Name: isolation of primary murine retinal ganglion cells (rgcs) by flow cytometry
Uploaded: 2017-07-05T15:00:00
Description: Watch this Scientific Journal Video about Isolation of Primary Murine Retinal Ganglion Cells RGCs by Flow Cytometry at JoVE.com

The authors would like to thank Mr. Tim Higgins, Senior Illustrator from the Department of Microbiology, Immunology and Biochemistry, for technical video assistance; Dr. Matthew W. Wilson for discussions and the members of the Jablonski and Morales-Tirado laboratories for their helpful comments. This work was supported by the Alcon Research Institute Young Investigator Award (VMM-T), the University of Tennessee Research Foundation (VMM-T), the National Eye Institute EY021200 (MMJ), the Gerwin Fellowship (VMM-T); the Gerwin Pre-doctoral Fellowship (ZKG), the Department of Defense Army Medical Research and Materiel Command (VMM-T), and the Unrestricted Grant from Research to Prevent Blindness.

All procedures detailed in the following protocol were approved by the Institutional Animal Care and Use Committee (IACUC) review board at the University of Tennessee Health Science Center (UTHSC) and followed the Association for Research in Vision and Ophthalmology (ARVO) Statements for the Use of Animals in Ophthalmic and Vision Research, in addition to the guidelines for laboratory animal experiments (Institute of Laboratory Animal Resources, Public Health Service Policy on Humane Care and Use of Laboratory Animals).<...

<ol>
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N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+murine+endothelial+cell+cultures+by+flow+cytometry+using+fluorescein-labeled+griffonia+simplicifolia+agglutinin.">Purification of murine endothelial cell cultures by flow cytometry using fluorescein-labeled griffonia simplicifolia agglutinin.</a> Am J Pathol. 134 (6), 1227-1232 (1989).</li><li>Shoge, 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=Rat+retinal+ganglion+cells+culture+enriched+with+the+magnetic+cell+sorter.">Rat retinal ganglion cells culture enriched with the magnetic cell sorter.</a> Neurosci Lett. 259 (2), 111-114 (1999).</li><li>Chintalapudi, S. 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(92), e51936 (2014).</li><li>Li, X., 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=Loss+of+AP-2delta+reduces+retinal+ganglion+cell+numbers+and+axonal+projections+to+the+superior+colliculus.">Loss of AP-2delta reduces retinal ganglion cell numbers and axonal projections to the superior colliculus.</a> Mol Brain. 9 (1), 62 (2016).</li><li>Moshiri, 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=Near+complete+loss+of+retinal+ganglion+cells+in+the+math5/brn3b+double+knockout+elicits+severe+reductions+of+other+cell+types+during+retinal+development.">Near complete loss of retinal ganglion cells in the math5/brn3b double knockout elicits severe reductions of other cell types during retinal development.</a> Dev Biol. 316 (2), 214-227 (2008).</li><li>Danias, 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=Quantitative+analysis+of+retinal+ganglion+cell+(RGC)+loss+in+aging+DBA/2NNia+glaucomatous+mice:+comparison+with+RGC+loss+in+aging+C57/BL6+mice.">Quantitative analysis of retinal ganglion cell (RGC) loss in aging DBA/2NNia glaucomatous mice: comparison with RGC loss in aging C57/BL6 mice.</a> Invest Ophthalmol Vis Sci. 44 (12), 5151-5162 (2003).</li><li>Jakobs, T. C., Ben, Y., Masland, R. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=CD15+immunoreactive+amacrine+cells+in+the+mouse+retina.">CD15 immunoreactive amacrine cells in the mouse retina.</a> J Comp Neurol. 465 (3), 361-371 (2003).</li><li>Uusitalo, M., Schlotzer-Schrehardt, U., Kivela, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrastructural+localization+of+the+HNK-1+carbohydrate+epitope+to+glial+and+neuronal+cells+of+the+human+retina.">Ultrastructural localization of the HNK-1 carbohydrate epitope to glial and neuronal cells of the human retina.</a> Invest Ophthalmol Vis Sci. 44 (3), 961-964 (2003).</li><li>Jackson, C. J., Garbett, P. K., Nissen, B., Schrieber, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Binding+of+human+endothelium+to+Ulex+europaeus+I-coated+Dynabeads:+application+to+the+isolation+of+microvascular+endothelium.">Binding of human endothelium to Ulex europaeus I-coated Dynabeads: application to the isolation of microvascular endothelium.</a> J Cell Sci. 96 ( Pt 2), 257-262 (1990).</li><li>Pennartz, S., Perraut, M., Pfrieger, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+retinal+ganglion+cells+from+postnatal+rats+by+magnetic+cell+sorting.">Purification of retinal ganglion cells from postnatal rats by magnetic cell sorting.</a> MACSmore. 12 (2), 16-18 (2010).</li><li>Nadal-Nicolas, F. 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FACS is the technique of choice to purify cell populations. Other isolation methods include immunopanning, magnetic beads, and complement fixation depletion. The advantage of FACS over these other methodologies is based on the simultaneous identification of cell-surface markers with varying degrees of intensity. The fluorescent intensity of the molecule is proportional to the amount of protein expression. Until now, the isolation of RGCs was based solely on Thy1 (CD90) positivity and CD48 negativity15</...

