This work is supported by the Office of Research and Development, Medical Research Service, Department of Veterans Affairs. This study was funded by a VA Merit Review Award (to MCL) and the University of Tennessee Health Science Center Multiple Sclerosis Research Fund.

1. Antibody Labeling (Figure 1)
<ol>
 <li>Make 0.1 M NaHCO3 buffer:
 <ul type="circle">
 <li>8.4 g NaHCO3</li>
 <li>29.2 g NaCl</li>
 <li>1 liter H2O</li>
 </ul>
 </li>
 <li>Bring the buffer up to a pH of 8.4 with this solution (10.6 g Na2CO3, 29.2 g NaCl, 1 liter H20).</li>
 <li>Add 35 &mu;l Atto550 NHS to 70 &mu;l anti-hnRNPA1 and 500 &mu;l NaHCO3 buffer and rotate for 1 hr at room temperature. After the hour-long rotation, inject the mixture into a dialyzer and dialyze in 2 liters of PBS overnight.</li>
 <li>The next day, concentrate the dialyzed Atto550 NHS anti-hnRNPA1 using a spin column (Amicon Ultra 0.5).</li>
 <li>After the Atto550 NHS labeled anti-hnRNPA1 antibody has been concentrated, nano-drop sample to determine the concentration.</li>
</ol>
2. Antibody Transfection (Figure 2)
<ol>
 <li>Seed 105 cells/well into 500 &mu;l of Dulbecco's Modified Eagle Medium (DMEM/F12+10% FBS+1% antibiotic) in an 8 well slide 24 hr prior to transfection. Cell confluency should be at least 70%.</li>
 <li>Twenty four hours after seeding, add 2 &mu;l of Ab-DeliverIN reagent into an Eppendorf tube.</li>
 <li>Next, add 2 &mu;g of Atto550 NHS labeled anti-hnRNPA1 antibody (0.5 &mu;g/&mu;l) to the same Eppendorf tube and incubate 10-15 min at RT.</li>
 <li>During the incubation, aspirate media and add 394 &mu;l of fresh DMEM media to the cells.</li>
</ol>
Note: Add 500 &mu;l DMEM to one chamber of untouched cells to act as a control.
<ol start="5">
 <li>After incubation, add 100 &mu;l of DMEM to the antibody mixture, mix by pipetting up and down, and add to the cells in DMEM for a total volume of 500 &mu;l.</li>
 <li>Change the media after 48 hr of antibody delivery.</li>
</ol>
Note: Protocol was repeated with FITC labeled rIgG as positive control.
3. Live and Fixed Imaging to Determine Efficiency
<ol>
 <li>Image cells live at 48 hr using the Cy3 filter on a fluorescent microscope to image the transfected Atto550 NHS labeled antibodies.</li>
 <li>After live imaging has been completed, aspirate the media and fix cells.</li>
 <li>After aspirating media, treat cells with 0.4% Paraformaldehyde for 15 min at room temperature. Wash cells 4 x 5 min each with PBS. Then, mount cells with mounting media containing DAPI reagent and fix coverslip. Measure transfection efficiency of the fixed cells with Axiovision software. If Axiovision software is not on hand, simply count the events from your image by hand and plug results into calculation in 3.7. Alternatively, ImageJ software can be used for these calculations.</li>
 <li>First, use the "Events" measurement to count the total number of cells in your image of choice at 20x magnification.</li>
 <li>Next, use the "Events" measurement to count the cells that were not successfully transfected with antibodies in the same 20x magnification image.</li>
 <li>To access the measured "Events" in an Excel style format, click on "Properties", click the "Measurement" tab, and click to view "As Table."</li>
 <li>Finally, use the following calculation to determine your transfection efficiency by comparing the two previously measured events: ((Total cells - Untransfected Cells) / Total Cells) x 100 = Transfection Efficiency.</li>
</ol>
4. Representative Results
The live images of untransfected (Figure 3A) compared to transfected (Figure 3B) neurons reveal that the labeling of the antibodies (red or green in each figure) is clearly observed within cells (Figure 3B, C, D). Following aspiration and washing with media to remove antibodies between or adherent to the surface of cells, labeled antibodies are still present within neurons (Figure 3C, D). To calculate the transfection efficiency, use the Axiovision software to calculate total cells compared to cells that were not successfully transfected. These values were entered into a transfection efficiency formula to acquire the transfection efficiency as a percentage of total cells (Figure 4).
<img alt="Figure 1" src="/files/ftp_upload/4154/4154fig1.jpg" /> 
Figure 1. Flow diagram of the procedures used to label antibodies with the Atto 550 NHS ester followed by steps required to concentrate the labeled antibodies. <a href="https://www.jove.com/files/ftp_upload/4154/4154fig1large.jpg" target="_blank">Click here to view larger figure</a>.
<img alt="Figure 2" src="/files/ftp_upload/4154/4154fig2.jpg" /> 
Figure 2. Flow diagram of the procedures used to transfect labeled antibodies into live cells in culture. <a href="https://www.jove.com/files/ftp_upload/4154/4154fig2large.jpg" target="_blank">Click here to view larger figure</a>.
<img alt="Figure 3" src="/files/ftp_upload/4154/4154fig3.jpg" /> 
Figure 3. Live images of the transfected neurons 48 hr following transfection.
<img alt="Figure 4" src="/files/ftp_upload/4154/4154fig4.jpg" /> 
Figure 4. Fixed and rinsed images with events counted in order to determine transfection efficiency.

