Name: isolation of stem cells from human pancreatic cancer xenografts
Uploaded: 2010-09-26T17:00:00
Duration: 11 min 44 s
Description: Watch this Scientific Journal Video about Isolation of Stem Cells from Human Pancreatic Cancer Xenografts at JoVE.com

This work was supported by grants from the National Institutes of Health (CA127574, CA107040 and CA09071) to W.M.

1. Harvest Xenografts from Mice
<ol>
 <li> Prepare the cell dissociation buffer: Dulbecco's modified Eagle medium (DMEM) supplemented with 10% fetal calf serum (FCS), penicillin-streptomycin, 200 U/mL Collagenase type IV, and 0.6 U/mL dispase.</li>
 <li> An athymic (nu+/nu+) mouse harboring a subcutaneous human pancreatic cancer xenograft that is less than 1 cm in greatest diameter is euthanized by carbon dioxide asphyxiation and cervical dislocation.</li>
 <li> The subcutaneous tumor is harvested from the flank of the mouse by blunt dissection using forceps and scissors and placed immediately in the cell dissociation buffer.</li>
 <li> Tumors are weighed and placed back into 10 mL cell dissociation buffer per 1 gram of tumor tissue.</li>
</ol>
2. Generate a Single-cell Suspension from the Xenografts
<ol>
 <li> Working in a sterile biosafety cabinet, the tumor is transferred to a 100 x 20 mm culture dish with 1 mL of cell dissociation buffer. Tumors are mechanically minced using sterile razor blades and forceps. The tumor cell suspension is triturated through a 5-mL serological pipet 10 times. The tumor pieces should be small enough to not clog the 5-mL serological pipet.</li>
 <li> The tumor cell suspension is transferred to a 50-mL conical tube containing the remaining volume of cell dissociation buffer (filled less than 50%) and vortexed at maximum speed for 1 minute.</li>
 <li> The tumor cell suspension is then incubated at 37&deg;C for 2 hours with intermittent vortexing for 1 minute every 20 minutes.</li>
</ol>
3. Deplete Cell Suspension of Tissue Debris and Dead Cells
<ol>
 <li> After the 2-hour incubation the cell suspension is vortexed at maximum speed for 1 minute.</li>
 <li> The cell suspension is then passed through a 70-&mu;m filter and collected in a fresh 50-mL conical tube and adjusted to a final volume of 15 mL per tube.</li>
 <li> To further separate viable cells from dead cells and tissue debris, the tumor cell suspension is separated by density centrifugation using Ficoll-Paque Plus. An underlayment of Ficoll-Paque Plus is created by pipeting 15 mL of Ficoll-Paque Plus slowly below the cell suspension being careful not to mix the two layers.</li>
 <li> The cell suspension and Ficoll layers are is centrifuged at 500x g for 30 minutes with the brakes turned off.</li>
 <li> Cells at the interface of the Ficoll-Paque Plus and cell dissociation buffer are collected and transferred to a fresh 50-mL conical tube.</li>
 <li> Fresh DMEM supplemented with 10% FCS is added to the cell suspension to dilute it 1:3 (e.g. 20 mL fresh media added to 10 mL of cell suspension).</li>
 <li> The cells are collected by centrifugation at 450x g for 10 minutes, the media decanted, and the cell pellet is resuspended in 1 mL of ALDEFLUOR buffer.</li>
 <li> Ten microliters of the cell suspension is diluted with 10 &mu;L trypan blue and viable cells are counted using a hemocytometer. If a large number of dead cells or tissue debris are noted during this step, then cell separation by density centrifugation can be repeated (steps 3.3 - 3.7).</li>
</ol>
4. Stain Cells for Fluorescence Activated Cell Sorting
<ol>
 <li> Label seven 12 x 75 mm polystyrene test tubes as follows:
 <ol>
 <li> Unstained</li>
 <li> CD44-APC</li>
 <li> CD24-PE</li>
 <li> mouse CD31-biotin + mouse lineage-biotin + mouse H-2Kd-biotin</li>
 <li> ALDEFLUOR</li>
 <li> ALDEFLUOR + DEAB + IgG2b&#954;-APC + IgG2a&#954;-PE</li>
 <li> ALDEFLUOR + CD44-APC + CD24-PE + mouse CD31-biotin + mouse lineage-biotin + mouse H-2Kd-biotin.</li>
 </ol>
 </li>
 <li> Dilute the cell suspension in 2 mL of ALDEFLUOR buffer to a final concentration of 5-10 million cells/mL and keep on ice. Add 100 &mu;L of the cell suspension to tubes #1, 2, 3, and 4 and keep them on ice. Add 1 &mu;L DEAB to tube #6 and keep on ice. Add ALDEFLUOR reagent to the remaining cell suspension diluted 1000- fold (e.g. add 1.6 &mu;L ALDEFLUOR reagent to 1.6 mL cell suspension), mix well, and place on ice. Transfer 100 &mu;L of this mixture to tubes #5 and 6, and the remaining mixture (1.4 mL) to tube #7. Incubate all of the tubes in a 37&deg;C water bath for 40 minutes. Mix the cell suspension every 10 minutes in order to prevent the cells from settling to the bottom of the tubes.</li>
