Thank you to Kevin Miyashiro for plating and maintaining cell cultures, to Dr. Terri Schochet for providing cell cultures for the pictures included in this document. In addition, thank you to Kevin Miyashiro, Dr. Peter Buckley, and Tiina Pertiz for input on the aRNA procedure. Funding for this work was from the National Institute on Aging, the National Institute on Mental Health and the Human Resources Fact Finder funds from the Commonwealth of Pennsylvania.

<ol>
	<li>Davis, J. E., Eberwine, J. H., Hinkle, D. A., Marciano, P. G., Meaney, D. F., McIntonsh, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Methodological+considerations+regarding+single-cell+gene+expression+profiling+for+brain+injury.">Methodological considerations regarding single-cell gene expression profiling for brain injury.</a> Neurochemical Research. 29, 1113-1121 (2004).</li><li>Eberwine, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+molecular+biology.">Single-cell molecular biology.</a> Nature Neuroscience. 4, 1155-1156 (2001).</li><li>Kamme, F., Salunga, R., Yu, J., Tran, D., Zhu, J., Luo, J., Bittner, A., Guo, H., Miller, N., Wan, J., Erlander, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+microarray+analysis+in+hippocampus+CA1:+Demonstration+and+Validation+of+Cellular+Heterogeneity.">Single-cell microarray analysis in hippocampus CA1: Demonstration and Validation of Cellular Heterogeneity.</a> The Journal of Neuroscience. 23, 3607-3607 (2003).</li><li>Hinkle, D., Glanzer, J., Sarabi, A., Pajunen, T., Zielinski, J., Belt, B., Miyashiro, K., McIntosh, T., Eberwine, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+neurons+as+experimental+systems+in+molecular+biology.">Single neurons as experimental systems in molecular biology.</a> Progress in Neurobiology. 72, 129-142 (2004).</li><li>Ginsberg, S. D., Elarova, I., Ruben, M., Tan, F., Counts, S. E., Eberwine, J. H., Trojanowski, J. Q., Hemby, S. E., Mufson, E. J., Che, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+gene+expression+analysis:+Implications+for+Neurodegenerative+and+Neuropsychiatric+Disorders.">Single-cell gene expression analysis: Implications for Neurodegenerative and Neuropsychiatric Disorders.</a> Neeurochemical Research. 29, 1053-1064 (2004).</li><li>Eberwine, J., Spencer, K., Miyashirto, K., Mackler, S., Finnell, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Complementary+DNA+synthesis+in+situ:+methods+and+applications.">Complementary DNA synthesis in situ: methods and applications.</a> Methods Enxymol. 216, 80-100 (1992).</li><li>Eberwine, J., Yeh, H., Miyashiro, K., Cao, Y., Nair, S., Finnell, R., Zettel, M., Coleman, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+gene+expression+in+single+live+neurons.">Analysis of gene expression in single live neurons.</a> Proc. Natl. Acad. Sci. USA. 89, 3010-3014 (1992).</li><li>Kelz, M. B., Dent, G. W., Therianos, S., Marciano, P. G., McIntosh, T. K., Coleman, P. D., Eberwine, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+antisense+RNA+amplification+and+microarray+analysis+as+a+tool+for+studying+neurological+degeneration+and+restoration.">Single-cell antisense RNA amplification and microarray analysis as a tool for studying neurological degeneration and restoration.</a> Sci. Aging Knowledge Eviron. 1, re1-re1 (2002).</li><li>Banker, G. A., Cowan, W. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rat+hippocampal+neurons+in+dispersed+cell+culture.">Rat hippocampal neurons in dispersed cell culture.</a> Brain Research. 126, 397-425 (1977).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> P-1000 &#38; P-97 Pipette Cookbook. , (2010).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> MinElute Handbook For MinElute Reaction Cleanup Kit. , 28-29 (2004).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Megascript kit. , 7-8 .</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> MEGAclear kit. , 4-5 .</li><li>Eberwine, J., Kacharmina, J. E., Andrews, C., Miyashiro, K., McIntosh, T., Becker, K., Barrett, T., Hinkle, D., Dent, G., Marciano, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=mRNA+expression+analysis+of+tissue+sections+and+single+cells.">mRNA expression analysis of tissue sections and single cells.</a> The Journal of Neuroscience. 21, 8310-8314 (2001).</li><li>Van Gelder, R. N., von Zastrow, M. E., Yool, A., Dement, W. C., Barchas, J. D., Eberwine, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amplified+RNA+synthesized+from+limited+quantities+of+heterogeneous+cDNA.">Amplified RNA synthesized from limited quantities of heterogeneous cDNA.</a> Proc. Natl. Acad. Sci. USA. 87, 1663-1667 (1990).</li><li>Miyashiro, K., Dichter, M., Eberwine, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=On+the+nature+and+differential+distribution+of+mRNAs+in+hippocampal+neuritis:+Implications+for+neuronal+functioning.">On the nature and differential distribution of mRNAs in hippocampal neuritis: Implications for neuronal functioning.</a> Proc. Natl. Acad. Sci. USA. 91, 10800-10804 (1994).</li><li>Sul, J., Wo, C. K., Zeng, F., Jochems, J., Lee, M. T., Kim, T. K., Peritz, T., Buckley, P., Cappelleri, D. J., Maronski, M., Kim, M., Kumar, V., Meaney, D., Kim, J., Eberwine, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transcriptional+transfer+produces+a+predictable+cellular+phenotype.">Transcriptional transfer produces a predictable cellular phenotype.</a> Proc. Natl. Acad. Sci. USA. 106, 7624-7629 (2009).</li><li>Sow, F. B., Gallup, J. M., Sacco, R. E., Ackerman, M. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+capture+microdissection+revisited+as+a+tool+for+transcriptomic+analysis:+Application+of+an+excel-based+qPCR+preparation+software+(PREXCEL-Q).">Laser capture microdissection revisited as a tool for transcriptomic analysis: Application of an excel-based qPCR preparation software (PREXCEL-Q).</a> Int. J. Biomed. Sci. 5, (2010).</li><li>Vandewoestyne, M., Deforce, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+capture+microdissection+in+forensic+research:+a+review.">Laser capture microdissection in forensic research: a review.</a> Int J Legal Med. 124, (2010).</li><li>Eberwine, J., Bartfai, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+cell+transcriptomics+of+hypothalamic+warm+sensitive+neurons+that+control+core+body+temperature+and+fever+response+Signaling+asymmetry+and+an+extension+of+chemical+neuroanatomy.">Single cell transcriptomics of hypothalamic warm sensitive neurons that control core body temperature and fever response Signaling asymmetry and an extension of chemical neuroanatomy.</a> Pharmacol. Ther. , (2010).</li></ol>

