We thank the National Center for Protein Sciences, Beijing (Peking University) and the Peking-Tsinghua Center for the Life Science Computing Platform. This work was supported by the Ministry of Science and Technology of China (2015CB942800), the National Natural Science Foundation of China (31521004, 31471358, and 31522036), and funding from Peking-Tsinghua Center for Life Sciences to C.-R.X.

All methods described here have been approved by the Institutional Animal Care and Use Committee (IACUC) of Peking University.
1. Pancreas Isolation
<ol>
	<li>For E17.5 (embryonic day 17.5) embryos:
	<ol>
		<li>Estimate embryonic day 0.5 based on the time point when the vaginal plug appears.</li>
		<li>Sacrifice the pregnant mice by CO2 administration. Spray the abdominal fur with 70% alcohol.</li>
		<li>Make a V-shaped incision with scissors from the genital area...

<ol>
	<li>Gu, G., Dubauskaite, J., Melton, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+evidence+for+the+pancreatic+lineage:+NGN3++cells+are+islet+progenitors+and+are+distinct+from+duct+progenitors.">Direct evidence for the pancreatic lineage: NGN3+ cells are islet progenitors and are distinct from duct progenitors.</a> Development. 129 (10), 2447-2457 (2002).</li><li>Oliver-Krasinski, J. M., Stoffers, D. A. <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+origin+of+the+beta+cell.">On the origin of the beta cell.</a> Genes &amp; Development. 22 (15), 1998-2021 (1998).</li><li>Dor, Y., Brown, J., Martinez, O. I., Melton, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+pancreatic+beta-cells+are+formed+by+self-duplication+rather+than+stem-cell+differentiation.">Adult pancreatic beta-cells are formed by self-duplication rather than stem-cell differentiation.</a> Nature. 429 (6987), 41-46 (2004).</li><li>Smukler, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+adult+mouse+and+human+pancreas+contain+rare+multipotent+stem+cells+that+express+insulin.">The adult mouse and human pancreas contain rare multipotent stem cells that express insulin.</a> Cell Stem Cell. 8 (3), 281-293 (2011).</li><li>Dorrell, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+islets+contain+four+distinct+subtypes+of+beta+cells.">Human islets contain four distinct subtypes of beta cells.</a> Nature Communications. 7, 11756 (2016).</li><li>Bader, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Identification+of+proliferative+and+mature+beta-cells+in+the+islets+of+Langerhans.">Identification of proliferative and mature beta-cells in the islets of Langerhans.</a> Nature. 535 (7612), 430-434 (2016).</li><li>Saliba, A. E., Westermann, A. J., Gorski, S. A., Vogel, 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+RNA-seq:+Advances+and+future+challenges.">Single-cell RNA-seq: Advances and future challenges.</a> Nucleic Acids Research. 42 (14), 8845-8860 (2014).</li><li>Qiu, W. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deciphering+pancreatic+islet+beta+cell+and+alpha+cell+maturation+pathways+and+characteristic+features+at+the+single-cell+level.">Deciphering pancreatic islet beta cell and alpha cell maturation pathways and characteristic features at the single-cell level.</a> Cell Metabolism. 25 (5), 1194-1205 (2017).</li><li>Picelli, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Smart-seq2+for+sensitive+full-length+transcriptome+profiling+in+single+cells.">Smart-seq2 for sensitive full-length transcriptome profiling in single cells.</a> Nature Methods. 10 (11), 1096-1098 (2013).</li><li>Picelli, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Full-length+RNA-seq+from+single+cells+using+Smart-seq2.">Full-length RNA-seq from single cells using Smart-seq2.</a> Nature Protocols. 9 (1), 171-181 (2014).</li><li>Piccand, 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=Pak3+promotes+cell+cycle+exit+and+differentiation+of+beta-cells+in+the+embryonic+pancreas+and+is+necessary+to+maintain+glucose+homeostasis+in+adult+mice.">Pak3 promotes cell cycle exit and differentiation of beta-cells in the embryonic pancreas and is necessary to maintain glucose homeostasis in adult mice.</a> Diabetes. 63 (1), 203-215 (2014).</li><li>Veite-Schmahl, M. J., Regan, D. P., Rivers, A. C., Nowatzke, J. F., Kennedy, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dissection+of+the+mouse+pancreas+for+histological+analysis+and+metabolic+profiling.">Dissection of the mouse pancreas for histological analysis and metabolic profiling.</a> Journal of Visualized Experiments. (126), (2017).</li><li>Hu, P., Zhang, W., Xin, H., Deng, G. <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+isolation+and+analysis.">Single cell isolation and analysis.