 <li> Centrifuge the cells at 450x g and 4&deg;C for 10 minutes and then decant the buffer. Resuspend the pellets in tubes #1 and 5 in 100 &mu;L ALDEFLUOR buffer. To tubes #2, 3, 4, and 6, add 100 &mu;L of ALDEFLUOR buffer containing the appropriate antibodies diluted as follows: 1:20 for IgG2b&#922;-APC, IgG2a&#922;-PE, CD44-APC, and CD24-PE antibodies; 1:100 for mouse CD31-biotin, mouse lineage-biotin, and mouse H-2Kd-biotin antibodies. To tube #7 add 1.4 mL of ALDEFLUOR buffer containing a 1:20 dilution of CD44-APC, and CD24-PE antibodies and a 1:100 dilution of mouse CD31-biotin, mouse lineage-biotin, and mouse H-2Kd-biotin antibodies. Incubate the cell suspensions on ice for 10 minutes.</li>
 <li> Centrifuge the cells at 450x g and 4&deg;C for 10 minutes and then decant the buffer. Resuspend the pellets in tubes #1, 2, 3, 5, and 6 in 100 &mu;L ALDEFLUOR buffer. Prepare 1.5 mL of ALDEFLUOR buffer containing a 1:100 dilution of streptavidin- PerCP protein. Add 100 &mu;L to tube #4 and add 1.4 mL to tube #7. Incubate the cell suspensions on ice for 10 minutes.</li>
 <li> Centrifuge the cells at 450x g and 4&deg;C for 10 minutes and then decant the buffer. Resuspend the pellets in tubes #1, 2, 3, 4, 5, and 6 in 200 &mu;L ALDEFLUOR buffer. Resuspend the pellet in tube #7 in 2.8 mL of ALDEFLUOR buffer containing 2 &mu;g/mL propidium iodide. Keep tubes on ice at all times.</li>
 <li> Pass cells through 35-&mu;m filter using 12 x 75 mm polystyrene test tubes with strainer caps.</li>
</ol>
5. Isolate Cancer Stem Cells by Fluorescence Activated Cell Sorting
<ol>
 <li> A FACSAria flow cytometer is prepared for cell sorting.</li>
 <li> Compensation controls are set using cells from tubes #1, 2, 3, 4, and 5.</li>
 <li> Gates are created based on forward- and side-scatter parameters to collect cell singlets.</li>
 <li> Non-mouse (PerCP-negative) and viable (non-propidium iodide stained) cells are gated using the FL-3 channel.</li>
 <li> ALDH+ cells are collected based on gates created using DEAB-treated cells (tube #6) and the FL-1 channel.</li>
 <li> CD44+CD24+ cells are collected based on gates created using cells stained with ALDEFLUOR, IgG2b&#922;-APC, and IgG2a&#954;-PE (tube #6) using the FL-4 and FL-2 channels.</li>
 <li> Cells are collected in 12 x 75 mm polystyrene test tubes containing 1 mL of DMEM supplemented with 10% FCS.</li>
 <li> After cells have been sorted, centrifuge the cell suspension at 450x g for 10 minutes, decant the media, and resuspend the cells in 500 &mu;L fresh DMEM supplemented with 10% FCS.</li>
 <li> Count the number of sorted cells using a hemocytometer as described in step 3.8.</li>
</ol>
6. Representative Results
This protocol will lead to the isolation of ALDH+ and CD44+CD24+ pancreatic CSCs.
 The percentage of mouse-derived cells is variable, but we have found that most human
 pancreatic cancer xenografts contain 20-60% mouse-derived cells using the mouse
 CD31, mouse lineage cocktail, and mouse H-2Kd biotin-conjugated antibodies (Figure
 1A). Likewise the frequency of each CSC population from different xenografts is
 variable, but generally we have found that 1-4% of the total cell population is ALDH+ (Figure 1B) and 0.2-5% is CD44+CD24+ (Figure 1C).
We routinely manually count sorted cells using a hemocytometer since the FACSAria
 machine counts are often inaccurate due to non-cellular particles detected by the
 FACSAria.
<img src="/files/ftp_upload/2169/2169fig1.jpg" alt="Figure 1" /> 
 Figure 1. Flow cytometry plot depicting specific populations from a pancreatic cancer
 xenograft. (A) Cells staining positively in the FL-3 channel (propidium iodide+, mouse
 CD31+ mouse lineage+, or mouse H-2Kd+) are excluded so as to isolate only viable and
 non-mouse derived cells. (B) ALDH activity in a human pancreatic cancer xenograft
 was measured by flow cytometry using the ALDEFLUOR reagent in the presence and
 absence of the ALDH1 inhibitor diethylamino-benzaldehyde (DEAB). The frames
 represent gates that depict ALDH+ cells that were created based on cells treated with
 DEAB and then applied to untreated cells. The percentages of ALDH+ cells are shown
 in the gate. (C) The CD44+CD24+ gate was created based on cells stained with
 ALDEFLUOR, and the IgG2b&#954;-APC (isotypic control for CD44-APC) and IgG2a&#954;-PE
 (isotypic control for CD24-PE) antibodies. The percentages of CD44+CD24+ cells are
 shown in the gate.

