The methodology was originally developed in Dr. Hongjun Song's laboratory at the Institute for Cell Engineering, Department of Neurology, Johns Hopkins School of Medicine. This work was funded by NIMH (R00MH090115), NARSAD, the Fraternal Order of Eagles' Mayo Cancer Research Fund and a start-up package from Mayo foundation awarded to M.H.J. and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (A3014385) awarded to W.R.K.

1. Pre-immunohistochemistry: Perfusion and Histology
<ol>
	<li>Perfuse mice as per a general transcardial protocol adapted for mice and extract the brains into 4% paraformaldehyde (PFA)9.</li>
	<li>Leave the brains in PFA overnight at 4 &#176;C (e.g. a 10 ml conical tube filled with PFA). Keep in PFA for at least 12-24 hr, no more than 36 hr for full fixation. After overnight fixation, empty out PFA from conical tube but leave brains inside. Pour 30% sucrose into tube and wash the brains for a brief 5 sec to remove any residual PFA. Finally, fill tube containing brains with 30% sucrose again. Keep brains in sucrose at 4 &#176;C until brains sink to the bottom of tube.</li>
	<li>Cut 40 &#956;m brain sections on a microtome. Consult a mouse brain atlas to start collecting sections from the beginning of the dentate gyrus till its end. Preserve sections in anti-freeze solution (a simple recipe is 300 g sucrose in 500 ml 0.1 M PBS and 300 ml ethylene glycol) until ready for immunohistochemistry.</li>
	<li>Mount the cut tissue on microscope slides specifically designed to adhere strongly to tissue. These slides provide a strong hold to tissue during the boiling stage. After mounting the tissue, please let the slide dry for 10 min or until it is fully dry. Drying can be expedited if the slide is rested against a vertical surface with the slide&#39;s bottom edge on a paper towel. If more than one slide is being mounted, the other slide(s) may be left dry during that time (1-2 hr is okay) until ready to proceed to the next step.</li>
	<li>Once slide is dry, wash with PBS three times for 5 min each and dry again (PBS buffer = 0.137 M NaCl, 0.0027 M KCl, 0.0119 M Na2PO4). This ensures any previous chemical (such as glycerol from anti-freeze storage solution) is sufficiently removed and cannot impair the tissue&#39;s adherence to the slide.</li>
</ol>
2. Preparation of Reagents and Minor Equipment
<ol>
	<li>Prepare Solution A (0.1 M or 19.21 g/l citric acid) and Solution B (0.1 M or 24.9 g/l tris-sodium citrate) in which tissue sections will be boiled.</li>
	<li>In a graduated cylinder, combine 9 ml of Solution A and 41 ml of Solution B. Add 450 ml of ddH2O to this mixture.</li>
	<li>Pour this mixture into an empty container (e.g. an empty pipette tips box) that is microwave safe.</li>
</ol>
3. Heat-induced Antigen Retrieval
<ol>
	<li>Boil solution made in step 2 for 5 min at standard setting in a standard microwave. The solution will start boiling at or above 100 &#176;C.</li>
	<li>Once boiling is complete, carefully remove container from microwave and place dried slides into it, ensuring the slide-face with hippocampal sections is facing down and fully exposed to the liquid. If possible, place slides at an angle against the walls of the box and stack other slides around them. Ensure their &#34;fit&#34; inside the box is tight so the slides have no room to move on top of each other.</li>
	<li>Boil this mixture with slides for 7 min at standard settings in the microwave. The solution will boil during this time at or above 100 &#176;C.</li>
	<li>During this boiling stage, fill two ice buckets halfway with ice.</li>
	<li>Once boiling in step 3.3 is complete, remove the container from the microwave and place it inside one of the ice buckets. Pour the rest of the ice from the other bucket all around the container and completely cover it. Let it sit for 1 hr.</li>
</ol>
4. Primary and Secondary Antibody Staining
<ol>
	<li>At the end of the 1 hr waiting period, remove the slides from the container and wash with TBS-T buffer 3x for 5 min each. Any apparatus may be used to perform these basic washes. (Buffer TBS = 50 mM Tris HCl, 150 mM NaCl, TBS-T = 0.05% Triton X-100 TBS buffer, TBS-TT = 4% donkey serum TBS-T buffer).</li>
	<li>After washing, let the slides dry in a dark place (e.g. inside a bench drawer, place a paper towel inside the drawer and tilt the slide against it) for 5-10 min or until slide is fully dry. During this period, prepare a chamber for overnight primary antibody staining. A simple staining chamber may include a container with large surface area filled with ddH2O and a stage inside the container, on top of which the slide may be rested above the ddH2O.</li>
	<li>Once the slide has dried, draw an outline around the tissue sections using a water-repellant pen. During step 4.5, this outline acts as a barrier preventing the antibody mixture from flowing over.</li>
	<li>Prepare the primary antibody mixture in TBS-TT. At least 500 &#956;l is required to cover one entire slide for instance, if antibody stock is at 1:500 concentration, add 1 &#956;l of particular antibody to 500 &#956;l of TBS-TT). Utilize primary antibodies as mentioned in the reagents table.</li>
	<li>Place the dried slide on top of the stage in the staining chamber. Add 500 &#956;l of the primary antibodies slowly and cover entire surface. Cover entire apparatus and wrap in aluminum foil to block external light. Let it sit overnight at room temperature.</li>
	<li>The next day, wash the slide three times for 5 min each with TBS-T buffer. Let it dry in a dark area as described in step 4.2.</li>
	<li>Prepare secondary antibody mixture similar to step 4.4. Refer to reagents table for secondary antibodies.</li>
	<li>Place the dried slide in the staining chamber as described in steps 4.2 and 4.5. Add 500 &#956;l of the secondary antibodies slowly and cover entire surface. Wrap the staining chamber in aluminum foil to protect it from external light. Let it sit covered and protected from external light for at least 2 hr at room temperature.</li>
	<li>After completion of secondary staining, wash the slide three times for 5 min each with TBS-T buffer. Let the slide dry in a dark area. After drying, put mounting solution and cover the slide with a cover slip carefully preventing any introduction of bubbles. Let the slide sit in a dark area for at least 2 hr before subsequent analysis.</li>
	<li>Perform time-lapse or confocal analysis on the stained tissue.</li>
</ol>