RGCs are terminally differentiated neurons, and therefore, primary cells are required for experimentation. The development of a protocol for the isolation and enrichment of primary murine retinal ganglion cells (RGCs) is fundamental to revealing the mechanisms of RGC health and degeneration in vitro. This is especially important for studies that seek to generate potential therapies to promote RGC function and to minimize their death. The degeneration of RGCs is associated with retinal degenerative diseases, such as glaucoma, diabetic retinopathy, and normal aging. Although the specific cellular mechanisms underlying RGC loss are unclear, a series of risk factors have been identified. Lack of oxygenation at the optic nerve head1,2,3 causes RGC death4 and acts as the disturbance of the homeostasis between the activation of excitatory and inhibitory receptors within individual RGCs5,6. A series of challenges impede progress towards the use of these cells for in-depth studies. First, the number of RGCs present in a murine retina is small. RGCs account for less than 1% of total retinal cells7,8,9. Second, most RGC-specific markers are intracellular proteins10,11,12. Selection based upon these markers leaves the cells non-viable, which precludes downstream functional analyses. Finally, currently available protocols are lengthy and lack standardization13,14. Early RGC isolation protocols were based on immunopanning methods. Barres et al.15 adapted the classic immunopanning technique and added a second step, which excluded monocytes and endothelial cells from the bulk of retinal cells prior to positive selection based upon immunopositivity to anti-thymocyte antigen (aka Thy1), a cell-surface marker. Years later, Hong et al. combined magnetic bead isolation techniques with cell sorting strategies to isolate RGCs with higher purity16. The use of magnetic beads is still used in many scientific applications. Together, magnetic beads and flow cytometry protocols improved the purity of isolated cells. However, these purification systems have not yet been standardized for the isolation of murine RGCs from dissociated retinae.
Flow cytometry is a powerful analytical method that measures the optical and fluorescence characteristics of cell suspensions. Cells are analyzed both quantitatively and qualitatively with a high level of sensitivity, providing a multi-dimensional analysis of the cell population. Cellular discrimination is based upon two main physical properties: cell size or surface area and granularity or internal complexity17. A multi-dimensional analysis can be performed by combining antibodies tagged with fluorochromes that have similar excitation wavelengths and different emissions. Flow cytometry is fast, reproducible, and sensitive. Multitpe lasers permit even greater multi-dimensional analyses of single cells by flow cytometry. Thus, it is an attractive methodology for the study of cytological specimens. Fluorescence activated cell sorting (FACS) uses the multi-dimensional phenotypic differences identified by flow cytometry to sort individual cells into distinct subpopulations.
In the last decade, multiple surface and intracellular proteins have been identified as potential biomarkers for the selection of cells, including neurons. Initial studies that sought to isolate RGCs from rats used Thy1 as a ganglion cell marker. Unfortunately, Thy1, aka CD90, has multiple isoforms in other rodent species18,19,20 and is expressed by multiple retinal cell types19,20, making it a non-specific marker for RGCs. Another surface marker, CD48, is found on monocytic populations in the retina, including macrophages and microglia. Using these two surface markers, a modified RGC signature-Thy1+ and CD48neg cells-was developed15,16,21,22. Unfortunately, these two selection criteria are not sufficient to select for a highly enriched RGC population. To address this unmet need, a flow cytometry protocol was developed23 based on multi-layered positive and negative selection criteria using known cell surface markers to enrich and purify primary murine RGCs.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Anti-mouse CD15 PE</td>
			<td>BioLegend</td>
			<td>125606</td>
			<td>Clone MC-480</td>
		</tr>
		<tr>
			<td>Anti-mouse CD48 PE-Cy7</td>
			<td>BioLegend</td>
			<td>103424</td>
			<td>Clone HM48-1</td>
		</tr>
		<tr>
			<td>Anti-mouse CD57</td>
			<td>Sigma Aldrich</td>
			<td>C6680-100TST</td>
			<td>Clone VC1.1</td>
		</tr>
		<tr>
			<td>Anti-mouse CD90.2 AF700</td>
			<td>BioLegend</td>
			<td>105320</td>
			<td>Clone 30-H12</td>
		</tr>
		<tr>
			<td>Brilliant Violet 421 Goat Anti-mouse IgG</td>
			<td>BioLegend</td>
			<td>405317</td>
			<td>Clone Poly4053</td>
		</tr>
		<tr>
			<td>Purified Anti-mouse CD16/32</td>
			<td>BioLegend</td>
			<td>101302</td>
			<td>FcgRII/III block, Clone 93</td>
		</tr>
		<tr>
			<td>Zombie Aqua&#160;</td>
			<td>BioLegend</td>
			<td>423102</td>
			<td>Live cell/ Dead cell discrimination</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>Hyclone</td>
			<td>SH30071.03</td>
			<td>U.S. origin</td>
		</tr>
		<tr>
			<td>AbC Total Antibody Compensation Bead Kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>A10497</td>
			<td>Multi-species Ig</td>
		</tr>
		<tr>
			<td>Neurobasal Medium</td>
			<td>Thermo Fisher Scientific</td>
			<td>21103049</td>
			<td>Add serum to media prior to culture.</td>
		</tr>
		<tr>
			<td>Phosphate-Buffered Saline (PBS)</td>
			<td>Thermo Fisher Scientific</td>
			<td>10010049</td>
			<td>Saline solution</td>
		</tr>
		<tr>
			<td>Dissection Microscope</td>
			<td>Olympus</td>
			<td>SZ-PT Model</td>
			<td>Stereo Microscope</td>
		</tr>
		<tr>
			<td>Sorvall Centrifuge</td>
			<td>Thermo Scientific</td>
			<td>ST 16R</td>
			<td>All centrifugation performed&#160; at RT</td>
		</tr>
		<tr>
			<td>Base Plate &#8211; Dissection Pan</td>
			<td>Fisher Scientific</td>
			<td>SB15233FIM</td>
			<td>A wax plate can also be used</td>
		</tr>
		<tr>
			<td>Forceps</td>
			<td>Aesculap</td>
			<td>5002-7</td>
			<td>4 &#189; inches</td>
		</tr>
		<tr>
			<td>Iris Scissors, Straight</td>
			<td>Aesculap</td>
			<td>1360</td>
			<td>5 &#189; inches</td>
		</tr>
		<tr>
			<td>Falcon 15 mL conical tubes</td>
			<td>Fisher Scientific</td>
			<td>352097</td>
			<td>Polypropylene tubes</td>
		</tr>
		<tr>
			<td>Falcon 50 mL conical tubes</td>
			<td>Fisher Scientific</td>
			<td>352098</td>
			<td>Polypropylene tubes</td>
		</tr>
		<tr>
			<td>BD FACS Tubes</td>
			<td>Fisher Scientific</td>
			<td>352003</td>
			<td>Polypropylene tubes</td>
		</tr>
		<tr>
			<td>40 mm dishes</td>
			<td>MidSci</td>
			<td>TP93040</td>
			<td>Tissue culture treated</td>
		</tr>
		<tr>
			<td>70 &#956;m nylon strainer</td>
			<td>MidSci</td>