Dr. Eberwine is an inventor on the aRNA patent that has been licensed to LBS technologies in which Dr. Eberwine is a share-holder.

Notes and Troubleshooting
<ul>
<li>You may want to take before and after images showing that the target cell was isolated and that the remaining penumbra was left untouched.</li>
<li>If too much solution is entering the pipette as you are harvesting, you can use 3 way Luer-Lock fittings and the plunger for the syringe to hold positive pressure in the tubing. The desired volume will vary with the type of processing but up to 5 &mu;l should be fine for most applications.</li>
</ul>
General tips on molecular biological techniques
<ul>
<li>Vortex all stock tubes and spin them down before adding to a reaction. NEVER vortex enzymes.</li>
<li>Thoroughly mix reactions before adding the enzyme to ensure that the buffer is at the proper concentration.</li>
<li>Keep enzyme stocks at -20&deg;C if possible by using a stratacooler. Otherwise, remove right before use, keep on ice, and return immediately to -20&deg;C.</li>
<li>Always make master mixes when preparing more than one reaction to reduce pipetting errors. Calculate the volume required based on the number of samples and add 10-20%.</li>
<li>Store RNA at -80&deg;C to retard degradation. RNA is most stable stored in buffer to retard apurination of RNA that occurs in acidic conditions.</li>
</ul>
General Outline of the aRNA Procedure
Figure 4A illustrates the first round of the aRNA procedure. In the first strand reaction, the poly-T portion of the T7-oligo(dT) primer selects for mRNA species (long white rectangle) by binding to the polyA tails. Some microRNAs are also polyadenylated and will be captured by this procedure. More importantly, however, the most abundant RNAs in the cell, ribosomal RNAs, will not. This oligo acts as a primer for Reverse Transcriptase to synthesize a complementary strand of cDNA (long grey rectangle) using the mRNA as a template. The T7 portion of the T7-oligo(dT) primer incorporates the T7 RNA polymerase promoter in frame with the sequence antisense to the starting mRNA. This is used later in the in vitro transcription reaction.
Next, the mRNA in the mRNA/DNA hybrid created in the preceding step is partially hydrolyzed by Rnase H creating RNA "primers" (small white rectangles) similar to the Okazaki fragments created in lagging strand DNA synthesis. DNA Polymerase I uses the RNA fragments to prime DNA synthesis using the DNA complementary to the mRNA as a template. When it reaches the next RNA fragment, its 5' to 3' nuclease activity removes the ribonucleotides and replaces them with deoxyribonucleotides. DNA ligase is added to ligate any strands where the replacement of the leading strand is not complete. T4 DNA Polymerase is added to fill in the areas where RNA fragments served as initial primers for DNA Polymerase I creating a blunt-ended double stranded cDNA that is then purified before performing the IVT reaction.
In the IVT reaction, T7 RNA polymerase binds to the T7 promoter incorporated into the double stranded cDNA and synthesizes antisense RNA molecules (long black rectangles) using the sense strand as a template. This serves as the amplification step in which thousands of antisense RNA molecules are produced from each double stranded cDNA molecule (Figure 4A).
The second round, as depicted in Figure 4B, begins with a reverse transcription reaction that is slightly different from that of the first round since the starting RNA is antisense (solid black rectangle) and lacks the polyadenylated tail that was targeted by the T7-oligo(dT) primer in the first round. Therefore, this reaction is primed with random primers (small grey rectangles) and the RNA subsequently denatured. The second strand reaction is then primed by the T7-oligo(dT) primer, which binds to the poly-A sequence at the 3' end of the sense RNA created in the preceding reverse transcription reaction. Another IVT reaction is performed in the same manner as in the first round. This second round is usually repeated at least once to achieve three rounds of amplification from a single cell.
Applications
The techniques that we have presented in this article can be translated into a large number of applications. The single cell isolation protocol can be modified for use in acute slices.14 Although technically more challenging, the same principles apply in this alternate preparation. Additionally, if the size of the pipette is slightly adjusted, recordings of the physiology of the cells can be made before harvest allowing for a well-controlled investigation of molecular mechanisms behind physiological outputs. Another slight modification is to isolate processes from the cell soma.15 For this application, collect cell bodies with one pipette and then go back with a fresh pipette and collect 100-300 identified dendrites or axons per collection tube.16