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Neuroimmunol. 18, 97-104 (1988).</li><li>Lee, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HTLV-1+induced+molecular+mimicry+in+neurological+disease.">HTLV-1 induced molecular mimicry in neurological disease.</a> Curr. Top Microbiol. Immunol. 29, 125-136 (2005).</li><li>Reeves, W. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Systemic+lupus+erythematosus.+Antibodies+to+DNA,+DNA-binding+proteins,+and+histones.">Systemic lupus erythematosus. Antibodies to DNA, DNA-binding proteins, and histones.</a> Rheum. Dis. Clin. North Am. 20, 1-28 (1994).</li><li>Levin, M. 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No conflicts of interest declared.

In order to test hypotheses about specific molecules and their expression, genes and other vectors are commonly transfected into cells. The unique aspect of this procedure is the ability to easily transfect antibodies into target cells. We performed this method in five separate experiments each in duplicates. Transfection efficiency results were similar among all experiments. Importantly, the method enables entry of antibodies into the cell without altering antibody structure or function. Further, with the use of fluores...

<table border="1">
 <tbody>
 <tr>
 <td>Name of Reagent</td>
 <td>Company</td>
 <td>Catalogue Number</td>
 </tr>
 <tr>
 <td>Fluorescent Microscope AxioObserver A1</td>
 <td>Zeiss</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Axiovision version 4.2</td>
 <td>Zeiss</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Anti-rhnRNPA1</td>
 <td>Abcam</td>
 <td>Ab4791</td>
 </tr>
 <tr>
 <td>FITC labeled anti-rIgG</td>
 <td>OZ Biosciences</td>
 <td>AI20100</td>
 </tr>
 <tr>
 <td>Atto550 NHS ester</td>
 <td>Sigma</td>
 <td>92835</td>
 </tr>
 <tr>
 <td>Ab-DeliverIN</td>
 <td>OZ Biosciences</td>
 <td>AI20100</td>
 </tr>
 <tr>
 <td>DMEM/F12 +10% FBS+1%antibiotics</td>
 <td>Gibco</td>
 <td>11320-033 </td>
 </tr>
 <tr>
 <td>Poly-D-Lysine 8-well Culture Slides </td>
 <td>BD</td>
 <td>354632 </td>
 </tr>
 <tr>
 <td>Multi-Purpose Rotator</td>
 <td>Scientific Industries Inc</td>
 <td>Model 151</td>
 </tr>
 <tr>
 <td>DAPI Mounting Media</td>
 <td>Millipore</td>
 <td>S7113</td>
 </tr>
 <tr>
 <td>PBS</td>
 <td>Ambion</td>
 <td>9626</td>
 </tr>
 <tr>
 <td>Dialyzer</td>
 <td>Thermo Fisher Scientific</td>
 <td>66380</td>
 </tr>
 <tr>
 <td>Amicon Ultra-0.5</td>
 <td>Millipore</td>
 <td>UFC501096</td>
 </tr>
 <tr>
 <td>Paraformaldehyde (4% solution)</td>
 <td>Electron Microscopy Sciences</td>
 <td>&nbsp;</td>
 </tr>
 <tr>
 <td>Nano-Drop</td>
 <td>Thermo Fisher Scientific</td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
</table>

