Name: a high throughput, multiplexed and targeted proteomic csf assay to quantify neurodegenerative biomarkers and apolipoprotein e isoforms status
Uploaded: 2016-10-20T14:00:00
Description: Watch this Scientific Journal Video about A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status at JoVE.com

This work was funded and facilitated through the GOSomics research initiative by the National Institute for Health Research, Biomedical Research Centre at Great Ormond Street Hospital and the UCL Biological Mass Spectrometry Centre at the UCL Institute of Child Health with kind donations from the Szeban Peto Foundation. The Dementia Research Centre is an Alzheimer's Research UK coordinating centre. The authors acknowledge the support of Alzheimer's Research UK, the NIHR Queen Square Dementia Biomedical Research Unit, UCL/H Biomedical Research Centre, and Leonard Wolfson Experimental Neurology Centre.

NOTE: A schematic of the overall protocol described here is given in Figure 1. All samples used for the development of this method are surplus clinical diagnostic samples and have ethical approval from the London Bloomsbury Ethics committee.
<img alt="Figure 1" src="/files/ftp_upload/54541/54541fig1.jpg" /> 
Figure 1. Schematic Illustrating the Overall Process of Creating a Targeted CSF MRM LC-MS/MS Assay....

<ol>
	<li>Prince, P. M., Guerchet, D. M., Prina, D. 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=.">.</a> Policy Brief: The Global Impact of Dementia 2013-2050. , (2013).</li><li>Hirtz, 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=Development+of+new+quantitative+mass+spectrometry+and+semi-automatic+isofocusing+methods+for+the+determination+of+Apolipoprotein+E+typing.">Development of new quantitative mass spectrometry and semi-automatic isofocusing methods for the determination of Apolipoprotein E typing.</a> Clin Chim Acta. 454, 33-38 (2015).</li><li>Marx, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Targeted+proteomics.">Targeted proteomics.</a> Nat Methods. 10 (1), 19-22 (2013).</li><li>Heywood, W., 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+development+of+a+peptide+SRM-based+tandem+mass+spectrometry+assay+for+prenatal+screening+of+Down+syndrome.">The development of a peptide SRM-based tandem mass spectrometry assay for prenatal screening of Down syndrome.</a> J Proteomics. 75 (11), 3248-3257 (2012).</li><li>Heywood, W. 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=Proteomic+Discovery+and+Development+of+a+Multiplexed+Targeted+MRM-LC-MS/MS+Assay+for+Urine+Biomarkers+of+Extracellular+Matrix+Disruption+in+Mucopolysaccharidoses+I,+II,+and+VI.">Proteomic Discovery and Development of a Multiplexed Targeted MRM-LC-MS/MS Assay for Urine Biomarkers of Extracellular Matrix Disruption in Mucopolysaccharidoses I, II, and VI.</a> Anal Chem. , (2015).</li><li>Manwaring, V., 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+identification+of+new+biomarkers+for+identifying+and+monitoring+kidney+disease+and+their+translation+into+a+rapid+mass+spectrometry-based+test:+evidence+of+presymptomatic+kidney+disease+in+pediatric+Fabry+and+type-I+diabetic+patients.">The identification of new biomarkers for identifying and monitoring kidney disease and their translation into a rapid mass spectrometry-based test: evidence of presymptomatic kidney disease in pediatric Fabry and type-I diabetic patients.</a> J Proteome Res. 12 (5), 2013-2021 (2013).</li><li>Moat, S. 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=Newborn+blood+spot+screening+for+sickle+cell+disease+by+using+tandem+mass+spectrometry:+implementation+of+a+protocol+to+identify+only+the+disease+states+of+sickle+cell+disease.">Newborn blood spot screening for sickle cell disease by using tandem mass spectrometry: implementation of a protocol to identify only the disease states of sickle cell disease.</a> Clin Chem. 60 (2), 373-380 (2014).</li><li>Heywood, W. 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+novel+CSF+biomarkers+for+neurodegeneration+and+their+validation+by+a+high-throughput+multiplexed+targeted+proteomic+assay.">Identification of novel CSF biomarkers for neurodegeneration and their validation by a high-throughput multiplexed targeted proteomic assay.</a> Mol Neurodegener. 10, 64 (2015).</li><li>MacLean, 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=Skyline:+an+open+source+document+editor+for+creating+and+analyzing+targeted+proteomics+experiments.">Skyline: an open source document editor for creating and analyzing targeted proteomics experiments.</a> Bioinformatics. 26 (7), 966-968 (2010).</li><li>Manes, N. P., Mann, J. M., Nita-Lazar, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selected+Reaction+Monitoring+Mass+Spectrometry+for+Absolute+Protein+Quantification.">Selected Reaction Monitoring Mass Spectrometry for Absolute Protein Quantification.</a> J Vis Exp. (102), e52959 (2015).</li><li>Craig-Schapiro, 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=YKL-40:+a+novel+prognostic+fluid+biomarker+for+preclinical+Alzheimer's+disease.">YKL-40: a novel prognostic fluid biomarker for preclinical Alzheimer's disease.</a> Biol Psychiatry. 68 (10), 903-912 (2010).</li><li>Perrin, R. 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=Identification+and+validation+of+novel+cerebrospinal+fluid+biomarkers+for+staging+early+Alzheimer's+disease.">Identification and validation of novel cerebrospinal fluid biomarkers for staging early Alzheimer's disease.</a> PLoS One. 6 (1), e16032 (2011).</li><li>Liguori, 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=Orexinergic+system+dysregulation,+sleep+impairment,+and+cognitive+decline+in+Alzheimer+disease.">Orexinergic system dysregulation, sleep impairment, and cognitive decline in Alzheimer disease.</a> JAMA Neurol. 71 (12), 1498-1505 (2014).</li></ol>