<ol>
	<li>Ming, G. L., Song, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+neurogenesis+in+the+mammalian+central+nervous+system.">Adult neurogenesis in the mammalian central nervous system.</a> Annual Reviews of Neuroscience. 28, 223-250 (2005).</li><li>Santarelli, L., Saxe, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Requirement+of+hippocampal+neurogenesis+for+the+behavioral+effects+of+antidepressants.">Requirement of hippocampal neurogenesis for the behavioral effects of antidepressants.</a> Science. 301 (5634), 805-809 (2003).</li><li>Sahay, 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=Increasing+adult+hippocampal+neurogenesis+is+sufficient+to+improve+pattern+separation.">Increasing adult hippocampal neurogenesis is sufficient to improve pattern separation.</a> Nature. 472 (7344), 466-4670 (2011).</li><li>Clelland, C. D., Choi, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+functional+role+for+adult+hippocampal+neurogenesis+in+spatial+pattern+separation.">A functional role for adult hippocampal neurogenesis in spatial pattern separation.</a> Science. 325 (5937), 210-213 (2009).</li><li>Wang, J. W., David, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+fluoxetine+stimulates+maturation+and+synaptic+plasticity+of+adult-born+hippocampal+granule+cells.">Chronic fluoxetine stimulates maturation and synaptic plasticity of adult-born hippocampal granule cells.</a> Journal of Neuroscience. 28 (6), 1374-1384 (2008).</li><li>D'Amico, F., Skarmoutsou, E., Stivala, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=State+of+the+art+in+antigen+retrieval+for+immunohistochemistry.">State of the art in antigen retrieval for immunohistochemistry.</a> Journal of Immunological Methods. 341 (1-2), 1-18 (2009).</li><li>Daneshtalab, N., 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=Troubleshooting+tissue+specificity+and+antibody+selection:+Procedures+in+immunohistochemical+studies.">Troubleshooting tissue specificity and antibody selection: Procedures in immunohistochemical studies.</a> Journal of Pharmacological and Toxicological Methods. 61 (2), 127-135 (2010).</li><li>Jang, M. H., Bonaguidi, 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=Secreted+frizzled-related+protein+3+regulates+activity-dependent+adult+hippocampal+neurogenesis.">Secreted frizzled-related protein 3 regulates activity-dependent adult hippocampal neurogenesis.</a> Cell Stem Cell. 12 (2), 215-223 (2013).</li><li>Gage, G. J., Kipke, D. R., Shain, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Whole+Animal+Perfusion+Fixation+for+Rodents.">Whole Animal Perfusion Fixation for Rodents.</a> J. Vis. Exp. (65), e3564 (2012).</li><li>Porcelli, M., Cacciapuoti, G., 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=Non-thermal+effects+of+microwaves+on+proteins:+Thermophilic+enzymes+as+model+system.">Non-thermal effects of microwaves on proteins: Thermophilic enzymes as model system.</a> FEBS Letters. 402 (2-3), 102-106 (1997).</li><li>Stone, J. R., Walker, S. A., Povlishock, J. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+visualization+of+a+new+class+of+traumatically+injured+axons+through+the+use+of+a+modified+method+of+microwave+antigen+retrieval.">The visualization of a new class of traumatically injured axons through the use of a modified method of microwave antigen retrieval.</a> Acta Neuropathologica. 97 (4), 335-346 (1999).</li></ol>

