This work was supported by the Alexander von Humboldt Foundation Sofja Kovalevskaja Award to VLK.

All experimental procedures were conducted with the approval of the ethics and animal care committees of Homburg University Medical Center.
1. Preparation of Materials and Buffers
<ol>
	<li>Freshly prepare all buffers required for liver digestion using sterile components and a laminar hood to avoid bacterial contamination.</li>
	<li>Prepare the collection buffer (CB) by mixing 49.5 mL of RPMI medium and 0.5 mL of fetal bovine serum (FBS; low endotoxin, heat inactivated) to achieve a 1% (v/v)...

<ol>
	<li>Dolle, 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=Successful+isolation+of+liver+progenitor+cells+by+aldehyde+dehydrogenase+activity+in+naive+mice.">Successful isolation of liver progenitor cells by aldehyde dehydrogenase activity in naive mice.</a> Hepatology. 55 (2), 540-552 (2012).</li><li>Dolle, 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=The+quest+for+liver+progenitor+cells:+a+practical+point+of+view.">The quest for liver progenitor cells: a practical point of view.</a> J Hepatol. 52 (1), 117-129 (2010).</li><li>Dorrell, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+markers+for+the+murine+oval+cell+response.">Surface markers for the murine oval cell response.</a> Hepatology. 48 (4), 1282-1291 (2008).</li><li>Gouw, A. S., Clouston, A. D., Theise, N. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ductular+reactions+in+human+liver:+diversity+at+the+interface.">Ductular reactions in human liver: diversity at the interface.</a> Hepatology. 54 (5), 1853-1863 (2011).</li><li>Tarlow, B. D., Finegold, M. J., Grompe, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clonal+tracing+of+Sox9++liver+progenitors+in+mouse+oval+cell+injury.">Clonal tracing of Sox9+ liver progenitors in mouse oval cell injury.</a> Hepatology. 60 (1), 278-289 (2014).</li><li>Shin, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Foxl1-Cre-marked+adult+hepatic+progenitors+have+clonogenic+and+bilineage+differentiation+potential.">Foxl1-Cre-marked adult hepatic progenitors have clonogenic and bilineage differentiation potential.</a> Genes Dev. 25 (11), 1185-1192 (2011).</li><li>Furuyama, 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=Continuous+cell+supply+from+a+Sox9-expressing+progenitor+zone+in+adult+liver,+exocrine+pancreas+and+intestine.">Continuous cell supply from a Sox9-expressing progenitor zone in adult liver, exocrine pancreas and intestine.</a> Nat Genet. 43 (1), 34-41 (2011).</li><li>Font-Burgada, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+Periportal+Hepatocytes+Regenerate+the+Injured+Liver+without+Giving+Rise+to+Cancer.">Hybrid Periportal Hepatocytes Regenerate the Injured Liver without Giving Rise to Cancer.</a> Cell. 162 (4), 766-779 (2015).</li><li>Kuramitsu, 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=Failure+of+fibrotic+liver+regeneration+in+mice+is+linked+to+a+severe+fibrogenic+response+driven+by+hepatic+progenitor+cell+activation.">Failure of fibrotic liver regeneration in mice is linked to a severe fibrogenic response driven by hepatic progenitor cell activation.</a> Am J Pathol. 183 (1), 182-194 (2013).</li><li>Pritchard, M. T., Nagy, L. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hepatic+fibrosis+is+enhanced+and+accompanied+by+robust+oval+cell+activation+after+chronic+carbon+tetrachloride+administration+to+Egr-1-deficient+mice.">Hepatic fibrosis is enhanced and accompanied by robust oval cell activation after chronic carbon tetrachloride administration to Egr-1-deficient mice.</a> Am J Pathol. 176 (6), 2743-2752 (2010).</li><li>Spee, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterisation+of+the+liver+progenitor+cell+niche+in+liver+diseases:+potential+involvement+of+Wnt+and+Notch+signalling.">Characterisation of the liver progenitor cell niche in liver diseases: potential involvement of Wnt and Notch signalling.</a> Gut. 59 (2), 247-257 (2010).</li><li>Eckert, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Podoplanin+discriminates+distinct+stromal+cell+populations+and+a+novel+progenitor+subset+in+the+liver.">Podoplanin discriminates distinct stromal cell populations and a novel progenitor subset in the liver.</a> Am J Physiol Gastrointest Liver Physiol. 310 (1), G1-G12 (2016).</li><li>Epting, C. 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=Stem+cell+antigen-1+is+necessary+for+cell-cycle+withdrawal+and+myoblast+differentiation+in+C2C12+cells.">Stem cell antigen-1 is necessary for cell-cycle withdrawal and myoblast differentiation in C2C12 cells.</a> J Cell Sci. 117 (Pt 25), 6185-6195 (2004).</li><li>Tirnitz-Parker, J. E., Tonkin, J. N., Knight, B., Olynyk, J. K., Yeoh, G. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation,+culture+and+immortalisation+of+hepatic+oval+cells+from+adult+mice+fed+a+choline-deficient,+ethionine-supplemented+diet.">Isolation, culture and immortalisation of hepatic oval cells from adult mice fed a choline-deficient, ethionine-supplemented diet.</a> Int J Biochem Cell Biol. 39 (12), 2226-2239 (2007).</li><li>Rountree, C. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+CD133-expressing+murine+liver+oval+cell+population+with+bilineage+potential.">A CD133-expressing murine liver oval cell population with bilineage potential.</a> Stem Cells. 25 (10), 2419-2429 (2007).</li><li>Rountree, C. B., Ding, W., Dang, H., Vankirk, C., Crooks, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+of+CD133++liver+stem+cells+for+clonal+expansion.">Isolation of CD133+ liver stem cells for clonal expansion.</a> J Vis Exp. (56), (2011).</li><li>Sidney, L. E., McIntosh, O. D., Hopkinson, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phenotypic+Change+and+Induction+of+Cytokeratin+Expression+During+In+Vitro+Culture+of+Corneal+Stromal+Cells.">Phenotypic Change and Induction of Cytokeratin Expression During In Vitro Culture of Corneal Stromal Cells.</a> Invest Ophthalmol Vis Sci. 56 (12), 7225-7235 (2015).</li><li>Hass, R., Kasper, C., Bohm, S., Jacobs, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Different+populations+and+sources+of+human+mesenchymal+stem+cells+(MSC):+A+comparison+of+adult+and+neonatal+tissue-derived+MSC.">Different populations and sources of human mesenchymal stem cells (MSC): A comparison of adult and neonatal tissue-derived MSC.</a> Cell Commun Signal. 9, 12 (2011).</li><li>Schmelzer, E., 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+hepatic+stem+cells+from+fetal+and+postnatal+donors.">Human hepatic stem cells from fetal and postnatal donors.</a> J Exp Med. 204 (8), 1973-1987 (2007).</li></ol>