antibody transfection into neurons as a tool to study disease pathogenesis

Antibodies provide the ability to gain novel insight into various events taking place in living systems. The ability to produce highly specific antibodies to target proteins has allowed for very precise biological questions to be addressed. Importantly, antibodies have been implicated in the pathogenesis of a number of human diseases including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), paraneoplastic syndromes, multiple sclerosis (MS) and human T-lymphotropic virus type 1 (HTLV-1) associated myelopathy/tropical spastic paraparesis (HAM/TSP) 1-9. How antibodies cause disease is an area of ongoing investigation, and data suggests that interactions between antibodies and various intracellular molecules results in inflammation, altered cellular messaging, and apoptosis 10. It has been shown that patients with MS and HAM/TSP produce autoantibodies to the intracellular RNA binding protein heterogeneous ribonuclear protein A1 (hnRNP A1) 3, 5-7, 9, 11. Recent data indicate that antibodies to both intra-neuronal and surface antigens are pathogenic 3, 5-9, 11. Thus, a procedure that allows for the study of intracellular antibody:protein interactions would lend great insight into disease pathogenesis.
Genes are commonly transfected into primary cells and cell lines in culture, however transfection of antibodies into cells has been hindered by alteration of antibody structure or poor transfection efficiency 12. Other methods of transfection include antibody transfection based on cationic liposomes (consisting of DOTAP/DOPE) and polyethylenimines (PEI); both of which resulted in a ten-fold decrease in antibody transfection compared to controls 12. The method performed in our study is similar to cationic lipid-mediated methods and uses a lipid-based mechanism to form non-covalent complexes with the antibodies through electrostatic and hydrophobic interactions 13. We utilized Ab-DeliverIN reagent, which is a lipid formulation capable of capturing antibodies through non-covalent electrostatic and hydrophobic interactions and delivering them inside cells. Thus chemical and genetic couplings are not necessary for delivery of functional antibodies into living cells. This method has enabled us to perform various antibody tracing and protein localization experiments, as well as the analyses of the molecular consequences of intracellular antibody:protein interactions 9.
In this protocol, we will show how to transfect antibodies into neurons rapidly, reproducibly and with a high degree of transfection efficiency. As an example, we will use anti-hnRNP A1 and anti-IgG antibodies. For easy quantification of transfection efficiency we used anti-hnRNP A1 antibodies labelled with Atto-550-NHS and FITC-labeled IgG. Atto550 NHS is a new label with high molecular absorbtion and quantum yield. Excitation source and fluorescent filters for Atto550 are similar to Cy3 (Ex. 556 Em. 578). In addition, Atto550 has high photostability. FITC-labeled IgG were used as a control to show that this method is versatile and not dye dependent. This approach and the data that is generated will assist in understanding of the role that antibodies to intracellular target antigens might play in the pathogenesis of human diseases.

Watch this Scientific Journal Video about Antibody Transfection into Neurons as a Tool to Study Disease Pathogenesis at JoVE.com

Antibody Transfection into Neurons as a Tool to Study Disease Pathogenesis

A rapid approach to investigate interactions and effects on molecular mechanisms related to the presence of antibodies in an intracellular environment is described. The method involves transfection of antibodies into live cells using a non-covalent complex formation based on a lipid formulation. The technique is adaptable to immortalized cell lines and primary cells.

Antibodies provide the ability to gain novel insight into various events taking place in living systems.  The ability to produce highly specific ...

antibody-transfection-into-neurons-as-tool-to-study-disease

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JoVE Journal

Neuroscience

10.7K Views.  Veterans Administration Medical Center, Memphis, TN. A rapid approach to investigate interactions and effects on molecular mechanisms related to the presence of antibodies in an intracellular environment is described. The method involves transfection of antibodies into live cells using a non-covalent complex formation based on a lipid formulation. The technique is adaptable to immortalized cell lines and primary cells.

