Name: a neuronal and astrocyte co-culture assay for high content analysis of neurotoxicity
Uploaded: 2009-05-05T00:00:00
Duration: 15 min 4 s
Description: Watch this Scientific Journal Video about A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity at JoVE.com

The authors would like to thank Drs. Rick Ryan, Umesh Patel, Jeff Till, Matthew Hsu, Jehangir Mistry and Michele Hatler for support during the development of these projects and protocols.

Cell Preparation:
<ol>
	<li>Prior to cell seeding for assay, culture neurons/astrocytes in growth media until ~70-80% confluent (unless cell seeding directly from thaw or isolation).</li>
	<li>Detach cells from culture flasks/plates via method appropriate for cell type of interest. If necessary, coat assay plate wells with poly-D-lysine or extracellular matrix protein to enhance cell adhesion. Co-cultures of astrocytes and neurons may be seeded simultaneously or sequentially. For sequential seedings, plating of astrocytes first as a &#34;basal&#34; layer is recommended, followed by neuronal plating and differentiation, if necessary. Adjust cell density as appropriate for cell type, subsequent culture time, parameters of interest, etc. Depending on culture age, cell source and seeding density, primary cultures may vary greatly in rate of proliferation, GFAP expression or neurite outgrowth - it is important to characterize and optimize your cell system to provide the most biological relevance for your experimental model, as well as to provide for effective imaging, segmentation and analysis using HCS (see Figure 1). After adding cells to plate (cells may be seeded in 90 &#956;L media, to facilitate toxin treatment as described in Step 3 below), allow plate to sit on a level surface at room temperature for 15-30 min, enabling even cell distribution. Following this period, incubate cells in growth media (37&#176;C/5% CO2) for at least 24 hours, then switch to differentiation culture conditions (e.g., low serum/NGF for PC12 cells), as appropriate. Continue culture until cells reach desired level of confluence or differentiation, changing media at intervals appropriate for cell type.</li>
	<li>Cell treatments (control compounds, test compounds, etc.) can be introduced at any point during this culture period, as appropriate for time-course of treatment of interest. Acrylamide, hydrogen peroxide and K-252a are provided as neurotoxic control compounds. Sufficient reagents are provided for duplicate 12-point dose response curves (including one dH2O or DMSO-control set within the dose response) for all five 96-well plates. The compounds are provided at 250X concentration (for K-252a, assuming a maximum treatment of 1 &#181;M) or 10X (for acrylamide and hydrogen peroxide, assuming maximum treatments of 100 mM and 10 mM, respectively). Recommended treatment preparation involves half-log (1:&#8730;10) serial dilution of the 250X compound in DMSO, followed by dilution in Compound Dilution Buffer to 10X (10X control compounds originating in dH2O may be serially diluted directly in sterile dH2O or Compound Dilution Buffer). 10 &#181;L of each treatment may then be added to the 90 &#181;L of culture media already present in each well, for a final 1X concentration (0.4% DMSO or 10% dH2O). Sample data is provided for 24 or 96 hours of compound treatment at 37&#176;C prior to fixation.</li>
</ol>
Cell Fixation and Immunofluorescent Staining:
Note: Staining time is ~2.5 hours post-fixation. Do not allow wells to dry out between staining steps. Aspiration and dispensation of reagents should be conducted at low flow rates to diminish any cell loss due to fluid shear. All recommended &#8216;per well&#8217; volumes refer to a single well of a 96-well microplate. All recommended &#8216;per 96-well plate&#8217; volumes include 25% excess for liquid handling volume loss. All staining steps are performed at room temperature (RT). All buffers and antibody solutions are stable for at least 24 hours at RT.
<ol start="4">
	<li>At end of culture period, pre-warm HCS Fixation Solution (2X) to room temperature (RT) or 37&#186;C if desired (12 mL/96-well plate). In a chemical fume hood, add 100 &#181;L/well directly to culture media and allow to fix for 30 min at RT. Remove fixative/toxin-containing media and dispose of in compliance with regulations for hazardous waste (see MSDS). If proceeding immediately to staining, rinse each well twice with 200 &#181;L of HCS Immunofluorescence Buffer. Alternatively, if plates are to be stained at a later time, rinse twice with 200 &#181;L of Wash Buffer, then leave second rinse volume in wells and store plates tightly sealed at 4&#186;C until staining.</li>
	<li>If fixed samples have been stored at 4&#186;C prior to staining, rinse twice with 200 &#181;L HCS Immunofluorescence Buffer before proceeding with staining protocol.</li>
	<li>Prepare working solution of Rabbit Anti-&#946;III Tubulin/Mouse Anti-GFAP HCS Primary Antibodies (6 mL/96-well plate) as follows: Add 60 &#181;L of each thawed primary antibody to 5.88 mL of HCS Immunofluorescence Buffer. Mix well. Remove previous Immunofluorescence Buffer rinse. Add 50 &#181;L of Primary Antibody solution to each well and incubate for 1 hour at RT.</li>
	<li>Remove Primary Antibody solution. Rinse three times with 200 &#181;L HCS Immunofluorescence Buffer.</li>
	<li>Prepare working solution of HCS Secondary Antibody/Hoechst HCS Nuclear Stain (6 mL/96-well plate) as follows: Add 30 &#181;L of each thawed secondary antibody and 30 &#181;L of thawed Hoechst HCS Nuclear Stain to 5.91 mL of HCS Immunofluorescence Buffer. Mix well, protecting solution from light. Remove previous HCS Immunofluorescence Buffer rinse. Add 50 &#181;L of HCS Secondary Antibody/Hoechst HCS Nuclear Stain solution and incubate for 1 hour at RT, protected from light.</li>
	<li>Remove HCS Secondary Antibody/Hoechst HCS Nuclear Stain solution. Rinse twice with 200 &#181;L HCS Immunofluorescence Buffer.</li>
	<li>Remove previous HCS Immunofluorescence Buffer rinse. Rinse twice with 200 &#181;L of HCS Wash Buffer, leaving second rinse volume in wells.</li>
	<li>Seal plate and image immediately, or store plate at 4&#186;C protected from light until ready for imaging.</li>
</ol>
Image Acquisition and Analysis:
<ol start="12">
	<li>Imaging and analysis of stained plates may be performed upon a variety of available HCS platforms, including the IN Cell Analyzer (GE Healthcare), ArrayScan (ThermoFisher Scientific) or Opera (Perkin Elmer). Some guidelines for imaging and analysis are provided in Table 1:</li>
</ol>
<table border="1" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td colspan="4" style="background:#000000; color:#FFFFFF;">HCS222 Image Acquisition Guidelines</td>
		</tr>
		<tr>
			<td>Detection Reagent</td>
			<td>Objective Lens</td>
			<td>Excitation Filter Range [peak/bandwidth (nm)]</td>
			<td>Emission Filter Range [peak/bandwidth (nm)]</td>
		</tr>
		<tr>
			<td>Hoechst HCS Nuclear Stain</td>
			<td>20X</td>
			<td>360/40</td>
			<td>460/40 (or 535/50 if necessary)</td>
		</tr>
		<tr>
			<td>HCS Secondary Antibody, FITC-Donkey anti-Rabbit IgG</td>
			<td>20X</td>
			<td>480/40</td>
			<td>535/50</td>
		</tr>
		<tr>
			<td>HCS Secondary Antibody, Cy3-Donkey anti-Mouse IgG</td>
			<td>20X</td>
			<td>535/50</td>
			<td>600/50</td>
		</tr>
	</tbody>
</table>