Once cells have been harvested, comparisons of mRNA abundances and compositions can be made between different and even within the same cell populations. Incorporating biotinylated-UTP into the third round aRNA allows for microarray analysis to determine these relative mRNA abundances. The composition of the original mRNA population can also be determined after the aRNA procedure using next generation sequencing. The amplified aRNA can also be used to confirm cell phenotype conversion studies in which a full set of mRNAs from one cell type are transfected into a different cell type in order to induce transition of the phenotype of the latter cell type into that of the former, a procedure developed by the lab and known as TIPeR.17 These studies are particularly useful for studying disease states and cell phenotypes and such studies are currently ongoing in the lab. RT-PCR or qPCR can be performed on the amplified material to confirm the expression of cell-specific genes. Additionally, evaluations of the efficiency of transfection or transduction can be made at the single cell level.
Advantages and Limitations
As stated in the abstract, isolation of single cells for analysis eliminates the averaging effects seen with analysis of heterogeneous cell populations. These averaging effects misrepresent mRNA abundances within a single cell by over-representing abundant transcripts and averaging out and preventing detection of many low-abundance transcripts. Flow cytometry can be used to sort individual cells, but this method requires knowledge of cell specific markers and expensive equipment.18 Laser capture microdissection either with UV or IR laser capture microdissection systems allow for single cell and even subcellular capture but requires cells of interest to be located at the surface of very thin sections.19 Similar to flow cytometry, laser capture microdissection also requires expensive equipment.
One of the major benefits of the electrode based collection technique described above is that valuable electrophysiological data can be obtained from the cell of interest before harvest, allowing for functional and transcriptome analysis to be performed on the same cell.20 A downside of our technique is that it does require experience using micromanipulators. Investigators familiar with micromanipulators will find this technique very intuitive; however, individuals with no such experience will need to become comfortable with the fine movements required.
Inherent in any amplification technique is the preferential amplification of certain transcripts based on size and nucleotide composition.4,6,7 Polymerase chain reaction (PCR) based techniques such as reverse-transcription polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) result in exponential amplification of transcripts, whereas the aRNA amplification procedure results in linear amplification. Thus, one of the major advantages of the aRNA procedure lies in its ability to better preserve the relative abundances of mRNA transcripts by only linearly amplifying any errors or biases that occur in the amplification process as opposed to exponentially amplifying said errors and biases. 
The aRNA procedure coupled with microarray analysis allows for comparison of mRNA abundances between single cells of similar or different morphology, treated or untreated. Additionally, amplified material can be submitted for next generation sequencing.5,8 However, care should be taken in such analyses since, in contrast to the use of random primers for the procedure, the oligo-dT primed procedure described above biases amplification of the 3' ends of mRNA and generally results in slight shortening of subsequent amplified material with each round. Care should be taken in analyzing microarray results with standard methods as some false absent calls can arise from slightly shortened amplified material. In addition, while sequencing results will indeed provide the full 5' sequence of most of the original mRNA, the 5' sequences of some mRNA might be missed. For these reasons, the number of rounds of amplifications should be limited.

A correction was made to <a href="http://http://www.jove.com/video/2634/transcriptome-analysis-of-single-cells">Transcriptome Analysis of Single Cells</a>. There were errors in the volumes used in the aRNA Amplification section.

Erratum: Transcriptome Analysis of Single Cells

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<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">	
		