<ol>
	<li>Clarke, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cancer+stem+cells--perspectives+on+current+status+and+future+directions:+AACR+Workshop+on+cancer+stem+cells.">Cancer stem cells--perspectives on current status and future directions: AACR Workshop on cancer stem cells.</a> Cancer Res. 66, 9339-9344 (2006).</li><li>Al-Hajj, M., Wicha, M. S., Benito-Hernandez, A., Morrison, S. J., Clarke, M. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prospective+identification+of+tumorigenic+breast+cancer+cells.">Prospective identification of tumorigenic breast cancer cells.</a> Proceedings of the National Academy of Sciences of the United States of America. 100, 3983-3988 (2003).</li><li>Ginestier, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ALDH1+Is+a+Marker+of+Normal+and+Malignant+Human+Mammary+Stem+Cells+and+a+Predictor+of+Poor+Clinical+Outcome.">ALDH1 Is a Marker of Normal and Malignant Human Mammary Stem Cells and a Predictor of Poor Clinical Outcome.</a> Cell stem cell. 1, 555-567 (2007).</li><li>Jones, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Circulating+clonotypic+B+cells+in+classic+Hodgkin+lymphoma.">Circulating clonotypic B cells in classic Hodgkin lymphoma.</a> Blood. 113, 5920-5926 (2009).</li><li>Matsui, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clonogenic+multiple+myeloma+progenitors,+stem+cell+properties,+and+drug+resistance.">Clonogenic multiple myeloma progenitors, stem cell properties, and drug resistance.</a> Cancer Res. 68, 190-197 (2008).</li><li>Li, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+pancreatic+cancer+stem+cells.">Identification of pancreatic cancer stem cells.</a> Cancer Res. 67, 1030-1037 (2007).</li><li>Hermann, P. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distinct+populations+of+cancer+stem+cells+determine+tumor+growth+and+metastatic+activity+in+human+pancreatic+cancer.">Distinct populations of cancer stem cells determine tumor growth and metastatic activity in human pancreatic cancer.</a> Cell stem cell. 1, 313-323 (2007).</li><li>Rasheed, Z. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prognostic+significance+of+tumorigenic+cells+with+mesenchymal+features+in+pancreatic+adenocarcinoma.">Prognostic significance of tumorigenic cells with mesenchymal features in pancreatic adenocarcinoma.</a> J Natl Cancer Inst. 102, 340-351 (2010).</li><li>Rubio-Viqueira, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+in+vivo+platform+for+translational+drug+development+in+pancreatic+cancer.">An in vivo platform for translational drug development in pancreatic cancer.</a> Clin Cancer Res. 12, 4652-4661 (2006).</li><li>Jones, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessment+of+aldehyde+dehydrogenase+in+viable+cells.">Assessment of aldehyde dehydrogenase in viable cells.</a> Blood. 85, 2742-2746 (1995).</li></ol>

No conflicts of interest declared.

This protocol describes the isolation of pancreatic CSCs from human xenografts. Several key steps in this procedure will enhance the yield of viable CSCs. The recovery of a pure population of pancreatic CSCs is dependent on the purity of viable cells present in the cell suspension before sorting on the FACSAria. Taking care to use xenografts that are less than 1-cm in greatest diameter helps to reduce the amount of necrotic tissue in the center of the tumor. Additionally, depleting the cell suspension of
tissue debris and dead cells during Ficoll-Paque gradient centrifugation is critical and can be repeated if a large number of tissue debris or non-viable cells are detected when the cells are counted on the hemocytometer.
The staining protocol described here utilizes the ALDEFLUOR reagent system to detect ALDH activity as well as fluorophore-conjugated antibodies to detect specific cell surface antigens. ALDEFLUOR staining is performed at 37&deg;C and, therefore, needs to be completed before antibody staining (on ice) to prevent the potential for antibody capping, which can happen at 37&deg;C. Since cells can efflux the ALDEFLUOR reagent, it is important to maintain the cells in ALDEFLUOR buffer at 4&deg;C after ALDEFLUOR staining has been completed. The ALDEFLUOR buffer contains a drug efflux inhibitor that helps maintain intracellular levels of ALDEFLUOR.
Since this method isolates viable pancreatic CSCs they can be applied in a number of experiments that measure the physiological function of these cells. We have used these cells for tumor-initiation assays utilizing immunocompromised mice and in vitro cell migration/invasion assays. Furthermore, RNA, DNA, and protein can be collected
from these cells for analytical studies comparing CSC and non-CSC populations.