<table border="1" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td colspan="4" style="background:#000000; color:#FFFFFF;" width="545"> 
			HCS222 Image Analysis Guidelines</td>
		</tr>
		<tr>
			<td>Cell Parameter</td>
			<td>Detection</td>
			<td>Segmentation/ Measurement</td>
			<td>Rationale </td>
		</tr>
		<tr>
			<td>Cell Number, Nuclear Characteristics</td>
			<td>Hoechst HCS Nuclear Stain</td>
			<td>Nuclear region (460 nm emission channel).&#160; Count number of nuclei.&#160; DNA content (nuclear intensity) or nuclear area analyses are also possible.</td>
			<td>Use cell number, nuclear characteristics to determine cell loss, toxicity phenotypes, etc.&#160; Can &#8220;filter&#8221; nuclei for those associated with &#946;III-tubulin or GFAP expression to obtain separate neuronal and astrocytic cell counts/characterizations (strongly recommended).</td>
		</tr>
		<tr>
			<td>&#946;III-Tubulin Expression, Neurite Outgrowth</td>
			<td>HCS Secondary Antibody, FITC-conjugated</td>
			<td>Cytoplasmic region (535 nm emission channel).&#160; FITC signal may be used to distinguish neuronal cell bodies from neurites (e.g., via minimum/average cell body areas, minimum/maximum neurite lengths and widths).&#160; Determine parameters such as total neurite length, neurite counts/cell, etc.</td>
			<td>Neurite outgrowth measurements may be modulated during neuronal differentiation or as a result of chemical injury, disease states, etc.&#160; Can &#8220;filter&#8221; cell bodies for those associated with &#946;III-tubulin expression to obtain distinct neuronal characterization (strongly recommended).</td>
		</tr>
		<tr>
			<td>GFAP Expression, Astrocyte Area 
			&#160;</td>
			<td>HCS Secondary Antibody, Cy3-conjugated 
			&#160;</td>
			<td>Cytoplasmic region (600 nm emission channel).&#160; Cy3 signal may be used to define astrocytic cytoplasmic segmentation.&#160; Determine parameters such as average cytoplasmic signal intensity, cell area, etc.</td>
			<td>GFAP expression and astrocyte cell area may be modulated during astrocyte development or as a result of chemical injury, disease states, etc.&#160; Can &#8220;filter&#8221; cell bodies for those associated with GFAP expression to obtain distinct astrocytic characterization (strongly recommended).</td>
		</tr>
	</tbody>
</table>
Table 1. Image Acquisition and Analysis Guidelines &#8211; HCS222 &#946;III-Tubulin/GFAP (Co-Culture) Assay
Representative Results:
<img alt="Figure 1" src="/files/ftp_upload/1173/figure1.jpg" /> 
Figure 1. &#946;III-tubulin and GFAP immunofluorescence of mixed rat neural cell cultures. 
 