		<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>Spiegelgas coverslips</td>
<td>&nbsp;</td>
<td>Carolina Biological</td>
<td>63-3029</td>
<td>&nbsp;</td>
<tr>
<td>Nunc 35x10 mm culture dishes</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>12-565-90</td>
<td>&nbsp;</td>
<tr>
<td>Water for cell culture</td>
<td>&nbsp;</td>
<td>Lonza</td>
<td>17-724Q</td>
<td>For making solutions used for cell culture and rinsing coverslips</td>
</tr>
<tr>
<td>Poly-D-Lysine MW70-150K</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>6407</td>
<td>&nbsp;</td>
<tr>
<td>Laminin, ultrapure</td>
<td>&nbsp;</td>
<td>BD Bioscience</td>
<td>354239</td>
<td>&nbsp;</td>
<tr>
<td>Boric acid</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>B0252</td>
<td>&nbsp;</td>
<tr>
<td>MEM with Earle&#x2019;s salts and glutamax</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>41090-101</td>
<td>For plating cells</td>
</tr>
<tr>
<td>D-glucose</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>G8769</td>
<td>&nbsp;</td>
<tr>
<td>Penicillin-streptomycin</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>15140-122</td>
<td>&nbsp;</td>
<tr>
<td>Horse serum</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>16050</td>
<td>&nbsp;</td>
<tr>
<td>Cytosine beta-D-arabinofuranoside</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>C1768</td>
<td>&nbsp;</td>
<tr>
<td>MEM with Earle&#x2019;s salts and L-glutamine</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>11095-098</td>
<td>For growing cells</td>
</tr>
<tr>
<td>Sodium pyruvate</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>P2256</td>
<td>&nbsp;</td>
<tr>
<td>B27 serum-free supplement</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>17504-044</td>
<td>&nbsp;</td>
<tr>
<td>Borosilicate glass capillary tubes (1.5mm O.D, 100mm length)</td>
<td>&nbsp;</td>
<td>Kimble Chase</td>
<td>34500 99</td>
<td>Any borosilicate glass pipette will work as long as the proper bore size is attained. </td>
</tr>
<tr>
<td>HBSS</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>14175</td>
<td>Any solution will work as long as the components won&#x2019;t interfere with any future processing (i.e. no Ca2+ or Mg2+)</td>
</tr>
<tr>
<td>1ml syringe</td>
<td>&nbsp;</td>
<td>BD</td>
<td>309628</td>
<td>&nbsp;</td>
<tr>
<td>Needle</td>
<td>&nbsp;</td>
<td>BD</td>
<td>&nbsp;</td>
<td>Gauge depends on the diameter of the pipettes</td>
</tr>
<tr>
<td>dNTP mix</td>
<td>&nbsp;</td>
<td>Amersham</td>
<td>28-4065-51</td>
<td>&nbsp;</td>
<tr>
<td>dt-T7 oligo</td>
<td>&nbsp;</td>
<td>Custom</td>
<td>Midland Certified</td>
<td>&nbsp;</td>
<tr>
<td>Second strand buffer (5x)</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>Y01129</td>
<td>&nbsp;</td>
<tr>
<td>DTT</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Supplied with second strand buffer</td>
</tr>
<tr>
<td>E.coli DNA Ligase</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>100002324</td>
<td>&nbsp;</td>
<tr>
<td>DNA polymerase I</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>100004926</td>
<td>&nbsp;</td>
<tr>
<td>Rnase H</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>18021-071</td>
<td>&nbsp;</td>
<tr>
<td>Megascript T7 kit</td>
<td>&nbsp;</td>
<td>Ambion</td>
<td>AM1334</td>
<td>&nbsp;</td>
<tr>
<td>Random primers</td>
<td>&nbsp;</td>
<td>BMB</td>
<td>11034731001</td>
<td>&nbsp;</td>
<tr>
<td>Superscript III Reverse Transcriptase</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>56575</td>
<td>in kit (18080-044) comes with first strand buffer (Y02321) and DTT</td>
</tr>
<tr>
<td>MEGAclear Kit</td>
<td>&nbsp;</td>
<td>Ambion</td>
<td>1908</td>
<td>&nbsp;</td>
<tr>
<td>MinElute Reaction Cleanup Kit</td>
<td>&nbsp;</td>
<td>Qiagen</td>
<td>28206</td>
<td>&nbsp;</td>
<tr>
<td>T4 DNA polymerase</td>
<td>&nbsp;</td>
<td>Invitrogen</td>
<td>100004994</td>
<td>&nbsp;</td>
<tr>
<td>Rnasin</td>
<td>&nbsp;</td>
<td>Promega</td>
<td>N251B</td>
<td>&nbsp;</td>
<tr>
<td>Illumina TotalPrep RNA Amplification Kit</td>
<td>&nbsp;</td>
<td>Ambion</td>
<td>AMIL1791</td>
<td>&nbsp;</td>
<tr>
<td>Flaming/Brown micropipette puller</td>
<td>&nbsp;</td>
<td>Sutter Instruments</td>
<td>P-87</td>
<td>Sutter has many other models, many are discussed in the cookbook</td>
</tr>
<tr>
<td>Micromanipulator</td>
<td>&nbsp;</td>
<td>Olympus</td>
<td>&nbsp;</td>
<td>Many other micromanipulators will work such as the newer Eppendorf models</td>
</tr>
<tr>
<td>Pipette Holder</td>
<td>&nbsp;</td>
<td>Warner Instruments</td>
<td>MP-S15A</td>
<td>Will vary with micromanipulator and pipette O.D.</td>
</tr>
<tr>
<td>Bioanalyzer RNA 6000 Nano Kit</td>
<td>&nbsp;</td>
<td>Agilent</td>
<td>5067-1511</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

