Name: automation of the micronucleus assay using imaging flow cytometry and artificial intelligence
Uploaded: 2023-01-27T13:00:00
Description: Watch this Scientific Journal Video about Automation of the Micronucleus Assay Using Imaging Flow Cytometry and Artificial Intelligence at JoVE.com

1. Data acquisition using imaging flow cytometry
NOTE: Refer to Rodrigues et al.16 with the following modifications, noting that the acquisition regions using IFC may need to be modified for optimal image capture:
<ol>
	<li>For the non-Cyt-B method, perform a cell count using a commercially available cell counter following the manufacturer&#39;s instructions (see Table of Materials) on each culture immediately before culture and immed...

<ol>
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D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+micronucleus+assay+scored+by+flow+cytometry+provides+a+comprehensive+evaluation+of+cytogenetic+damage+and+cytotoxicity.">In vitro micronucleus assay scored by flow cytometry provides a comprehensive evaluation of cytogenetic damage and cytotoxicity.</a> Mutation Research/Genetic Toxicology and Environmental Mutagenesis. 630 (1), 78-91 (2007).</li><li>Avlasevich, S. L., Bryce, S. M., Cairns, S. E., Dertinger, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+micronucleus+scoring+by+flow+cytometry:+Differential+staining+of+micronuclei+versus+apoptotic+and+necrotic+chromatin+enhances+assay+reliability.">In vitro micronucleus scoring by flow cytometry: Differential staining of micronuclei versus apoptotic and necrotic chromatin enhances assay reliability.</a> Environmental and Molecular Mutagenesis. 47 (1), 56-66 (2006).</li><li>Basiji, 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=Principles+of+Amnis+imaging+flow+cytometry.">Principles of Amnis imaging flow cytometry.</a> Methods in Molecular Biology. 1389, 13-21 (2016).</li><li>Rodrigues, 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=Automation+of+the+in+vitro+micronucleus+assay+using+the+Imagestream&#174;+imaging+flow+cytometer.">Automation of the in vitro micronucleus assay using the Imagestream&#174; imaging flow cytometer.</a> Cytometry Part A. 93 (7), 706-726 (2018).</li><li>Verma, J. 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=Investigating+FlowSight&#174;+imaging+flow+cytometry+as+a+platform+to+assess+chemically+induced+micronuclei+using+human+lymphoblastoid+cells+in+vitro.">Investigating FlowSight&#174; imaging flow cytometry as a platform to assess chemically induced micronuclei using human lymphoblastoid cells in vitro.</a> Mutagenesis. 33 (4), 283-289 (2018).</li><li>Wills, J. 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=Inter-laboratory+automation+of+the+in+vitro+micronucleus+assay+using+imaging+flow+cytometry+and+deep+learning.">Inter-laboratory automation of the in vitro micronucleus assay using imaging flow cytometry and deep learning.</a> Archives of Toxicology. 95 (9), 3101-3115 (2021).</li><li>Rodrigues, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+in+vitro+micronucleus+assay+using+imaging+flow+cytometry+and+deep+learning.">The in vitro micronucleus assay using imaging flow cytometry and deep learning.</a> Npj Systems Biology and Applications. 7 (1), 20 (2021).</li><li>Rodrigues, M. 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The work presented here describes the use of deep learning algorithms to automate the scoring of the MN assay. Several recent publications have shown that intuitive, interactive tools allow the creation of deep learning models to analyze image data without the need for in-depth computational knowledge18,19. The protocol described in this work using a user interface-driven software package has been designed to work well with very large data files and permit the cr...