Co-cultures of primary rat hippocampal astrocytes with either primary rat hippocampal neurons or rat PC12 cells were generated by pre-plating astrocytes for several days in culture, followed by neuronal seeding. Primary neurons were cultured for an additional 11 days, while PC12s were cultured for an additional 2 days under differentiation conditions (low serum/NGF). Cell handling, fixation and immunostaining were performed according to HCS222 assay protocols. Cells were imaged on the GE IN Cell Analyzer 1000 (3.3) at 20X (primary neurons) or 10X (PC12) objective magnification and analyzed using the GE IN Cell Analyzer 1000 Workstation (3.4) Neurite Outgrowth and Multi Target Analysis algorithms. Top panel: Fused images of Hoechst HCS Nuclear Stain (blue), &#946;III-tubulin (green) and GFAP (red) fluorescence. Separate analysis of the &#946;III-tubulin fluorescence channel allows for neurite outgrowth segmentation (middle panel: cell bodies outlined in blue (primary neurons) or yellow (PC12), neurites in green (primary neurons) or light blue (PC12)). Analysis of the GFAP channel allows for astrocyte segmentation (bottom panel: nuclei outlined in blue, cytoplasm in green). GFAP segmentation for the primary rat hippocampal neuron/astrocyte co-culture demonstrates the ability to distinguish between nuclei/cell bodies that are GFAP (+) (green outlines) and those that are GFAP (-) (red), enabling separate cell counts for neurons and astrocytes in a mixed culture setting. 
 
<img alt="Figure 2" src="/files/ftp_upload/1173/figure2.jpg" /> 
Figure 2. Dose responses of primary rat hippocampal neuron/astrocyte co-cultures to toxic stresses. 
 
Primary rat hippocampal astrocytes (P6) were plated on 96-well plates in growth media and cultured for 6 days. Primary rat hippocampal neurons (direct from thaw) were then seeded on top of pre-plated astrocytes and cultured in growth media for 11 days. Cells were treated with serial dilutions of acrylamide or hydrogen peroxide (max. concentrations = 100mM and 10mM, respectively) for the last 24 hours of culture. Cell handling, fixation and immunostaining were performed according to HCS222 assay protocols. Cells were imaged on the GE IN Cell Analyzer 1000 (3.3) at 20X (10 fields/well) and analyzed (nuclear/cytoplasmic/neurite segmentation) using the GE IN Cell Analyzer 1000 Workstation (3.4) Neurite Outgrowth and Multi Target Analysis algorithms. Data presented are mean &#177; SEM, n = 3. Multiple parameters (neurite outgrowth, GFAP intensity, astrocyte area and neuronal or astrocytic cell counts) were investigated for dose-dependent trends.

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The authors are all employees of Millipore Corporation.

To date, in vitro experiments designed to study neurotoxicity risk assessment using mixed cultures of neurons and astrocytes have been limited. It is well-accepted that glial cells are integral in providing spatial and metabolic support to neurons, and play a critical role in modulating several neuronal functions, including neuronal migration, differentiation and synaptic activity. Glial astrocytes also release cytokines and other soluble factors which are capable of both inducing adverse responses in surrounding neuronal tissue, as well as promoting neuronal tolerance of many toxins. Demonstrating the depth of neuronal-glial interactions, in co-culture studies, astrocytes have been shown to protect neurons against the toxicity of oxidative stress, whereas impairment of astrocytic functions, such as maintenance of antioxidant defense and cellular energy levels, has been shown to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test-system may prove more relevant to human central nervous system structure and function than neuronal cells alone. Despite the growing awareness of the physiological significance of neuronal-astrocytic interactions, it has previously been difficult to perform quantitative analyses of these interactions in intact cells. The advent of High Content Screening enables the development of powerful new assays to address this.
In this study, we have demonstrated that quantitative analyses of multiple neuronal and astrocytic phenotypes within a single assay are made possible by HCA. In primary neurons we have performed quantitative measurements of neurotoxicity markers such as neuronal number, neurite count and neurite length. In astrocytes, reactive gliosis is a known biomarker of neurotoxicity, characterized by alterations in GFAP expression, astrocyte number and astrocyte morphology. We have demonstrated that each of these endpoints may readily be assessed via HCA. These studies support the concept that HCA of neural-specific biomarkers could be used as part of a battery of in vitro tests to rapidly screen large numbers of chemicals for neurotoxic endpoints.
Millipore&rsquo;s HCS222 High Content Analysis kit for co-culture of neurons and astrocytes is comprised of high-quality detection reagents and protocols for simultaneously profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP) in a wide variety of cellular models of neurotoxicity. The highly-validated reagents provided with this kit allow the user to standardize assays, minimize assay-to-assay variability, and to reproducibly generate images with a high signal-to-background ratio.