As with all MS based assays, the critical steps in the method are the determination of the appropriate and accurate amounts of internal standards. If absolute quantitation is being used, then the correct amounts of spiked peptides in the standard curve are also critical.
Our assay does not require the precipitation of the CSF or the use of any type of clean up or desalting steps prior to MS analysis -&#160;it is an entirely one-pot reaction method. Due to the small volume of CSF and its limite...

The growing impact of neurodegenerative diseases such as Alzheimer&#39;s Disease, Lewy Body Dementia and Parkinson&#39;s Disease, is becoming a socioeconomic issue in many countries1. There is a need in additional&#160;biomarkers that can be used to identify and classify patients in the early stages of the disease,&#160;and to monitor any potential new treatments. The overall goal of this method is to create a generic pipeline for a streamlined, economic and faster way of validating potential CSF markers of neurodegeneration. The rationale is to use targeted proteomics or peptide MRM LC-MS/MS as an easily amendable method to assess multiple potential protein biomarkers from&#160;discovery experiments. These can be further multiplexed over a rapid chromatographic separation (&#60;10 min) and assessed. Within this multiplex screen for neurodegenerative biomarkers, we have included the known dementia risk factor apolipoprotein isoform E4 (ApoE4) so we can determine simultaneously its status and level of expression, by that eliminating the need for separate genotyping tests2. LC MS/MS is routinely used as the method of choice for accurately quantitating small molecules over other methods such as ELISA or radioimmunoassay (RIA). This shift in the use of MS technology to analyzing proteins, has been driven mainly by issues with the immuno-based technologies. These include cross-specificity, batch to batch variation, limited shelf life, and high cost. Therefore, targeted proteomics is rapidly becoming a growing alternative to antibody based methods such as Western blotting, RIA and ELISA. However, the ability to multiplex many markers into one assay is the major advantage of this technique over immuno-based methods3. The technique is applicable to many tissues and has been used as a validation strategy for many proteomics studies including plasma4 and urine5,6.
The technique can be applied to any laboratory that has access and expertise in using triple quadrupole mass spectrometers. Peptide design is relatively simple with the growing use of open source databases. The competitive market of&#160;custom peptides synthesis&#160;makes them much more affordable. Heavy peptides, however, are expensive and therefore the markers should&#160;be assessed on a small cohort&#160;before moving to a larger scale. There is growing potential for the technique to be used in the clinical diagnostic settings, with most large hospitals having triple quadrupole based platforms&#160;which can easily be adapted to run targeted proteomic assays. One such application of the method, making it into the routine diagnostic setting, is its recent application to newborn blood spot screening for sickle cell anemia7.

