This work was supported by the Tau Consortium (M.I.D); National Institutes of Health Grant 1R01NS071835 (M.I.D.), a Department of Defense Grant PT110816 (to M.I.D.), 1F32NS087805 (to J.L.F.), and 1F31NS079039 (to B.B.H.).

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This assay has been licensed to Janssen Pharmaceuticals.

La cytométrie en flux système de FRET décrit ici est un outil puissant pour évaluer rapidement et quantitativement l&#39;activité de la protéine tau ensemencement. Elle exige seulement une expérience de culture cellulaire modérée et une connaissance pratique de FRET et cytométrie de flux. D&#39;autres essais de semis, comme Thioflavine T - qui présente une fluorescence améliorée lorsqu&#39;il est lié à la structure de feuillet bêta - sont laborieux et nécessitent un substrat de protéine pure, recombina...

L&#39;accumulation intracellulaire de la protéine tau amyloïdes tauopathies définit comme la maladie d&#39;Alzheimer. Dans les stades précoces de la maladie, la pathologie est généralement localisée à des régions discrètes du cerveau, mais avec la progression de la maladie, la pathologie se propage le long de invariablement réseaux neuronaux distincts 1-5. L&#39;accumulation de preuves suggère transcellulaire propagation d&#39;agrégats de protéines toxiques à la base de cette pathologie (revue dans 10/06). Dans ce modèle, les graines proteopathic (par exemple, tau) sont libérés de cellules du donneur et pénètrent dans les cellules voisines, la transformation de la protéine tau natif dans le formulaire mal repliées via templated changement conformationnel 11-15. L&#39;essai décrit ici a été développé pour détecter sensibilité telle activité d&#39;ensemencement. Il est compatible avec la protéine recombinante et des échantillons biologiques et permet la quantification des niveaux d&#39;activité minute d&#39;ensemencement proteopathic 16. Des cellules HEK 293T qui expriment de manière stable la protéine tau répétition dOMAINE (RD) contenant le P301S mutation associée à la maladie soit fusionnée à PCP ou YFP (ci-après dénommé cellules tau-RD-CFP / YFP) servir un biocapteur stable de l&#39;activité d&#39;ensemencement. En l&#39;absence de graines proteopathic, maintenir les cellules tau en tant que monomère soluble, pas de fond et ont FRET appréciable. L&#39;absorption spontanée ou transduction médiée par des liposomes de graines de tau dans les cellules, cependant, conduit à RD-CFP et YFP-agrégation RD, qui produit un signal de FRET qui est mesurée dans des cellules individuelles par cytométrie en flux. De nombreux composants de cet essai ont été conçus pour améliorer la sensibilité et de réduire la variabilité. Une lignée cellulaire monoclonal avec un 1: RD-CFP / YFP 1 ratio d&#39;expression a été choisi, car il fournit un signal optimal: le bruit. Pour augmenter la sensibilité, les phospholipides sont utilisés pour introduire les graines directement dans les cellules (bien que d&#39;étudier les mécanismes biologiques de l&#39;absorption, cela peut être omise). Enfin, la cytométrie de flux moniteurs FRET au niveau de la population et une seule cellule<html> niveau, contrairement à d&#39;autres essais d&#39;agrégation des protéines. Le critère d&#39;évaluation finale, la densité de FRET intégré, est hautement quantitative et représente à la fois pour le nombre de cellules présentant l&#39;agrégation, et la mesure dans laquelle l&#39;agrégation a eu lieu au sein de chaque cellule. Tous ces paramètres optimisés améliorer la sensibilité et de garantir la reproductibilité. Ce système a été récemment utilisé dans une étude approfondie dans les souris transgéniques tauopathie P301S 17 qui a évalué l&#39;apparition temporelle et la progression de l&#39;activité d&#39;ensemencement de tau par rapport à d&#39;autres marqueurs pathologiques de la protéine tau couramment utilisés (par exemple, MC1, AT8, PG5, et thioflavines). L&#39;activité de semis est de loin le marqueur précoce et le plus robuste de la pathologie tau évalué, précédant la détection histologique par au moins 6 semaines. Semis activité apparaît à 1,5 mois et augmente progressivement avec l&#39;âge, ce qui suggère un rôle causal de graines proteopathic dans l&#39;apparition et / ou la progression de la neurodégénérescence 16. e_content &quot;&gt; quantification précise des niveaux infimes de matériel de semence à partir d&#39;échantillons biologiques peut faciliter les études qui surveillent la progression de la maladie au stade précoce. En raccourcissant la durée du procès et permettant l&#39;utilisation d&#39;animaux plus jeunes, ce qui pourrait accroître l&#39;efficacité et la précision des essais précliniques animales. Par exemple, dans P301S la souris décrit ci-dessus, les composés du plomb peuvent être fournis aussi tôt que 4-6 semaines (juste avant, ou au début de l&#39;activité d&#39;ensemencement), et pour surveiller l&#39;efficacité 2-4 semaines plus tard. Le dosage devrait quantifier avec précision toute réduction des semis activité. FRET cytométrie en flux a in vitro applications de criblage ainsi. Par exemple, des réactifs anti-tau (par exemple, des anticorps, de petites molécules, etc.) peut être testé rapidement pour leur capacité à bloquer l&#39;ensemencement induction directement dans la culture, en utilisant soit la protéine tau recombinante agrégats ou lysats dérivé du cerveau comme une source de graines (figure 5). Avec cette configuration, une fois matériel de semence est préparé, un exexpé- prend seulement trois jours pour compléter, y compris l&#39;analyse de données. La quantification rapide de l&#39;activité d&#39;ensemencement proteopathic peut donc faciliter de nombreuses études de la neurodégénérescence.