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		<div>
		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>DMEM </td>
<td>&nbsp;</td>
<td>Invitrogen (Carlsbad, CA) </td>
<td>11965-118 </td>
<td>&nbsp;</td>
<tr>
<td>Fetal calf serum </td>
<td>&nbsp;</td>
<td>Harlan (Indianapolis, IN)</td>
<td>BT-9501</td>
<td>&nbsp;</td>
<tr>
<td>Penicillin-streptomycin </td>
<td>&nbsp;</td>
<td>Invitrogen </td>
<td>15140-122 </td>
<td>&nbsp;</td>
<tr>
<td>Collagenase type IV </td>
<td>&nbsp;</td>
<td>Invitrogen </td>
<td>17104-019 </td>
<td>&nbsp;</td>
<tr>
<td>Dispase </td>
<td>&nbsp;</td>
<td>Sigma (St. Louis, MO) </td>
<td>D4818 </td>
<td>&nbsp;</td>
<tr>
<td>100 x 20 mm culture dish </td>
<td>&nbsp;</td>
<td>BD Biosciences (San Jose, CA) </td>
<td>353003 </td>
<td>&nbsp;</td>
<tr>
<td>70-&mu;m filter </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>352350 </td>
<td>&nbsp;</td>
<tr>
<td>50-mL conical tube </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>352070 </td>
<td>&nbsp;</td>
<tr>
<td>Ficoll-Paque Plus </td>
<td>&nbsp;</td>
<td>GE Healthcare (Upsala, Sweden) </td>
<td>17-1440 </td>
<td>&nbsp;</td>
<tr>
<td>ALDEFLUOR reagent system </td>
<td>&nbsp;</td>
<td>Stem Cell Technologies (Vancouver, BC, Canada) </td>
<td>01700 </td>
<td>&nbsp;</td>
<tr>
<td>Trypan blue </td>
<td>&nbsp;</td>
<td>Invitrogen </td>
<td>15250-061 </td>
<td>&nbsp;</td>
<tr>
<td>12 x 75 mm polystyrene test tubes </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>352054 </td>
<td>&nbsp;</td>
<tr>
<td>CD44-APC (clone G44-26) </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>559942 </td>
<td>&nbsp;</td>
<tr>
<td>CD24-PE (clone ML5) </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>555428 </td>
<td>&nbsp;</td>
<tr>
<td>Mouse CD31-biotin </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>553371 </td>
<td>&nbsp;</td>
<tr>
<td>Mouse lineage-biotin </td>
<td>&nbsp;</td>
<td>Miltenyi Biotec (Auburn, CA) </td>
<td>130-092-613 </td>
<td>&nbsp;</td>
<tr>
<td>Mouse H-2Kd-biotin </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>553564 </td>
<td>&nbsp;</td>
<tr>
<td>IgG2b&#x03BA;-APC</td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>555745 </td>
<td>&nbsp;</td>
<tr>
<td>IgG2a&#x03BA;-PE</td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>555574 </td>
<td>&nbsp;</td>
<tr>
<td>Streptavidin-PerCP protein </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>554064 </td>
<td>&nbsp;</td>
<tr>
<td>Propidium iodide </td>
<td>&nbsp;</td>
<td>Sigma </td>
<td>P4170 </td>
<td>&nbsp;</td>
<tr>
<td>12 x 75 mm polystyrene test tubes with strainer caps </td>
<td>&nbsp;</td>
<td>BD Biosciences </td>
<td>352235 </td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

isolation of stem cells from human pancreatic cancer xenografts

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal and produce differentiated progeny1. These properties allow CSCs to recapitulate the original tumor when injected into immunocompromised mice. CSCs within an epithelial malignancy were first described in breast cancer and found to display specific cell surface antigen expression (CD44+CD24low/-)2. Since then, CSCs have been identified in an increasing number of other human malignancies using CD44 and CD24 as well as a number of other surface antigens. Physiologic properties, including aldehyde dehydrogenase (ALDH) activity, have also been used to isolate CSCs from malignant tissues3-5.
Recently, we and others identified CSCs from pancreatic adenocarcinoma based on
ALDH activity and the expression of the cell surface antigens CD44 and CD24, and CD1336-8. These highly tumorigenic populations may or may not be overlapping and display other functions. We found that ALDH+ and CD44+CD24+ pancreatic CSCs are similarly tumorigenic, but ALDH+ cells are relatively more invasive8. In this protocol we describe a method to isolate viable pancreatic CSCs from low-passage human
xenografts9. Xenografted tumors are harvested from mice and made into a single-cell suspension. Tissue debris and dead cells are separated from live cells and then stained using antibodies against CD44 and CD24 and using the ALDEFLUOR reagent,
a fluorescent substrate of ALDH10. CSCs are then isolated by fluorescence activated cell sorting. Isolated CSCs can then be used for analytical or functional assays requiring viable cells.