</a> Frontiers in Cell and Developmental Biology. 4, 116 (2016).</li><li>Haque, A., Engel, J., Teichmann, S. A., Lonnberg, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+practical+guide+to+single-cell+RNA-sequencing+for+biomedical+research+and+clinical+applications.">A practical guide to single-cell RNA-sequencing for biomedical research and clinical applications.</a> Genome Medicine. 9 (1), 75 (2017).</li><li>. FastQC: A quality control tool for high throughput sequence data Available from: <a target="_blank" href="https://www.bioinformatics.babraham.ac.uk/projects/fastqc/">https://www.bioinformatics.babraham.ac.uk/projects/fastqc/</a> (2010)</li><li>Langmead, B., Salzberg, S. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+gapped-read+alignment+with+Bowtie+2.">Fast gapped-read alignment with Bowtie 2.</a> Nature Methods. 9 (4), 357-359 (2012).</li><li>Kim, D., 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=TopHat2:+accurate+alignment+of+transcriptomes+in+the+presence+of+insertions,+deletions+and+gene+fusions.">TopHat2: accurate alignment of transcriptomes in the presence of insertions, deletions and gene fusions.</a> Genome Biology. 14 (4), (2013).</li><li>Anders, S., Pyl, P. T., Huber, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HTSeq--a+Python+framework+to+work+with+high-throughput+sequencing+data.">HTSeq--a Python framework to work with high-throughput sequencing data.</a> Bioinformatics. 31 (2), 166-169 (2015).</li><li>Wagner, G. P., Kin, K., Lynch, V. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurement+of+mRNA+abundance+using+RNA-seq+data:+RPKM+measure+is+inconsistent+among+samples.">Measurement of mRNA abundance using RNA-seq data: RPKM measure is inconsistent among samples.</a> Theory in Biosciences. 131 (4), 281-285 (2012).</li><li>Brennecke, P., 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=Accounting+for+technical+noise+in+single-cell+RNA-seq+experiments.">Accounting for technical noise in single-cell RNA-seq experiments.</a> Nature Methods. 10 (11), 1093-1095 (2013).</li><li>Le, S., Josse, J., Husson, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FactoMineR:+An+R+package+for+multivariate+analysis.">FactoMineR: An R package for multivariate analysis.</a> Journal of Statistical Software. 25 (1), (2008).</li><li>Hadley, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> ggplot2: Elegant graphics for data analysis. , (2009).</li><li>. gplots: Various R Programming Tools for Plotting Data Available from: <a target="_blank" href="https://cran.r-project.org/package=gplots">https://cran.r-project.org/package=gplots</a> (2016)</li><li>Marcheva, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Disruption+of+the+clock+components+CLOCK+and+BMAL1+leads+to+hypoinsulinaemia+and+diabetes.">Disruption of the clock components CLOCK and BMAL1 leads to hypoinsulinaemia and diabetes.</a> Nature. 466 (7306), 627-631 (2010).</li><li>Li, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-cell+RNA-seq+analysis+maps+development+of+human+germline+cells+and+gonadal+niche+interactions.">Single-cell RNA-seq analysis maps development of human germline cells and gonadal niche interactions.</a> Cell Stem Cell. , (2017).</li><li>Qi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+pancreatic+islet+isolation:+Part+I:+Digestion+and+collection+of+pancreatic+tissue.">Human pancreatic islet isolation: Part I: Digestion and collection of pancreatic tissue.</a> Journal of Visualized Experiments. (27), (2009).</li><li>Qi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+pancreatic+islet+isolation:+Part+II:+Purification+and+culture+of+human+islets.">Human pancreatic islet isolation: Part II: Purification and culture of human islets.</a> Journal of Visualized Experiments. (27), (2009).</li><li>Teo, A. K. 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=Single-cell+analyses+of+human+islet+cells+reveal+de-differentiation+signatures.">Single-cell analyses of human islet cells reveal de-differentiation signatures.</a> Cell Death Discovery. 4 (14), (2018).</li></ol>

In this protocol, we demonstrated an effective and easy-to-use method for studying the single-cell expression profiles of pancreatic &#946; cells. This method could be used to isolate endocrine cells from embryonic, neonatal and postnatal pancreases and to perform single-cell transcriptomic analyses.
The most critical step is the isolation of single &#946; cells in good condition. Fully perfused pancreases respond better to subsequent digestion. Insufficient perfusion, which usually occurs in ...