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			<td height="21" style="height:21px;width:352px;">Acetonitrile (ACN), LC-MS grade&#160;</td>
			<td style="width:71px;">Fisher</td>
			<td style="width:119px;">A955-1</td>
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			<td height="21" style="height:21px;">Formic acid, LC-MS grade,</td>
			<td>Fisher</td>
			<td>A117-50</td>
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		<tr height="21">
			<td height="21" style="height:21px;">Dithiothreitol (DTT)</td>
			<td>Sigma&#160;</td>
			<td style="width:119px;">D5545-5G</td>
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			<td height="21" style="height:21px;">Hydrochloric acid, 37% w/w</td>
			<td>VWR&#160;</td>
			<td style="width:119px;">BDH3028-2.5LG</td>
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			<td height="21" style="height:21px;">Iodoacetamide&#160;&#160;</td>
			<td style="width:71px;">Sigma&#160;</td>
			<td style="width:119px;">I1149-5G</td>
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			<td height="21" style="height:21px;">Sodium hydroxide (NaOH)</td>
			<td>Fisher</td>
			<td>S318-500</td>
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			<td height="21" style="height:21px;">Trypsin, sequencing grade, modified</td>
			<td>Promega</td>
			<td>V5113</td>
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			<td height="21" style="height:21px;">Trifluoroacetic acid (TFA), LC-MS grade</td>
			<td>Fisher</td>
			<td>A116-50</td>
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			<td height="21" style="height:21px;">Urea</td>
			<td>Sigma</td>
			<td>U0631-500g</td>
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			<td height="21" style="height:21px;">Water, LC-MS ULTRA Chromasolv</td>
			<td>Fluka</td>
			<td>14263</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Custom synthesised peptides desalted 1-4mg</td>
			<td style="width:71px;">Genscript</td>
			<td style="width:119px;">custom</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">heavy labelled amino acid [C13 N15] custom peptides</td>
			<td style="width:71px;">Genscript</td>
			<td style="width:119px;">custom</td>
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		<tr height="42">
			<td height="42" style="height:42px;width:352px;">ASB 14</td>
			<td style="width:71px;">Merck Millipore</td>
			<td style="width:119px;">182750-25gm</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Thiourea</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">T7875-500G</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Tris base</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">T6066</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:352px;">VanGuard precolumn</td>
			<td style="width:71px;">Waters</td>
			<td style="width:119px;">186007125</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Cortecs UPLC C18+ 1.6um&#160; 2.1 x50mm column</td>
			<td style="width:71px;">Waters</td>
			<td style="width:119px;">186007114</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Yeast Enolase&#160;</td>
			<td style="width:71px;">Sigma</td>
			<td style="width:119px;">E6126</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">300ul clear screw top glass vials&#160;&#160;</td>
			<td style="width:71px;">Fisher scientific</td>
			<td style="width:119px;">03-FISV</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">Y slit screw caps&#160;</td>
			<td style="width:71px;">Fisher scientific</td>
			<td style="width:119px;">9SCK-(B)-ST1X</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">Freeze dryer</td>
			<td style="width:71px;">Edwards Mudulyo&#160;</td>
			<td style="width:119px;">Mudulyo system</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:352px;">Concentrator/Speed vaccum</td>
			<td style="width:71px;">Eppendof&#160;</td>
			<td style="width:119px;">concentrator&#160; plus 5301</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Xevo -TQ-S mass spectrometer</td>
			<td style="width:71px;">Waters</td>
			<td style="width:119px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:352px;">Acquity UPLC system</td>
			<td style="width:71px;">Waters</td>
			<td style="width:119px;"></td>
		</tr>
	</tbody>
</table>

a high throughput, multiplexed and targeted proteomic csf assay to quantify neurodegenerative biomarkers and apolipoprotein e isoforms status

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be important in the development of future novel therapies. Often&#160;potential new biomarkers do not make it&#160;into the clinic&#160;due to limitations&#160;in their development and&#160;high costs.&#160;However,&#160;targeted proteomics using Multiple Reaction Monitoring Liquid Chromatography-tandem/Mass Spectrometry (MRM LC-MS/MS), specifically using triple quadrupole mass spectrometers, is one method that can be used to rapidly evaluate and validate biomarkers&#160;for clinical translation into diagnostic laboratories. Traditionally, this platform has been used extensively for measurement of small molecules&#160;in clinical laboratories, but it is the potential to analyze proteins, that makes it an attractive alternative to ELISA (Enzyme-Linked Immunosorbent Assay)-based methods. We describe here how targeted proteomics can be used to measure multiplexed markers of dementia, including the detection and quantitation of the known risk factor apolipoprotein E isoform 4 (ApoE4).
In order to make the assay suitable for translation, it is designed to be rapid, simple, highly specific and cost effective. To achieve this, every step in the development of the assay must be optimized for the individual proteins and tissues they are analyzed in. This method describes a typical workflow including various tips and tricks to developing a targeted proteomics MRM LC-MS/MS for translation.
The method development is optimized using custom synthesized versions of tryptic quantotypic peptides, which calibrate&#160;the MS for detection and then spiked into CSF to determine correct identification of the endogenous peptide in the chromatographic separation prior to analysis in the MS. To achieve absolute quantitation, stable isotope-labeled internal standard versions of the peptides with short amino acid sequence tags and containing a trypsin cleavage site, are included in the assay.

Using the method described above, a high throughput 10 min multiplex assay consisting of 74 peptides from 54 proteins was developed, as an assay for markers of the neurodegenerative disorders Alzheimer&#39;s Disease and Lewy Body Dementia (LBD)8. Figure 3 shows a multiplex chromatogram published previously8 of the significant peptide markers from the assay. The peptides included in the assay and their quantitative transitions are given in Tab...