Watch this Scientific Journal Video about Isolation of Stem Cells from Human Pancreatic Cancer Xenografts at JoVE.com

Isolation of Stem Cells from Human Pancreatic Cancer Xenografts

Cancer stem cells (CSCs) have been identified in a number of malignancies. In this protocol we describe a flow cytometric method utilizing aldehyde dehydrogenase activity and CD44 and CD24 expression to isolate CSCs from human pancreatic adenocarcinoma xenografts. These viable cells can then be used in functional and analytical studies.

Cancer stem cells (CSCs) have been identified in a growing number of malignancies and are functionally defined by their ability to undergo self-renewal ...

isolation-of-stem-cells-from-human-pancreatic-cancer-xenografts

Research

JoVE Journal

Biology

Isolation and Analysis of Hematopoietic Stem Cells from the Placenta

Hematopoietic stem cells (HSCs) have the ability to self-renew and generate all cell types of the blood lineages throughout the lifetime of an individual. All HSCs emerge during embryonic development, after which their pool size is maintained by self-renewing cell divisions. Identifying the anatomical origin of HSCs and the critical developmental events regulating the process of HSC development has been complicated as many anatomical sites participate during fetal hematopoiesis. Recently, we identified the placenta as a major hematopoietic organ where HSCs are generated and expanded in unique microenvironmental niches (Gekas, et al 2005, Rhodes, et al 2008). Consequently, the placenta is an important source of HSCs during their emergence and initial expansion.
In this article, we show dissection techniques for the isolation of murine placenta from E10.5 and E12.5 embryos, corresponding to the developmental stages of initiation of HSCs and the peak in the size of the HSC pool in the placenta, respectively. In addition, we present an optimized protocol for enzymatic and mechanical dissociation of placental tissue into single-cell suspension for use in flow cytometry or functional assays. We have found that use of collagenase for single-cell suspension of placenta gives sufficient yields of HSCs. An important factor affecting HSC yield from the placenta is the degree of mechanical dissociation prior to, and duration of, enzymatic treatment.
We also provide a protocol for the preparation of fixed-frozen placental tissue sections for the visualization of developing HSCs by immunohistochemistry in their precise cellular niches. As hematopoietic specific antigens are not preserved during preparation of paraffin embedded sections, we routinely use fixed frozen sections for localizing placental HSCs and progenitors.

We have identified the placenta as a major hematopoietic organ during development. We found that hematopoietic stem cells (HSCs) are both generated and expanded in the placenta in unique microenvironmental niches. Here, we describe experimental techniques required for isolation and visualization of HSCs in the mouse placenta.

Hematopoietic stem cells (HSCs) have the ability to self-renew and generate all cell types of the blood lineages throughout the lifetime of an individual. ...

Chromatin Immunoprecipitation from Human Embryonic Stem Cells

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are characterized by two fundamental properties: self-renewal and multipotency that allows a stem cell to differentiate into virtually any cell type 1. The progression stem cell to differentiated cell is characterized by loss of multipotency, structural and morphological changes and the hierarchic activity of transcription factors and signaling molecules, whose activities establish and maintain cell-type specific gene expression patterns. At the molecular level, cell differentiation involves dynamic changes of the structure and composition of chromatin and the detection of those dynamic changes can provide valuable insights into the functional features of stem cells and the cell differentiation process 2,3. Chromatin is a highly compacted DNA-protein complex that forms when cells package chromosomal DNA with proteins, mainly histones 4. Stemcellness and cell differentiation has been correlated with the presence of specific arrays of regulatory proteins such as epigenetic factors, histone variants, and transcription factors 2,3,5.
 Chromatin immunoprecipitation (ChIP) provides a valuable method to monitor the presence of RNA, proteins, and protein modifications in chromatin 6,7. The comparison of chromatin from different cell types can elucidate dynamic changes in protein-chromatin associations that occur during cell differentiation.
Chromatin immunoprecipitation involves the purification of in vivo cross-linked chromatin. The isolated chromatin is reduced to smaller fragments by enzymatic digestion or mechanical force. Chromatin fragments are precipitated using specific antibodies to target proteins or protein and DNA modifications. The precipitated DNA or RNA is purified and used as a template for PCR or DNA microarray based assays. Prerequisites for a successful ChIP are high quality antibodies to the desired antigen and the availability of chromatin from control cells that do not express the target molecule. ChIP can correlate the presence of proteins, protein and RNA modifications, and RNA with specific target DNA, and depending on the choice of outread tool, detects the association of target molecules at specific target genes or in the context of an entire genome. The comparison of the distribution of proteins in the chromatin of differentiating cells can elucidate the dynamic changes of chromatin composition that coincide with the progression of cells along a cell lineage.

The differentiation of ESC coincides with cell-type specific changes in the structure and composition of chromatin. The detection of those changes provides valuable insights into the mechanisms that define stemcellness and cell differentiation. Chromatin immunoprecipitation (ChIP) represents a valuable method to dissect the molecular mechanisms underlying stem cell differentiation.

The functional and structural complexity of the myriad of cells in metazoan organisms arises from a small number of stem cells. Stem cells are ...