The authors declare that they have no competing financial interests.

The most critical steps for successful antigen-retrieval and staining of progenitor cell types are: 1) utilizing well perfused and fixed tissue of the optimal coronal thickness; 2) allowing sufficient time for boiling and subsequent cooling during antigen retrieval; 3) manual dexterity in mounting fixed coronal sections and preventing their damage when doing so.
It is critical in IHC to use perfused tissue that has undergone sufficient fixation but not over-fixation. A primary difficulty can b...

Neurogenesis, the generation of new neurons from neural stem cells, is now known to constantly occur into adulthood in two specialized regions in the brain. These include the subventricular zone (SVZ) of the olfactory bulb and the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. Over the past decade, the field of adult hippocampal neurogenesis has seen significant work. The region has attracted much interest since newborn neurons in the SGZ contribute to enhanced neural plasticity that can sustain specific brain functions1-5. Adult hippocampal neurogenesis has been implicated to play important roles in mood regulation, regeneration, and learning and memory. Thus, there has been a concerted effort to understand the development and regulation of neurons in this rich neurogenic niche.
An unavoidable and important aspect of studying adult hippocampal neurogenesis is the identification of separate stages that an activated neural stem cell passes through on its way to becoming a fully functional neuron. In this process, the quiescent neural stem cell is activated and proceeds through a series of early active and late active progenitor cell types (Figure 1). These distinct populations of neural progenitors can be identified by morphology and their expression of molecular markers such as MCM2, nestin, Tbr2 and Doublecortin (DCX) and NeuN that guide the conversion of RGLs into their respective progenitor cell types. Nestin is an intermediate filament protein that is expressed across the radial glia-like cells and some early progenitor cell types. Another marker is Tbr2 that is specifically expressed in the amplifying progenitor cells. The Tbr2 transgene expression is initially switched off in the Type-1 cells (radial-glia like), turned on across the Type-2a, Type-2ab and Type-2b progenitors and switched off among the more differentiated Type-3 and immature neurons (Figure 1). DCX is a neuronal migration marker which is expressed in the Type-2ab, Type-2b and Type-3 neural progenitors. Using this combination of three markers, we can label distinct subtypes of neural progenitors. These include the Type-1 (MCM2+nestin+Tbr2-), Type-2a (MCM2+nestin+Tbr2+), Type-2ab (partial MCM2+nestin-Tbr2+ and partial MCM2+Tbr2+DCX-), Type-2b (MCM2+Tbr2+DCX+) and Type-3 (MCM2+Tbr2-DCX+). Post-mitotic cells such as the immature and functionally integrated neurons can be identified by utilizing DCX and the mature neuronal marker, NeuN.
Traditional methods of IHC utilize antibodies to identify antigens for specific cell types based on their gene expression. Subsequent visualization through high resolution imaging techniques such as confocal microscopy can be utilized for their identification. However, currently there are problems that exist with these methods that don't allow efficient identification of the radial glia-like cells and early progenitor cell types. It is difficult to identify these particular cell types because the applied antibody is not able to penetrate and efficiently bind the nestin protein. Nestin is the intermediate filament protein that comprises the radial processes produced by the radial glia-like cell. The inefficient binding of an antibody to the antigen can be a result of many factors including fixation time, temperature and technique utilized6-7. To help solve such issues, we have developed an antigen-retrieval or "boiling" method. Besides nestin, this method of antigen-retrieval also improves staining for other markers such as Ki67, BrdU, glial fibrillary acidic protein (GFAP), Tbr2 and MCM2. Our method combines together chemical and physical approaches. It involves chemical fixation of the tissue in paraformaldehyde and subsequent high temperature boiling of thin coronal hippocampal sections in a buffer of a denaturant and chaotropic treatment. This enhances accessibility of the antigen to the antibody, improves antibody specificity and allows improved identification of progenitor cell types. Our approach is simple to use requiring mostly already available tools and reagents in the laboratory. We have utilized it extensively to study development of neural stem cells and their regulation via intrinsic genetic or extrinsic environmental factors8.