Video: Antibody Transfection into Neurons as a Tool to Study Disease Pathogenesis

Laser Capture Microdissection of Drosophila Peripheral Neurons

The dendritic arborization (da) neurons of the Drosophila peripheral nervous system (PNS) provide an excellent model system in which to investigate the molecular mechanisms underlying class-specific dendrite morphogenesis1,2. To facilitate molecular analyses of class-specific da neuron development, it is vital to obtain these cells in a pure population. Although a range of different cell, and tissue-specific RNA isolation techniques exist for Drosophila cells, including magnetic bead based cell purification3,4, Fluorescent Activated Cell Sorting (FACS)5-8, and RNA binding protein based strategies9, none of these methods can be readily utilized for isolating single or multiple class-specific Drosophila da neurons with a high degree of spatial precision. Laser Capture Microdissection (LCM) has emerged as an extremely powerful tool that can be used to isolate specific cell types from tissue sections with a high degree of spatial resolution and accuracy. RNA obtained from isolated cells can then be used for analyses including qRT-PCR and microarray expression profiling within a given cell type10-16. To date, LCM has not been widely applied in the analysis of Drosophila tissues and cells17,18, including da neurons at the third instar larval stage of development. 
Here we present our optimized protocol for isolation of Drosophila da neurons using the infrared (IR) class of LCM. This method allows for the capture of single, class-specific or multiple da neurons with high specificity and spatial resolution. Age-matched third instar larvae expressing a UAS-mCD8::GFP19 transgene under the control of either the class IV da neuron specific ppk-GAL420 driver or the pan-da neuron specific 21-7-GAL421 driver were used for these experiments. RNA obtained from the isolated da neurons is of very high quality and can be directly used for downstream applications, including qRT-PCR or microarray analyses. Furthermore, this LCM protocol can be readily adapted to capture other Drosophila cell types a various stages of development dependent upon the cell type specific, GAL4-driven expression pattern of GFP.

Laser Capture Microdissection of Drosophila Peripheral Neurons

In this video-article we present a method for isolating single or multiple Drosophila da neurons from third instar larvae using the infrared capture (IR) class of Laser Capture Microdissection (LCM). RNA obtained from the isolated neurons can be readily used for downstream applications including qRT-PCR or microarray analyses.

The dendritic arborization (da) neurons of the Drosophila peripheral nervous system (PNS) provide an excellent model system in which to investigate the ...

Cut-loading: A Useful Tool for Examining the Extent of Gap Junction Tracer Coupling Between Retinal Neurons

In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic transmission. Increasing evidence indicates that gap junctions not only permit electrical current flow and synchronous activity between interconnected or coupled cells, but that the strength or effectiveness of electrical communication between coupled cells can be modulated to a great extent1,2. In addition, the large internal diameter (~1.2 nm) of many gap junction channels permits not only electric current flow, but also the diffusion of intracellular signaling molecules and small metabolites between interconnected cells, so that gap junctions may also mediate metabolic and chemical communication. The strength of gap junctional communication between neurons and its modulation by neurotransmitters and other factors can be studied by simultaneously electrically recording from coupled cells and by determining the extent of diffusion of tracer molecules, which are gap junction permeable, but not membrane permeable, following iontophoretic injection into single cells. However, these procedures can be extremely difficult to perform on neurons with small somata in intact neural tissue.
Numerous studies on electrical synapses and the modulation of electrical communication have been conducted in the vertebrate retina, since each of the five retinal neuron types is electrically connected by gap junctions3,4. Increasing evidence has shown that the circadian (24-hour) clock in the retina and changes in light stimulation regulate gap junction coupling3-8. For example, recent work has demonstrated that the retinal circadian clock decreases gap junction coupling between rod and cone photoreceptor cells during the day by increasing dopamine D2 receptor activation, and dramatically increases rod-cone coupling at night by reducing D2 receptor activation7,8. However, not only are these studies extremely difficult to perform on neurons with small somata in intact neural retinal tissue, but it can be difficult to adequately control the illumination conditions during the electrophysiological study of single retinal neurons to avoid light-induced changes in gap junction conductance.
Here, we present a straightforward method of determining the extent of gap junction tracer coupling between retinal neurons under different illumination conditions and at different times of the day and night. This cut-loading technique is a modification of scrape loading9-12, which is based on dye loading and diffusion through open gap junction channels. Scrape loading works well in cultured cells, but not in thick slices such as intact retinas. The cut-loading technique has been used to study photoreceptor coupling in intact fish and mammalian retinas7, 8,13, and can be used to study coupling between other retinal neurons, as described here.

An easy and convenient method to determine the extent of gap junction tracer coupling between retinal neurons is described. This technique enables one to investigate the function of the electrical synapses between neurons in the intact retina under different illumination conditions and at different times of the day and night.