The micronucleus (MN) assay is fundamental in genetic toxicology to evaluate DNA damage in the development of cosmetics, pharmaceuticals, and chemicals for human use1,2,3,4. Micronuclei are formed from whole chromosomes or chromosome fragments that do not incorporate into the nucleus following division and condense into small, circular bodies separate from the nucleus. Thus, MN can be used as an endpoint to quantify DNA damage in genotoxicity testing1.
The preferred method for quantifying MN is within once-divided binucleated cells (BNCs) by blocking division using Cytochalasin-B (Cyt-B). In this version of the assay, cytotoxicity is also assessed by scoring mononucleated (MONO) and polynucleated (POLY) cells. The assay can also be performed by scoring MN in unblocked MONO cells, which is faster and easier to score, with cytotoxicity being assessed using pre- and post-exposure cell counts to assess proliferation5,6.
Physical scoring of the assay has historically been performed through manual microscopy, since this permits visual confirmation of all key events. However, manual microscopy is challenging and subjective1. Thus, automated techniques have been developed, including microscope slide scanning and flow cytometry, each with their own advantages and limitations. While slide-scanning methods allow key events to be visualized, slides must be created at optimal cell density, which can be difficult to achieve. Additionally, this technique often lacks cytoplasmic visualization, which can compromise the scoring of MONO and POLY cells7,8. While flow cytometry offers high-throughput data capture, the cells must be lysed, thus not permitting the use of the Cyt-B form of the assay. Additionally, as a non-imaging technique, conventional flow cytometry does not provide visual validation of key events9,10.
Therefore, imaging flow cytometry (IFC) has been investigated to perform the MN assay. The ImageStreamX Mk II combines the speed and statistical robustness of conventional flow cytometry with the high-resolution imaging capabilities of microscopy in a single system11. It has been shown that by using IFC, high-resolution imagery of all key events can be captured and automatically scored using feature-based12,13 or artificial intelligence (AI) techniques14,15. By using IFC to perform the MN assay, the automatic scoring of many more cells compared to microscopy in a shorter amount of time is achievable.
This work deviates from a previously described image analysis workflow16 and discusses all steps required to develop and train a Random Forest (RF) and/or&#160;convolutional neural network (CNN) model using the Amnis AI software (henceforth referred to as &#34;AI software&#34;). All necessary steps are described, including populating ground truth data using AI-assisted tagging tools, interpretation of model training results, and application of the model to classify additional data, permitting calculation of genotoxicity and cytotoxicity15.