<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>Rabbit Anti-&#x03B2;III-Tubulin HCS Primary Antibody, 100X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS201672</td>
<td>1 vial containing 300 &micro;L 
Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>HCS Secondary Antibody (donkey anti-rabbit IgG, FITC conjugate), 200X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS201649</td>
<td>1 vial containing 150 &micro;L Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>Mouse Anti-GFAP HCS Primary Antibody, 100X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS201671</td>
<td>1 vial containing 300 &micro;L Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>HCS Secondary Antibody (donkey anti-mouse IgG, Cy3 conjugate), 200X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200437</td>
<td>1 vial containing 150 &micro;L Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>Hoechst HCS Nuclear Stain, 200X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200438</td>
<td>1 vial containing 150 &micro;L Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>HCS Fixation Solution with Phenol Red, 2X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200434</td>
<td>1 bottle containing 100 mL Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>HCS Immunofluorescence Buffer, 1X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200435</td>
<td>1 bottle containing 1000 mL Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>HCS Wash Buffer, 1X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. 2007643</td>
<td>1 bottle containing 500 mL Millipore HCS222 Kit Components</td>
</tr>
<tr>
<td>Acrylamide (Control Compound), 10X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS201679</td>
<td>1 vial containing 500 &micro;L of 1M acrylamide in dH2O Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>Hydrogen Peroxide (Control Compound), 10X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS201730</td>
<td>1 vial containing 500 &micro;L of 100 mM hydrogen peroxide in dH2O Millipore HCS222 Kit Components</td>
</tr>
<tr>
<td>K-252a (Control Compound), 250X</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS201741</td>
<td>1 vial containing 100 &micro;L of 250 &micro;M K-252a in DMSO Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>DMSO for Compound Serial Dilution</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200441</td>
<td>1 bottle containing 10 mL Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>Compound Dilution Buffer</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200442</td>
<td>1 bottle containing 25 mL Millipore HCS222 Kit Component</td>
</tr>
<tr>
<td>Plate Sealers</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>Part No. CS200443</td>
<td>10 each Millipore HCS222 Kit Components</td>
</tr>
<tr>
<td>tissue culture-treated black/clear bottom microplates </td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>HCS imaging/analysis system</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<td>&nbsp;</td>		</tbody>
		</table>

a neuronal and astrocyte co-culture assay for high content analysis of neurotoxicity

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing measurement of multiple cellular phenotypes within a single assay. In this study, we utilized HCA to develop a novel assay for neurotoxicity. Neurotoxicity assessment represents an important part of drug safety evaluation, as well as being a significant focus of environmental protection efforts. Additionally, neurotoxicity is also a well-accepted in vitro marker of the development of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Recently, the application of HCA to neuronal screening has been reported. By labeling neuronal cells with &beta;III-tubulin, HCA assays can provide high-throughput, non-subjective, quantitative measurements of parameters such as neuronal number, neurite count and neurite length, all of which can indicate neurotoxic effects. However, the role of astrocytes remains unexplored in these models. Astrocytes have an integral role in the maintenance of central nervous system (CNS) homeostasis, and are associated with both neuroprotection and neurodegradation when they are activated in response to toxic substances or disease states. GFAP is an intermediate filament protein expressed predominantly in the astrocytes of the CNS. Astrocytic activation (gliosis) leads to the upregulation of GFAP, commonly accompanied by astrocyte proliferation and hypertrophy. This process of reactive gliosis has been proposed as an early marker of damage to the nervous system. The traditional method for GFAP quantitation is by immunoassay. This approach is limited by an inability to provide information on cellular localization, morphology and cell number. We determined that HCA could be used to overcome these limitations and to simultaneously measure multiple features associated with gliosis - changes in GFAP expression, astrocyte hypertrophy, and astrocyte proliferation - within a single assay. In co-culture studies, astrocytes have been shown to protect neurons against several types of toxic insult and to critically influence neuronal survival. Recent studies have suggested that the use of astrocytes in an in vitro neurotoxicity test system may prove more relevant to human CNS structure and function than neuronal cells alone. Accordingly, we have developed an HCA assay for co-culture of neurons and astrocytes, comprised of protocols and validated, target-specific detection reagents for profiling &beta;III-tubulin and glial fibrillary acidic protein (GFAP). This assay enables simultaneous analysis of neurotoxicity, neurite outgrowth, gliosis, neuronal and astrocytic morphology and neuronal and astrocytic development in a wide variety of cellular models, representing a novel, non-subjective, high-throughput assay for neurotoxicity assessment. The assay holds great potential for enhanced detection of neurotoxicity and improved productivity in neuroscience research and drug discovery.

Watch this Scientific Journal Video about A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity at JoVE.com

A Neuronal and Astrocyte Co-Culture Assay for High Content Analysis of Neurotoxicity

This article describes a novel protocol and reagent set designed for sensitive measurement of neurotoxic effects of compounds and treatments on co-cultures of neurons and astrocytes using high content analysis. Results demonstrate that high content analysis represents an exciting novel technology for neurotoxicity assessment.