<table border="1">
 <tbody>
 <tr>
 <td>Name of the reagent</td>
 <td>Company</td>
 <td>Catalogue number</td>
 <td>Comments (optional)</td>
 </tr>
 <tr>
 <td>SuperFrost Plus Slide</td>
 <td>Fisherbrand</td>
 <td>12-550-15</td>
 <td>Provides strong adherence to hippocampal tissue during boiling</td>
 </tr>
 <tr>
 <td>PVA/DABCO Mounting Media</td>
 <td>Sigma Aldrich</td>
 <td>10981-100 ml</td>
 <td></td>
 </tr>
 <tr>
 <td>Nestin (chicken) </td>
 <td>Aves Lab</td>
 <td>NES</td>
 <td>Neural stem cell marker</td>
 </tr>
 <tr>
 <td>GFAP (rabbit)</td>
 <td>Dako North America</td>
 <td>Z033401-2</td>
 <td>Astrocyte and neural stem cell marker</td>
 </tr>
 <tr>
 <td>MCM2 (mouse)</td>
 <td>BD Transduction Laboratory</td>
 <td>610701</td>
 <td>Proliferation marker</td>
 </tr>
 <tr>
 <td>DCX (goat)</td>
 <td>Santa Cruz Biotechnology</td>
 <td>SC8066</td>
 <td>Immature neuron marker</td>
 </tr>
 <tr>
 <td>Tbr2 (rabbit)</td>
 <td>Abcam</td>
 <td>Ab23345</td>
 <td>Amplifying progenitor marker</td>
 </tr>
 <tr>
 <td>NeuN (mouse)</td>
 <td>Millipore</td>
 <td>MAB377</td>
 <td>Mature neuron marker</td>
 </tr>
 <tr>
 <td>Cy2 (anti-rabbit)</td>
 <td>Jackson Immunoresearch</td>
 <td>111-226-047</td>
 <td></td>
 </tr>
 <tr>
 <td>Cy2 (anti-chicken)</td>
 <td>Jackson Immunoresearch</td>
 <td>303-165-006</td>
 <td></td>
 </tr>
 <tr>
 <td>Cy5 (anti-mouse)</td>
 <td>Jackson Immunoresearch</td>
 <td>315-175-047</td>
 <td></td>
 </tr>
 <tr>
 <td>Cy5 (anti-goat)</td>
 <td>Jackson Immunoresearch</td>
 <td>305-165-047</td>
 <td></td>
 </tr>
 <tr>
 <td>DAPI</td>
 <td>Life Technologies Corporation</td>
 <td>D1306</td>
 <td></td>
 </tr>
 <tr>
 <td>Dako Pen</td>
 <td>S2002</td>
 <td>Dako</td>
 <td>Water-repellant pen</td>
 </tr>
 </tbody>
</table>

heat-induced antigen retrieval: an effective method to detect and identify progenitor cell types during adult hippocampal neurogenesis

Traditional methods of immunohistochemistry (IHC) following tissue fixation allow visualization of various cell types. These typically proceed with the application of antibodies to bind antigens and identify cells with characteristics that are a function of the inherent biology and development. Adult hippocampal neurogenesis is a sequential process wherein a quiescent neural stem cell can become activated and proceed through stages of proliferation, differentiation, maturation and functional integration. Each phase is distinct with a characteristic morphology and upregulation of genes. Identification of these phases is important to understand the regulatory mechanisms at play and any alterations in this process that underlie the pathophysiology of debilitating disorders. Our heat-induced antigen retrieval approach improves the intensity of the signal that is detected and allows correct identification of the progenitor cell type. As discussed in this paper, it especially allows us to circumvent current problems in detection of certain progenitor cell types.