Watch this Scientific Journal Video about A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status at JoVE.com

A High Throughput, Multiplexed and Targeted Proteomic CSF Assay to Quantify Neurodegenerative Biomarkers and Apolipoprotein E Isoforms Status

We describe a high-throughput, multiplex, and targeted proteomic cerebrospinal fluid (CSF) assay developed with potential for clinical translation. The test can quantitate potential markers and risk factors for neurodegeneration, such as the apolipoprotein E variants (E2, E3 and E4), and measure their allelic expression.

Many neurodegenerative diseases are&#160;still lacking effective treatments. Reliable biomarkers for identifying and classifying these diseases will be ...

The overall goal of this method is to quickly and affordably quantitate multiple biomarkers in cerebrospinal fluid, or CSF, to assess their use towards diagnosis and treatment monitoring. This is a new assay that allows us to measure biomarkers that were not possible to measure before. And we think this can be used for diagnostic purposes and also to differentiate between different neurodegenerative diseases and potentially also give prognostic information.The main advantage of this technique is that it's designed to be rapid, simple in sample preparation, highly specific, and cost effective for translation into the clinical lab. The implications of this technique extend toward therapy or diagnosis, as this high-throughput test can be used in future clinical trials for novel therapies in neurodegeneration. This methodology can also be applied to other diseases and tissues, such as urine for kidney disorders, plasma for cardiomyopathy, and cells for pluripotency.To begin this procedure, resuspend the desired synthetic peptides to a one-milligram-per-milliliter stock concentration, according to the manufacturer's instructions. Prepare one-in-10 dilutions of the peptide from the stock concentration, and pool 1, 000 picomoles of each peptide into a low-binding microcentrifuge tube. Dry the pooled peptide sample in a SpeedVac concentrator.When finished, store the sample at minus 20 degrees Celsius. Next, aliquot 100 microliters of CSF into low-binding microcentrifuge tubes. Freeze-dry the CSF samples.Resuspend an aliquot of the pooled peptide sample in digestion buffer to obtain concentrations of 10 and one picomole per microliter. Now, spike the pooled peptide sample into the freeze-dried 100-microliter aliquots of CSF, at zero, one, two, five, 10, and 15 picomolar concentrations. Then, add 20 nanograms of intact unrelated protein to act as an internal standard and control for the digestion efficiency of trypsin.Add digest buffer to the CSF aliquots to a final volume of 20 microliters, and vortex the samples. Following this, digest the samples per standard protocol by adding 1.5 microliters of dithiothreitol, and shaking at room temperature for one hour. Following this, add three microliters of iodoacetamide to the samples and shake at room temperature for 45 minutes in the dark.Then, add 165 microliters of double-distilled water. Add 10 microliters of a 0.1-microgram-per-microliter, sequencing-grade modified trypsin solution, resuspended in 50-millimolar ammonium bicarbonate buffer to the samples. Incubate the samples in a water bath at 37 degrees Celsius overnight.Then, stop the digestion by freezing the samples. After defrosting the CSF digests on ice, centrifuge at 16, 000 times g for 10 minutes. When finished, transfer 60 microliters of each digest into a 300-microliter glass insert vile.Using an LC-MS system, equipped with a C18 UPLC column, inject the highest concentration from the standard curve point using a 10-minute, one-to-40%acetonitrile linear gradient. Once the run is complete, open the resulting chromatogram in the software, and note the retention time and the top two most intense transitions per peptide. Based on this information, update a previously created multiple reaction monitoring, or MRM method with timed channels to measure peptides.To maintain sensitivity, keep each channel with points per peak greater than eight and dwell time greater than 0.01 seconds for at least one transition for each peptide. Include solvent delays in the MRM method by selecting solvent delays in method events in the MS method file. It is critical to correctly match the correct peak in a short HPLC method.This can be done using the spiked peptides in the matrix that are used for a standard curve and observing the multiple transitions during the method development. Finally, manually review the data annotation to ensure accuracy. Analyze each peptide and ratio to an appropriate stable isotope-labeled internal standard.A chromatogram of the significant peptide markers from the high-throughput CSF assay is shown here. The data gives standardized ratios to the relevant stable isotope-labeled internal standard, which can be used to determine absolute CSF concentrations and statistically analyzed for changes in clinical samples. Quantitation of the 74 peptides included in this CSF assay revealed that 25 were altered significantly in the CSF of dementia patients, and results from dementia markers pro-orexin and YKL chitinase-3-like protein are displayed here.ApoE4 is a known risk factor for Alzheimer's disease, and the detection of ApoE isoforms is based on the detection of the corresponding peptides for the amino acid changes for isoforms E2 and E4.The peak pattern expected for each isoform combination is shown here. Once the method is set up, the assay can be done in a day if it is performed properly. After the development of this method, it was possible to measure a new set of biomarkers with high analytical sensitivity and specificity, and this will make it possible for researchers to assess neurodegenerative diseases in a new manner.After watching this video, you should have a good understanding of how to design and optimize an MRM assay for sensitivity and specificity. Don't forget that working with DTE, termite, formic acid, and human tissue can be extremely dangerous and precautions, such as wearing gloves, should be applied during this procedure.