<table>
	<tbody>
		<tr>
			<td>TBS</td>
			<td>Sigma</td>
			<td>T5912</td>
		</tr>
		<tr>
			<td>cOmplete Protease Inhibitors (EDTA-free)</td>
			<td>Roche</td>
			<td>4693159001</td>
		</tr>
		<tr>
			<td>Cryo-vials</td>
			<td>Sarstedt</td>
			<td>72.694.006</td>
		</tr>
		<tr>
			<td>Analytical Balance</td>
			<td>Mettler Toledo</td>
			<td>XSE 105DU</td>
		</tr>
		<tr>
			<td>Weighing Boats</td>
			<td>Fisher Scientific</td>
			<td>13-735-743</td>
		</tr>
		<tr>
			<td>15 mL conical tube</td>
			<td>USA Scientific</td>
			<td>1475-0501</td>
		</tr>
		<tr>
			<td>Omni Sonic Ruptor Ultrasonic Homogenizer</td>
			<td>Omni International</td>
			<td>18-000-115</td>
		</tr>
		<tr>
			<td>Micro-Tip for Ultrasonic Homogenizer</td>
			<td>Omni International</td>
			<td>OR-T-156</td>
		</tr>
		<tr>
			<td>2-Propanol</td>
			<td>Fisher Scientific</td>
			<td>A451</td>
		</tr>
		<tr>
			<td>Noise Cancelling Ear Muffs</td>
			<td>Fisher Scientific</td>
			<td>19-145-412</td>
		</tr>
		<tr>
			<td>Kimwipes</td>
			<td>Fisher Scientific</td>
			<td>S47299</td>
		</tr>
		<tr>
			<td>1.5 mL tubes</td>
			<td>USA Scientific</td>
			<td><a href="http://www.usascientific.com/Seal-Rite-1.5-ml-tube-sterile.aspx">1615-5510</a></td>
		</tr>
		<tr>
			<td>Microcentrifuge&#160;</td>
			<td>Eppendorf</td>
			<td>5424 000.215</td>
		</tr>
		<tr>
			<td>DPBS</td>
			<td>Life Technologies</td>
			<td>14190-136</td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Life Technologies</td>
			<td>11965-084</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>HyClone</td>
			<td>SH30071.03</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Life Technologies</td>
			<td>15140-122</td>
		</tr>
		<tr>
			<td>GlutaMax</td>
			<td>Life Technologies</td>
			<td>35050-061</td>
		</tr>
		<tr>
			<td>Trypsin-EDTA</td>
			<td>Life Technologies</td>
			<td>25300-054</td>
		</tr>
		<tr>
			<td>50 mL Conical Tubes</td>
			<td>Phenix Research</td>
			<td>SS-PH15</td>
		</tr>
		<tr>
			<td>25 mL reagent resevoirs</td>
			<td>VWR</td>
			<td>41428-954</td>
		</tr>
		<tr>