Human Pancreatic Islet Isolation: Part I: Digestion and Collection of Pancreatic Tissue

Management of Type 1 diabetes is burdensome, both to the individual and society, costing over 100 billion dollars annually. Despite the widespread use of glucose monitoring and new insulin formulations, many individuals still develop devastating secondary complications. Pancreatic islet transplantation can restore near normal glucose control in diabetic patients 1, without the risk of serious hypoglycemic episodes that are associated with intensive insulin therapy. Providing sufficient islet mass is important for successful islet transplantation. However, donor characteristic, organ procurement and preservation affect the isolation outcome 2. At University of Illinois at Chicago (UIC) we have developed a successful isolation protocol with an improved purification gradient 3. The program started in January 2004, and more than 300 isolations were performed up to November 2008. The pancreata were sent in cold preservation solutions (UW, University of Wisconsin or HTK, Histidine-Tryptophan Ketoglutarate) 4-7 to the Cell Isolation Laboratory at UIC for islet isolation. Pancreatic islets were isolated using the UIC method, which is a modified version of the method originally described by Ricordi et al 8. Briefly, after cleaning the pancreas from the surrounding tissue, it was perfused with enzyme solution (Serva Collagenase + Neutral Protease or Sigma V enzyme). The distended pancreas was then transferred to the Ricordi digestion chamber, connected to a modified, closed circulation tubing system, and warmed up to 37&deg;C. During the digestion, the chamber was shaken gently. Samples were taken continuously to monitor the digestion progress. Once free islets were detected under the microscope, the digestion was stopped by flushing cold (4&deg;C) RPMI dilution solution (Mediatech, Herndon, VA) into the circulation system to dilute the enzyme. After being collected and washed in M199 media supplemented with human albumin, the tissue was sampled for pre-purification count and incubated with UW solution before purification. Purification process will be described in Part II: Purification and Culture of Human Islets.

Achieving high quality and appropriate quantity of human islets is one of the prominent prerequisites for successful islet transplantation. In this video, we describe step by step the procedures for human pancreatic islet isolation (part I: digestion and collection of pancreatic tissue) using a modified automated method.

Management of Type 1 diabetes is burdensome, both to the individual and society, costing over 100 billion dollars annually. Despite the widespread use of ...

Isolation and Large Scale Expansion of Adult Human Endothelial Colony Forming Progenitor Cells

This paper introduces a novel recovery strategy for endothelial colony forming progenitor cells (ECFCs) from heparinized but otherwise unmanipulated adult human peripheral blood within a mean of 12 days. After large scale expansion &gt;1x108 ECFCs can be obtained for further tests. Advantageously by using pHPL the contact of human cells with bovine serum antigens can be excluded. By flow cytometry and immunohistochemistry the isolated cells can be characterized as ECFC and their in vitro functionality to form vascular like structures can be tested in a matrigel assay. Further these cells can be subcutaneously injected in a mouse model to form functional, perfused vessels in vivo. After long term expansion and cryopreservation proliferation, function and genomic stability appear to be preserved. 3,4
This animal-protein free isolation and expansion method is easily applicable to generate a large quantity of ECFCs.

Endothelial colony forming progenitor cells (ECFCs) are a promising tool to study vascular homeostasis and repair.1,2 This paper introduces a novel animal-serum free method for isolation and expansion of ECFC from heparinised adult human peripheral blood with pooled human platelet lysate (pHPL) diminishing the risk of anti-bovine immunisation.

This paper introduces a novel recovery strategy for endothelial colony forming progenitor cells (ECFCs) from heparinized but otherwise unmanipulated adult ...

Isolation and Culture of Adult Epithelial Stem Cells from Human Skin

The homeostasis of all self-renewing tissues is dependent on adult stem cells. As undifferentiated stem cells undergo asymmetric divisions, they generate daughter cells that retain the stem cell phenotype and transit-amplifying cells (TA cells) that migrate from the stem cell niche, undergo rapid proliferation and terminally differentiate to repopulate the tissue.
Epithelial stem cells have been identified in the epidermis, hair follicle, and intestine as cells with a high in vitro proliferative potential and as slow-cycling label-retaining cells in vivo 1-3. Adult, tissue-specific stem cells are responsible for the regeneration of the tissues in which they reside during normal physiologic turnover as well as during times of stress 4-5. Moreover, stem cells are generally considered to be multi-potent, possessing the capacity to give rise to multiple cell types within the tissue 6. For example, rodent hair follicle stem cells can generate epidermis, sebaceous glands, and hair follicles 7-9. We have shown that stem cells from the human hair follicle bulge region exhibit multi-potentiality 10.
Stem cells have become a valuable tool in biomedical research, due to their utility as an in vitro system for studying developmental biology, differentiation, tumorigenesis and for their possible therapeutic utility. It is likely that adult epithelial stem cells will be useful in the treatment of diseases such as ectodermal dysplasias, monilethrix, Netherton syndrome, Menkes disease, hereditary epidermolysis bullosa and alopecias 11-13. Additionally, other skin problems such as burn wounds, chronic wounds and ulcers will benefit from stem cell related therapies 14,15. Given the potential for reprogramming of adult cells into a pluripotent state (iPS cells)16,17, the readily accessible and expandable adult stem cells in human skin may provide a valuable source of cells for induction and downstream therapy for a wide range of disease including diabetes and Parkinson's disease.