transcriptome analysis of single cells

Many gene expression analysis techniques rely on material isolated from heterogeneous populations of cells from tissue homogenates or cells in culture.1,2,3 In the case of the brain, regions such as the hippocampus contain a complex arrangement of different cell types, each with distinct mRNA profiles. The ability to harvest single cells allows for a more in depth investigation into the molecular differences between and within cell populations. We describe a simple and rapid method for harvesting cells for further processing. Pipettes often used in electrophysiology are utilized to isolate (using aspiration) a cell of interest and conveniently deposit it into an Eppendorf tube for further processing with any number of molecular biology techniques. Our protocol can be modified for the harvest of dendrites from cell culture or even individual cells from acute slices.
We also describe the aRNA amplification method as a major downstream application of single cell isolations. This method was developed previously by our lab as an alternative to other gene expression analysis techniques such as reverse-transcription or real-time polymerase chain reaction (PCR).4,5,6,7,8 This technique provides for linear amplification of the polyadenylated RNA beginning with only femtograms of material and resulting in microgram amounts of antisense RNA. The linearly amplified material provides a more accurate estimation than PCR exponential amplification of the relative abundance of components of the transcriptome of the isolated cell. The basic procedure consists of two rounds of amplification. Briefly, a T7 RNA polymerase promoter site is incorporated into double stranded cDNA created from the mRNA transcripts. An overnight in vitro transcription (IVT) reaction is then performed in which T7 RNA polymerase produces many antisense transcripts from the double stranded cDNA. The second round repeats this process but with some technical differences since the starting material is antisense RNA. It is standard to repeat the second round, resulting in three rounds of amplification. Often, the third round in vitro transcription reaction is performed using biotinylated nucleoside triphosphates so that the antisense RNA produced can be hybridized and detected on a microarray.7,8

Watch this Scientific Journal Video about Transcriptome Analysis of Single Cells at JoVE.com

Transcriptome Analysis of Single Cells

In this article we describe a simple method for the harvesting of single cells from rat primary neuronal cultures and subsequent transcriptome analysis using aRNA amplification. This approach is generalizable to any cell type.

Many gene expression analysis techniques rely on material isolated from heterogeneous populations of cells from tissue homogenates or cells in ...

Research

JoVE Journal

Neuroscience

29.6K Views.  University of Pennsylvania. In this article we describe a simple method for the harvesting of single cells from rat primary neuronal cultures and subsequent transcriptome analysis using aRNA amplification. This approach is generalizable to any cell type.

Video: Transcriptome Analysis of Single Cells

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding fundamental biological mechanisms. Striking progress has been particularly evident in Drosophila, whose extensive toolkit of mutants and transgenic lines provides a convenient model to study evolutionarily-conserved developmental and cell biological mechanisms. We are interested in understanding the mechanisms that control cell fate specification in the adult peripheral nervous system (PNS) in Drosophila. Bristles that cover the head, thorax, abdomen, legs and wings of the adult fly are individual mechanosensory organs, and have been studied as a model system for understanding mechanisms of Notch-dependent cell fate decisions. Sensory organ precursor (SOP) cells of the microchaetes (or small bristles), are distributed throughout the epithelium of the pupal thorax, and are specified during the first 12 hours after the onset of pupariation. After specification, the SOP cells begin to divide, segregating the cell fate determinant Numb to one daughter cell during mitosis. Numb functions as a cell-autonomous inhibitor of the Notch signaling pathway.
Here, we show a method to follow protein dynamics in SOP cell and its progeny within the intact pupal thorax using a combination of tissue-specific Gal4 drivers and GFP-tagged fusion proteins 1,2.This technique has the advantage over fixed tissue or cultured explants because it allows us to follow the entire development of an organ from specification of the neural precursor to growth and terminal differentiation of the organ. We can therefore directly correlate changes in cell behavior to changes in terminal differentiation. Moreover, we can combine the live imaging technique with mosaic analysis with a repressible cell marker (MARCM) system to assess the dynamics of tagged proteins in mitotic SOPs under mutant or wildtype conditions. Using this technique, we and others have revealed novel insights into regulation of asymmetric cell division and the control of Notch signaling activation in SOP cells (examples include references 1-6,7 ,8).

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

In this video, we describe a method for live cell imaging of asymmetrically dividing sensory organ progenitor cells and epidermal cells in intact Drosophila pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding ...

Sequential Photo-bleaching to Delineate Single Schwann Cells at the Neuromuscular Junction