The authors have no competing financial interests.

Liver inflammation and injury of different origins trigger regenerative processes in the liver that are accompanied by progenitor cell expansion and activation2,3. These liver progenitor cells possess stem cell characteristics and likely play a significant role in the pathomechanism of various liver diseases.
The heterogeneity of liver progenitor cells has long been suggested. The re-evaluation of liver progenitor subsets using a novel...

Liver regeneration is mostly associated with the self-renewal capacity of hepatocytes. Nevertheless, chronic liver injuries occur with progenitor cell activation and expansion, which have been associated with their ability to differentiate into hepatocytes and cholangiocytes1,2,3,4. This is especially relevant because, during chronic injuries, hepatocyte proliferation is not effective. Despite multiple genetic tracing studies targeting progenitor cells, their role in liver regeneration remains controversial5,6,7,8. Moreover, the activation of progenitor cells has been linked to increased fibrotic response in the liver, which raises questions about their exact role during injuries9,10.
The heterogeneous nature of the progenitor cell compartment has long been suggested by gene expression studies that isolated progenitor cells expressing a single surface marker using microdissection or cell sorting-based methods1,11. Indeed, recently, a novel surface marker combination using gp38 (podoplanin) unequivocally linked previous single markers of progenitor cells to various subsets12. Importantly, these subsets not only differed in their surface marker expression but also exhibited functional alterations during injuries12.
Multiple animal models have been utilized to investigate progenitor cell activation and liver regeneration. It seems that the various injury types promote the activation of differing subsets of progenitor cells12. This might explain the phenotypic divergence of the ductular reaction observed in humans4. Thus, the complex phenotypic and functional analyses of progenitor cells are pivotal to understand their role in injuries and the true significance of the ductular reaction in liver diseases.
Besides surface marker combinations, the crucial differences in cell isolation protocols further complicate the conclusions based on previous studies2. A substantial amount of studies addressed the role of progenitor cells that greatly differ in their isolation protocol (e.g., liver dissociation (enzyme combination and duration of the process), density medium, and centrifugation speed)2. An optimized isolation technique, providing better viability for rare cell populations and reflective of subset composition, has been developed and published recently12. The aim of this article is to provide a more detailed protocol of this liver cell isolation procedure and the subset analysis to allow for the proper reproduction of the technique. Additionally, the protocol includes a comparison with the previous isolation method to demonstrate the differences compared to the new protocol.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>RPMI</td>
			<td>Life Technologies</td>
			<td>21875-034</td>
			<td></td>
		</tr>
		<tr>
			<td>phenol red free DMEM</td>
			<td>Life Technologies</td>
			<td>31053-028</td>
			<td></td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Life Technologies</td>
			<td>10270-106</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase P</td>
			<td>Sigma-Aldrich</td>
			<td>11249002001</td>
			<td></td>
		</tr>
		<tr>
			<td>DNAse-I</td>
			<td>Sigma-Aldrich</td>
			<td>10104159001</td>
			<td></td>
		</tr>
		<tr>
			<td>Dispase</td>
			<td>Life Technologies</td>
			<td>17105041</td>
			<td></td>
		</tr>
		<tr>
			<td>ACK Lysing Buffer</td>
			<td>Life Technologies</td>
			<td>A10492-01</td>
			<td></td>
		</tr>
		<tr>
			<td>HBSS</td>
			<td>Life Technologies</td>
			<td>14025-050</td>
			<td></td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Sigma-Aldrich</td>
			<td>D8537</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Azide</td>
			<td>Sigma-Aldrich</td>
			<td>S2002</td>
			<td>Prepare 1 % stock solution</td>
		</tr>
		<tr>
			<td>10 % BSA</td>
			<td>Miltenyi Biotec</td>
			<td>130-091-376</td>
			<td></td>
		</tr>
		<tr>
			<td>autoMACS Rinsing Solution</td>
			<td>Miltenyi Biotec</td>
			<td>130-091-222</td>
			<td>add 0.5 % (v/v) BSA and store on ice</td>
		</tr>
		<tr>
			<td>Phenol-red free DMEM</td>
			<td>Sigma-Aldrich</td>
			<td>D1145</td>
			<td></td>
		</tr>
		<tr>
			<td>counting Beads Count Bright</td>