			<td>70ICS</td>
			<td>sterile</td>
		</tr>
		<tr>
			<td>40 &#956;m nylon strainer</td>
			<td>MidSci</td>
			<td>40ICS</td>
			<td>sterile</td>
		</tr>
		<tr>
			<td>&#160;BD 10 mL syringe</td>
			<td>Fisher Scientific</td>
			<td>301604</td>
			<td>Disposable Syringe without needle</td>
		</tr>
		<tr>
			<td>Pestles</td>
			<td>MidSci</td>
			<td>PEST</td>
			<td>sterile</td>
		</tr>
		<tr>
			<td>Wheaton Vials</td>
			<td>Fisher Scientific</td>
			<td>986734</td>
			<td>No Liner</td>
		</tr>
		<tr>
			<td>BD 30 G needle</td>
			<td>Fisher Scientific</td>
			<td>305128</td>
			<td>1 inch</td>
		</tr>
		<tr>
			<td>Hausser Scientific Bright-Line Glass Counting Chamber</td>
			<td>Fisher Scientific</td>
			<td>0267151B</td>
			<td>Hemocytometer</td>
		</tr>
		<tr>
			<td>Gibco Trypan blue 0.4% Solution</td>
			<td>Fisher Scientific</td>
			<td>15250061</td>
			<td>Viability Dye</td>
		</tr>
		<tr>
			<td>Eppendorf tubes</td>
			<td>Fisher Scientific</td>
			<td>05-402-25</td>
			<td>1.5mL</td>
		</tr>
		<tr>
			<td>EVOS Floid Cell Imaging</td>
			<td>Thermo Fisher Scientific</td>
			<td>447113</td>
			<td>Fluorescence Imaging with a 20x objective</td>
		</tr>
		<tr>
			<td>100% Ethanol</td>
			<td>Fisher Scientific</td>
			<td>04-355-452</td>
			<td>Used to make 70% Ethanol</td>
		</tr>
		<tr>
			<td>Pipet-Lite LTS Pipette L-1000XLS+</td>
			<td>Rainin</td>
			<td>17014282</td>
			<td>LTS Pipette</td>
		</tr>
		<tr>
			<td>Pipet-Lite LTS Pipette L-200XLS+</td>
			<td>Rainin</td>
			<td>17014391</td>
			<td>LTS Pipette</td>
		</tr>
		<tr>
			<td>Pipet-Lite LTS Pipette L-20XLS+</td>
			<td>Rainin</td>
			<td>17014392</td>
			<td>LTS Pipette</td>
		</tr>
		<tr>
			<td>Rack LTS 1000 mL &#8211; GPS-L1000S</td>
			<td>Rainin</td>
			<td>17005088</td>
			<td>Blue Rack Sterile Tips</td>
		</tr>
		<tr>
			<td>Rack LTS 250 mL &#8211; GPS-L250S</td>
			<td>Rainin</td>
			<td>17005092</td>
			<td>Green Rack Sterile Tips</td>
		</tr>
		<tr>
			<td>Rack LTS 20 mL &#8211; GPS-L10S</td>
			<td>Rainin</td>
			<td>17005090</td>
			<td>Red Rack Sterile Tips</td>
		</tr>
		<tr>
			<td>FACSAria II Cell Sorter</td>
			<td>BD Biosciences</td>
			<td>N/A</td>
			<td>Custom order</td>
		</tr>
		<tr>
			<td>LSR II Cytometer</td>
			<td>BD Biosciences</td>
			<td>N/A</td>
			<td>Custom order</td>
		</tr>
		<tr>
			<td>Abca8a</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00462440_m1</td>
			<td>M&#252;ller cells</td>
		</tr>
		<tr>
			<td>Aldh1al</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00657317_m1</td>
			<td>M&#252;ller cells</td>
		</tr>
		<tr>
			<td>Aqp4</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00802131_m1</td>
			<td>Astrocytes</td>
		</tr>
		<tr>
			<td>Calb2</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00801461_m1</td>
			<td>Amacrine, Horizontal</td>
		</tr>
		<tr>
			<td>Cd68</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm03047340_m1</td>
			<td>Retinal Pigment Epithelial Cells</td>
		</tr>
		<tr>
			<td>Gad2</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00484623_m1</td>
			<td>Amacrine</td>
		</tr>
		<tr>
			<td>Hprt</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm01545399_m1</td>
			<td>House keeping gene</td>
		</tr>
		<tr>
			<td>Lhx1</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm01297482_m1</td>
			<td>Horizontal</td>
		</tr>
		<tr>
			<td>Lim2</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00624623_m1</td>
			<td>Horizontal</td>
		</tr>
		<tr>
			<td>Nrl</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00476550_m1</td>
			<td>Photoreceptors</td>
		</tr>
		<tr>
			<td>Ntrk1</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm01219406_m1</td>
			<td>Horizontal</td>
		</tr>
		<tr>
			<td>Pcp4</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00500973_m1</td>
			<td>Bipolar, Amacrine</td>
		</tr>
		<tr>
			<td>Pou4f1</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm02343791_m1</td>
			<td>Retinal Ganglion Cells</td>
		</tr>
		<tr>
			<td>Prdx6</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00725435_s1</td>
			<td>Astrocytes</td>
		</tr>
		<tr>
			<td>Prkca</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00440858_m1</td>
			<td>Bipolar</td>
		</tr>
		<tr>
			<td>Prox1</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00435969_m1</td>
			<td>Horizontal</td>
		</tr>
		<tr>
			<td>Pvalb</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00443100_m1</td>
			<td>Amacrine</td>
		</tr>
		<tr>
			<td>Rbpms</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm02343791_m1</td>
			<td>Retinal Ganglion Cells</td>
		</tr>
		<tr>
			<td>Rom1</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00436364_g1</td>
			<td>Photoreceptors</td>
		</tr>
		<tr>
			<td>Rpe65</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00504133_m1</td>
			<td>Retinal Pigment Epithelial cells</td>
		</tr>
		<tr>
			<td>Slc1a3</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00600697_m1</td>
			<td>Astrocytes</td>
		</tr>
		<tr>
			<td>Slc6a9</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00433662_m1</td>
			<td>Amacrine</td>
		</tr>
		<tr>
			<td>Sncg</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00488345_m1</td>
			<td>Retinal Ganglion Cells</td>
		</tr>
		<tr>
			<td>Tubb3</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm00727586_s1</td>
			<td>Retinal Ganglion Cells</td>
		</tr>
		<tr>
			<td>Vim</td>
			<td>Thermo Fisher Scientific</td>
			<td>Mm01333430_m1</td>
			<td>M&#252;ller cells</td>
		</tr>
		<tr>
			<td>Taqman Universal Master Mix</td>
			<td>Thermo Fisher Scientific</td>
			<td>4440047</td>
			<td>qPCR Reagent</td>
		</tr>
		<tr>
			<td>miRNeasy Mini Kit</td>
			<td>Qiagen</td>
			<td>217004</td>
			<td>RNA Isolation</td>
		</tr>
		<tr>
			<td>SuperScript VILO cDNA Synthesis Kit</td>
			<td>Thermo Fisher Scientific</td>
			<td>11754250</td>
			<td>cDNA synthesis</td>
		</tr>
		<tr>
			<td>Taqman PreAmp Master Mix</td>
			<td>Thermo Fisher Scientific</td>
			<td>4391128</td>
			<td>Pre-Amplification step</td>
		</tr>
		<tr>
			<td>BD Cytofix/ Cytoperm</td>
			<td>BD Biosciences</td>
			<td>554714</td>
			<td>Fixation/ Permeabilization Buffer</td>
		</tr>
		<tr>
			<td>BD Perm/ Wash</td>
			<td>BD Biosciences</td>
			<td>554723</td>
			<td>Permeabilization Solution</td>
		</tr>
		<tr>
			<td>RBPMS</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-86815</td>
			<td>intracellular antibody</td>
		</tr>
		<tr>
			<td>SNCG</td>
			<td>Gene Tex</td>
			<td>GTX110483</td>
			<td>intracellular antibody</td>
		</tr>
		<tr>
			<td>BRN3A</td>
			<td>Santa Cruz Biotechnology</td>
			<td>sc-8429</td>
			<td>intracellular antibody</td>
		</tr>
		<tr>
			<td>TUJ1</td>
			<td>BioLegend</td>
			<td>801202</td>
			<td>intracellular antibody</td>
		</tr>
	</tbody>
</table>