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	<tbody>
		<tr>
			<td>15 mL centrifuge tube</td>
			<td>Falcon</td>
			<td>352096</td>
			<td></td>
		</tr>
		<tr>
			<td>Cleanser - Coulter Clenz&#160;</td>
			<td>Beckman Coulter</td>
			<td>8546931</td>
			<td>Fill container with 200 mL of Cleanser.&#160; https://www.beckmancoulter.com/wsrportal/page/itemDetails?itemNumber=8546931#2/10//0/25/ 
			1/0/asc/2/8546931///0/1//0/</td>
		</tr>
		<tr>
			<td>Colchicine</td>
			<td>MilliporeSigma</td>
			<td>64-86-8</td>
			<td></td>
		</tr>
		<tr>
			<td>Corning bottle-top vacuum filter&#160;</td>
			<td>MilliporeSigma</td>
			<td>CLS430769</td>
			<td>0.22 &#181;m filter, 500 mL bottle</td>
		</tr>
		<tr>
			<td>Cytochalasin B</td>
			<td>MilliporeSigma</td>
			<td>14930-96-2</td>
			<td>5 mg bottle</td>
		</tr>
		<tr>
			<td>Debubbler - 70% Isopropanol</td>
			<td>MilliporeSigma</td>
			<td>1.3704</td>
			<td>Fill container with 200 mL of Debubbler.&#160; http://www.emdmillipore.com/US/en/product/2-Propanol-70%25-%28V%2FV%29-0.1-%C2%B5m-filtred,MDA_CHEM-137040?ReferrerURL=https%3A%2F%2Fwww.google.com%2F</td>
		</tr>
		<tr>
			<td>Dimethyl Sulfoxide (DMSO)</td>
			<td>MilliporeSigma</td>
			<td>67-68-5</td>
			<td></td>
		</tr>
		<tr>
			<td>Dulbecco&#39;s Phosphate Buffered Saline 1X</td>
			<td>EMD Millipore</td>
			<td>BSS-1006-B</td>
			<td>PBS Ca++MG++ Free&#160;</td>
		</tr>
		<tr>
			<td>Fetal Bovine Serum</td>
			<td>HyClone</td>
			<td>SH30071.03</td>
			<td></td>
		</tr>
		<tr>
			<td>Formaldehyde, 10%, methanol free, Ultra Pure</td>
			<td>Polysciences, Inc.</td>
			<td>04018</td>
			<td>This is what is used for the 4% and 1% Formalin. CAUTION: Formalin/Formaldehyde toxic by inhalation and if swallowed.&#160; Irritating to the eyes, respiratory systems and skin.&#160; May cause sensitization by inhalation or skin contact. Risk of serious damage to eyes.&#160; Potential cancer hazard.&#160; http://www.polysciences.com/default/catalog-products/life-sciences/histology-microscopy/fixatives/formaldehydes/formaldehyde-10-methanol-free-pure/</td>
		</tr>
		<tr>
			<td>Guava Muse Cell Analyzer</td>
			<td>Luminex</td>
			<td>0500-3115</td>
			<td>A standard configuration Guava Muse Cell Analyzer was used.</td>
		</tr>
		<tr>
			<td>Hoechst 33342</td>
			<td>Thermo Fisher</td>
			<td>H3570</td>
			<td>10 mg/mL solution</td>
		</tr>
		<tr>
			<td>Mannitol</td>
			<td>MilliporeSigma</td>
			<td>69-65-8</td>
			<td></td>
		</tr>
		<tr>
			<td>MEM Non-Essential Amino Acids 100X</td>
			<td>HyClone</td>
			<td>SH30238.01</td>
			<td></td>
		</tr>
		<tr>
			<td>MIFC - ImageStreamX Mark II</td>
			<td>Luminex, a DiaSorin company</td>
			<td>100220</td>
			<td>A 2 camera ImageStreamX Mark II eqiped with the 405 nm, 488 nm, and 642 nm lasers was used.</td>
		</tr>
		<tr>
			<td>MIFC analysis software - IDEAS</td>
			<td>Luminex, a DiaSorin company</td>
			<td>100220</td>
			<td>&#34;Image analysis sofware&#34; 
			The companion software to the MIFC (ImageStreamX MKII)</td>
		</tr>
		<tr>
			<td>MIFC software - INSPIRE</td>
			<td>Luminex, a DiaSorin company</td>
			<td>100220</td>
			<td>&#34;Image acquisition software&#34; 
			This is the software that runs the MIFC (ImageStreamX MKII)</td>
		</tr>
		<tr>
			<td>Amnis AI software</td>
			<td>Luminex, a DiaSorin company</td>
			<td>100221</td>
			<td>&#34;AI software&#34; 
			This is the software that permits the creation of artificial intelligence models to analyze data</td>
		</tr>
		<tr>
			<td>Mitomycin C</td>
			<td>MilliporeSigma</td>
			<td>50-07-7</td>
			<td></td>
		</tr>
		<tr>
			<td>NEAA Mixture 100x</td>
			<td>Lonza BioWhittaker</td>
			<td>13-114E</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicllin/Streptomycin/Glutamine solution 100X</td>
			<td>Gibco</td>
			<td>15070063</td>
			<td></td>
		</tr>
		<tr>
			<td>Potassium Chloride (KCl)</td>
			<td>MilliporeSigma</td>
			<td>P9541</td>
			<td></td>
		</tr>
		<tr>
			<td>Rinse - Ultrapure water or deionized water</td>
			<td>NA</td>
			<td>NA</td>
			<td>Use any ultrapure water or deionized water.&#160; Fill container with 900 mL of Rinse.</td>
		</tr>
		<tr>
			<td>RNase</td>
			<td>MilliporeSigma</td>
			<td>9001-99-4</td>
			<td></td>
		</tr>
		<tr>
			<td>RPMI-1640 Medium 1x</td>
			<td>HyClone</td>
			<td>SH30027.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Sheath - PBS</td>
			<td>MilliporeSigma</td>
			<td>BSS-1006-B</td>
			<td>This is the same as Dulbecco&#39;s Phosphate Buffered Saline 1x&#160; Ca++MG++ free.&#160; Fill container with 900 mL of Sheath.</td>
		</tr>
		<tr>
			<td>Sterile water</td>
			<td>HyClone</td>
			<td>SH30529.01</td>
			<td></td>
		</tr>
		<tr>
			<td>Sterilizer - 0.4%&#8211;0.7% Hypochlorite</td>
			<td>VWR</td>
			<td>JT9416-1</td>
			<td>This is assentually 10% Clorox bleach that can be made by deluting Clorox bleach with water.&#160; Fill container with 200 mL of Sterilzer.</td>
		</tr>
		<tr>
			<td>T25 flask</td>
			<td>Falcon</td>
			<td>353109</td>
			<td></td>
		</tr>
		<tr>
			<td>T75 flask</td>
			<td>Falcon</td>
			<td>353136</td>
			<td></td>
		</tr>
		<tr>
			<td>TK6 cells</td>
			<td>MilliporeSigma</td>
			<td>95111735</td>
			<td></td>
		</tr>
	</tbody>
</table>

automation of the micronucleus assay using imaging flow cytometry and artificial intelligence

The micronucleus (MN) assay is used worldwide by regulatory bodies to evaluate chemicals for genetic toxicity. The assay can be performed in two ways: by scoring MN in once-divided, cytokinesis-blocked binucleated cells or fully divided mononucleated cells. Historically, light microscopy has been the gold standard method to score the assay, but it is laborious and subjective. Flow cytometry has been used in recent years to score the assay, but is limited by the inability to visually confirm key aspects of cellular imagery. Imaging flow cytometry (IFC) combines high-throughput image capture and automated image analysis, and has been successfully applied to rapidly acquire imagery of and score all key events in the MN assay. Recently, it has been demonstrated that artificial intelligence (AI) methods based on convolutional neural networks can be used to score MN assay data acquired by IFC. This paper describes all steps to use AI software to create a deep learning model to score all key events and to apply this model to automatically score additional data. Results from the AI deep learning model compare well to manual microscopy, therefore enabling fully automated scoring of the MN assay by combining IFC and AI.