High Content Analysis (HCA) assays combine cells and detection reagents with automated imaging and powerful image analysis algorithms, allowing ...

a-neuronal-astrocyte-co-culture-assay-for-high-content-analysis

Research

JoVE Journal

Biology

Neuronal Cell Cultures from Aplysia for High-Resolution Imaging of Growth Cones

Neuronal growth cones are the highly motile structures at the tip of axons that can detect guidance cues in the environment and transduce this information into directional movement towards the appropriate target cell. To fully understand how guidance information is transmitted from the cell surface to the underlying dynamic cytoskeletal networks, one needs a model system suitable for live cell imaging of protein dynamics at high temporal and spatial resolution. Typical vertebrate growth cones are too small to quantitatively analyze F-actin and microtubule dynamics. Neurons from the sea hare Aplysia californica are 5-10 times larger than vertebrate neurons, can easily be kept at room temperature and are very robust cells for micromanipulation and biophysical measurements. Their growth cones have very defined cytoplasmic regions and a well-described cytoskeletal system. The neuronal cell bodies can be microinjected with a variety of probes for studying growth cone motility and guidance. In the present protocol we demonstrate a procedure for dissection of the abdominal ganglion, culture of bag cell neurons and setting up an imaging chamber for live cell imaging of growth cones.

Aplysia californica neurons develop large growth cones in culture that are excellent for high-resolution imaging of growth cone motility and guidance. Here, we present a protocol for dissection and plating of Aplysia bag cell neurons as well as for setting up a chamber for live cell imaging.

Neuronal growth cones are the highly motile structures at the tip of axons that can detect guidance cues in the environment and transduce this information ...

A Multi-compartment CNS Neuron-glia Co-culture Microfluidic Platform

We present a novel multi-compartment neuron co-culture microsystem platform for in vitro CNS axon-glia interaction research, capable of conducting up to six independent experiments in parallel for higher-throughput. We developed a new fabrication method to create microfluidic devices having both micro and macro scale structures within the same device through a single soft-lithography process, enabling mass fabrication with good repeatability.
The multi-compartment microfluidic co-culture platform is composed of one soma compartment for neurons and six axon/glia compartments for oligodendrocytes (OLs). The soma compartment and axon/glia compartments are connected by arrays of axon-guiding microchannels that function as physical barriers to confine neuronal soma in the soma compartment, while allowing axons to grow into axon/glia compartments. OLs loaded into axon/glia compartments can interact only with axons but not with neuronal soma or dendrites, enabling localized axon-glia interaction studies. The microchannels also enabled fluidic isolation between compartments, allowing six independent experiments to be conducted on a single device for higher throughput.
Soft-lithography using poly(dimethylsiloxane) (PDMS) is a commonly used technique in biomedical microdevices. Reservoirs on these devices are commonly defined by manual punching. Although simple, poor alignment and time consuming nature of the process makes this process not suitable when large numbers of reservoirs have to be repeatedly created. The newly developed method did not require manual punching of reservoirs, overcoming such limitations. First, seven reservoirs (depth: 3.5 mm) were made on a poly(methyl methacrylate) (PMMA) block using a micro-milling machine. Then, arrays of ridge microstructures, fabricated on a glass substrate, were hot-embossed against the PMMA block to define microchannels that connect the soma and axon/glia compartments. This process resulted in macro-scale reservoirs (3.5 mm) and micro-scale channels (2.5 &mu;m) to coincide within a single PMMA master. A PDMS replica that served as a mold master was obtained using soft-lithography and the final PDMS device was replicated from this master.
Primary neurons from E16-18 rats were loaded to the soma compartment and cultured for two weeks. After one week of cell culture, axons crossed microchannels and formed axonal only network layer inside axon/glia compartments. Axons grew uniformly throughout six axon/glia compartments and OLs from P1-2 rats were added to axon/glia compartments at 14 days in vitro for co-culture.

We developed a novel multi-compartment neuron co-culture microsystem platform for in vitro CNS axon-glia interaction research. The platform is capable of conducting up to six independent experiments in parallel and was fabricated using a newly developed macro/micro hybrid fabrication method.

We present a novel multi-compartment neuron co-culture microsystem platform for in vitro CNS axon-glia interaction research, capable of conducting up to ...

Microfluidic Co-culture of Epithelial Cells and Bacteria for Investigating Soluble Signal-mediated Interactions

The human gastrointestinal (GI) tract is a unique environment in which intestinal epithelial cells and non-pathogenic (commensal) bacteria coexist. It has been proposed that the microenvironment that the pathogen encounters in the commensal layer is important in determining the extent of colonization. Current culture methods for investigating pathogen colonization are not well suited for investigating this hypothesis as they do not enable co-culture of bacteria and epithelial cells in a manner that mimics the GI tract microenvironment. Here we describe a microfluidic co-culture model that enables independent culture of eukaryotic cells and bacteria, and testing the effect of the commensal microenvironment on pathogen colonization. The co-culture model is demonstrated by developing a commensal Escherichia coli biofilm among HeLa cells, followed by introduction of enterohemorrhagic E. coli (EHEC) into the commensal island, in a sequence that mimics the sequence of events in GI tract infection.

This protocol describes a microfluidic co-culture model for simultaneous and localized culture of epithelial cells and bacteria. This model can be used for investigating the role of different soluble molecular signals on pathogenesis as well as screen the effectiveness of putative probiotic bacterial strains.

The human gastrointestinal (GI) tract is a unique environment in which intestinal epithelial cells and non-pathogenic (commensal) bacteria coexist. It has ...