			<td>Multi channel pipet</td>
			<td>Fisher Scientific</td>
			<td>TI13-690-049</td>
		</tr>
		<tr>
			<td>96 well flat bottom plates</td>
			<td>Corning</td>
			<td>3603</td>
		</tr>
		<tr>
			<td>Opti-MEM</td>
			<td>Life Technologies</td>
			<td>31985-070</td>
		</tr>
		<tr>
			<td>Lipofectamine 2000</td>
			<td>Invitrogen</td>
			<td>11668019</td>
		</tr>
		<tr>
			<td>96 well round bottom plates</td>
			<td>Corning</td>
			<td>3788</td>
		</tr>
		<tr>
			<td>16% Paraformaldehyde</td>
			<td>Electron Microscopy Sciences</td>
			<td>RT 15710</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Sigma-Aldrich</td>
			<td>P5493</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Sigma-Aldrich</td>
			<td>ED2SS</td>
		</tr>
		<tr>
			<td>HBSS</td>
			<td>Life Technologies</td>
			<td>14185-052</td>
		</tr>
		<tr>
			<td>Sorvall ST 40 Centrifuge</td>
			<td>Thermo Scientific</td>
			<td>75004509</td>
		</tr>
		<tr>
			<td>BIOLiner Swinging Bucket Rotor</td>
			<td>Thermo Scientific</td>
			<td>75003796</td>
		</tr>
		<tr>
			<td>Hemacytometer</td>
			<td>VWR</td>
			<td>15170-172</td>
		</tr>
		<tr>
			<td>MACSQuant VYB Flow Cytomter</td>
			<td>Miltenyi Biotec</td>
			<td>130-096-116</td>
		</tr>
		<tr>
			<td>Chill 96 Rack</td>
			<td>Miltenyi Biotec</td>
			<td>130-094-459</td>
		</tr>
		<tr>
			<td>Flow Jo analysis software</td>
			<td>Flow Jo</td>
			<td></td>
		</tr>
		<tr>
			<td>20 uL pipet tips</td>
			<td>Rainin</td>
			<td>GPS-L10</td>
		</tr>
		<tr>
			<td>200 uL pipet tips</td>
			<td>Rainin</td>
			<td>GPS-250</td>
		</tr>
		<tr>
			<td>1 mL pipet tips</td>
			<td>Rainin</td>
			<td>GPS-1000</td>
		</tr>
		<tr>
			<td>200 uL pipet tips</td>
			<td>USA Scientific</td>
			<td>1111-1800</td>
		</tr>
		<tr>
			<td>5 mL serological pipett</td>
			<td>Phenix Research</td>
			<td>SPG-606180</td>
		</tr>
		<tr>
			<td>10 mL serological pipett</td>
			<td>Phenix Research</td>
			<td>SPG-607180</td>
		</tr>
		<tr>
			<td>25 mL Serological pipett</td>
			<td>Phenix Research</td>
			<td>SPG-760180</td>
		</tr>
	</tbody>
</table>