The pancreas is a vital metabolic organ in mammals. The pancreas is comprised of endocrine and exocrine compartments. Pancreatic endocrine cells, including insulin-producing &#946; cells and glucagon-producing &#945; cells, cluster together in the islets of Langerhans and coordinately regulate systemic glucose homeostasis. Dysfunction of the endocrine cells results in diabetes mellitus, which has become a major public health issue worldwide.
Pancreatic endocrine cells are derived from Ngn3+ progenitors during embryogenesis1. Later, during the perinatal period, the endocrine cells proliferate to form immature islets. These immature cells continue to develop and gradually become mature islets, which become richly vascularized to regulate blood glucose homeostasis in adults2.
Although a group of transcriptional factors has been identified that regulate &#946; cell differentiation, the precise maturation pathway of &#946; cells is still unclear. Moreover, the &#946; cell maturation process also involves the regulation of cell number expansion3,4 and the generation of cellular heterogeneity5,6. However, the regulatory mechanisms of these processes have not been well studied.
Single-cell RNA-sequencing is a powerful approach that can profile cell subpopulations and trace cell lineage developmental pathways7. Taking advantage of this technology, the key events that occur during pancreatic islet development can be deciphered at the single-cell level8. Among the single-cell RNA-sequencing protocols, Smart-seq2 allows the generation of full-length cDNA with improved sensitivity and accuracy, and the use of standard reagents at lower cost9. Smart-seq2 takes approximately two days to construct a cDNA library for sequencing10.
Here, we propose a method for the isolation of fluorescence-labeled &#946; cells from the pancreases of fetal to adult Ins1-RFP transgenic mice11, using fluorescence-activated cell sorting (FACS), and the performance of transcriptomic analyses at the single-cell level, using Smart-seq2 technology (Figure 1).This protocol can be extended to analyze the transcriptomes of all pancreatic endocrine cell types in normal, pathological and aging states.