Analysis of Schwann-astrocyte Interactions Using In Vitro Assays

Schwann cells are one of the commonly used cells in repair strategies following spinal cord injuries. Schwann cells are capable of supporting axonal regeneration and sprouting by secreting growth factors 1,2 and providing growth promoting adhesion molecules 3 and extracellular matrix molecules 4. In addition they myelinate the demyelinated axons at the site of injury 5.
However following transplantation, Schwann cells do not migrate from the site of implant and do not intermingle with the host astrocytes 6,7. This results in formation of a sharp boundary between the Schwann cells and astrocytes, creating an obstacle for growing axons trying to exit the graft back into the host tissue proximally and distally. Astrocytes in contact with Schwann cells also undergo hypertrophy and up-regulate the inhibitory molecules 8-13.
In vitro assays have been used to model Schwann cell-astrocyte interactions and have been important in understanding the mechanism underlying the cellular behaviour.
These in vitro assays include boundary assay, where a co-culture is made using two different cells with each cell type occupying different territories with only a small gap separating the two cell fronts. As the cells divide and migrate, the two cellular fronts get closer to each other and finally collide. This allows the behaviour of the two cellular populations to be analyzed at the boundary. Another variation of the same technique is to mix the two cellular populations in culture and over time the two cell types segregate with Schwann cells clumped together as islands in between astrocytes together creating multiple Schwann-astrocyte boundaries.
The second assay used in studying the interaction of two cell types is the migration assay where cellular movement can be tracked on the surface of the other cell type monolayer 14,15. This assay is commonly known as inverted coverslip assay. Schwann cells are cultured on small glass fragments and they are inverted face down onto the surface of astrocyte monolayers and migration is assessed from the edge of coverslip.
Both assays have been instrumental in studying the underlying mechanisms involved in the cellular exclusion and boundary formation. Some of the molecules identified using these techniques include N-Cadherins 15, Chondroitin Sulphate proteoglycans(CSPGs) 16,17, FGF/Heparin 18, Eph/Ephrins19.
This article intends to describe boundary assay and migration assay in stepwise fashion and elucidate the possible technical problems that might occur.

Analysis of Schwann-astrocyte Interactions Using In Vitro Assays

This article intends to describe in stepwise fashion the commonly used in vitro assays used in studying Schwann cell-asrtocyte interactions.

Schwann cells are one of the commonly used cells in repair strategies following spinal cord injuries. Schwann cells are capable of supporting axonal ...

Quantification of dsDNA using the Hitachi F-7000 Fluorescence Spectrophotometer and PicoGreen Dye

Quantification of DNA, especially in small concentrations, is an important task with a wide range of biological applications including standard molecular biology assays such as synthesis and purification of DNA, diagnostic applications such as quantification of DNA amplification products, and detection of DNA molecules in drug preparations. During this video we will demonstrate the capability of the Hitachi F-7000 Fluorescence Spectrophotometer equipped with a Micro Plate Reader accessory to perform dsDNA quantification using Molecular Probes Quant-it PicoGreen dye reagent kit.
The F-7000 Fluorescence Spectrophotometer offers high sensitivity and high speed measurements. It is a highly flexible system capable of measuring fluorescence, luminescence, and phosphorescence. Several measuring modes are available, including wavelength scan, time scan, photometry and 3-D scan measurement. The spectrophotometer has sensitivity in the range of 50 picomoles of fluorescein when using a 300 &#956;L sample volume in the microplate, and is capable of measuring scan speeds of 60,000 nm/minute. It also has a wide dynamic range of up to 5 orders of magnitude which allows for the use of calibration curves over a wide range of concentrations. The optical system uses all reflective optics for maximum energy and sensitivity. The standard wavelength range is 200 to 750 nm, and can be extended to 900 nm when using one of the optional near infrared photomultipliers. The system allows optional temperature control for the plate reader from 5 to 60 degrees Celsius using an optional external temperature controlled liquid circulator. The microplate reader allows for the use of 96 well microplates, and the measuring speed for 96 wells is less than 60 seconds when using the kinetics mode.
Software controls for the F-7000 and Microplate Reader are also highly flexible. Samples may be set in either column or row formats, and any combination of wells may be chosen for sample measurements. This allows for optimal utilization of the microplate. Additionally, the software allows importing micro plate sample configurations created in Excel and saved in comma separated values, or "csv" format. Microplate measuring configurations can be saved and recalled by the software for convenience and increased productivity. Data results can be output to a standard report, to Excel, or to an optional Report Generator Program.

Demonstration of quantification of dsDNA using Molecular Probes PicoGreen dye and Hitachi F-7000 Fluorescence Spectrophotometer equipped with a microplate reader accessory.

Quantification of DNA, especially in small concentrations, is an important task with a wide range of biological applications including standard molecular ...