			<td>Life Technologies</td>
			<td>C36950</td>
			<td></td>
		</tr>
		<tr>
			<td>PI</td>
			<td>Miltenyi Biotec</td>
			<td>130-093-233</td>
			<td></td>
		</tr>
		<tr>
			<td>FcR Blocking Reagent</td>
			<td>Miltenyi Biotec</td>
			<td>130-092-575</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-CD31 MicroBeads</td>
			<td>Miltenyi Biotec</td>
			<td>130-097-418</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-CD45 MicroBeads</td>
			<td>Miltenyi Biotec</td>
			<td>130-052-301</td>
			<td></td>
		</tr>
		<tr>
			<td>Dead Cell Removal Kit</td>
			<td>Miltenyi Biotec</td>
			<td>130-090-101</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-Biotin MicroBeads</td>
			<td>Miltenyi Biotec</td>
			<td>130-090-485</td>
			<td></td>
		</tr>
		<tr>
			<td>CD64 Purified</td>
			<td>BioLegend</td>
			<td>139302</td>
			<td>Dilution: 1:100</td>
		</tr>
		<tr>
			<td>CD16/32 Purified</td>
			<td>BioLegend</td>
			<td>101302</td>
			<td>Dilution: 1:100</td>
		</tr>
		<tr>
			<td>CD45 APC/Cy7</td>
			<td>BioLegend</td>
			<td>103116</td>
			<td>Dilution: 1:200, marks hematopoetic cells</td>
		</tr>
		<tr>
			<td>CD31 Biotin</td>
			<td>BioLegend</td>
			<td>102504</td>
			<td>Dilution: 1:200, marks endothelial cells</td>
		</tr>
		<tr>
			<td>ASGPR1 Purified</td>
			<td>Bio-Techne</td>
			<td>AF2755-SP</td>
			<td>Dilution: 1:100, marks hepatocytes</td>
		</tr>
		<tr>
			<td>Podoplanin APC</td>
			<td>BioLegend</td>
			<td>127410</td>
			<td>Dilution: 1:1400, marks progenior cells</td>
		</tr>
		<tr>
			<td>Podoplanin Biotin</td>
			<td>BioLegend</td>
			<td>127404</td>
			<td>Dilution: 1:1400</td>
		</tr>
		<tr>
			<td>CD133 PE</td>
			<td>Miltenyi Biotec</td>
			<td>130-102-210</td>
			<td>use 3 &#181;l, marks progenitor cells</td>
		</tr>
		<tr>
			<td>CD133 Biotin</td>
			<td>BioLegend</td>
			<td>141206</td>
			<td>Dilution: 1:100</td>
		</tr>
		<tr>
			<td>CD34 Biotin</td>
			<td>eBioScience</td>
			<td>13-0341-81</td>
			<td>Dilution: 1:100</td>
		</tr>
		<tr>
			<td>CD90.2 Pacific Blue</td>
			<td>BioLegend</td>
			<td>140306</td>
			<td>Dilution: 1:800</td>
		</tr>
		<tr>
			<td>CD157 PE</td>
			<td>BioLegend</td>
			<td>140203</td>
			<td>Dilution: 1:600</td>
		</tr>
		<tr>
			<td>EpCAM Brilliant Violet 421</td>
			<td>BioLegend</td>
			<td>118225</td>
			<td>Dilution: 1:100</td>
		</tr>
		<tr>
			<td>Sca-1 Biotin</td>
			<td>Miltenyi Biotec</td>
			<td>130-101-885</td>
			<td>use 10 &#181;l</td>
		</tr>
		<tr>
			<td>Mouse IgG2b, &#954; PE</td>
			<td>BioLegend</td>
			<td>400311</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat IgG1 PE</td>
			<td>BioLegend</td>
			<td>400407</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat IgG2b, &#954; APC/Cy7</td>
			<td>BioLegend</td>
			<td>400624</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat IgG2a, &#954; Biotin</td>
			<td>BioLegend</td>
			<td>400504</td>
			<td></td>
		</tr>
		<tr>
			<td>Rat IgG2a, &#954; Brilliant Violet 421</td>
			<td>BioLegend</td>
			<td>400535</td>
			<td></td>
		</tr>
		<tr>
			<td>Syrian Hamster IgG APC</td>
			<td>BioLegend</td>
			<td>402012</td>
			<td></td>
		</tr>
		<tr>
			<td>Syrian Hamster IgG Biotin</td>
			<td>BioLegend</td>
			<td>402004</td>
			<td></td>
		</tr>
		<tr>
			<td>Normal Goat IgG Control Purified</td>
			<td>Bio-Techne</td>
			<td>AB-108-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Donkey anti-Goat IgG Alexa Fluor 488</td>
			<td>Life Technologies</td>
			<td>A11055</td>
			<td>Dilution: 1:800</td>
		</tr>
		<tr>
			<td>Streptavidin Alexa Fluor 405</td>
			<td>Life Technologies</td>
			<td>S32351</td>
			<td>Dilution: 1:400</td>
		</tr>
		<tr>
			<td>100 &#181;m Filter mesh</td>
			<td>A. Hartenstein</td>
			<td>PAS3</td>
			<td></td>
		</tr>
		<tr>
			<td>LS Column</td>
			<td>Miltenyi Biotec</td>
			<td>130-042-401</td>
			<td></td>
		</tr>
		<tr>
			<td>QuadroMACS separator</td>
			<td>Miltenyi Biotec</td>
			<td>130-090-976</td>
			<td></td>
		</tr>
		<tr>
			<td>MACSQuant Analyzer 10</td>
			<td>Miltenyi Biotec</td>
			<td>130-096-343</td>
			<td></td>
		</tr>
		<tr>
			<td>AutoMACS Pro Separator</td>
			<td>Miltenyi Biotec</td>
			<td>130-092-545</td>
			<td></td>
		</tr>
		<tr>
			<td>FACS AriaTMIII</td>
			<td>BD Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>FACSDiva sofware</td>
			<td>BD Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Polypropylene Round bottom tube</td>
			<td>Falcon</td>
			<td>352063</td>
			<td></td>
		</tr>
		<tr>
			<td>Rneasy plus mini kit</td>
			<td>Qiagen</td>
			<td>74134</td>
			<td>RLT lysis buffer is included</td>
		</tr>
	</tbody>
</table>