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Research

JoVE Journal

Medicine

Mouse Eye Enucleation for Remote High-throughput Phenotyping

The mouse eye is an important genetic model for the translational study of human ophthalmic disease. Blinding diseases in humans, such as macular degeneration, photoreceptor degeneration, cataract, glaucoma, retinoblastoma, and diabetic retinopathy have been recapitulated in transgenic mice.1-5 Most transgenic and knockout mice have been generated by laboratories to study non-ophthalmic diseases, but genetic conservation between organ systems suggests that many of the same genes may also play a role in ocular development and disease. Hence, these mice represent an important resource for discovering new genotype-phenotype correlations in the eye. Because these mice are scattered across the globe, it is difficult to acquire, maintain, and phenotype them in an efficient, cost-effective manner. Thus, most high-throughput ophthalmic phenotyping screens are restricted to a few locations that require on-site, ophthalmic expertise to examine eyes in live mice. 6-9 An alternative approach developed by our laboratory is a method for remote tissue-acquisition that can be used in large or small-scale surveys of transgenic mouse eyes. Standardized procedures for video-based surgical skill transfer, tissue fixation, and shipping allow any lab to collect whole eyes from mutant animals and send them for molecular and morphological phenotyping. In this video article, we present techniques to enucleate and transfer both unfixed and perfusion fixed mouse eyes for remote phenotyping analyses.

The dissection technique illustrates enucleation of the mouse eye for tissue fixation to perform phenotyping in high-throughput screens.

The mouse eye is an important genetic model for the translational study of human ophthalmic disease. Blinding diseases in humans, such as macular ...

Biomarkers in an Animal Model for Revealing Neural, Hematologic, and Behavioral Correlates of PTSD

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for objective diagnosis but also for the evaluation of therapeutic efficacy and resilience to trauma. Ongoing research is directed at identifying molecular biomarkers for PTSD, including traumatic stress induced proteins, transcriptomes, genomic variances and genetic modulators, using biologic samples from subjects' blood, saliva, urine, and postmortem brain tissues. However, the correlation of these biomarker molecules in peripheral or postmortem samples to altered brain functions associated with psychiatric symptoms in PTSD remains unresolved. Here, we present an animal model of PTSD in which both peripheral blood and central brain biomarkers, as well as behavioral phenotype, can be collected and measured, thus providing the needed correlation of the central biomarkers of PTSD, which are mechanistic and pathognomonic but cannot be collected from people, with the peripheral biomarkers and behavioral phenotypes, which can.
Our animal model of PTSD employs restraint and tail shocks repeated for three continuous days - the inescapable tail-shock model (ITS) in rats. This ITS model mimics the pathophysiology of PTSD 17, 7, 4, 10. We and others have verified that the ITS model induces behavioral and neurobiological alterations similar to those found in PTSD subjects 17, 7, 10, 9. Specifically, these stressed rats exhibit (1) a delayed and exaggerated startle response appearing several days after stressor cessation, which given the compressed time scale of the rat's life compared to a humans, corresponds to the one to three months delay of symptoms in PTSD patients (DSM-IV-TR PTSD Criterian D/E 13), (2) enhanced plasma corticosterone (CORT) for several days, indicating compromise of the hypothalamopituitary axis (HPA), and (3) retarded body weight gain after stressor cessation, indicating dysfunction of metabolic regulation.
The experimental paradigms employed for this model are: (1) a learned helplessness paradigm in the rat assayed by measurement of acoustic startle response (ASR) and a charting of body mass; (2) microdissection of the rat brain into regions and nuclei; (3) enzyme-linked immunosorbent assay (ELISA) for blood levels of CORT; (4) a gene expression microarray plus related bioinformatics tools 18. This microarray, dubbed rMNChip, focuses on mitochondrial and mitochondria-related nuclear genes in the rat so as to specifically address the neuronal bioenergetics hypothesized to be involved in PTSD.

We describe a rat model of post traumatic stress disorder (PTSD) that reveals the persistent alterations in neuroendocrine function and the delayed long-term, exaggerated fear response, characteristic of PTSD patients. The animal model and methods described here are useful for correlating biomarkers in brain nuclei, which are mechanistic but cannot be measured in patients, with biomarkers in peripheral white blood cells, which can.

Identification of biomarkers representing the evolution of the pathophysiology of Post Traumatic Stress Disorder (PTSD) is vitally important, not only for ...