Adult hippocampal neurogenesis is a sequential process where the representative progenitor cell type at each stage may be identified with a combination of markers. Careful chemical fixation and antigen-retrieval improves the effectiveness and accessibility of markers that are otherwise difficult to detect. One of these is nestin which is expressed among the radial glia-like neural stem cells and some early active progenitor cell types. Nestin can be a key protein in identifying early progenitor cell types as its expressi...

Watch this Scientific Journal Video about Heat-Induced Antigen Retrieval: An Effective Method to Detect and Identify Progenitor Cell Types during Adult Hippocampal Neurogenesis at JoVE.com

Heat-Induced Antigen Retrieval: An Effective Method to Detect and Identify Progenitor Cell Types during Adult Hippocampal Neurogenesis

During adult hippocampal neurogenesis, a distinct set of genetic markers are expressed when a quiescent neural stem cell sequentially progresses and develops into a functionally integrated neuron in the circuit. Using heat-induced antigen retrieval, progenitor cell types that are otherwise difficult to detect are identified with improved effectiveness.

Traditional  methods of immunohistochemistry (IHC) following tissue fixation allow visualization  of various cell types. These typically proceed with the ...

heat-induced-antigen-retrieval-an-effective-method-to-detect-identify

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12.4K Views.  Mayo Clinic College of Medicine. During adult hippocampal neurogenesis, a distinct set of genetic markers are expressed when a quiescent neural stem cell sequentially progresses and develops into a functionally integrated neuron in the circuit. Using heat-induced antigen retrieval, progenitor cell types that are otherwise difficult to detect are identified with improved effectiveness.

Video: Heat-Induced Antigen Retrieval: An Effective Method to Detect and Identify Progenitor Cell Types during Adult Hippocampal Neurogenesis

Growth and Differentiation of Adult Hippocampal Arctic Ground Squirrel Neural Stem Cells

Arctic ground squirrels (Urocitellus parryii, AGS) are unique in their ability to hibernate with a core body temperature near or below freezing 1. These animals also resist ischemic injury to the brain in vivo 2,3 and oxygen-glucose deprivation in vitro 4,5. These unique qualities provided the impetus to isolate AGS neurons to examine inherent neuronal characteristics that could account for the capacity of AGS neurons to resist injury and cell death caused by ischemia and extremely cold temperatures. Identifying proteins or gene targets that allow for the distinctive properties of these cells could aid in the discovery of effective therapies for a number of ischemic indications and for the study of cold tolerance. Adult AGS hippocampus contains neural stem cells that continue to proliferate, allowing for easy expansion of these stem cells in culture. We describe here methods by which researchers can utilize these stem cells and differentiated neurons for any number of purposes. By closely following these steps the AGS neural stem cells can be expanded through two passages or more and then differentiated to a culture high in TUJ1-positive neurons (~50%) without utilizing toxic chemicals to minimize the number of dividing cells. Ischemia induces neurogenesis 6 and neurogenesis which proceeds via MEK/ERK and PI3K/Akt survival signaling pathways contributes to ischemia resistance in vivo7 and in vitro 8 (Kelleher-Anderson, Drew et al., in preparation). Further characterization of these unique neural cells can advance on many fronts, using some or all of these methods.

Neural stem cells were prepared from the hippocampus of adult non-hibernating yearling Arctic ground squirrels (AGS). These neural stem cells can be expanded through numerous passages, differentiated and maintained as a nearly 50:50 neuron to glial culture.

Arctic ground squirrels (Urocitellus parryii, AGS) are unique in their ability to hibernate with a core body temperature near or below freezing 1. These ...

