;</td>
			<td style="width:212px;"></td>
			<td style="width:136px;"></td>
			<td style="width:88px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Animal Implantable Nano Transponder with Canula</td>
			<td style="width:212px;">Trovan&#160;</td>
			<td style="width:136px;">ID-100B(1.25)</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">EMLA lidocaine anesthetic cream (obtain by presciption through animal care facility)</td>
			<td style="width:212px;">perscription</td>
			<td style="width:136px;">perscription</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">BD &#189; cc LO-DOSE U-100 Insulin Syringe 28G&#189;&#160;</td>
			<td style="width:212px;">BD</td>
			<td style="width:136px;">#329461</td>
			<td></td>
		</tr>
		<tr height="25">
			<td height="25" style="height:25px;width:665px;">BD Microtainer Tubes with K2EDTA</td>
			<td style="width:212px;">BD&#160;</td>
			<td style="width:136px;">#365974</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Centrifuge</td>
			<td>Beckman Coulter</td>
			<td style="width:136px;">Alegra X-15R&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FisherBrand Capillary Tubes (Heparinized)</td>
			<td style="width:212px;">Fisher Scientific</td>
			<td style="width:136px;">22-260-950</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Hemocytometer</td>
			<td style="width:212px;">Fisher</td>
			<td style="width:136px;">02-671-6</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">MACSQuant Analyzer 10</td>
			<td style="width:212px;">Miltenyi Biotec</td>
			<td style="width:136px;">130-096-343</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Mouse Pie Cage</td>
			<td style="width:212px;">Braintree Scientific, Inc.</td>
			<td style="width:136px;">MPC-1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Mouse Tail Illuminator Restrainer</td>
			<td style="width:212px;">Braintree Scientific, Inc.</td>
			<td style="width:136px;">MTI STD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">Pistol Grip Implanter</td>
			<td style="width:212px;">Trovan&#160;</td>
			<td style="width:136px;">IM-300(1.25)</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">&#181;Quant&#160;</td>
			<td style="width:212px;">Bio-Tek Instruments Inc.</td>
			<td style="width:136px;">MQX200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:665px;">FlowJo flow cytometry analysis software</td>
			<td>FlowJo, LLC</td>
			<td style="width:136px;">Version 10</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">*All antibodies are anti-human unless otherwise stated.</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

expression of exogenous cytokine in patient-derived xenografts via injection with a cytokine-transduced stromal cell line

Patient-derived xenograft (PDX) mice are produced by transplanting human cells into immune deficient mice. These models are an important tool for studying the mechanisms of normal and malignant hematopoiesis and are the gold standard for identifying effective chemotherapies for many malignancies. PDX models are possible because many of the mouse cytokines also act on human cells. However, this is not the case for all cytokines, including many that are critical for studying normal and malignant hematopoiesis in human cells. Techniques that engineer mice to produce human cytokines (transgenic and knock-in models) require significant expense before the usefulness of the model has been demonstrated. Other techniques are labor intensive (injection of recombinant cytokine or lentivirus) and in some cases require high levels of technical expertise (hydrodynamic injection of DNA). This report describes a simple method for generating PDX mice that have exogenous human cytokine (TSLP, thymic stromal lymphopoietin) via weekly intraperitoneal injection of stroma that have been transduced to overexpress this cytokine. Use of this method provides an in vivo source of continuous cytokine production that achieves physiological levels of circulating human cytokine in the mouse. Plasma levels of human cytokine can be varied based on the number of stromal cells injected, and cytokine production can be initiated at any point in the experiment. This method also includes cytokine-negative control mice that are similarly produced, but through intraperitoneal injection of stroma transduced with a control vector. We have previously demonstrated that leukemia cells harvested from TSLP-expressing PDX, as compared to control PDX, exhibit a gene expression pattern more like the original patient sample. Together the cytokine-producing and cytokine-negative PDX mice produced by this method provide a model system that we have used successfully to study the role of TSLP in normal and malignant hematopoiesis.