Absolute Quantum Yield Measurement of Powder Samples

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and research of illumination, AV equipment, organic EL material, films, filters and fluorescent probes for bio-industry.
Quantum yield is calculated as the ratio of the number of photons absorbed, to the number of photons emitted by a material. The higher the quantum yield, the better the efficiency of the fluorescent material.
For the measurements featured in this video, we will use the Hitachi F-7000 fluorescence spectrophotometer equipped with the Quantum Yield measuring accessory and Report Generator program. All the information provided applies to this system. 
Measurement of quantum yield in powder samples is performed following these steps:
<ol>
 <li>Generation of instrument correction factors for the excitation and emission monochromators. This is an important requirement for the correct measurement of quantum yield. It has been performed in advance for the full measurement range of the instrument and will not be shown in this video due to time limitations.</li>
 <li>Measurement of integrating sphere correction factors. The purpose of this step is to take into consideration reflectivity characteristics of the integrating sphere used for the measurements.</li>
 <li>Reference and Sample measurement using direct excitation and indirect excitation.</li>
 <li>Quantum Yield calculation using Direct and Indirect excitation. Direct excitation is when the sample is facing directly the excitation beam, which would be the normal measurement setup. However, because we use an integrating sphere, a portion of the emitted photons resulting from the sample fluorescence are reflected by the integrating sphere and will re-excite the sample, so we need to take into consideration indirect excitation. This is accomplished by measuring the sample placed in the port facing the emission monochromator, calculating indirect quantum yield and correcting the direct quantum yield calculation.</li>
 <li>Corrected quantum yield calculation.</li>
 <li>Chromaticity coordinates calculation using Report Generator program.</li>
</ol>
The Hitachi F-7000 Quantum Yield Measurement System offer advantages for this
application, as follows:
<ul>
 <li>High sensitivity (S/N ratio 800 or better RMS). Signal is the Raman band of water measured under the following conditions: Ex wavelength 350 nm, band pass Ex and Em 5 nm, response 2 sec), noise is measured at the maximum of the Raman peak. High sensitivity allows measurement of samples even with low quantum yield. Using this system we have measured quantum yields as low as 0.1 for a sample of salicylic acid and as high as 0.8 for a sample of magnesium tungstate.</li>
 <li>Highly accurate measurement with a dynamic range of 6 orders of magnitude allows for measurements of both sharp scattering peaks with high intensity, as well as broad fluorescence peaks of low intensity under the same conditions. </li>
 <li>High measuring throughput and reduced light exposure to the sample, due to a high scanning speed of up to 60,000 nm/minute and automatic shutter function. </li>
 <li>Measurement of quantum yield over a wide wavelength range from 240 to 800 nm.</li>
 <li>Accurate quantum yield measurements are the result of collecting instrument spectral response and integrating sphere correction factors before measuring the sample.</li>
 <li>Large selection of calculated parameters provided by dedicated and easy to use software.
</li>
</ul> 
During this video we will measure sodium salicylate in powder form which is known to have a quantum yield value of 0.4 to 0.5.

In this video we will demonstrate measuring and calculating absolute quantum yield and chromaticity coordinates directly in powder samples using the Hitachi F-7000 Quantum Yield Measuring System.

Measurement of fluorescence quantum yield has become an important tool in the search for new solutions in the development, evaluation, quality control and ...

A High-content Imaging Workflow to Study Grb2 Signaling Complexes by Expression Cloning

Signal transduction by growth factor receptors is essential for cells to maintain proliferation and differentiation and requires tight control. Signal transduction is initiated by binding of an external ligand to a transmembrane receptor and activation of downstream signaling cascades. A key regulator of mitogenic signaling is Grb2, a modular protein composed of an internal SH2 (Src Homology 2) domain flanked by two SH3 domains that lacks enzymatic activity. Grb2 is constitutively associated with the GTPase Son-Of-Sevenless (SOS) via its N-terminal SH3 domain. The SH2 domain of Grb2 binds to growth factor receptors at phosphorylated tyrosine residues thus coupling receptor activation to the SOS-Ras-MAP kinase signaling cascade. In addition, other roles for Grb2 as a positive or negative regulator of signaling and receptor endocytosis have been described. The modular composition of Grb2 suggests that it can dock to a variety of receptors and transduce signals along a multitude of different pathways1-3.
	Described here is a simple microscopy assay that monitors recruitment of Grb2 to the plasma membrane. It is adapted from an assay that measures changes in sub-cellular localization of green-fluorescent protein (GFP)-tagged Grb2 in response to a stimulus4-6. Plasma membrane receptors that bind Grb2 such as activated Epidermal Growth Factor Receptor (EGFR) recruit GFP-Grb2 to the plasma membrane upon cDNA expression and subsequently relocate to endosomal compartments in the cell. In order to identify in vivo protein complexes of Grb2, this technique can be used to perform a genome-wide high-content screen based on changes in Grb2 sub-cellular localization. The preparation of cDNA expression clones, transfection and image acquisition are described in detail below. Compared to other genomic methods used to identify protein interaction partners, such as yeast-two-hybrid, this technique allows the visualization of protein complexes in mammalian cells at the sub-cellular site of interaction by a simple microscopy-based assay. Hence both qualitative features, such as patterns of localization can be assessed, as well as the quantitative strength of the interaction.

A high-content screening method for the identification of novel signaling competent transmembrane receptors is described. This method is amenable to large-scale automation and allows predictions about in vivo protein binding and the sub-cellular localization of protein complexes in mammalian cells.

Signal  transduction by growth factor receptors is essential for cells to maintain  proliferation and differentiation and requires tight control. Signal  ...