Sequential photo-bleaching provides a non-invasive way to label individual SCs at the NMJ. The NMJ is the largest synapse of the mammalian nervous system and has served as guiding model to study synaptic structure and function. In mouse NMJs motor axon terminals form pretzel-like contact sites with muscle fibers. The motor axon and its terminal are sheathed by SCs. Over the past decades, several transgenic mice have been generated to visualize motor neurons and SCs, for example Thy1-XFP1 and Plp-GFP mice2, respectively.
Along motor axons, myelinating axonal SCs are arranged in non-overlapping internodes, separated by nodes of Ranvier, to enable saltatory action potential propagation. In contrast, terminal SCs at the synapse are specialized glial cells, which monitor and promote neurotransmission, digest debris and guide regenerating axons. NMJs are tightly covered by up to half a dozen non-myelinating terminal SCs - these, however, cannot be individually resolved by light microscopy, as they are in direct membrane contact3.
Several approaches exist to individually visualize terminal SCs. None of these are flawless, though. For instance, dye filling, where single cells are impaled with a dye-filled microelectrode, requires destroying a labelled cell before filling a second one. This is not compatible with subsequent time-lapse recordings3. Multi-spectral "Brainbow" labeling of SCs has been achieved by using combinatorial expression of fluorescent proteins4. However, this technique requires combining several transgenes and is limited by the expression pattern of the promoters used. In the future, expression of "photo-switchable" proteins in SCs might be yet another alternative5. Here we present sequential photo-bleaching, where single cells are bleached, and their image obtained by subtraction. We believe that this approach - due to its ease and versatility - represents a lasting addition to the neuroscientist's technology palette, especially as it can be used in vivo and transferred to others cell types, anatomical sites or species6.
In the following protocol, we detail the application of sequential bleaching and subsequent confocal time-lapse microscopy to terminal SCs in triangularis sterni muscle explants. This thin, superficial and easily dissected nerve-muscle preparation7,8 has proven useful for studies of NMJ development, physiology and pathology9. Finally, we explain how the triangularis sterni muscle is prepared after fixation to perform correlated high-resolution confocal imaging, immunohistochemistry or ultrastructural examinations.

Visualizing individual cells in densely packed tissues, such as terminal Schwann cells (SCs) at neuromuscular junctions (NMJs), is challenging. "Sequential photo-bleaching" allows delineating single terminal SCs, for instance in the triangularis sterni muscle explant, a convenient nerve-muscle preparation, where sequential bleaching can be combined with time-lapse imaging and post-hoc immunostainings.

Sequential photo-bleaching provides a non-invasive way to label individual SCs at the NMJ. The NMJ is the largest synapse of the mammalian nervous system ...

Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

In this article we describe how to individually label neurons in the embryonic CNS of Drosophila melanogaster by juxtacellular injection of the lipophilic fluorescent membrane marker DiI. This method allows the visualization of neuronal cell morphology in great detail. It is possible to label any cell in the CNS: cell bodies of target neurons are visualized under DIC optics or by expression of a fluorescent genetic marker such as GFP. After labeling, the DiI can be transformed into a permanent brown stain by photoconversion to allow visualization of cell morphology with transmitted light and DIC optics. Alternatively, the DiI-labeled cells can be observed directly with confocal microscopy, enabling genetically introduced fluorescent reporter proteins to be colocalised. The technique can be used in any animal, irrespective of genotype, making it possible to analyze mutant phenotypes at single cell resolution.

Labeling of Single Cells in the Central Nervous System of Drosophila melanogaster

We present a technique for labeling single neurons in the central nervous system (CNS) of Drosophila embryos, which allows the analysis of neuronal morphology by either transmitted light or confocal microscopy.

In this  article we describe how to individually label neurons in the embryonic CNS of Drosophila melanogaster by juxtacellular injection of the ...

Laser Capture Microdissection of Enriched Populations of Neurons or Single Neurons for Gene Expression Analysis After Traumatic Brain Injury

Long-term cognitive disability after TBI is associated with injury-induced neurodegeneration in the hippocampus-a region in the medial temporal lobe that is critical for learning, memory and executive function.1,2 Hence our studies focus on gene expression analysis of specific neuronal populations in distinct subregions of the hippocampus. The technique of laser capture microdissection (LCM), introduced in 1996 by Emmert-Buck, et al.,3 has allowed for significant advances in gene expression analysis of single cells and enriched populations of cells from heterogeneous tissues such as the mammalian brain that contains thousands of functional cell types.4 We use LCM and a well established rat model of traumatic brain injury (TBI) to investigate the molecular mechanisms that underlie the pathogenesis of TBI. Following fluid-percussion TBI, brains are removed at pre-determined times post-injury, immediately frozen on dry ice, and prepared for sectioning in a cryostat. The rat brains can be embedded in OCT and sectioned immediately, or stored several months at -80 &deg;C before sectioning for laser capture microdissection. Additionally, we use LCM to study the effects of TBI on circadian rhythms. For this, we capture neurons from the suprachiasmatic nuclei that contain the master clock of the mammalian brain. Here, we demonstrate the use of LCM to obtain single identified neurons (injured and degenerating, Fluoro-Jade-positive, or uninjured, Fluoro-Jade-negative) and enriched populations of hippocampal neurons for subsequent gene expression analysis by real time PCR and/or whole-genome microarrays. These LCM-enabled studies have revealed that the selective vulnerability of anatomically distinct regions of the rat hippocampus are reflected in the different gene expression profiles of different populations of neurons obtained by LCM from these distinct regions. The results from our single-cell studies, where we compare the transcriptional profiles of dying and adjacent surviving hippocampal neurons, suggest the existence of a cell survival rheostat that regulates cell death and survival after TBI.

We describe how to use laser capture microdissection (LCM) to obtain enriched populations of hippocampal neurons or single neurons from frozen sections of the injured rat brain for subsequent gene expression analysis using quantitative real time PCR and/or whole-genome microarrays.