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding fundamental biological mechanisms. Striking progress has been particularly evident in Drosophila, whose extensive toolkit of mutants and transgenic lines provides a convenient model to study evolutionarily-conserved developmental and cell biological mechanisms. We are interested in understanding the mechanisms that control cell fate specification in the adult peripheral nervous system (PNS) in Drosophila. Bristles that cover the head, thorax, abdomen, legs and wings of the adult fly are individual mechanosensory organs, and have been studied as a model system for understanding mechanisms of Notch-dependent cell fate decisions. Sensory organ precursor (SOP) cells of the microchaetes (or small bristles), are distributed throughout the epithelium of the pupal thorax, and are specified during the first 12 hours after the onset of pupariation. After specification, the SOP cells begin to divide, segregating the cell fate determinant Numb to one daughter cell during mitosis. Numb functions as a cell-autonomous inhibitor of the Notch signaling pathway.
Here, we show a method to follow protein dynamics in SOP cell and its progeny within the intact pupal thorax using a combination of tissue-specific Gal4 drivers and GFP-tagged fusion proteins 1,2.This technique has the advantage over fixed tissue or cultured explants because it allows us to follow the entire development of an organ from specification of the neural precursor to growth and terminal differentiation of the organ. We can therefore directly correlate changes in cell behavior to changes in terminal differentiation. Moreover, we can combine the live imaging technique with mosaic analysis with a repressible cell marker (MARCM) system to assess the dynamics of tagged proteins in mitotic SOPs under mutant or wildtype conditions. Using this technique, we and others have revealed novel insights into regulation of asymmetric cell division and the control of Notch signaling activation in SOP cells (examples include references 1-6,7 ,8).

Live-cell Imaging of Sensory Organ Precursor Cells in Intact Drosophila Pupae

In this video, we describe a method for live cell imaging of asymmetrically dividing sensory organ progenitor cells and epidermal cells in intact Drosophila pupae

Since the discovery of Green Fluorescent Protein (GFP), there has been a revolutionary change in the use of live-cell imaging as a tool for understanding ...

Functional Interrogation of Adult Hypothalamic Neurogenesis with Focal Radiological Inhibition

The functional characterization of adult-born neurons remains a significant challenge. Approaches to inhibit adult neurogenesis via invasive viral delivery or transgenic animals have potential confounds that make interpretation of results from these studies difficult. New radiological tools are emerging, however, that allow one to noninvasively investigate the function of select groups of adult-born neurons through accurate and precise anatomical targeting in small animals. Focal ionizing radiation inhibits the birth and differentiation of new neurons, and allows targeting of specific neural progenitor regions. In order to illuminate the potential functional role that adult hypothalamic neurogenesis plays in the regulation of physiological processes, we developed a noninvasive focal irradiation technique to selectively inhibit the birth of adult-born neurons in the hypothalamic median eminence. We describe a method for Computer tomography-guided focal irradiation (CFIR) delivery to enable precise and accurate anatomical targeting in small animals. CFIR uses three-dimensional volumetric image guidance for localization and targeting of the radiation dose, minimizes radiation exposure to nontargeted brain regions, and allows for conformal dose distribution with sharp beam boundaries. This protocol allows one to ask questions regarding the function of adult-born neurons, but also opens areas to questions in areas of radiobiology, tumor biology, and immunology. These radiological tools will facilitate the translation of discoveries at the bench to the bedside.

The function of adult-born mammalian neurons remains an active area of investigation. Ionizing radiation inhibits the birth of new neurons. Using computer tomography-guided focal irradiation (CFIR), three-dimensional anatomical targeting of specific neural progenitor populations can now be used to assess the functional role of adult neurogenesis.

The functional characterization of adult-born neurons remains a significant challenge. Approaches to inhibit adult neurogenesis via invasive viral ...