<table>
	<tbody>
		<tr>
			<td>Collagenase P</td>
			<td>Roche</td>
			<td>11213873001</td>
			<td></td>
		</tr>
		<tr>
			<td>Trypsin-EDTA (0.25 %), phenol red</td>
			<td>Thermo Fisher Scientific</td>
			<td>25200114</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum (FBS)</td>
			<td>Hyclone</td>
			<td>SH30071.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #4 Forceps</td>
			<td>Roboz</td>
			<td>RS-4904</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #5 Forceps</td>
			<td>Roboz</td>
			<td>RS-5058</td>
			<td></td>
		</tr>
		<tr>
			<td>30 G BD Needle 1/2&#34; Length</td>
			<td>BD</td>
			<td>305106</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereo Microscope</td>
			<td>Zeiss</td>
			<td>Stemi DV4</td>
			<td></td>
		</tr>
		<tr>
			<td>Stereo Fluorescence microscope</td>
			<td>Zeiss</td>
			<td>Stereo Lumar V12</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5810R</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge</td>
			<td>Eppendorf</td>
			<td>5424R</td>
			<td></td>
		</tr>
		<tr>
			<td>Polystyrene Round-Bottom Tube with Cell-Strainer Cap</td>
			<td>BD-Falcon</td>
			<td>352235</td>
			<td></td>
		</tr>
		<tr>
			<td>96-Well PCR Microplate</td>
			<td>Axygen</td>
			<td>PCR-96-C</td>
			<td></td>
		</tr>
		<tr>
			<td>Silicone Sealing Mat</td>
			<td>Axygen</td>
			<td>AM-96-PCR-RD</td>
			<td></td>
		</tr>
		<tr>
			<td>Thin Well PCR Tube</td>
			<td>Extragene</td>
			<td>P-02X8-CF</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell sorter</td>
			<td>BD Biosciences</td>
			<td>BD FACSAria</td>
			<td></td>
		</tr>
		<tr>
			<td>Capillary pipette</td>
			<td>Sutter</td>
			<td>B100-58-10</td>
			<td></td>
		</tr>
		<tr>
			<td>RNaseZap</td>
			<td>Ambion</td>
			<td>AM9780</td>
			<td></td>
		</tr>
		<tr>
			<td>ERCC RNA Spike-In Mix</td>
			<td>Life Technologies</td>
			<td>4456740</td>
			<td></td>
		</tr>
		<tr>
			<td>Distilled water</td>
			<td>Gibco</td>
			<td>10977</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma-Aldrich</td>
			<td>T9284</td>
			<td></td>
		</tr>
		<tr>
			<td>dNTP mix</td>
			<td>New England Biolabs</td>
			<td>N0447</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant RNase Inhibitor</td>
			<td>Takara</td>
			<td>2313</td>
			<td></td>
		</tr>
		<tr>
			<td>Superscript II reverse transcriptase</td>
			<td>Invitrogen</td>
			<td>18064-014</td>
			<td></td>
		</tr>
		<tr>
			<td>First-strand buffer (5x)</td>
			<td>Invitrogen</td>
			<td>18064-014</td>
			<td></td>
		</tr>
		<tr>
			<td>DTT</td>
			<td>Invitrogen</td>
			<td>18064-014</td>
			<td></td>
		</tr>
		<tr>
			<td>Betaine</td>
			<td>Sigma-Aldrich</td>
			<td>107-43-7</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma-Aldrich</td>
			<td>7786-30-3</td>
			<td></td>
		</tr>
		<tr>
			<td>Nuclease-free water</td>
			<td>Invitrogen</td>
			<td>AM9932</td>
			<td></td>
		</tr>
		<tr>
			<td>KAPA HiFi HotStart ReadyMix (2x)</td>
			<td>KAPA Biosystems</td>
			<td>KK2601</td>
			<td></td>
		</tr>
		<tr>
			<td>VAHTS DNA Clean Beads XP beads</td>
			<td>Vazyme</td>
			<td>N411-03</td>
			<td></td>
		</tr>
		<tr>
			<td>Qubit dsDNA HS Assay Kit</td>
			<td>Invitrogen</td>
			<td>Q32854</td>
			<td></td>
		</tr>
		<tr>
			<td>AceQ qPCR SYBR Green Master Mix</td>
			<td>Vazyme</td>
			<td>Q121-02</td>
			<td></td>
		</tr>
		<tr>
			<td>TruePrep DNA Library Prep Kit V2 for Illumina</td>
			<td>Vazyme</td>
			<td>TD502</td>
			<td>Include 5x TTBL, 5x TTE, 5x TS, 5x TAB, TAE</td>
		</tr>
		<tr>
			<td>TruePrep Index Kit V3 for Illumina</td>
			<td>Vazyme</td>
			<td>TD203</td>
			<td>Include 16 N6XX and 24 N8XX</td>
		</tr>
		<tr>
			<td>High Sensitivity NGS Fragment Analysis Kit</td>
			<td>Advanced Analytical Technologies</td>
			<td>DNF-474</td>
			<td></td>
		</tr>
		<tr>
			<td>1x HBSS without Ca2+ and Mg2+</td>
			<td></td>
			<td></td>
			<td>138 mM NaCl; 5.34 mM KCl 
			4.17 mM NaHCO3; 0.34 mM Na2HPO4 
			0.44 mM KH2PO4</td>
		</tr>
		<tr>
			<td>Isolation buffer</td>
			<td></td>
			<td></td>
			<td>1 &#215; HBSS containing 10 mM HEPES, 1 mM MgCl2, 5 mM Glucose, pH 7.4</td>
		</tr>
		<tr>
			<td>FACS buffer</td>
			<td></td>
			<td></td>
			<td>1 &#215; HBSS containing 15 mM HEPES, 5.6 mM Glucose, 1% FBS, pH 7.4</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>S5886</td>
			<td></td>
		</tr>
		<tr>
			<td>KCl</td>
			<td>Sigma-Aldrich</td>
			<td>P9541</td>
			<td></td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td>Sigma-Aldrich</td>
			<td>S6297</td>
			<td></td>
		</tr>
		<tr>
			<td>Na2HPO4</td>
			<td>Sigma-Aldrich</td>
			<td>S5136</td>
			<td></td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Sigma-Aldrich</td>
			<td>P5655</td>
			<td></td>
		</tr>
		<tr>
			<td>D-(+)-Glucose</td>
			<td>Sigma-Aldrich</td>
			<td>G5767</td>
			<td></td>
		</tr>
		<tr>
			<td>HEPES</td>
			<td>Sigma-Aldrich</td>
			<td>H4034</td>
			<td></td>
		</tr>
		<tr>
			<td>MgCl2</td>
			<td>Sigma-Aldrich</td>
			<td>M2393</td>
			<td></td>
		</tr>
		<tr>
			<td>Oligo-dT30VN primer</td>
			<td>5&#39;-AAGCAGTGGTATCAACGCAGAGTACT30VN-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TSO</td>
			<td>5&#39;-AAGCAGTGGTATCAACGCAGAGTACATrGrG+G-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ISPCR primers</td>
			<td>5&#39;-AAGCAGTGGTATCAACGCAGAGT-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gapdh Forward primer</td>
			<td>5&#39;-ATGGTGAAGGTCGGTGTGAAC-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Gapdh Reverse primer</td>
			<td>5&#39;-GCCTTGACTGTGCCGTTGAAT-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ins2 Forward primer</td>
			<td>5&#39;-TGGCTTCTTCTACACACCCA-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ins2 Reverse primer</td>
			<td>5&#39;-TCTAGTTGCAGTAGTTCTCCA-3&#39;</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