Long-term cognitive disability after TBI is associated with injury-induced neurodegeneration in the hippocampus-a region in the medial temporal lobe that ...

Peering at Brain Polysomes with Atomic Force Microscopy

The translational machinery, i.e., the polysome or polyribosome, is one of the biggest and most complex cytoplasmic machineries in cells. Polysomes, formed by ribosomes, mRNAs, several proteins and non-coding RNAs, represent integrated platforms where translational controls take place. However, while the ribosome has been widely studied, the organization of polysomes is still lacking comprehensive understanding. Thus much effort is required in order to elucidate polysome organization and any novel mechanism of translational control that may be embedded. Atomic force microscopy (AFM) is a type of scanning probe microscopy that allows the acquisition of 3D images at nanoscale resolution. Compared to electron microscopy (EM) techniques, one of the main advantages of AFM is that it can acquire thousands of images both in air and in solution, enabling the sample to be maintained under near physiological conditions without any need for staining and fixing procedures. Here, a detailed protocol for the accurate purification of polysomes from mouse brain and their deposition on mica substrates is described. This protocol enables polysome imaging in air and liquid with AFM and their reconstruction as three-dimensional objects. Complementary to cryo-electron microscopy (cryo-EM), the proposed method can be conveniently used for systematically analyzing polysomes and studying their organization.

While ribosome structure has been extensively characterized, the organization of polysomes is still understudied. To overcome this lack of knowledge, we present here a detailed preparation protocol for accurate imaging of mammalian polysomes by atomic force microscopy (AFM) in air and liquid.

The translational machinery, i.e., the polysome or polyribosome, is one of the biggest and most complex cytoplasmic machineries in cells. Polysomes, ...

Single-cell RNA-Seq of Defined Subsets of Retinal Ganglion Cells

The discovery of cell type-specific markers can provide insight into cellular function and the origins of cellular heterogeneity. With a recent push for the improved understanding of neuronal diversity, it is important to identify genes whose expression defines various subpopulations of cells. The retina serves as an excellent model for the study of central nervous system diversity, as it is composed of multiple major cell types. The study of each major class of cells has yielded genetic markers that facilitate the identification of these populations. However, multiple subtypes of cells exist within each of these major retinal cell classes, and few of these subtypes have known genetic markers, although many have been characterized by morphology or function. A knowledge of genetic markers for individual retinal subtypes would allow for the study and mapping of brain targets related to specific visual functions and may also lend insight into the gene networks that maintain cellular diversity. Current avenues used to identify the genetic markers of subtypes possess drawbacks, such as the classification of cell types following sequencing. This presents a challenge for data analysis and requires rigorous validation methods to ensure that clusters contain cells of the same function. We propose a technique for identifying the morphology and functionality of a cell prior to isolation and sequencing, which will allow for the easier identification of subtype-specific markers. This technique may be extended to non-neuronal cell types, as well as to rare populations of cells with minor variations. This protocol yields excellent-quality data, as many of the libraries have provided read depths greater than 20 million reads for single cells. This methodology overcomes many of the hurdles presented by Single-cell RNA-Seq and may be suitable for researchers aiming to profile cell types in a straightforward and highly efficient manner.

Here, we present a combinatorial approach for classifying neuronal cell types prior to isolation and for the subsequent characterization of single-cell transcriptomes. This protocol optimizes the preparation of samples for successful RNA Sequencing (RNA-Seq) and describes a methodology designed specifically for the enhanced understanding of cellular diversity.

The discovery of cell type-specific markers can provide insight into cellular function and the origins of cellular heterogeneity. With a recent push for ...

Analysis of Immune Cells in Single Sciatic Nerves and Dorsal Root Ganglion from a Single Mouse Using Flow Cytometry

Nerve-resident immune cells in the peripheral nervous system (PNS) are essential to maintaining neuronal integrity in a healthy nerve. The immune cells of the PNS are affected by injury and disease, affecting the nerve function and the capacity for regeneration. Neuronal immune cells are commonly analyzed by immunofluorescence (IF). While IF is essential for determining the location of the immune cells in the nerve, IF is only semi-quantitative and the method is limited to the number of markers that can be analyzed simultaneously and the degree of surface expression. In this study, flow cytometry was used for quantitative analysis of leukocyte infiltration into sciatic nerves or dorsal root ganglions (DRGs) of individual mice. Single cell analysis was performed using DAPI and several proteins were analyzed simultaneously for either surface or intracellular expression. Both sciatic nerves from one mouse that were treated according to this protocol generated &#8805; 30,000 single nucleated events. The proportion of leukocytes in the sciatic nerves, determined by expression of CD45, was approximately 5% of total cell content in the sciatic nerve and approximately 5-10% in the DRG. Although this protocol focuses primarily on the immune cell population within the PNS, the flexibility of flow cytometry to measure a number of markers simultaneously means that the other cells populations present within the nerve, such as Schwann cells, pericytes, fibroblasts, and endothelial cells, can also be analyzed using this method. This method therefore provides a new means for studying systemic effects on the PNS, such as neurotoxicology and genetic models of neuropathy or in chronic diseases, such as diabetes.