isolation and enrichment of liver progenitor subsets identified by a novel surface marker combination

During chronic liver injuries, progenitor cells expand in a process called ductular reaction, which also entails the appearance of inflammatory cellular infiltrate and epithelial cell activation. The progenitor cell population during such inflammatory reactions has mostly been investigated using single surface markers, either by histological analysis or by flow cytometry-based techniques. However, novel surface markers identified various functionally distinct subsets within the liver progenitor/stem cell compartment. The method presented here describes the isolation and detailed flow cytometry analysis of progenitor subsets using novel surface marker combinations. Moreover, it demonstrates how the various progenitor cell subsets can be isolated with high purity using automated magnetic and FACS sorting-based methods. Importantly, novel and simplified enzymatic dissociation of the liver allows for the isolation of these rare cell populations with a high viability that is superior in comparison to other existing methods. This is especially relevant for further studying progenitor cells in vitro or for isolating high-quality RNA to analyze the gene expression profile.

The procedure presented here for the digestion of the liver using a novel mixture of enzymes results in a single-cell suspension containing parenchymal and non-parenchymal liver cells (Figures 1 and 2a). After the ACK-lysing of red blood cells, the direct flow cytometry analysis of the single-cell suspension is possible (Figures 1 and 2). The gating strategy involves the exclusion of doublets and dead cells (Figur...

Watch this Scientific Journal Video about Isolation and Enrichment of Liver Progenitor Subsets Identified by a Novel Surface Marker Combination at JoVE.com

Isolation and Enrichment of Liver Progenitor Subsets Identified by a Novel Surface Marker Combination

Liver injuries are accompanied by progenitor cell expansion that represents a heterogeneous cell population. Novel classification of this cellular compartment allows for the distinguishing of multiple subsets. The method described here illustrates the flow cytometry analysis and high purity isolation of various subsets that can be used for further assays.

During chronic liver injuries, progenitor cells expand in a process called ductular reaction, which also entails the appearance of inflammatory cellular ...