single-cell transcriptomic analyses of mouse pancreatic endocrine cells

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, including insulin-secreting &#946; cells, are differentiated from common endocrine progenitors during the embryonic stage. Immature endocrine cells expand via cell proliferation and mature during a long postnatal developmental period. However, the mechanisms underlying these processes are not clearly defined. Single-cell RNA-sequencing is a promising approach for the characterization of distinct cell populations and tracing cell lineage differentiation pathways. Here, we describe a method for the single-cell RNA-sequencing of isolated pancreatic &#946; cells from embryonic, neonatal and postnatal pancreases.

Pancreases were dissected from embryonic, neonatal and postnatal mice (Figure 2A and 2B). For mice older than postnatal day 18, the digestive effect depends on the degree of perfusion; therefore, the injection is the most important step for islet isolation (Figure 2C-2E and Table 6). As much collagenase was injected as was possible to fill the pancreas during thi...

Watch this Scientific Journal Video about Single-cell Transcriptomic Analyses of Mouse Pancreatic Endocrine Cells at JoVE.com

Single-cell Transcriptomic Analyses of Mouse Pancreatic Endocrine Cells

We describe a method for the isolation of endocrine cells from embryonic, neonatal and postnatal pancreases followed by single-cell RNA sequencing. This method allows analyses of pancreatic endocrine lineage development, cell heterogeneity and transcriptomic dynamics.

Pancreatic endocrine cells, which are clustered in islets, regulate blood glucose stability and energy metabolism. The distinct cell types in islets, ...