Figure 1&#160;shows the workflow for using the AI software to create a model for the MN assay. The user loads the desired .daf files into the AI software, then assigns objects to the ground truth model classes using the AI-assisted cluster (Figure 2) and predict (Figure 3) tagging algorithms. Once all ground truth model classes have been populated with sufficient objects, the model can be trained using the RF or CNN algorithms. Foll...

Watch this Scientific Journal Video about Automation of the Micronucleus Assay Using Imaging Flow Cytometry and Artificial Intelligence at JoVE.com

Automation of the Micronucleus Assay Using Imaging Flow Cytometry and Artificial Intelligence

The micronucleus (MN) assay is a well-established test for quantifying DNA damage. However, scoring the assay using conventional techniques such as manual microscopy or feature-based image analysis is laborious and challenging. This paper describes the methodology to develop an artificial intelligence model to score the MN assay using imaging flow cytometry data.

The micronucleus (MN) assay is used worldwide by regulatory bodies to evaluate chemicals for genetic toxicity. The assay can be performed in two ways: by ...

Performing the micronucleus assay using imaging flow cytometry overcomes many limitations of traditional methods, including low throughput, score variability, and lack of visual confirmation of events. The main advantage of this technique is that all key events can be acquired using imaging flow cytometry and analyzed using artificial intelligence. This method has a potential to be used in large scale screening of chemicals and other compounds to test for toxicity at higher throughput than is currently available.When building a new AI model, the main challenge is obtaining sufficient images of cells with micronuclei, so it is important to use the image tagging algorithms. To begin, launch the Artificial Intelligence or AI software. Under Experiment Type, click the radio button beside Train to start a training experiment for building the Convolutional Neural Network or CNN model, and click on Next.On the Class Names, click on Add. In the pop-up window, type Mononucleated, and click on OK to add the mononucleated class to the list of class names. Repeat this process to add the other class names, such as Mononucleated with MN, Binucleated, Binucleated with MN, Polynucleated, and Irregular morphology.Under Select Files, click on Add Files, and browse for the desired files to be added to the AI software, to build the ground truth data. Next on the Select Base Population screen, locate the Non-apoptotic population from the population hierarchy. Then right click on the Non-apoptotic population, choose Select All Matching Populations, and click on Next.To assign a tagged truth population of mononucleated cells with micronucleus, click on the Mononucleated with MN class under Model Classes on the left, and then click on the appropriate tagged truth population on the right. Once all appropriate truth populations are assigned, click on Next. On the Select Channels screen, ensure that the appropriate channels for the experiment are chosen.Here, choose Bright Field or BF as channel one, herds for DNA as channel seven, and then click Next. Finally, on the Confirmation screen, click on Create Experiment. Click on Tagging to launch the tagging tool interface.Then click on the zoom tools to crop the images for easier viewing. And click on the slider bar to adjust the image size and decide the number of images to be shown in the gallery. Click on the Display Setting option and choose min-max, which provides the best contrast image for identifying all key events.Next, click on Setup Gallery Display to change the color of the DNA image to yellow or white, which will improve the visualization of small objects. Click on Cluster to run the algorithm to group images with similar morphology together. Once clustering is complete, click on the individual clusters and begin assigning images to appropriate model classes.After a minimum of 25 objects are assigned to each model class, the predict algorithm becomes available. Click on Predict. Once the predict algorithm has completed running, add objects from the predicted classes to the appropriate model classes.Once a minimum of 100 objects are assigned to each model class, click on the Training tab at the top of the screen, and then click on the Train button. Once model training is complete, click on View Results to assess model accuracy. Once the model training is complete, click the menu button to define a new experiment.Under Experiment Type, click the radio button beside Classify to start a classification experiment, and click Next. Click on the model to be used for classification, then click on Next. On the Select Files screen, click on Add Files.Browse for the files to be classified by the CNN model, and then click on Next. Next, on the Select Base Population screen, click on the checkbox next to the Non-apoptotic population in one of the loaded files. Right click on the Non-apoptotic population, click on Select All Matching Populations to select this population from all loaded files, and then click Next.On the Select Channels screen, verify channel one is selected for the Bright Field, and channel seven is selected for the DNA stain, and click Next. Finally, on the confirmation screen, click on Create Experiment. The AI software loads the selected model and all images from the chosen data files.After loading, click on Finish. Next, click on Classify to launch the classification screen. And use the check boxes to choose to use Random Forest or RF, and CNN.Then click on the Classify button. This begins the process of using the RF and CNN models to classify additional data and identify all objects that belong in the specified model classes. Once the classification is complete, click on View Results.Click the Update DAFs button to bring up the update DAFs with classification results window, and then click on OK to update the DAF files. To generate the report, on the results screen, click on Generate Report. If an individual report for each input DAF is required, select the checkbox beside Create report for each input DAF.Otherwise, just click on OK to obtain the reports. The AI assisted cluster algorithm groups similar objects within a segment together, according to the morphology of both unclassified objects and the objects that have been assigned to the ground truth model classes. Clusters containing mononucleated cells fall on one side of the object map, while the multinucleated cells are on the opposite side.Binucleated cell clusters fall between mono and multinucleated cell clusters. Finally, clusters with irregular morphology, fall in different areas of the object map. The predict algorithm is more robust than the cluster algorithm in identifying subtle morphologies in images.For example, Mononucleated Cells with MN versus Mononucleated cells without MN.The performance of the model can be assessed using tools, including class distribution histograms, accuracy statistics, and an interactive confusion matrix. In class distribution histograms, the closer the percentage values between the truth and predicted populations, the more accurate the model. In the accuracy statistics, The closer these metrics are to 100%the more accurate the model is at identifying events in the model classes.Finally, the interactive confusion matrix indicates where the model missclassifies events. Genotoxicity was measured by the percentage of micronuclei by microscopy, indicated by clear bars, and AI indicated by dotted bars following a 3 hour exposure and 24 hours recovery, for Mannitol, Etoposide and Mitomycin C, using both the Cytochalasin B and Non-Cytochalasin B methods. When creating a training experiment, ensure the loaded data contains imagery from positive and negative control samples.Micronuclei are rare, and sufficient imagery is required to build an accurate AI model. This procedure permits the creation of AI models to analyze imaging flow micronucleus data in any field of study, such as radiation biodosimetry. A rapid and robust AI-based method to identify micronuclei, may extend to other applications, such as quantifying micronuclei that may be predictive for the risk of cancer development.