Quantitative analysis of cell content within the murine sciatic nerve is difficult due to the scarcity of the tissue. This protocol describes a method for tissue digestion and preparation that provides sufficient cells for flow cytometry analysis of immune cell populations from nerves of individual mice.

Nerve-resident immune cells in the peripheral nervous system (PNS) are essential to maintaining neuronal integrity in a healthy nerve. The immune cells of ...

Isolation of Adult Spinal Cord Nuclei for Massively Parallel Single-nucleus RNA Sequencing

Probing an individual cell&#39;s gene expression enables the identification of cell type and cell state. Single-cell RNA sequencing has emerged as a powerful tool for studying transcriptional profiles of cells, particularly in heterogeneous tissues such as the central nervous system. However, dissociation methods required for single cell sequencing can lead to experimental changes in the gene expression and cell death. Furthermore, these methods are generally restricted to fresh tissue, thus limiting studies on archival and bio-bank material. Single nucleus RNA sequencing (snRNA-Seq) is an appealing alternative for transcriptional studies, given that it accurately identifies cell types, permits the study of tissue that is frozen or difficult to dissociate, and reduces dissociation-induced transcription. Here, we present a high-throughput protocol for rapid isolation of nuclei for downstream snRNA-Seq. This method enables isolation of nuclei from fresh or frozen spinal cord samples and can be combined with two massively parallel droplet encapsulation platforms.

Here, we present a protocol to rapidly isolate high-quality nuclei from the fresh or frozen tissue for downstream massively parallel RNA sequencing. We include detergent-mechanical and hypotonic-mechanical tissue disruption and cell lysis options, both of which can be used for isolation of nuclei.

Probing an individual cell&#39;s gene expression enables the identification of cell type and cell state. Single-cell RNA sequencing has emerged as a ...

Analysis of Spliceosomal snRNA Localization in Human Hela Cells Using Microinjection

Biogenesis of spliceosomal snRNAs is a complex process involving both nuclear and cytoplasmic phases and the last step occurs in a nuclear compartment called the Cajal body. However, sequences that direct snRNA localization into this subnuclear structure have not been known until recently. To determine sequences important for accumulation of snRNAs in Cajal bodies, we employed microinjection of fluorescently labelled snRNAs followed by their localization inside cells. First, we prepared snRNA deletion mutants, synthesized DNA templates for in vitro transcription and transcribed snRNAs in the presence of UTP coupled with Alexa488. Labelled snRNAs were mixed with 70 kDa-Dextran conjugated with TRITC, and microinjected to the nucleus or the cytoplasm of human HeLa cells. Cells were incubated for 1 h and fixed and the Cajal body marker coilin was visualized by indirect immunofluorescence, while snRNAs and dextran, which serves as a marker of nuclear or cytoplasmic injection, were observed directly using a fluorescence microscope. This method allows for efficient and rapid testing of how various sequences influence RNA localization inside cells. Here, we show the importance of the Sm-binding sequence for efficient localization of snRNAs into the Cajal body.

Biogenesis of spliceosomal snRNAs is a complex process involving various cellular compartments. Here, we employed microinjection of fluorescently labelled snRNAs in order to monitor their transport inside the cell.

Biogenesis of spliceosomal snRNAs is a complex process involving both nuclear and cytoplasmic phases and the last step occurs in a nuclear compartment ...

A Scalable Model to Study the Effects of Blunt-Force Injury in Adult Zebrafish

Blunt-force traumatic brain injuries (TBI) are the most common form of head trauma, which spans a range of severities and results in complex and heterogenous secondary effects. While there is no mechanism to replace or regenerate the lost neurons following a TBI in humans, zebrafish possess the ability to regenerate neurons throughout their body, including the brain. To examine the breadth of pathologies exhibited in zebrafish following a blunt-force TBI and to study the mechanisms underlying the subsequent neuronal regenerative response, we modified the commonly used rodent Marmarou weight drop for the use in adult zebrafish. Our simple blunt-force TBI model is scalable, inducing a mild, moderate, or severe TBI, and recapitulates many of the phenotypes observed following human TBI, such as contact- and post-traumatic seizures, edema, subdural and intracerebral hematomas, and cognitive impairments, each displayed in an injury severity-dependent manner. TBI sequelae, which begin to appear within minutes of the injury, subside and return to near undamaged control levels within 7 days post-injury. The regenerative process begins as early as 48 hours post-injury (hpi), with the peak cell proliferation observed by 60 hpi. Thus, our zebrafish blunt-force TBI model produces characteristic primary and secondary injury TBI pathologies similar to human TBI, which allows for investigating disease onset and progression, along with the mechanisms of neuronal regeneration that is unique to zebrafish.

We modified the Marmarou weight drop model for adult zebrafish to examine a breadth of pathologies following blunt-force traumatic brain injury (TBI) and the mechanisms underlying subsequent neuronal regeneration. This blunt-force TBI model is scalable, induces a mild, moderate, or severe TBI, and recapitulates injury heterogeneity observed in human TBI.