High Content Screening in Neurodegenerative Diseases

The functional annotation of genomes, construction of molecular networks and novel drug target identification, are important challenges that need to be addressed as a matter of great urgency1-4. Multiple complementary 'omics' approaches have provided clues as to the genetic risk factors and pathogenic mechanisms underlying numerous neurodegenerative diseases, but most findings still require functional validation5. For example, a recent genome wide association study for Parkinson's Disease (PD), identified many new loci as risk factors for the disease, but the underlying causative variant(s) or pathogenic mechanism is not known6, 7. As each associated region can contain several genes, the functional evaluation of each of the genes on phenotypes associated with the disease, using traditional cell biology techniques would take too long. 
	There is also a need to understand the molecular networks that link genetic mutations to the phenotypes they cause. It is expected that disease phenotypes are the result of multiple interactions that have been disrupted. Reconstruction of these networks using traditional molecular methods would be time consuming. Moreover, network predictions from independent studies of individual components, the reductionism approach, will probably underestimate the network complexity8. This underestimation could, in part, explain the low success rate of drug approval due to undesirable or toxic side effects. Gaining a network perspective of disease related pathways using HT/HC cellular screening approaches, and identifying key nodes within these pathways, could lead to the identification of targets that are more suited for therapeutic intervention.
	High-throughput screening (HTS) is an ideal methodology to address these issues9-12. but traditional methods were one dimensional whole-well cell assays, that used simplistic readouts for complex biological processes. They were unable to simultaneously quantify the many phenotypes observed in neurodegenerative diseases such as axonal transport deficits or alterations in morphology properties13, 14. This approach could not be used to investigate the dynamic nature of cellular processes or pathogenic events that occur in a subset of cells. To quantify such features one has to move to multi-dimensional phenotypes termed high-content screening (HCS)4, 15-17. HCS is the cell-based quantification of several processes simultaneously, which provides a more detailed representation of the cellular response to various perturbations compared to HTS. 
	HCS has many advantages over HTS18, 19, but conducting a high-throughput (HT)-high-content (HC) screen in neuronal models is problematic due to high cost, environmental variation and human error. In order to detect cellular responses on a 'phenomics' scale using HC imaging one has to reduce variation and error, while increasing sensitivity and reproducibility. 
	Herein we describe a method to accurately and reliably conduct shRNA screens using automated cell culturing20 and HC imaging in neuronal cellular models. We describe how we have used this methodology to identify modulators for one particular protein, DJ1, which when mutated causes autosomal recessive parkinsonism21. 
	Combining the versatility of HC imaging with HT methods, it is possible to accurately quantify a plethora of phenotypes. This could subsequently be utilized to advance our understanding of the genome, the pathways involved in disease pathogenesis as well as identify potential therapeutic targets.

We describe a methodology combining automated cell culturing with high-content imaging to visualize and quantify multiple cellular processes and structures, in a high-throughput manner. Such methods can aid in the further functional annotation of genomes as well as identify disease gene networks and potential drug targets.

The functional annotation of genomes, construction of molecular networks and novel drug target identification, are important challenges that need to be ...

High Throughput Sequential ELISA for Validation of Biomarkers of Acute Graft-Versus-Host Disease

Unbiased discovery proteomics strategies have the potential to identify large numbers of novel biomarkers that can improve diagnostic and prognostic testing in a clinical setting and may help guide therapeutic interventions. When large numbers of candidate proteins are identified, it may be difficult to validate candidate biomarkers in a timely and efficient fashion from patient plasma samples that are event-driven, of finite volume and irreplaceable, such as at the onset of acute graft-versus-host disease (GVHD), a potentially life-threatening complication of allogeneic hematopoietic stem cell transplantation (HSCT).
Here we describe the process of performing commercially available ELISAs for six validated GVHD proteins: IL-2R&alpha;5, TNFR16, HGF7, IL-88, elafin2, and REG3&alpha;3 (also known as PAP1) in a sequential fashion to minimize freeze-thaw cycles, thawed plasma time and plasma usage. For this procedure we perform the ELISAs in sequential order as determined by sample dilution factor as established in our laboratory using manufacturer ELISA kits and protocols with minor adjustments to facilitate optimal sequential ELISA performance. The resulting plasma biomarker concentrations can then be compiled and analyzed for significant findings within a patient cohort. While these biomarkers are currently for research purposes only, their incorporation into clinical care is currently being investigated in clinical trials.
This technique can be applied to perform ELISAs for multiple proteins/cytokines of interest on the same sample(s) provided the samples do not need to be mixed with other reagents. If ELISA kits do not come with pre-coated plates, 96-well half-well plates or 384-well plates can be used to further minimize use of samples/reagents.

High throughput validation of multiple candidate biomarkers can be performed by sequential ELISA in order to minimize freeze/thaw cycles and use of precious plasma samples. Here, we demonstrate how to sequentially perform ELISAs for six different validated plasma biomarkers1-3 of graft-versus-host disease (GVHD)4 on the same plasma sample.