A rapid, robust way of isolating viable adult epithelial stem cells from human skin is described. The method utilizes enzymatic digestion of skin collagen matrix , followed by plucking of hair follicles and isolation of single cell suspensions or tissue fragments for cell culture.

The homeostasis of all self-renewing tissues is dependent on adult stem cells. As undifferentiated stem cells undergo asymmetric divisions, they generate ...

Selecting and Isolating Colonies of Human Induced Pluripotent Stem Cells Reprogrammed from Adult Fibroblasts

Herein we present a protocol of reprogramming human adult fibroblasts into human induced pluripotent stem cells (hiPSC) using retroviral vectors encoding Oct3/4, Sox2, Klf4 and c-myc (OSKM) in the presence of sodium butyrate 1-3. We used this method to reprogram late passage (&gt;p10) human adult fibroblasts derived from Friedreich's ataxia patient (GM03665, Coriell Repository). The reprogramming approach includes highly efficient transduction protocol using repetitive centrifugation of fibroblasts in the presence of virus-containing media. The reprogrammed hiPSC colonies were identified using live immunostaining for Tra-1-81, a surface marker of pluripotent cells, separated from non-reprogrammed fibroblasts and manually passaged 4,5. These hiPSC were then transferred to Matrigel plates and grown in feeder-free conditions, directly from the reprogramming plate. Starting from the first passage, hiPSC colonies demonstrate characteristic hES-like morphology. Using this protocol more than 70% of selected colonies can be successfully expanded and established into cell lines. The established hiPSC lines displayed characteristic pluripotency markers including surface markers TRA-1-60 and SSEA-4, as well as nuclear markers Oct3/4, Sox2 and Nanog. 
The protocol presented here has been established and tested using adult fibroblasts obtained from Friedreich's ataxia patients and control individuals 6, human newborn fibroblasts, as well as human keratinocytes.

We present a protocol for efficient reprogramming of human somatic cells into human induced pluripotent stem cells (hiPSC) using retroviral vectors encoding Oct3/4, Sox2, Klf4 and c-myc (OSKM) and identification of correctly reprogrammed hiPSC by live staining with Tra-1-81 antibody.

Herein we present a protocol of reprogramming human adult fibroblasts into human induced pluripotent stem cells (hiPSC) using retroviral vectors encoding ...

Isolation of Immune Cells from Primary Tumors

Tumors create a unique immunosuppressive microenvironment (tumor microenvironment, TME) whereby leukocytes are recruited into the tumor by various chemokines and growth factors 1,2. However, once in the TME, these cells lose the ability to promote anti-tumor immunity and begin to support tumor growth and down-regulate anti-tumor immune responses 3-4. Studies on tumor-associated leukocytes have mainly focused on cells isolated from tumor-draining lymph nodes or spleen due to the inherent difficulties in obtaining sufficient cell numbers and purity from the primary tumor. While identifying the mechanisms of cell activation and trafficking through the lymphatic system of tumor bearing mice is important and may give insight to the kinetics of immune responses to cancer, in our experience, many leukocytes, including dendritic cells (DCs), in tumor-draining lymph nodes have a different phenotype than those that infiltrate tumors 5,6 . Furthermore, we have previously demonstrated that adoptively-transferred T cells isolated from the tumor-draining lymph nodes are not tolerized and are capable of responding to secondary stimulation in vitro unlike T cells isolated from the TME, which are tolerized and incapable of proliferation or cytokine production 7,8. Interestingly, we have shown that changing the tumor microenvironment, such as providing CD4+ T helper cells via adoptive transfer, promotes CD8+ T cells to maintain pro-inflammatory effector functions 5. The results from each of the previously mentioned studies demonstrate the importance of measuring cellular responses from TME-infiltrating immune cells as opposed to cells that remain in the periphery. To study the function of immune cells which infiltrate tumors using the Miltenyi Biotech isolation system9, we have modified and optimized this antibody-based isolation procedure to obtain highly enriched populations of antigen presenting cells and tumor antigen-specific cytotoxic T lymphocytes. The protocol includes a detailed dissection of murine prostate tissue from a spontaneous prostate tumor model (TRansgenic Adenocarcinoma of the Mouse Prostate -TRAMP) 10 and a subcutaneous melanoma (B16) tumor model followed by subsequent purification of various leukocyte populations.

In this report, we describe a protocol for isolating highly purified populations of leukocytes that infiltrate tumors. This protocol is adapted from the Miltenyi Biotech protocol to enhance yield and purity for isolating cells from complex tumor tissue.

Tumors create a unique immunosuppressive microenvironment (tumor microenvironment, TME) whereby leukocytes are recruited into the tumor by various ...