An overview of the model is shown in Figure 1. Once cytokine-producing (TSLP+ stroma) and control stroma have been obtained they are expanded in culture. Prior to stroma injection into mice, stromal cell supernatant is assessed by ELISA to verify cytokine production (Figure 2) and phospho-flow cytometry (Protocol #3) is used to verify the activity of the cytokine produced by the stroma. Supernatant is collected from confluent stromal cell cultures (contro...

Watch this Scientific Journal Video about Expression of Exogenous Cytokine in Patient-derived Xenografts via Injection with a Cytokine-transduced Stromal Cell Line at JoVE.com

Expression of Exogenous Cytokine in Patient-derived Xenografts via Injection with a Cytokine-transduced Stromal Cell Line

Described here is a method for producing exogenous cytokine in patient-derived xenograft (PDX) mice via weekly intraperitoneal injection of a cytokine-transduced stromal cell line. This method broadens the utility of PDX and provides the option for transient or sustained exogenous cytokine delivery in a multitude of PDX models.

Patient-derived xenograft (PDX) mice are produced by transplanting human cells into immune deficient mice. These models are an important tool for studying ...

The overall goal of this procedure is to produce xenograft mice with circulating human cytokines. This method can help answer key questions in the cancer and hematopoiesis fields such as, What is the role of a specific cytokine in normal and malignant lymphocyte development? The main advantage of this technique is that investigators can ingest the circulating concentrations of exogenous cytokine in their xenograft animals according to the needs of their experiment.This eliminates the need to produce new and expensive transgenic mouse lines. This technique will be useful for researching new cancer therapies, because this preclinical model can be used to test anticancer drugs, similar to what is used in the clinic. Though this method can provide insight into normal hematopoiesis, it can also be used to study specific diseases such as leukemia.I first developed this idea when we needed an in vivo model to evaluate the role of the TSLP cytokine in normal and malignant human B-cell production. Begin by plating freshly thawed control empty vector-transduced stroma in cytokine-producing cells in five milliliters of R-10 medium in individual T25 flasks. For their culture, at 37 degrees Celsius in five percent CO2 for 24 to 48 hours.When the stroma are confluent, detach the cells with Trypsan in EDTA for replating in T150 culture flasks for three to four days. When the stroma achieve confluence in the T150 flasks, collect the supernatants and freeze them at 80 degrees Celsius for later evaluation of their cytokine production by ELISA. Then, passage each T150 flask culture into three new T150 flasks for their culture until confluency.To store the cells after the appropriate number of passages, transfer the harvested cell suspensions to a conical tube for centrifugation and resuspend the pellets in a freezing medium. Then transfer 1.5E6 cell aliquots into long-term storage tubes for their storage in liquid nitrogen. To validate the supernatant produced from engineered stroma, thaw the supernatant samples harvested from the control in cytokine-expressing stroma, and plate three wells of leukemia cell lines per condition in Au-20 medium at a 2E5 cells per well concentration in a 96-well tissue culture plate.Incubate the cells for two hours at 37 degrees Celsius to allow for the phosphorylation from their prior culture to be lost. Then transfer the cells from each well into individual four milliliter tubes and collect the cells by centrifugation. Resuspend the pellets in 600 microliters per experimental condition.Plate 200 microliters of cells per well for each condition in triplicate. Incubate the cells for the appropriate period according to the specific commercial phosphoassay. At the end of the incubation, pellet the cells by centrifugation.Label the cells via phospho-flow cytometry staining according to the manufacturer's protocol. Then analyze the cells by flow cytometry using standard flow cytometric analysis protocols to verify that cytokine in the stroma supernatant phosphorylates the leukemia cells. After a minimum of three post-thaw passages, transfer the harvested stromal cell suspensions into individual conical tubes for counting.Pellet the cells by centrifugation and gently resuspend them in the appropriate volumes of sterile PBS for injection. Hold the cells at four degrees Celsius until immediately before the injection at which point the suspension should be warmed to at least room temperature. When the cells are ready, gently mix the first sample by inversion and draw 200 microliters of the cells into a tuberculin syringe.Then restrain the first animal and