In addition to chemical synaptic transmission, neurons that are connected by gap junctions can also communicate rapidly via electrical synaptic ...

Calcium Phosphate Transfection of Primary Hippocampal Neurons

Calcium phosphate precipitation is a convenient and economical method for transfection of cultured cells. With optimization, it is possible to use this method on hard-to-transfect cells like primary neurons. Here we describe our detailed protocol for calcium phosphate transfection of hippocampal neurons cocultured with astroglial cells.

Calcium phosphate precipitation is a convenient and economical method for transfection of cultured cells. With optimization, it is possible to use this ...

Real-Time Impedance-based Cell Analyzer as a Tool to Delineate Molecular Pathways Involved in Neurotoxicity and Neuroprotection in a Neuronal Cell Line

Many brain-related disorders have neuronal cell death involved in their pathophysiology. Improved in vitro models to study neuroprotective or neurotoxic effects of drugs and downstream pathways involved would help gain insight into the molecular mechanisms of neuroprotection/neurotoxicity and could potentially facilitate drug development. However, many existing in vitro toxicity assays have major limitations &#8211; most assess neurotoxicity and neuroprotection at a single time point, not allowing to observe the time-course and kinetics of the effect. Furthermore, the opportunity to collect information about downstream signaling pathways involved in neuroprotection in real-time would be of great importance. In the current protocol we describe the use of a real-time impedance-based cell analyzer to determine neuroprotective effects of serotonin 2A (5-HT2A) receptor agonists in a neuronal cell line under label-free and real-time conditions using impedance measurements. Furthermore, we demonstrate that inhibitors of second messenger pathways can be used to delineate downstream molecules involved in the neuroprotective effect. We also describe the utility of this technique to determine whether an effect on cell proliferation contributes to an observed neuroprotective effect. The system utilizes special microelectronic plates referred to as E-Plates which contain alternating gold microelectrode arrays on the bottom surface of the wells, serving as cell sensors. The impedance readout is modified by the number of adherent cells, cell viability, morphology, and adhesion. A dimensionless parameter called Cell Index is derived from the electrical impedance measurements and is used to represent the cell status. Overall, the real-time impedance-based cell analyzer allows for real-time, label-free assessment of neuroprotection and neurotoxicity, and the evaluation of second messenger pathways involvement, contributing to more detailed and high-throughput assessment of potential neuroprotective compounds in vitro, for selecting therapeutic candidates.

Improved in vitro neurotoxicity assays would aid the identification of new neuroprotective compounds. The utility of a real-time impedance-based cell analyzer to determine cytotoxicity and cytoprotection in neuronal cell lines and to delineate the involvement of second messenger pathways, thus gaining insight in the mechanism of neuroprotection is presented.

Many brain-related disorders have neuronal cell death involved in their pathophysiology. Improved in vitro models to study neuroprotective or neurotoxic ...

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of the olfactory epithelium continuously give rise to new sensory neurons that extend their axons into the olfactory bulb, where they face the challenge to integrate into existing circuitry. Because of this particular feature, the olfactory system represents a unique opportunity to monitor axonal wiring and guidance, and to investigate synapse formation. Here we describe a procedure for in vivo labeling of sensory neurons and subsequent visualization of axons in the olfactory system of larvae of the amphibian Xenopus laevis. To stain sensory neurons in the olfactory organ we adopt the electroporation technique. In vivo electroporation is an established technique for delivering fluorophore-coupled dextrans or other macromolecules into living cells. Stained sensory neurons and their axonal processes can then be monitored in the living animal either using confocal laser-scanning or multiphoton microscopy. By reducing the number of labeled cells to few or single cells per animal, single axons can be tracked into the olfactory bulb and their morphological changes can be monitored over weeks by conducting series of in vivo time lapse imaging experiments. While the described protocol exemplifies the labeling and monitoring of olfactory sensory neurons, it can also be adopted to other cell types within the olfactory and other systems.

The Olfactory System as a Model to Study Axonal Growth Patterns and Morphology In Vivo

We describe a protocol for in vivo labeling of olfactory sensory neurons by electroporation and subsequent confocal laser-scanning or multiphoton microscopy to visualize neuronal morphology and its development over time.

The olfactory system has the unusual capacity to generate new neurons throughout the lifetime of an organism. Olfactory stem cells in the basal portion of ...