This method can have answer key questions in the pancreatic islet field about pancreatic islet lineage differentiation, maturation, and the regeneration. The main advantage of this technique is that it allows the collection of single pancreatic islet cells for the generation of high quality single cell RNA sequencing data. The application of this technique extend toward the therapy of diabetes and the other pancreatic endocrine related diseases through the transcriptomic analysis of pancreatic endocrine single cells on the pathological conditions.Visual demonstration of this method is critical as the insertion of the needle into the narrow bile duct of the pancreas for the perfusion can be tricky. For embryonic day 17.5 embryos. After opening the abdominal cavity, use elbow tweezers to transfer the visceral tissue to a six centimeter black bottom dish containing cold PBS.Use forceps to detach the pancreas from the visceral tissue. And place the pancreatic tissue in a 20 milliliter vial containing five milliliters of cold collagenase solution. For post natal day zero to 15 mice, carefully dissect all of the lobes of the pancreas before placing the tissue into the collagenase.For post natal day 18 to 60 mice, first remove the xiphoid and extract the bowel to the right side of the abdominal cavity. Push the left and right medial lobes of the liver to each side to expose the gall bladder and the common bile duct. And clamp the duodenum with a pair of small vessel clamps at the upper and lower positions to flank the site where the bile duct enters the duodenum.Next, load a 5 milliliter syringe equipped with a 30 gauge needle with cold collagenase solution. And use the microscope to insert the needle tip into the gall bladder. Carefully and smoothly manipulate the needle through the common bile duct.And depress the plunger to perfuse the pancreas with one to five milliliters of the collagenase solution according to the size of the mouse. When all of the solution has been perfused, use forceps to immediately transfer the pancreas to a 20 milliliter vial containing five milliliters of fresh cold collagenase solution. When all of the pancreatic tissue has been collected, place the vial in a 37 degree Celsius water bath for three minutes, followed by three to five minutes of gentle shaking.Then filter the digested product through a 0.25 millimeter nylon strainer into a new 50 milliliter centrifuge tube. And use a 20 milliliter syringe containing ice cold PBS to thoroughly wash the strainer. For post natal day 18 to 60 pancreata, centrifuge the filtered sample and resuspend the tissue in 30 milliliters of cold PBS.Then decant the tissue suspension into a six centimeter black bottom dish, and use a 200 microliter pipette and a dissecting microscope to pick the islets for transfer into a 1.5 milliliter microcentrifuge tube containing a small volume of cold PBS. For embryonic day 17.5 post natal day 15 pancreata, centrifuge the filtered pancreatic tissue and resuspend the pellet in trypsin-EDTA solution for a four minute incubation in a 37 degree Celsius water bath. At the end of the incubation, gently try to rate the pellet for one minute with a 200 microliter pipette, followed by the addition of 0.5 times the volume of cold fetal bovine serum with a gentle vortexing to stop the digestion.Then collect the digest by centrifugation and resuspend the cells in 200 microliters of FACS buffer in a 5 milliliter FACS tube for sorting by flow cytometry. For single cell picking and lysis, aliquot freshly prepared cell lysis buffer into eight strip PCR tubes, and transfer a single cell into each. Vortex the samples to lyse the cells for release of the RNA, followed by centrifugation for 30 seconds at four degrees Celsius, and immediate storage on ice.For reverse transcription, incubate the lysates for three minutes at 72 degree Celsius followed by one minute on ice. Briefly centrifuge the samples for 30 seconds at four degree Celsius and add 5.7 microliters of reverse transcription mix to each sample to bring the total volume to 10 microliters for each sample. After gentle vortexing and centrifugation, load the samples into a thermocycler and start the reverse transcription program.For polymerase chain reaction preamplification, or PCR, add 15 microliters of PCR mix to each sample containing the first strand reactions, followed by gentle vortexing and centrifugation. Then load the samples into the thermocycler and start the PCR program. For PCR purification, add 25 microliters of resuspended DNA purification beads to each sample, and mix well by vortexing.Then quickly spin the samples at room temperature to collect the liquid while avoiding settlement of the beads. After five minutes at room temperature, place the samples on an appropriate magnetic stand, carefully removing and discarding the supernatant when the solution is clear. Wash the beads with two 30 second washes in 200 microliters of freshly prepared 80%ethanol per wash.And discard the remaining ethanol after the second wash. When the beads have air dried, add 11 microliters of nuclease-free water to elute the DNA target from the beads, followed by vortexing. Then quickly centrifuge the samples, return the samples to the magnetic stand until the solution is clear and transfer 10 microliters of each sample to a new PCR tube.Successfully amplified cDNA should have a full length above 500 base pairs, and be enriched from 1.5 to two kilo base pairs. Moreover, there is usually a 500 to 600 base pair enrichment of cDNA observed in insulin one RFP plus cells, which may represent the insulin transcripts. However, the cDNA fragments near 100 base pairs are primer dimers, which are usually caused by excessive primers and which must be removed by repeating the DNA purification step.The cDNA fragments between 100 and 500 base pairs usually represent degraded cDNA, which is caused by bad cell status or region problems, such as RNase contamination and should be excluded. After the purification of the cDNA libraries for sequencing, cDNA ranging from 250 to 450 base pairs can be obtained through the addition of DNA purification beads to the first and second rounds of purification. After DNA bead purification, the sequencing quality score should be greater than 30 during the sequencing quality evaluation.To obtain high quality cells for downstream analyses, cells with fewer than 0.5 million mapped reads or with fewer than 4, 000 detected genes are excluded, facilitating the characterization of different groups of cells and the identification of genes that are heterogeneously expressed in different groups after principal component analysis and hierarchical clustering. While attempting this procedure, it's important to remember to perfuse the pancreas quickly before the collagenase digestion to avoid islet over digestion and to maintain RNase free environment during the single cell procedures. Following this procedure, other methods like islet imaging and culture can be performed to facilitate visualization of the islet structure and to examine cellular responses and drug stimulation.After development, this technique paved the way for researchers in the field of pancreatic research to explore the mechanisms of islet lineage development and regeneration, as well as diabetes progression in mammals.

single-cell-transcriptomic-analyses-mouse-pancreatic-endocrine

Research

JoVE Journal

Developmental Biology

10.8K Views.  Peking University. Questo metodo può avere risposta a domande chiave nel campo dell'isolotto pancreatico sulla differenziazione del lignaggio dell'isolotto pancreatico, sulla maturazione e sulla rigenerazione. Il vantaggio principale di questa tecnica è che consente la raccolta di singole cellule isolotti pancreatiche per la generazione di dati di sequenziamento dell'RNA a singola cella di alta qualità. L'applicazione di questa tecnica si estende verso la terapia del diabete e delle altre malattie endocrine ...