automation-micronucleus-assay-using-imaging-flow-cytometry-artificial

Research

JoVE Journal

Bioengineering

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Sensitive Detection of Proteopathic Seeding Activity with FRET Flow Cytometry

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

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

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

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.

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.

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.

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.

The success of implanting laboratory-grown tissue or a medical device in an individual is subject to the immune response of the recipient host. ...

Blood Flow Imaging with Ultrafast Doppler

The pulsed-Doppler effect is the main technique used in clinical echography to assess blood flow. Applied with conventional focused ultrasound Doppler modes, it has several limits. Firstly, a finely tuned signal filtering operation is needed to distinguish blood flows from surrounding moving tissues. Secondly, the operator must choose between localizing the blood flows or quantifying them. In the last two decades, ultrasound imaging has undergone a paradigm shift with the emergence of ultrafast ultrasound using unfocused waves. In addition to a hundredfold increase in framerate (up to 10000 Hz), this new technique also breaks the conventional quantification/localization trade-off, offering a complete blood flow mapping of the field of view and a simultaneous access to fine velocities measurements at the single-pixel level (down to 50 &#181;m). This data continuity in both spatial and temporal dimensions strongly improves the tissue/blood filtering process, which results in an increase sensitivity to small blood flow velocities (down to 1 mm/s). In this method paper, we aim to introduce the concept of ultrafast Doppler as well as its main parameters. Firstly, we summarize the physical principles of unfocused wave imaging. Then, we present the Doppler signal processing main steps. Particularly, we explain the practical implementation of the critical tissue/blood flow separation algorithms and on the extraction of velocities from these filtered data. This theoretical description is supplemented by in vitro experiences. A tissue phantom embedding a canal with flowing blood-mimicking fluid is imaged with a research programmable ultrasound system. A blood flow image is obtained and the flow characteristics are displayed for several pixels in the canal. Finally, a review of in vivo applications is proposed, showing examples in several organs such as carotids, kidney, thyroid, brain and heart.

This protocol shows how to apply ultrafast ultrasound Doppler imaging to quantify blood flows. After a 1 s long acquisition, the experimenter has access to a movie of the full field of view with axial velocity values for each pixel every &#8776;0.3 ms (depending on the ultrasound time of flight).

The pulsed-Doppler effect is the main technique used in clinical echography to assess blood flow. Applied with conventional focused ultrasound Doppler ...