Intramuscular Injections Along the Motor End Plates: A Minimally Invasive Approach to Shuttle Tracers Directly into Motor Neurons

Diseases affecting the integrity of spinal cord motor neurons are amongst the most debilitating neurological conditions. Over the last decades, the development of several animal models of these neuromuscular disorders has provided the scientific community with different therapeutic scenarios aimed at delaying or reversing the progression of these conditions. By taking advantage of the retrograde machinery of neurons, one of these approaches has been to target skeletal muscles in order to shuttle therapeutic genes into corresponding spinal cord motor neurons. Although once promising, the success of such gene delivery approach has been hampered by the sub-optimal number of transduced motor neurons it has so far shown to yield. Motor end plates (MEPs) are highly specialized regions on the skeletal musculature that are in direct synaptic contact to the spinal cord &#945; motor neurons. In this regard, it is important to note that, so far, the efforts to retrogradely transfer genes into motor neurons were made without reference to the location of the MEP region in the targeted muscles. Here, we describe a simple protocol 1) to reveal the exact location of the MEPs on the surface of skeletal muscles and 2) to use this information to guide the intramuscular delivery and subsequent optimal retrograde transport of retrograde tracers into motor neurons. We hope to utilize the results from these tracing experiments in further studies into investigating retrograde transport of therapeutic genes to spinal cord motor neurons through the targeting of MEPs.

The efficacy of intramuscular uptake and retrograde transport of molecules to corresponding motor neurons depends on the location of the injection sites with respect to the motor end plates (MEPs). Here, we describe how to locate MEPs on skeletal muscles to optimise retrograde transport of tracers into motor neurons.

Diseases affecting the integrity of spinal cord motor neurons are amongst the most debilitating neurological conditions. Over the last decades, the ...

Stripe Assay to Study the Attractive or Repulsive Activity of a Protein Substrate Using Dissociated Hippocampal Neurons

Growing axons develop a highly motile structure at their tip, termed the growth cone. The growth cone contacts extracellular environmental cues to navigate axonal growth. Netrin, slit, semaphorin, and ephrins are known guidance molecules that can attract or repel axons upon binding to receptors and co-receptors on the axon. The activated receptors initiate various signaling molecules in the growth cone that alter the structure and movement of the neuron. Here, we describe the detailed protocol for a stripe assay to assess the ability of a guidance molecule to attract or repel neurons. In this method, dissociated hippocampal neurons from E15.5 mice are cultured on laminin-coated dishes processed with alternating stripes of ectodomain of fibronectin and leucine-rich transmembrane protein-2 (FLRT2) and control immunoglobulin G (IgG) fragment crystallizable region (Fc) protein. Both axons and cell bodies were strongly repelled from the FLRT2-coated stripe regions after 24 h of culture. Immunostaining with tau1 showed that ~90% of the neurons were distributed on the Fc-coated stripes compared to the FLRT2-Fc-coated stripes (~10%). This result indicates that FLRT2 has a strong repulsive effect on these neurons. This powerful method is applicable not only for primary cultured neurons but also for a variety of other cells, such as neuroblasts.

Axon guidance molecules regulate neuronal migration and targeted growth-cone navigation. We present a powerful method, the stripe assay, to assess the ability of guidance molecules to attract or repulse neurons. In this protocol, we demonstrate the stripe assay by showing FLRT2's ability to repel cultured hippocampal neurons.

Growing axons develop a highly motile structure at their tip, termed the growth cone. The growth cone contacts extracellular environmental cues to ...

Organotypic Hippocampal Slice Cultures As a Model to Study Neuroprotection and Invasiveness of Tumor Cells

In organotypic hippocampal slice cultures (OHSC), the morphological and functional characteristics of both neurons and glial cells are well preserved. This model is suitable for addressing different research questions that involve studies on neuroprotection, electrophysiological experiments on neurons, neuronal networks or tumor invasion. The hippocampal architecture and neuronal activity in multisynaptic circuits are well conserved in OHSC, even though the slicing procedure itself initially lesions and leads to formation of a glial scar. The scar formation alters presumably the mechanical properties and diffusive behavior of small molecules, etc. Slices allow the monitoring of time dependent processes after brain injury without animal surgery, and studies on interactions between various brain-derived cell types, namely astrocytes, microglia and neurons under both physiological and pathological conditions. An ambivalent aspect of this model is the absence of blood flow and immune blood cells. During the progression of the neuronal injury, migrating immune cells from the blood play an important role. As those cells are missing in slices, the intrinsic processes in the culture may be observed without external interference. Moreover, in OHSC the composition of the medium-external environment is precisely controlled. A further advantage of this method is the lower number of sacrificed animals compared to standard preparations. Several OHSC can be obtained from one animal making simultaneous studies with multiple treatments in one animal possible. For these reasons, OHSC are well suited to analyze the effects of new protective therapeutics after tissue damage or during tumor invasion. 
The protocol presented here describes a preparation method of OHSC that allows generating highly reproducible, well preserved slices that can be used for a variety of experimental research, like neuroprotection or tumor invasion studies.