inject the cells into the peritoneal cavity using standard intraperitoneal injection techniques. To collect a peripheral blood sample, first gently position the mouse in a disinfected small animal restrainer and secure the tube to minimize the animal's movements. Next, scrub the tail with fresh isopropyl alcohol followed by the application of topical anesthetic cream.Using very sharp surgical scissors, snip about 5 to one millimeter from the tip of the tail and collect approximately 80 microliters of peripheral blood into heparinized capillary tubes. Use a bulb syringe to transfer the blood samples into labeled potassium EDTA microtainer tubes and invert the tube 20 times to prevent coagulation. After centrifuging blood collection tubes per manufacturer's instructions, carefully collect the plasma layer and store the aliquots at 20 degrees Celsius and aliquot the plasma for 20 degree Celsius storage.On the day of the ELISA, thaw the frozen mouse plasma samples and serially dilute the ELISA standard into 120-microliter volumes. Now plate 40 microliters of each standard in triplicate into the appropriate wells of the ELISA plate followed by the addition of 40 microliters of each mouse plasma sample to the appropriate wells. Then complete the ELISA analysis according to the manufacturer's instructions.24 hours after irradiating the mice, prepare the human hematopoietic cells for xenograft transplantation. When you resuspend the hematopoietic cells in sterile PBS, it is a good idea to prepare about 15 to 20 percent extra, in case you have a spill during the transplantation. Keep the cells at four degrees Celsius until transplant and transfer the first recipient animal into a warming cage for at least five minutes to facilitate tail-vein dilation.Now warm the cells to room temperature. Gently mix the cell suspension and draw 200 microliters into a tuberculin syringe. Place the mouse in the restrainer and disinfect the tail with isopropyl alcohol.Inject the cells into a lateral tail vein. Then monitor the mouse for at least five minutes to confirm a lack of adverse effects related to the transplant. Patient-derived xenografted, or PDX animals, injected with control stroma consistently demonstrate levels of human thymic stromal lymphopoietin, or TSLP, in mouse plasma that are below the threshold for ELISA detection.The plasma levels of human TSLP in PDX mice injected with TSLP-transduced stroma is proportional to the amount of TSLP stromal cells injected during the previous one to two weeks. Despite being performed in simplicate, this weekly assessment of plasma TSLP levels using the modified ELISA gives results that are, in general, consistent over time. TSLP has been shown to increase the production of normal human B-cell precursors.Indeed, B-lineage cells are significantly increased in TSLP-plus mice compared to the control PDX animals as early as the B-cell precursor stage, suggesting that human TSLP produced in TSLP-plus PDX animals exerts the expected in vivo functional effects on target cell populations. Once optimized, these procedures can generate xenograft mice with detectable levels of human cytokines in three to four weeks. It's important to monitor the cytokine concentration in the stroma cell supernatant over time.This ensures that the cytokine production is sustained in the cytokine-producing stroma and absent in the control stroma. PDX mice can be used for preclinical studies to answer additional questions, such as, How is the efficacy of a specific drug of interest altered by varying the physiological levels of an experimental cytokine of interest in vivo? This innovative model provides a new way for researchers in the fields of hematology and oncology to study the role of TSLP in the development and progression of leukemia, as well as its role in normal hematopoiesis.Provided that you have access to cytokine-transduced cell lines, you can use the techniques demonstrated in this video to supply any exogenous cytokine to patient-derived xenograft disease models using a wide range of immune-deficient mouse strains. Don't forget that working with human hematopoietic cells can be hazardous. You should always use precautions to avoid the transmission of bloodborne pathogens while working with these fluids and cells.

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9.2K vistas.  Loma Linda University. The overall goal of this procedure is to produce xenograft mice with circulating human cytokines. This method can help answer key questions in the cancer and hematopoiesis fields such as, What is the role of a specific cytokine in normal and malignant lymphocyte development? The main advantage of this technique is that investigators can ingest the circulating concentrations of exogenous cytokine in their xenograft animals according to the needs of their experiment.This eliminates the n...