A High Throughput MHC II Binding Assay for Quantitative Analysis of Peptide Epitopes

Biochemical assays with recombinant human MHC II molecules can provide rapid, quantitative insights into immunogenic epitope identification, deletion, or design1,2. Here, a peptide-MHC II binding assay is scaled to 384-well format. The scaled down protocol reduces reagent costs by 75% and is higher throughput than previously described 96-well protocols1,3-5. Specifically, the experimental design permits robust and reproducible analysis of up to 15 peptides against one MHC II allele per 384-well ELISA plate. Using a single liquid handling robot, this method allows one researcher to analyze approximately ninety test peptides in triplicate over a range of eight concentrations and four MHC II allele types in less than 48 hr. Others working in the fields of protein deimmunization or vaccine design and development may find the protocol to be useful in facilitating their own work. In particular, the step-by-step instructions and the visual format of JoVE should allow other users to quickly and easily establish this methodology in their own labs.

Biochemical assays with recombinant human MHC II molecules can provide rapid, quantitative insights into immunogenic epitope identification, deletion, or design. &#160;Here, a peptide-MHC II binding assay scaled to 384-well plates is described. This cost effective format should prove useful in the fields of protein deimmunization and vaccine design and development.

Biochemical assays with recombinant human MHC II molecules can provide rapid, quantitative insights into immunogenic epitope identification, deletion, or ...

qPCRTag Analysis - A High Throughput, Real Time PCR Assay for Sc2.0 Genotyping

The Synthetic Yeast Genome Project (Sc2.0) aims to build 16 designer yeast chromosomes and combine them into a single yeast cell. To date one synthetic chromosome, synIII1, and one synthetic chromosome arm, synIXR2, have been constructed and their in vivo function validated in the absence of the corresponding wild type chromosomes. An important design feature of Sc2.0 chromosomes is the introduction of PCRTags, which are short, re-coded sequences within open reading frames (ORFs) that enable differentiation of synthetic chromosomes from their wild type counterparts. PCRTag primers anneal selectively to either synthetic or wild type chromosomes and the presence/absence of each type of DNA can be tested using a simple PCR assay. The standard readout of the PCRTag assay is to assess presence/absence of amplicons by agarose gel electrophoresis. However, with an average PCRTag amplicon density of one per 1.5 kb and a genome size of ~12 Mb, the completed Sc2.0 genome will encode roughly 8,000 PCRTags. To improve throughput, we have developed a real time PCR-based detection assay for PCRTag genotyping that we call qPCRTag analysis. The workflow specifies 500 nl reactions in a 1,536 multiwell plate, allowing us to test up to 768 PCRTags with both synthetic and wild type primer pairs in a single experiment.

Designer chromosomes of the Synthetic Yeast Genome project, Sc2.0, can be distinguished from their native counterparts using a PCR-based genotyping assay called PCRTagging, which has a presence/absence endpoint. Here we describe a high-throughput real time PCR detection method for PCRTag genotyping.

The Synthetic Yeast Genome Project (Sc2.0) aims to build 16 designer yeast chromosomes and combine them into a single yeast cell. To date one synthetic ...

High Content Screening Analysis to Evaluate the Toxicological Effects of Harmful and Potentially Harmful Constituents (HPHC)

Cigarette smoke (CS) is a major risk factor for cardiovascular and lung diseases. Because CS is a complex aerosol containing more than 7,000 chemicals1 it is challenging to assess the contributions of individual constituents to its overall toxicity. Toxicological profiles of individual constituents as well as mixtures can be however established in vitro, by applying high through-put screening tools, which enable the profiling of Harmful and Potentially Harmful Constituents (HPHCs) of tobacco smoke, as defined by the U.S. Food and Drug Administration (FDA).2
For an initial assessment, an impedance-based instrument was used for a real-time, label-free assessment of the compound&#39;s toxicity. The instrument readout relies on cell adhesion, viability and morphology that all together provide an overview of the cell status. A dimensionless parameter, named cell index, is used for quantification. A set of different staining protocols was developed for a fluorescence imaging-based investigation and a HCS platform was used to gain more in-depth information on the kind of cytotoxicity elicited by each HPHC.
Of the 15 constituents tested, only five were selected for HCS-based analysis as they registered a computable LD50 (&#60; 20 mM). These included 1-aminonaphtalene, Arsenic (V), Chromium (VI), Crotonaldehyde and Phenol. Based on their effect in the HCS, 1-aminonaphtalene and Phenol could be identified to induce mitochondrial dysfunction, and, together with Chromium (VI) as genotoxic based on the increased histone H2AX phosphorylation. Crotonaldehyde was identified as an oxidative stress inducer and Arsenic as a stress kinase pathway activator.
This study demonstrates that a combination of impedance-based and HCS technologies provides a robust tool for in vitro assessment of CS constituents.

High Content Screening Analysis to Evaluate the Toxicological Effects of Harmful and Potentially Harmful Constituents HPHC

The objective of the study was to assess the biological impact of 15 cigarette smoke constituents using a combination of an impedance-based real time cell analyzer and a high-content screening (HCS)-based platform for toxicological assessment in vitro. This study provides information on effective doses, toxicity and modes of action of the tested compounds.

Cigarette smoke (CS) is a major risk factor for cardiovascular and lung diseases. Because CS is a complex aerosol containing more than 7,000 chemicals1 it ...