isolation of primary murine retinal ganglion cells (rgcs) by flow cytometry

Neurodegenerative diseases often have a devastating impact on those affected. Retinal ganglion cell (RGC) loss is implicated in an array of diseases, including diabetic retinopathy and glaucoma, in addition to normal aging. Despite their importance, RGCs have been extremely difficult to study until now due in part to the fact that they comprise only a small percentage of the wide variety of cells in the retina. In addition, current isolation methods use intracellular markers to identify RGCs, which produce non-viable cells. These techniques also involve lengthy isolation protocols, so there is a lack of practical, standardized, and dependable methods to obtain and isolate RGCs. This work describes an efficient, comprehensive, and reliable method to isolate primary RGCs from mice retinae using a protocol based on both positive and negative selection criteria. The presented methods allow for the future study of RGCs, with the goal of better understanding the major decline in visual acuity that results from the loss of functional RGCs in neurodegenerative diseases.

The in-depth study of RGCs is impeded by many factors, including their low frequency and the lack of a robust and standardized methodology for their isolation. Figure 1 shows the methodology used for retinae isolation. Variations in the enucleation procedure exist based on the type of analysis, such as if the enucleation is part of in vivo experimentation27. Enucleation in this protocol is performed on euthanized mice. As show...

Watch this Scientific Journal Video about Isolation of Primary Murine Retinal Ganglion Cells RGCs by Flow Cytometry at JoVE.com

Isolation of Primary Murine Retinal Ganglion Cells RGCs by Flow Cytometry

Millions of people suffer from retinal degenerative diseases that result in irreversible blindness. A common element of many of these diseases is the loss of retinal ganglion cells (RGCs). This detailed protocol describes the isolation of primary murine RGCs by positive and negative selection with flow cytometry.

Isolation of Primary Murine Retinal Ganglion Cells (RGCs) by Flow Cytometry

Neurodegenerative diseases often have a devastating impact on those affected. Retinal ganglion cell (RGC) loss is implicated in an array of diseases, ...