Unbiased discovery proteomics strategies have  the potential to identify large numbers of novel biomarkers that can improve  diagnostic and prognostic ...

A Sensitive Method to Quantify Senescent Cancer Cells

Human cells do not indefinitely proliferate. Upon external and/or intrinsic cues, cells might die or enter a stable cell cycle arrest called senescence. Several cellular mechanisms, such as telomere shortening and abnormal expression of mitogenic oncogenes, have been shown to cause senescence. Senescence is not restricted to normal cells; cancer cells have also been reported to senesce.
	Chemotherapeutical drugs have been shown to induce senescence in cancer cells. However, it remains controversial whether senescence prevents or promotes tumorigenesis. As it might eventually be patient-specific, a rapid and sensitive method to assess senescence in cancer cell will soon be required.
	To this end, the standard &beta;-galactosidase assay, the currently used method, presents major drawbacks: it is time consuming and not sensitive. We propose here a flow cytometry-based assay to study senescence on live cells. This assay offers the advantage of being rapid, sensitive, and can be coupled to the immunolabeling of various cellular markers.

Whether senescence prevents or promotes tumorigenesis remains controversial. Since chemotherapeutical drugs can induce cancer cells to senesce, studying senescence is essential for proposing new therapies. However, the standard and broadly used &beta;-galactosidase assay presents major drawbacks. We propose here a rapid and sensitive flow cytometry-based assay to quantify senescence.

Human cells do not indefinitely proliferate. Upon external and/or intrinsic  cues, cells might die or enter a stable cell cycle arrest called senescence. ...

High-throughput Flow Cytometry Cell-based Assay to Detect Antibodies to N-Methyl-D-aspartate Receptor or Dopamine-2 Receptor in Human Serum

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases in children and adults. These antibodies have been used to guide diagnosis and treatment. Cell-based assays have improved the detection of antibodies in patient serum. They are based on the surface expression of brain antigens on eukaryotic cells, which are then incubated with diluted patient sera followed by fluorochrome-conjugated secondary antibodies. After washing, secondary antibody binding is then analyzed by flow cytometry. Our group has developed a high-throughput flow cytometry live cell-based assay to reliably detect antibodies against specific neurotransmitter receptors. This flow cytometry method is straight forward, quantitative, efficient, and the use of a high-throughput sampler system allows for large patient cohorts to be easily assayed in a short space of time. Additionally, this cell-based assay can be easily adapted to detect antibodies to many different antigenic targets, both from the central nervous system and periphery. Discovering additional novel antibody biomarkers will enable prompt and accurate diagnosis and improve treatment of immune-mediated disorders.

Over the recent years, live cell-based assays have been used successfully to detect antibodies against surface and conformational antigens. Here, we describe a method using high-throughput flow cytometry enabling the analysis of large cohorts of patients. Detection of novel antibodies will improve diagnosis and treatment of immune-mediated disorders.

Over the recent years, antibodies against surface and conformational proteins involved in neurotransmission have been detected in autoimmune CNS diseases ...

High Throughput Characterization of Adult Stem Cells Engineered for Delivery of Therapeutic Factors for Neuroprotective Strategies

Mesenchymal stem cells (MSCs) derived from bone marrow are a powerful cellular resource and have been used in numerous studies as potential candidates to develop strategies for treating a variety of diseases. The purpose of this study was to develop and characterize MSCs as cellular vehicles engineered for delivery of therapeutic factors as part of a neuroprotective strategy for rescuing the damaged or diseased nervous system. In this study we used mouse MSCs that were genetically modified using lentiviral vectors, which encoded brain-derived neurotrophic factor (BDNF) or glial cell-derived neurotrophic factor (GDNF), together with green fluorescent protein (GFP). 
Before proceeding with in vivo transplant studies it was important to characterize the engineered cells to determine whether or not the genetic modification altered aspects of normal cell behavior. Different culture substrates were examined for their ability to support cell adhesion, proliferation, survival, and cell migration of the four subpopulations of engineered MSCs. High content screening (HCS) was conducted and image analysis performed. 
Substrates examined included: poly-L-lysine, fibronectin, collagen type I, laminin, entactin-collagen IV-laminin (ECL). Ki67 immunolabeling was used to investigate cell proliferation and Propidium Iodide staining was used to investigate cell viability. Time-lapse imaging was conducted using a transmitted light/environmental chamber system on the high content screening system.
Our results demonstrated that the different subpopulations of the genetically modified MSCs displayed similar behaviors that were in general comparable to that of the original, non-modified MSCs. The influence of different culture substrates on cell growth and cell migration was not dramatically different between groups comparing the different MSC subtypes, as well as culture substrates. 
This study provides an experimental strategy to rapidly characterize engineered stem cells and their behaviors before their application in long-term in vivo transplant studies for nervous system rescue and repair.