sensitive detection of proteopathic seeding activity with fret flow cytometry

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

FRET cytométrie en flux permet sensible, quantitative, et la détection rapide de l&#39;activité de l&#39;ensemencement à partir d&#39;échantillons recombinantes ou biologiques. Configuration de test est facile: lignées cellulaires stables monoclonaux dérivés exprimant la protéine tau-RD-CFP / YFP sont transduites avec du matériel de semences, incubées pendant 24-48 h, et ​​soumis à l&#39;analyse par cytométrie de flux (figure 1A). En l&#39;absence de semences, les cellules de biocapteur...

Watch this Scientific Journal Video about Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry at JoVE.com

Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry

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

Détection sensible de Proteopathic semis Activité FRET avec la cytométrie en flux

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

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JoVE Journal

Bioengineering

14.8K vues.  University of Texas Southwestern Medical Center. Cell-to-cell transfer of protein aggregates, or proteopathic seeds, may underlie the progression of pathology in neurodegenerative diseases. Here, a novel FRET flow cytometry assay is described that enables specific and sensitive detection of seeding activity from recombinant or biological samples.

Vidéo: Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry

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

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

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

Analyser l&#39;internalisation cellulaire de nanoparticules et de bactéries multi-spectrale par cytométrie de flux d&#39;imagerie

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

Recherche

Bio-ingénierie

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

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

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

Évaluation de livraison Gene polymère nanoparticules d&#39;analyse de suivi par des nanoparticules et de cytométrie en flux à haut débit

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

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

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

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

Champ large Microscopie fluorescente et cytométrie de flux fluorescente imagerie sur un téléphone portable

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

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

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

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

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

Flying Insect Detection and Classification with Inexpensive Sensors

An inexpensive, noninvasive system that could accurately classify flying insects would have important implications for entomological research, and allow for the development of many useful applications in vector and pest control for both medical and agricultural entomology. Given this, the last sixty years have seen many research efforts devoted to this task. To date, however, none of this research has had a lasting impact. In this work, we show that pseudo-acoustic optical sensors can produce superior data; that additional features, both intrinsic and extrinsic to the insect&#8217;s flight behavior, can be exploited to improve insect classification; that a Bayesian classification approach allows to efficiently learn classification models that are very robust to over-fitting, and a general classification framework allows to easily incorporate arbitrary number of features. We demonstrate the findings with large-scale experiments that dwarf all previous works combined, as measured by the number of insects and the number of species considered.

We proposed a system that uses inexpensive, noninvasive pseudo-acoustic optical sensors to automatically and accurately detect, count, and classify flying insects based on their flying sound.

Insectes volants Détection et classification des capteurs peu coûteux

An inexpensive, noninvasive system that could accurately classify flying insects would have important implications for entomological research, and allow ...

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor

The vast majority of mass spectrometry (MS)-based protein analysis methods involve an enzymatic digestion step prior to detection, typically with trypsin. This step is necessary for the generation of small molecular weight peptides, generally with MW &#60; 3,000-4,000 Da, that fall within the effective scan range of mass spectrometry instrumentation. Conventional protocols involve O/N enzymatic digestion at 37 &#186;C. Recent advances have led to the development of a variety of strategies, typically involving the use of a microreactor with immobilized enzymes or of a range of complementary physical processes that reduce the time necessary for proteolytic digestion to a few minutes (e.g., microwave or high-pressure). In this work, we describe a simple and cost-effective approach that can be implemented in any laboratory for achieving fast enzymatic digestion of a protein. The protein (or protein mixture) is adsorbed on C18-bonded reversed-phase high performance liquid chromatography (HPLC) silica particles preloaded in a capillary column, and trypsin in aqueous buffer is infused over the particles for a short period of time. To enable on-line MS detection, the tryptic peptides are eluted with a solvent system with increased organic content directly in the MS ion source. This approach avoids the use of high-priced immobilized enzyme particles and does not necessitate any aid for completing the process. Protein digestion and complete sample analysis can be accomplished in less than ~3 min and ~30 min, respectively.

A quick protocol for proteolytic digestion with an in-house built flow-through tryptic microreactor coupled to an electrospray ionization (ESI) mass spectrometer is presented. The fabrication of the microreactor, the experimental setup and the data acquisition process are described.

Fast Processing Enzymatic des protéines pour MS de détection avec un microréacteur Flow-through

The vast majority of mass spectrometry (MS)-based protein analysis methods involve an enzymatic digestion step prior to detection, typically with trypsin. ...

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

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

Isolation of Primary Murine Retinal Ganglion Cells RGCs by Flow Cytometry

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

Isolement des cellules de ganglion rétiniennes murines primaires (RGC) par cytométrie de flux

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

An Automated Method to Perform The In Vitro Micronucleus Assay using Multispectral Imaging Flow Cytometry