Organotypic hippocampal slice cultures (OHSC) represent an in vitro model that simulates the in vivo situation very well. Here we describe a vibratome-based improved slicing protocol to obtain high quality slices for use in assessing the neuroprotective potential of novel substances or the biological behavior of tumor cells.

In organotypic hippocampal slice cultures (OHSC), the morphological and functional characteristics of both neurons and glial cells are well preserved. ...

Exogenous Administration of Microsomes-associated Alpha-synuclein Aggregates to Primary Neurons As a Powerful Cell Model of Fibrils Formation

For years, the inability of replicating formation of insoluble alpha-synuclein (&#945;S) inclusions in cell cultures has been a great limitation in the study of &#945;S aggregation in Parkinson&#39;s Disease (PD). Recently, the development of new animal models through the exogenous inoculation of brain extracts from diseased &#945;S transgenic mice or PD patients has given new hopes to the possibility of creating more adequate cell models of &#945;S aggregation. Unfortunately, when it comes to cells in cultures, administration of raw brain extracts has not proven as successful as in mice and the source of choice of exogenous aggregates is still in vitro preformed &#945;S fibrils.
We have developed a method to induce the formation of intracellular &#945;S inclusions in primary neurons through the exogenous administration of native microsomes-associated &#945;S aggregates, a highly toxic &#945;S species isolated from diseased areas of transgenic mice. This fraction of &#945;S aggregates that is associated with the microsomes vesicles, is efficiently internalized and induces the formation of intracellular inclusions positive for aggregated and phosphorylated &#945;S. Compared to in vitro-preformed fibrils which are made from recombinant &#945;S, our method is faster and guarantees that the pathogenic seeding is made with authentic &#945;S aggregates extracted from diseased animal models of PD, mimicking more closely the type of inclusions obtained in vivo. As a result, availability of tissues rich in &#945;S inclusions is mandatory.
We believe that this method will provide a versatile cell-based model to study the microscopic aspects of &#945;S aggregation and the related cellular pathophysiology in vivo and will be a starting point for the creation of more accurate and sophisticated cell paradigm of PD.

The goal of this protocol is to provide a cell-based system that replicates the formation of alpha-synuclein aggregates in vivo. Intracellular alpha-synuclein inclusions are seeded in primary neurons by the internalization and propagation of exogenous administered native microsomes-associated alpha-synuclein aggregates isolated from diseased alpha-synuclein transgenic mice.

For years, the inability of replicating formation of insoluble alpha-synuclein (&#945;S) inclusions in cell cultures has been a great limitation in the ...

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing neuronal dysfunction which eventually leads to cognitive decline. Hyperphosphorylated tau aggregates in the neuron are believed to cause most of the pathology associated with AD. These aggregates are assumed to be released into the extracellular compartment and taken up by adjacent healthy neurons where they induce further tau aggregation. This &#34;prion-like&#34; spreading can be interrupted by antibodies capable of binding and &#34;neutralizing&#34; extracellular tau aggregates as shown in preclinical mouse models of AD. One of the proposed mechanisms by which therapeutic antibodies reduce pathology is antibody-mediated uptake and clearance of pathological aggregated forms of tau by microglia. Here, we describe a quantitative cell-based assay to assess tau uptake by microglia. This assay uses the mouse microglial cell line BV-2, allows for high specificity, low variability and medium throughput. Data generated with this assay can contribute to a better characterization of anti-tau antibody effector functions.

Here we describe a cell-based assay to quantitatively assess tau uptake by microglia with the aim of creating an investigational tool to better characterize the mechanisms of action of anti-tau antibodies.

Alzheimer&#39;s disease (AD) is a progressive neurodegenerative condition in which aggregated tau and amyloid proteins accumulate in the brain causing ...