The overall goal of this procedure is to isolate an enriched homogeneous population of primary murine retinal ganglion cells. This method can help answer questions in the retinal ganglion cell field about the mechanisms underlying the declining visual acuity in age populations and in retinal degenerative disease populations. The main advantage of this technique is that it can offer a fast, visible, reproducible, and standardized protocol for the isolation of enriched primary murine retinal ganglion cells.We first had the idea for this method when Sumana Chintalapudi, who was then a graduate student in my lab and first author on this study, presented at our journal club a 2013 paper by Krishna Murtheadol, and their study clearly demonstrated that the RGC five cell line, which was originally generated as an immortalized rat retinal ganglion cell line, was no longer of rat origin, nor did it possess the RGC phenotype. It became apparent to us that this problem left a large gap in the resources available to the vision research community, including our own lab. Sumana and I reached out Dr.Morales-Tirado and together the three of us developed a new method for isolating live and highly enriched RGCs.Generally, individuals new to this method will struggle because the goals of this method are to isolate a live and highly enriched cell population that can be either cultured as primary cells, or immortalized as a cell line. Because of this one must be very careful not to damage the cells that one is trying to isolate. In addition, the parameters of cell sorting method must be tailored for the specific cells one is trying to isolate.Both methods require special skill sets. Demonstrating the procedures will be Dr.Xiang Di Wang, a research associate from Dr.Jablonski's lab, and Mr.Zach Goldsmith, PhD candidate from my laboratory. To enucleate the eye, first insert forceps under the globe of the eye.Grip the optic nerve and pull up. The globe will be enucleated with the optic nerve intact. Place the eye in a vial of PBS on ice, and enucleate the other eye.When all of the eyes have been collected, place one eye in a Petri dish of fresh PBS under a dissection microscope, and use forceps to carefully grasp the globe at the base of the optic nerve. Using a sharp 30 gauge needle, puncture the cornea to allow the aqueous humor to drain making it easier to hold the eye with the forceps. Holding the cornea with the forceps, use scissors to make a small incision in the corneal tissue and use the forceps to gently peel away the cornea and the sclera.When the globe is peeled halfway, use the forceps to roll out the retina and the lens. Place the retina in a small 40 millimeter Petri dish containing PBS and 1%FPS in a biosafety cabinet and wash the retina three times in fresh PBS plus FBS for each wash. When all of the eyes have been washed, place up to 12 retinae onto a sterile 70 micron nylon strainer moistened with PBS and FBS and gently macerate the retinae with the back end of a 10 milliliter syringe plunger, using a circular motion.When all of the cells have been dissociated place the strainer over a polypropylene collection tube and use a P1000 pipette to filter the cells through the strainer into the collection tube. Rinse the strainer with PBS and FBS, pooling the wash in the collection tube. Add enough PBS plus FBS to bring the final volume up to one milliliter of solution per retina and collect the cells by centrifugation.Then, resuspend the pellet in PBS plus FBS at a one milliliter of medium per five retinae concentration, if immunolabeling is to be performed immediately. Alternatively, incubate the cells resuspended in neural cell medium overnight at four degrees Celsius in the horizontal position. To immunolabel the retinal cells, centrifuge the retinal cell suspension, and resuspend the pellet in 50 microliters of fresh PBS plus FBS in a fax tube.Set aside five times 10 to the sixth cells for the unlabeled negative control. Next, block any non specific FC receptor binding in each tube with one microliter of anti mouse CD 16 32 antibody per one times 10 to the sixth cells, for 10 minutes at room temperature. At the end of the blocking incubation, add the antibody cocktail of interest to the cells with gentle pipetting for a 30 minute incubation on ice protected from light.Then wash the cells two times in a formula liter final volume of PBS and FBS. Label the cells with an appropriate secondary antibody for another 30 minutes on ice protected from light, followed by two washes in PBS plus FBS as just demonstrated. Resuspend the pellets in fresh PBS and FBS for counting cells.To adjust the compensation add three drops of polystyrene microspheres into one sterile fax tube per florafor and one microgram of the respective florafor to each tube. Incubate the microspheres for 15 minutes at room temperature protected from light. Then wash the microspheres in three milliliters of PBS and FBS and carefully remove the supernatant.Resuspend the microsphere pellets in 250 microliters of PBS and FBS and load the unlabeled sample tube onto the flow cytometer. In the flow cytometer software, select experiment, compensation set up, and create compensation controls. Add the florafor specific controls from the displayed list and click OK.Verify the forward scattered and side scattered light, and gate the initial population.Then install the negative control tube onto the cytometer and click load. Verify that the population of interest or P1 is displayed and select the population. Right click the P1 gate and select calculate compensation.Then click record data. When the recording is finished, click unload to remove the tube and load the next control tube to adjust the compensation controls. When all of the control samples have been recorded, create a forward versus side scatter plot for the first experimental tube, and gate the P1 population.Next, open a side scatter height versus side scatter width pseudo color plot and gate the single cells. Using the single cells, create a forward scatter height versus forward scatter width plot, and gate to exclude the dublets. Then generate a CD48 versus CD90.2 pseudo color plot and gate the CD90.2 positive CD48 negative cells to eliminate the monocytes, followed by a CD57 versus CD15 pseudo color plot to eliminate any amacrine cell contaminants.Now define the populations to be collected for the sample in the sort layout sheet, and sort the cells. At the end of the sort, use a 2.5 times 10 to the fourth cell aliquot to confirm the purity of the isolated cell population. After meshing the retinae in the cell strainer multiple inner retinal cells can be visualized, even though the retinal ganglion cells have lost their signature morphology, due to axotomy during the cell isolation procedure.The classic dye one positive CD48 negative surface phenotype is not sufficient for identifying and isolating the murine retinal ganglion cells, as these cells express genes associated with amacrine, muller, bipolar, horizontal photo receptor, and retinal pigment epithelial cells. The sorted cells also express retinal ganglion cell associated intracellular markers such as synuclein gamma, BRN3A, TUJ1, and RBPMS, with the intracellular localization of the markers further confirmed by imaging flow cytometry. Some of the sorted cells even begin to exhibit retinal ganglion cell morphology after in vitro cell culture.Further, quantitative PCR analysis of the highly enriched sorted cell population reveals a many fold increase in the genes coding for retinal ganglion specific intracellular markers. Once mastered, this technique can be completed in less than six hours if it's performed properly. While attempting this procedure, it's important to remember to keep your cell suspension sterile, to block the FC receptors from the cell suspension, to avoid non specific binding of the antibodies, and to discuss your cell sorting details or strategy with the cell sorter operator.Following this procedure, other methods like QPCR can be performed to answer additional questions about gene expression profiling. Don't forget that working specialized equipment, such as a cell sorter, requires a highly specialized operator. After its development, this technique paved the way for researchers in the vision field to help understand survival and death mechanisms in retinal ganglion cells, for the development of novel therapeutics for vision preservation.After watching this video, you should have a good understanding of how to isolate an enriched homogeneous population of primary murine retinal ganglion cells.

isolation-primary-murine-retinal-ganglion-cells-rgcs-flow

Research

JoVE Journal

Bioengineering

Parallel-plate Flow Chamber and Continuous Flow Circuit to Evaluate Endothelial Progenitor Cells under Laminar Flow Shear Stress