Na&iuml;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

Over the last decade, several adult stem cell populations have been identified in human skin 1-4. The isolation of multipotent adult dermal precursors was first reported by Miller F. D laboratory 5, 6. These early studies described a multipotent precursor cell population from adult mammalian dermis 5. These cells--termed SKPs, for skin-derived precursors-- were isolated and expanded from rodent and human skin and differentiated into both neural and mesodermal progeny, including cell types never found in skin, such as neurons 5. Immunocytochemical studies on cultured SKPs revealed that cells expressed vimentin and nestin, an intermediate filament protein expressed in neural and skeletal muscle precursors, in addition to fibronectin and multipotent stem cell markers 6. Until now, the adult stem cells population SKPs have been isolated from freshly collected mammalian skin biopsies.
Recently, we have established and reported that a population of skin derived precursor cells could remain present in primary fibroblast cultures established from skin biopsies 7. The assumption that a few somatic stem cells might reside in primary fibroblast cultures at early population doublings was based upon the following observations: (1) SKPs and primary fibroblast cultures are derived from the dermis, and therefore a small number of SKP cells could remain present in primary dermal fibroblast cultures and (2) primary fibroblast cultures grown from frozen aliquots that have been subjected to unfavorable temperature during storage or transfer contained a small number of cells that remained viable 7. These rare cells were able to expand and could be passaged several times. This observation suggested that a small number of cells with high proliferation potency and resistance to stress were present in human fibroblast cultures 7.
We took advantage of these findings to establish a protocol for rapid isolation of adult stem cells from primary fibroblast cultures that are readily available from tissue banks around the world (Figure 1). This method has important significance as it allows the isolation of precursor cells when skin samples are not accessible while fibroblast cultures may be available from tissue banks, thus, opening new opportunities to dissect the molecular mechanisms underlying rare genetic diseases as well as modeling diseases in a dish.

Na&amp;#239;ve Adult Stem Cells Isolation from Primary Human Fibroblast Cultures

We report a method to isolate na&#239;ve multipotent skin-derived precursor (SKP) cells from primary human fibroblast cultures. We show that these SKPs derived from fibroblast cultures share similar stem cell properties to the ones derived directly from human skin biopsies. These cells express the neural crest marker, nestin, in addition to the multipotent markers such as OCT4 and Nanog.

Over the last decade, several adult stem cell  populations have been identified in human skin 1-4.  The isolation of multipotent adult dermal precursors ...

Manual Isolation of Adipose-derived Stem Cells from Human Lipoaspirates

In 2001, researchers at the University of California, Los Angeles, described the isolation of a new population of adult stem cells from liposuctioned adipose tissue that they initially termed Processed Lipoaspirate Cells or PLA cells. Since then, these stem cells have been renamed as Adipose-derived Stem Cells or ASCs and have gone on to become one of the most popular adult stem cells populations in the fields of stem cell research and regenerative medicine. Thousands of articles now describe the use of ASCs in a variety of regenerative animal models, including bone regeneration, peripheral nerve repair and cardiovascular engineering. Recent articles have begun to describe the myriad of uses for ASCs in the clinic. The protocol shown in this article outlines the basic procedure for manually and enzymatically isolating ASCs from large amounts of lipoaspirates obtained from cosmetic procedures. This protocol can easily be scaled up or down to accommodate the volume of lipoaspirate and can be adapted to isolate ASCs from fat tissue obtained through abdominoplasties and other similar procedures.

In 2001, researchers at UCLA described the isolation of a population of adult stem cells, termed Adipose-derived Stem Cells or ASCs, from adipose tissue. This article outlines the isolation of ASCs from lipoaspirates using a manual, enzymatic digestion protocol using collagenase.

In 2001, researchers at the University of  California, Los Angeles, described the isolation of a new population of adult  stem cells from liposuctioned ...

Isolation and Culture of Dental Epithelial Stem Cells from the Adult Mouse Incisor

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest1-4, and the mouse incisor provides a model for these processes. This remarkable organ grows continuously throughout the animal&#39;s life and generates all the necessary cell types from active pools of adult stem cells housed in the labial (toward the lip) and lingual (toward the tongue) cervical loop (CL) regions. Only the dental stem cells from the labial CL give rise to ameloblasts that generate enamel, the outer covering of teeth, on the labial surface. This asymmetric enamel formation allows abrasion at the incisor tip, and progenitors and stem cells in the proximal incisor ensure that the dental tissues are constantly replenished. The ability to isolate and grow these progenitor or stem cells in vitro allows their expansion and opens doors to numerous experiments not achievable in vivo, such as high throughput testing of potential stem cell regulatory factors. Here, we describe and demonstrate a reliable and consistent method to culture cells from the labial CL of the mouse incisor.

The continuously growing mouse incisor provides a model for studying renewal of dental tissues from dental epithelial stem cells (DESCs). A robust system for consistently and reliably obtaining these cells from the incisor and expanding them in vitro is reported here.

Understanding the cellular and molecular mechanisms that underlie tooth regeneration and renewal has become a topic of great interest1-4, and the mouse ...