The in vitro micronucleus (MN) assay is often used to evaluate cytotoxicity and genotoxicity but scoring the assay via manual microscopy is laborious and introduces uncertainty in results due to variability between scorers. To remedy this, automated slide-scanning microscopy as well as conventional flow cytometry methods have been introduced in an attempt to remove scorer bias and improve throughput. However, these methods have their own inherent limitations such as inability to visualize the cytoplasm of the cell and the lack of visual MN verification or image data storage with flow cytometry. Multispectral Imaging Flow Cytometry (MIFC) has the potential to overcome these limitations. MIFC combines the high resolution fluorescent imagery of microscopy with the statistical robustness and speed of conventional flow cytometry. In addition, all collected imagery can be stored in dose-specific files. This paper describes the protocol developed to perform a fully automated version of the MN assay on MIFC. Human lymphoblastoid TK6 cells were enlarged using a hypotonic solution (75 mM KCl), fixed with 4% formalin and the nuclear content was stained with Hoechst 33342. All samples were run in suspension on the MIFC, permitting acquisition of high resolution images of all key events required for the assay (e.g. binucleated cells with and without MN as well as mononucleated and polynucleated cells). Images were automatically identified, categorized and enumerated in the MIFC data analysis software, allowing for automated scoring of both cytotoxicity and genotoxicity. Results demonstrate that using MIFC to perform the in vitro MN assay allows statistically significant increases in MN frequency to be detected at several different levels of cytotoxicity when compared to solvent controls following exposure of TK6 cells to Mitomycin C and Colchicine, and that no significant increases in MN frequency are observed following exposure to Mannitol.

The in vitro micronucleus assay is a well-established method for evaluating genotoxicity and cytotoxicity but scoring the assay using manual microscopy is laborious and suffers from subjectivity and inter-scorer variability. This paper describes the protocol developed to perform a fully automated version of the assay using multispectral imaging flow cytometry.

Une méthode automatisée pour effectuer l'essai micronutrique in vitro à l'aide de la cytométrie du flux d'imagerie multispectrale

The in vitro micronucleus (MN) assay is often used to evaluate cytotoxicity and genotoxicity but scoring the assay via manual microscopy is laborious and ...

Ovarian Cancer Detection Using Photoacoustic Flow Cytometry

Many studies suggest that the enumeration of circulating tumor cells (CTCs) may show promise as a prognostic tool for ovarian cancer. Current strategies for the detection of CTCs include flow cytometry, microfluidic devices, and real-time polymerase chain reaction (RT-PCR). Despite recent advances, methods for the detection of early ovarian cancer metastasis still lack the sensitivity and specificity required for clinical translation. Here, a novel method is presented for the detection of ovarian circulating tumor cells by photoacoustic flow cytometry (PAFC) utilizing a custom three dimensional (3D) printed system, including a flow chamber and syringe pump. This method utilizes folic acid-capped copper sulfide nanoparticles (FA-CuS NPs) to target SKOV-3 ovarian cancer cells by PAFC. This work demonstrates the affinity of these contrast agents for ovarian cancer cells. The results show NP characterization, PAFC detection, and NP uptake by fluorescence microscopy, thus demonstrating the potential of this novel system to detect ovarian CTCs at physiologically relevant concentrations.

A protocol is presented to detect circulating ovarian tumor cells utilizing a custom-made photoacoustic flow system and targeted folic acid-capped copper sulfide nanoparticles.

Détection du cancer de l'ovaire à l'aide de la cytométrie du flux photoacoustique

Many studies suggest that the enumeration of circulating tumor cells (CTCs) may show promise as a prognostic tool for ovarian cancer. Current strategies ...

High-Dimensionality Flow Cytometry for Immune Function Analysis of Dissected Implant Tissues

The success of implanting laboratory-grown tissue or a medical device in an individual is subject to the immune response of the recipient host. Considering an implant as a foreign body, a hostile and dysregulated immune response may result in the rejection of the implant, while a regulated response and regaining of homeostasis can lead to its acceptance. Analyzing the microenvironments of implants dissected out under in vivo or ex vivo&#160;settings can help in understanding the pattern of immune response, which can ultimately help in developing new generations of biomaterials. Flow cytometry is a well-known technique for characterizing immune cells and their subsets based on their cell surface markers. This review describes a protocol based on manual dicing, enzymatic digestion, and filtration through a cell strainer for the isolation of uniform cell suspensions from dissected implant tissue. Further, a multicolor flow cytometry staining protocol has been explained, along with steps for initial cytometer settings to characterize and quantify these isolated cells by flow cytometry.

Isolation of cells from dissected implants and their characterization by flow cytometry can significantly contribute to understanding the pattern of immune response against implants. This paper describes a precise method for the isolation of cells from dissected implants and their staining for flow cytometric analysis.