The overall goal of this method is to describe a technique to subject adherent cells to laminar flow conditions and evaluate their response to well quantifiable fluid shear stresses1.
Our flow chamber design and flow circuit (Fig. 1) contains a transparent viewing region that enables testing of cell adhesion and imaging of cell morphology immediately before flow (Fig. 11A, B), at various time points during flow (Fig. 11C), and after flow (Fig. 11D). These experiments are illustrated with human umbilical cord blood-derived endothelial progenitor cells (EPCs) and porcine EPCs2,3.
This method is also applicable to other adherent cell types, e.g. smooth muscle cells (SMCs) or fibroblasts.
The chamber and all parts of the circuit are easily sterilized with steam autoclaving. In contrast to other chambers, e.g. microfluidic chambers, large numbers of cells (&gt; 1 million depending on cell size) can be recovered after the flow experiment under sterile conditions for cell culture or other experiments, e.g. DNA or RNA extraction, or immunohistochemistry (Fig. 11E), or scanning electron microscopy5. The shear stress can be adjusted by varying the flow rate of the perfusate, the fluid viscosity, or the channel height and width. The latter can reduce fluid volume or cell needs while ensuring that one-dimensional flow is maintained. It is not necessary to measure chamber height between experiments, since the chamber height does not depend on the use of gaskets, which greatly increases the ease of multiple experiments. Furthermore, the circuit design easily enables the collection of perfusate samples for analysis and/or quantification of metabolites secreted by cells under fluid shear stress exposure, e.g. nitric oxide (Fig. 12)6.

We are describing a method to subject adherent cells to laminar flow shear stress in a sterile continuous flow circuit. The cells' adhesion, morphology can be studied through the transparent chamber, samples obtained from the circuit for metabolite analysis and cells harvested after shear exposure for future experiments or culture.

The overall goal of this method is to describe a technique to subject adherent cells to laminar flow conditions and evaluate their response to well ...

Analyzing Cellular Internalization of Nanoparticles and Bacteria by Multi-spectral Imaging Flow Cytometry

Nanoparticulate systems have emerged as valuable tools in vaccine delivery through their ability to efficiently deliver cargo, including proteins, to antigen presenting cells1-5. Internalization of nanoparticles (NP) by antigen presenting cells is a critical step in generating an effective immune response to the encapsulated antigen. To determine how changes in nanoparticle formulation impact function, we sought to develop a high throughput, quantitative experimental protocol that was compatible with detecting internalized nanoparticles as well as bacteria. To date, two independent techniques, microscopy and flow cytometry, have been the methods used to study the phagocytosis of nanoparticles. The high throughput nature of flow cytometry generates robust statistical data. However, due to low resolution, it fails to accurately quantify internalized versus cell bound nanoparticles. Microscopy generates images with high spatial resolution; however, it is time consuming and involves small sample sizes6-8. Multi-spectral imaging flow cytometry (MIFC) is a new technology that incorporates aspects of both microscopy and flow cytometry that performs multi-color spectral fluorescence and bright field imaging simultaneously through a laminar core. This capability provides an accurate analysis of fluorescent signal intensities and spatial relationships between different structures and cellular features at high speed.
	Herein, we describe a method utilizing MIFC to characterize the cell populations that have internalized polyanhydride nanoparticles or Salmonella enterica serovar Typhimurium. We also describe the preparation of nanoparticle suspensions, cell labeling, acquisition on an ImageStreamX system and analysis of the data using the IDEAS application. We also demonstrate the application of a technique that can be used to differentiate the internalization pathways for nanoparticles and bacteria by using cytochalasin-D as an inhibitor of actin-mediated phagocytosis.

In this article, we describe a method utilizing multi-spectral imaging flow cytometry to quantify the internalization of polyanhydride nanoparticles or bacteria by RAW 264.7 cells.

Nanoparticulate  systems have emerged as valuable tools in vaccine delivery through their  ability to efficiently deliver cargo, including proteins, to ...

Evaluation of Polymeric Gene Delivery Nanoparticles by Nanoparticle Tracking Analysis and High-throughput Flow Cytometry

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases1 and as a technology for regenerative medicine2. Unlike viruses, which have significant safety issues, polymeric nanoparticles can be designed to be non-toxic, non-immunogenic, non-mutagenic, easier to synthesize, chemically versatile, capable of carrying larger nucleic acid cargo and biodegradable and/or environmentally responsive. Cationic polymers self-assemble with negatively charged DNA via electrostatic interaction to form complexes on the order of 100 nm that are commonly termed polymeric nanoparticles. Examples of biomaterials used to form nanoscale polycationic gene delivery nanoparticles include polylysine, polyphosphoesters, poly(amidoamines)s and polyethylenimine (PEI), which is a non-degradable off-the-shelf cationic polymer commonly used for nucleic acid delivery1,3 . Poly(beta-amino ester)s (PBAEs) are a newer class of cationic polymers4 that are hydrolytically degradable5,6 and have been shown to be effective at gene delivery to hard-to-transfect cell types such as human retinal endothelial cells (HRECs)7, mouse mammary epithelial cells8, human brain cancer cells9 and macrovascular (human umbilical vein, HUVECs) endothelial cells10.
A new protocol to characterize polymeric nanoparticles utilizing nanoparticle tracking analysis (NTA) is described. In this approach, both the particle size distribution and the distribution of the number of plasmids per particle are obtained11. In addition, a high-throughput 96-well plate transfection assay for rapid screening of the transfection efficacy of polymeric nanoparticles is presented. In this protocol, poly(beta-amino ester)s (PBAEs) are used as model polymers and human retinal endothelial cells (HRECs) are used as model human cells. This protocol can be easily adapted to evaluate any polymeric nanoparticle and any cell type of interest in a multi-well plate format.

A protocol for nanoparticle tracking analysis (NTA) and high-throughput flow cytometry to evaluate polymeric gene delivery nanoparticles is described. NTA is utilized to characterize the nanoparticle particle size distribution and the plasmid per particle distribution. High-throughput flow cytometry enables quantitative transfection efficacy evaluation for a library of gene delivery biomaterials.