This study describes an experimental platform to rapidly characterize engineered stem cells and their behaviors before their application in long-term in vivo transplant studies for nervous system rescue and repair.

Mesenchymal stem cells (MSCs) derived from bone marrow are a powerful cellular resource and have been used in numerous studies as potential candidates to ...

An Optimized Hemagglutination Inhibition (HI) Assay to Quantify Influenza-specific Antibody Titers

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody production pre- and post-vaccination is required to understand vaccine-induced immunity. This article describes a reliable point-by-point protocol to determine influenza-specific antibody titers. The first protocol describes a method to specify the antigen amounts required for hemagglutination, which standardizes the concentrations for subsequent usage in the second protocol (hemagglutination assay, HA assay). The second protocol describes the quantification of influenza-specific antibody titers against different viral strains by using a serial dilution of human serum or cell culture supernatants (hemagglutination inhibition assay, HI assay).
As an applied example, we show the antibody response of a healthy cohort, which received a trivalent inactivated influenza vaccine. Additionally, the cross-reactivity between the different influenza viruses is shown and methods to minimize cross-reactivity by using different types of animal red blood cells (RBCs) are explained. The discussion highlights advantages and disadvantages of the presented assays and how the determination of influenza-specific antibody titers can improve the understanding of vaccine-related immunity.

An Optimized Hemagglutination Inhibition HI Assay to Quantify Influenza-specific Antibody Titers

The presented protocols describe how to perform a hemagglutination inhibition assay to quantify influenza-specific antibody titers from serum samples of influenza vaccine recipients. The first assay determines optimal viral antigen concentrations by hemagglutination. The second assay quantifies influenza-specific antibody titers by hemagglutination inhibition.

Antibody titers are commonly used as surrogate markers for serological protection against influenza and other pathogens. Detailed knowledge of antibody ...

Induction of Atherosclerotic Plaques Through Activation of Mineralocorticoid Receptors in Apolipoprotein E-deficient Mice

Atherosclerosis is due to a chronic inflammatory response affecting vascular endothelium and is promoted by several factors such as hypertension, dyslipidemia, and diabetes. To date, there is evidence to support a role for circulating aldosterone as a risk factor for the development of cardiovascular disease. Transgenic mouse models have been generated to study cellular and molecular processes leading to atherosclerosis. In this manuscript, we describe a protocol that takes advantage of continuous infusion of aldosterone in ApoE-/- mice and generates atherosclerotic plaques in the aortic root after 4 weeks of treatment. We, therefore, illustrate a method for quantification and characterization of atherosclerotic lesions at the aortic root level. The added value of aldosterone infusion is represented by the generation of atherosclerotic lesions rich in lipid and inflammatory cells after 4 weeks of treatment. We describe in detail the staining procedures to quantify lipid and macrophage content within the plaque. Notably, in this protocol, we perform heart tissue-embedding in OCT in order to preserve the antigenicity of cardiac tissue and facilitate detectability of antigens of interest. Analysis of the plaque phenotype represents a valid approach to study the pathophysiology of atherosclerosis development and to identify novel pharmacological targets for the development of anti-atherogenic drugs.

We describe a protocol to induce atherosclerosis in the aortic root of ApoE-/- mice fed with an atherogenic diet, through a continuous release of aldosterone. Methods to characterize plaque composition are also described.

Atherosclerosis is due to a chronic inflammatory response affecting vascular endothelium and is promoted by several factors such as hypertension, ...

High-throughput Nitrobenzoxadiazole-labeled Cholesterol Efflux Assay

Atherosclerosis leads to cardiovascular disease (CVD). It is still unclear whether cholesterol-HDL (cHDL) concentration plays a causal role in atherosclerosis development. However, an important factor in early stages of atheroma plaque formation is cholesterol efflux capacity to HDL (the ability of HDL particles to accept cholesterol from macrophages) in order to avoid foam cell formation. This is a key step in avoiding the accumulation of cholesterol in the endothelium and a part of reverse cholesterol transport (RCT) to eliminate cholesterol through the liver. Cholesterol efflux capacity to serum or plasma in macrophage cell models is a promising tool that can be used as biomarker for atherosclerosis. Traditionally, [3H]-cholesterol has been used in cholesterol efflux assays. In this study, we aim to develop a safer and faster strategy using fluorescent labelled-cholesterol (NBD-cholesterol) in a cellular assay to trace the cholesterol uptake and efflux process in THP-1-derived macrophages. Finally, we optimize and standardize the NBD-cholesterol efflux method and develop a high-throughput analysis using 96-well plates.

Measurement of in vitro cholesterol efflux capacity to serum or plasma in macrophage cell models is a promising tool as a biomarker for atherosclerosis. In the present study, we optimize and standardize a fluorescent NBD-cholesterol efflux method and develop a high-throughput analysis using 96-well plates.