The overall goals of this liver digestion protocol are to assess the various liver progenitor subsets by flow cytometry and to isolate these cells to a high purity using a novel surface marker cocktail for further downstream analysis. This method can help answer various questions about the biology of liver progenitor cells, for example, what are their subset specific features and what are their distant cause during liver injury. The main advantage of this technique is that it allows the isolation of progenitor cells for high purity and viability which is important for the in-vitro analysis.Although this digestion technique provides insight into progenitor cell biology, it can actually be utilized for the isolation of hematopoietic and endothelial cell populations. To prepare a single cell preparation from a mouse liver, transfer the lobes onto a dried petri dish and use a scalpel to cut the tissues into approximately two millimeters cubed homogenous cubes. Transfer the pieces into two 15 milliliter conical centrifuge tubes per liver containing 2.5 milliliters of digestion buffer each.And place the samples in a 37 degrees Celsius water bath with gentle shaking at five and 10 minutes. After 15 minutes of digestion, use a 1, 000 microliter pipette with a cut tip to gently titrate the liver pieces. Then return the tubes to the bath and allow the pieces to settle for two minutes.Next, filter two approximately 700 microliter aliquots of the supernatant through a 100 micron strainer pre-wet with 800 microliters of collection buffer. And replace the removed supernatant with fresh digestion buffer. When the liver tissue is no longer visible, pass all of the supernatant from the digestion tubes through the filter.And collect all of the cells by centrifugation. Resuspend the pellets in one milliliter of ammonium chloride potassium lysis buffer at room temperature stopping the lysis with five milliliters of fresh collection buffer after one minute. Collect the cells with another centrifugation.Then, carefully aspirate the supernatant without disturbing the loose pellet. And resuspend the cells in four milliliters of fresh collection buffer on ice. To determine the liver sample cell numbers by flow cytometry, first, mix 20 microliters of the liver cell suspension with 174 microliters of PBS in a 1.5 milliliter polystyrene tube and six microliters of propidium iodine.Add counting beads that allow for cell quantification and load the bead and cell mixture onto the flow cytometer. Gate on the side scatter by forward-scatter parameters to avoid debris. Excluding the doublets via a forward-scatter height versus forward scatter area gate and the propidium iodine positive dead cells.Then, load a 30 microliter sample onto the flow cytometer and record the events. To stain the liver cells for flow cytometric analysis of the progenitor subsets, transfer 2x10^5 aliquots of the cells into 1.5 milliliter reaction tubes. And pellet the cells by centrifugation.Resuspend the pellets in Fc block for five minute incubation on ice. Then add 50 microliters of the cell-surface staining antibody cocktail of interest to the appropriate tubes for a 20 minute incubation on ice protected from light. At the end of the incubation, wash the samples in 400 microliters of staining buffer per sample.And resuspend the pellets in 100 microliters of the appropriate secondary antibody cocktail for 20 minutes on ice protected from light. Then wash the cells with another 400 microliters of staining buffer. And resuspend the pellets in 300 microliters of staining buffer containing propidium iodide.Measure the sample using a flow cytometer. To enrich for the progenitor cell population by magnetic microbead-based separation, transfer 1.5-2x10^6 cells into the appropriate number of 15 milliliter conical tubes and collect the cells by centrifugation. Resuspend the pellets in 400 microliters of HBSS supplemented with BSA.And add 40 microliters of anti-CD31 Microbeads and 30 microliters of anti-CD45 Microbeads for 15 minute incubation at four degrees Celsius. Next, wash the cells in five milliliters of HBSS plus BSA. And resuspend the pellets in 100 microliters of dead cell removal beads for a 15 minute incubation at room temperature.While the cells are incubating, equilibrate one appropriately-sized positive selection column per liver with three milliliters of HBSS plus BSA. Then add 900 microliters of HBSS plus BSA to the cells and filter the cells through a 100 micron polyamide filter mesh. Load the filtered bead-incubated cells onto the columns collecting the eluate in the centrifuge tube.When all of the cells have flowed through the column, wash the columns three times with three milliliters of HBSS plus BSA. Pellet the cells by centrifugation and resuspend the cell pellet in 100 microliters of rinsing buffer and Fc block. Pull the cell pellets from four to six livers or up to less than 1x10^6 negatively-selected cells.After five minutes, label the cells with anti-GP38 biotinylated antibody for 10 minutes on ice. At the end of the incubation, collect the cells by centrifugation for resuspension in 400 microliters of rinsing buffer and five microliters of Anti-Biotin Microbeads. After 15 minutes at four degrees Celsius, immediately wash the cells in five milliliters of rinsing buffer.And resuspend the pellet in one milliliter of fresh rinsing buffer. Place the resuspended cells on a chilled 15-rack and start the automatic magnetic separation. Then centrifuge the flow-through and resuspend the pellets in the appropriate solution for the planned downstream experimental analysis.Gating on the cells that are negative for CD45, CD31, and asialoglycoprotein one receptor selects for the liver progenitor cells which can then be grouped according to their glycoprotein 38 and CD133 expression. The gp38 positive CD133 positive and the gp38 negative CD133 positive cells represent the most abundant cell populations among the CD45 negative CD31 negative ASGPR1 negative cells in the healthy adult mouse liver with apparent differences in their expression of various surface markers previously associated with progenitor cells. Magnetic-microbead-based isolation of these progenitor cells, as just demonstrated, results in an over 90%purity of the liver cells with a high degree of viability.When attempting to isolate these uncommon cells, it is important to take into consideration the enzymes used during the liver digestion steps as different enzymes can preferentially yield specific progenitor subpopulations and greatly reduce CD133 expression levels. It's important to remember that the cell purity and yield depend on the gentle preparation of the liver single cell suspensions. And that the high amount of cellular debris and dying cell contamination can negatively effect the success of this protocol.

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JoVE Journal

Developmental Biology

10.8K visualizações.  Saarland University Medical Center. The overall goals of this liver digestion protocol are to assess the various liver progenitor subsets by flow cytometry and to isolate these cells to a high purity using a novel surface marker cocktail for further downstream analysis. This method can help answer various questions about the biology of liver progenitor cells, for example, what are their subset specific features and what are their distant cause during liver injury. The main advantage of this technique is that it allows the isola...