Non-viral gene delivery using polymeric nanoparticles has emerged as an attractive approach for gene therapy to treat genetic diseases1 and as a ...

Wide-field Fluorescent Microscopy and Fluorescent Imaging Flow Cytometry on a Cell-phone

Fluorescent microscopy and flow cytometry are widely used tools in biomedical research and clinical diagnosis. However these devices are in general relatively bulky and costly, making them less effective in the resource limited settings. To potentially address these limitations, we have recently demonstrated the integration of wide-field fluorescent microscopy and imaging flow cytometry tools on cell-phones using compact, light-weight, and cost-effective opto-fluidic attachments. In our flow cytometry design, fluorescently labeled cells are flushed through a microfluidic channel that is positioned above the existing cell-phone camera unit. Battery powered light-emitting diodes (LEDs) are butt-coupled to the side of this microfluidic chip, which effectively acts as a multi-mode slab waveguide, where the excitation light is guided to uniformly excite the fluorescent targets. The cell-phone camera records a time lapse movie of the fluorescent cells flowing through the microfluidic channel, where the digital frames of this movie are processed to count the number of the labeled cells within the target solution of interest. Using a similar opto-fluidic design, we can also image these fluorescently labeled cells in static mode by e.g. sandwiching the fluorescent particles between two glass slides and capturing their fluorescent images using the cell-phone camera, which can achieve a spatial resolution of e.g. ~ 10 &mu;m over a very large field-of-view of ~ 81 mm2. This cell-phone based fluorescent imaging flow cytometry and microscopy platform might be useful especially in resource limited settings, for e.g. counting of CD4+ T cells toward monitoring of HIV+ patients or for detection of water-borne parasites in drinking water.

We review our recent results on the integration of fluorescent microscopy and imaging flow cytometry tools on a cell-phone using compact and cost-effective opto-fluidic attachments. These cell-phone based micro-analysis devices might be useful for cytometric analysis, such as performing various cell counting tasks as well as for high-throughput screening of e.g., water samples in resource limited settings.

Fluorescent microscopy and flow cytometry are widely used tools in biomedical research and clinical diagnosis. However these devices are in general ...

Localization and Relative Quantification of Carbon Nanotubes in Cells with Multispectral Imaging Flow Cytometry

Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich cell structures and de facto there is still no quantitative method to assess their distribution at cell and tissue levels. What we propose here is an innovative method allowing the detection and quantification of CNTs in cells using a multispectral imaging flow cytometer (ImageStream, Amnis). This newly developed device integrates both a high-throughput of cells and high resolution imaging, providing thus images for each cell directly in flow and therefore statistically relevant image analysis. Each cell image is acquired on bright-field (BF), dark-field (DF), and fluorescent channels, giving access respectively to the level and the distribution of light absorption, light scattered and fluorescence for each cell. The analysis consists then in a pixel-by-pixel comparison of each image, of the 7,000-10,000 cells acquired for each condition of the experiment. Localization and quantification of CNTs is made possible thanks to some particular intrinsic properties of CNTs: strong light absorbance and scattering; indeed CNTs appear as strongly absorbed dark spots on BF and bright spots on DF with a precise colocalization.
This methodology could have a considerable impact on studies about interactions between nanomaterials and cells given that this protocol is applicable for a large range of nanomaterials, insofar as they are capable of absorbing (and/or scattering) strongly enough the light.

In this study, the main purpose was to monitor the cellular uptake and eventual exocytosis of carbon nanotubes (CNTs). From this perspective, we proposed here a unique method using multispectral imaging flow cytometry allowing a quantification and localization of CNTs in a statistically relevant number of cells.

Carbon-based nanomaterials, like carbon nanotubes (CNTs), belong to this type of nanoparticles which are very difficult to discriminate from carbon-rich ...

Isolation of Primary Human Colon Tumor Cells from Surgical Tissues and Culturing Them Directly on Soft Elastic Substrates for Traction Cytometry

Cancer cells respond to matrix mechanical stiffness in a complex manner using a coordinated, hierarchical mechano-chemical system composed of adhesion receptors and associated signal transduction membrane proteins, the cytoskeletal architecture, and molecular motors1, 2. Mechanosensitivity of different cancer cells in vitro are investigated primarily with immortalized cell lines or murine derived primary cells, not with primary human cancer cells. Hence, little is known about the mechanosensitivity of primary human colon cancer cells in vitro. Here, an optimized protocol is developed that describes the isolation of primary human colon cells from healthy and cancerous surgical human tissue samples. Isolated colon cells are then successfully cultured on soft (2 kPa stiffness) and stiff (10 kPa stiffness) polyacrylamide hydrogels and rigid polystyrene (~3.6 GPa stiffness) substrates functionalized by an extracellular matrix (fibronectin in this case). Fluorescent microbeads are embedded in soft gels near the cell culture surface, and traction assay is performed to assess cellular contractile stresses using free open access software. In addition, immunofluorescence microscopy on different stiffness substrates provides useful information about primary cell morphology, cytoskeleton organization and vinculin containing focal adhesions as a function of substrate rigidity.

A protocol is described to extract primary human cells from surgical colon tumor and normal tissues. The isolated cells are then cultured on soft elastic substrates (polyacrylamide hydrogels) functionalized by an extracellular matrix protein, and embedded with fluorescent microbeads. Traction cytometry is performed to assess cellular contractile stresses.

Cancer cells respond to matrix mechanical stiffness in a complex manner using a coordinated, hierarchical mechano-chemical system composed of adhesion ...

Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry

Increasing evidence supports transcellular propagation of toxic protein aggregates, or proteopathic seeds, as a mechanism for the initiation and progression of pathology in several neurodegenerative diseases, including Alzheimer's disease and the related tauopathies. The potentially critical role of tau seeds in disease progression strongly supports the need for a sensitive assay that readily detects seeding activity in biological samples. 
By combining the specificity of fluorescence resonance energy transfer (FRET), the sensitivity of flow cytometry, and the stability of a monoclonal cell line, an ultra-sensitive seeding assay has been engineered and is compatible with seed detection from recombinant or biological samples, including human and mouse brain homogenates. The assay employs monoclonal HEK 293T cells that stably express the aggregation-prone repeat domain (RD) of tau harboring the disease-associated P301S mutation fused to either CFP or YFP, which produce a FRET signal upon protein aggregation. The uptake of proteopathic tau seeds (but not other proteins) into the biosensor cells stimulates aggregation of RD-CFP and RD-YFP, and flow cytometry sensitively and quantitatively monitors this aggregation-induced FRET. The assay detects femtomolar concentrations (monomer equivalent) of recombinant tau seeds, has a dynamic range spanning three orders of magnitude, and is compatible with brain homogenates from tauopathy transgenic mice and human tauopathy subjects. With slight modifications, the assay can also detect seeding activity of other proteopathic seeds, such as &#945;-synuclein, and is also compatible with primary neuronal cultures. The ease, sensitivity, and broad applicability of FRET flow cytometry makes it useful to study a wide range of protein aggregation disorders.

Cell-to-cell transfer of protein aggregates, or proteopathic seeds, may underlie the progression of pathology in neurodegenerative diseases. Here, a novel FRET flow cytometry assay is described that enables specific and sensitive detection of seeding activity from recombinant or biological samples.

Increasing evidence supports transcellular propagation of toxic protein aggregates, or proteopathic seeds, as a mechanism for the initiation and ...

Microfluidic Flow Chambers Using Reconstituted Blood to Model Hemostasis and Platelet Transfusion In Vitro

Blood platelets prepared for transfusion gradually lose hemostatic function during storage. Platelet function can be investigated using a variety of (indirect) in vitro experiments, but none of these is as comprehensive as microfluidic flow chambers. In this protocol, the reconstitution of thrombocytopenic fresh blood with stored blood bank platelets is used to simulate platelet transfusion. Next, the reconstituted sample is perfused in microfluidic flow chambers which mimic hemostasis on exposed subendothelial matrix proteins. Effects of blood donation, transport, component separation, storage and pathogen inactivation can be measured in paired experimental designs. This allows reliable comparison of the impact every manipulation in blood component preparation has on hemostasis. Our results demonstrate the impact of temperature cycling, shear rates, platelet concentration and storage duration on platelet function. In conclusion, this protocol analyzes the function of blood bank platelets and this ultimately aids in optimization of the processing chain including phlebotomy, transport, component preparation, storage and transfusion.

Microfluidic Flow Chambers Using Reconstituted Blood to Model Hemostasis and Platelet Transfusion In Vitro

Platelet transfusion and hemostasis was modeled using blood reconstitution and microfluidic flow chambers to investigate the function of blood banking platelets. The data demonstrate the consequences of platelet storage lesion on hemostasis, in vitro.

Blood platelets prepared for transfusion gradually lose hemostatic function during storage. Platelet function can be investigated using a variety of ...

A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time

Microfluidic models of hemostasis assess platelet function under conditions of hydrodynamic shear, but in the presence of anticoagulants, this analysis is restricted to platelet deposition only. The intricate relationship between Ca2+-dependent coagulation and platelet function requires careful and controlled recalcification of blood prior to analysis. Our setup uses a Y-shaped mixing channel, which supplies concentrated Ca2+/Mg2+ buffer to flowing blood just prior to perfusion, enabling rapid recalcification without sample stasis. A ten-fold difference in flow velocity between both reservoirs minimizes dilution. The recalcified blood is then perfused in a collagen-coated analysis chamber, and differential labeling permits real-time imaging of both platelet and fibrin deposition using fluorescence video microscopy. The system uses only commercially available tools, increasing the chances of standardization. Reconstitution of thrombocytopenic blood with platelets from banked concentrates furthermore models platelet transfusion, proving its use in this research domain. Exemplary data demonstrated that coagulation onset and fibrin deposition were linearly dependent on the platelet concentration, confirming the relationship between primary and secondary hemostasis in our model. In a timeframe of 16 perfusion min, contact activation did not take place, despite recalcification to normal Ca2+ and Mg2+ levels. When coagulation factor XIIa was inhibited by corn trypsin inhibitor, this time frame was even longer, indicating a considerable dynamic range in which the changes in the procoagulant nature of the platelets can be assessed. Co-immobilization of tissue factor with collagen significantly reduced the time to onset of coagulation, but not its rate. The option to study the tissue factor and/or the contact pathway increases the versatility and utility of the assay.

This paper describes an experimental model of hemostasis that simultaneously measures platelet function and coagulation. Platelet and fibrin fluorescence is measured in real-time, and platelet adhesion rate, coagulation rate, and onset of coagulation are determined. The model is used to determine platelet procoagulant properties under flow in concentrates for transfusion.

Microfluidic models of hemostasis assess platelet function under conditions of hydrodynamic shear, but in the presence of anticoagulants, this analysis is ...

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate (LAL) Assays

When present in pharmaceutical products, a Gram-negative bacterial cell wall component endotoxin (often also called lipopolysaccharide) can cause inflammation, fever, hypo- or hypertension, and, in extreme cases, can lead to tissue and organ damage that may become fatal. The amounts of endotoxin in pharmaceutical products, therefore, are strictly regulated. Among the methods available for endotoxin detection and quantification, the Limulus Amoebocyte Lysate (LAL) assay is commonly used worldwide. While any pharmaceutical product can interfere with the LAL assay, nano-formulations represent a particular challenge due to their complexity. The purpose of this paper is to provide a practical guide to researchers inexperienced in estimating endotoxins in engineered nanomaterials and nanoparticle-formulated drugs. Herein, practical recommendations for performing three LAL formats including turbidity, chromogenic and gel-clot assays are discussed. These assays can be used to determine endotoxin contamination in nanotechnology-based drug products, vaccines, and adjuvants.

Detection of Endotoxin in Nano-formulations Using Limulus Amoebocyte Lysate LAL Assays

Detection of endotoxins in engineered nanomaterials represents one of the grand challenges in the field of nanomedicine. Here, we present a case study that describes the framework composed of three different LAL formats to estimate potential endotoxin contamination in nanoparticles.