Methods for the Modulation and Analysis of NF-&#954;B-dependent Adult Neurogenesis

The hippocampus plays a pivotal role in the formation and consolidation of episodic memories, and in spatial orientation. Historically, the adult hippocampus has been viewed as a very static anatomical region of the mammalian brain. However, recent findings have demonstrated that the dentate gyrus of the hippocampus is an area of tremendous plasticity in adults, involving not only modifications of existing neuronal circuits, but also adult neurogenesis. This plasticity is regulated by complex transcriptional networks, in which the transcription factor NF-&#954;B plays a prominent role. To study and manipulate adult neurogenesis, a transgenic mouse model for forebrain-specific neuronal inhibition of NF-&#954;B activity can be used.
In this study, methods are described for the analysis of NF-&#954;B-dependent neurogenesis, including its structural aspects, neuronal apoptosis and progenitor proliferation, and cognitive significance, which was specifically assessed via a dentate gyrus (DG)-dependent behavioral test, the spatial pattern separation-Barnes maze (SPS-BM). The SPS-BM protocol could be simply adapted for use with other transgenic animal models designed to assess the influence of particular genes on adult hippocampal neurogenesis. Furthermore, SPS-BM could be used in other experimental settings aimed at investigating and manipulating DG-dependent learning, for example, using pharmacological agents.

Methods for the Modulation and Analysis of NF-&amp;#954;B-dependent Adult Neurogenesis

Methods for the manipulation and analysis of NF-&#954;B-dependent adult hippocampal neurogenesis are described. A detailed protocol is presented for a dentate gyrus-dependent behavioral test (termed the spatial pattern separation-Barnes maze) for the investigation of cognitive outcome in mice. This technique should also help enable investigations in other experimental settings.

The hippocampus plays a pivotal role in the formation and consolidation of episodic memories, and in spatial orientation. Historically, the adult ...

Stab Wound Injury of the Zebrafish Adult Telencephalon: A Method to Investigate Vertebrate Brain Neurogenesis and Regeneration

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular mechanisms involved in zebrafish adult central nervous system (CNS) regeneration and repair, we developed a zebrafish model of adult telencephalic injury.
In this approach, we manually generate an injury by pushing an insulin syringe needle into the zebrafish adult telencephalon. At different post injury days, fish are sacrificed, their brains are dissected out and stained by immunohistochemistry and/or in situ hybridization (ISH) with appropriate markers to observe cell proliferation, gliogenesis, and neurogenesis. The contralateral unlesioned hemisphere serves as an internal control. This method combined for example with RNA deep sequencing can help to screen for new genes with a role in zebrafish adult telencephalon neurogenesis, regeneration, and repair.

To shed light on the cellular and molecular mechanisms of zebrafish adult neurogenesis and regeneration, we developed a protocol for invasive surgery causing mechanical injuries in the zebrafish adult telencephalon and subsequent monitoring of changes in the stabbed hemisphere by immunohistochemistry or in situ hybridization.

Adult zebrafish have an amazing capacity to regenerate their central nervous system after injury. To investigate the cellular response and the molecular ...

Flow Cytometry Protocols for Surface and Intracellular Antigen Analyses of Neural Cell Types

Flow cytometry has been extensively used to define cell populations in immunology, hematology and oncology. Here, we provide a detailed description of protocols for flow cytometric analysis of the cluster of differentiation (CD) surface antigens and intracellular antigens in neural cell types. Our step-by-step description of the methodological procedures include: the harvesting of neural in vitro cultures, an optional carboxyfluorescein succinimidyl ester (CFSE)-labeling step, followed by surface antigen staining with conjugated CD antibodies (e.g., CD24, CD54), and subsequent intracellar antigen detection via primary/secondary antibodies or fluorescently labeled Fab fragments (Zenon labeling). The video demonstrates the most critical steps. Moreover, principles of experimental planning, the inclusion of critical controls, and fundamentals of flow cytometric analysis (identification of target population and exclusion of debris; gating strategy; compensation for spectral overlap) are briefly explained in order to enable neurobiologists with limited prior knowledge or specific training in flow cytometry to assess its utility and to better exploit this powerful methodology.

We provide a detailed description of a protocol for flow cytometric analysis of surface antigens and/or intracellular antigens in neural cell types. Critical aspects of experimental planning, step-by-step methodological procedures, and fundamental principles of flow cytometry are explained in order to enable neurobiologists to exploit this powerful technology.

Flow cytometry has been extensively used to define cell populations in immunology, hematology and oncology. Here, we provide a detailed description of ...

Immunohistochemistry and Multiple Labeling with Antibodies from the Same Host Species to Study Adult Hippocampal Neurogenesis

Adult neurogenesis is a highly regulated, multi-stage process in which new neurons are generated from an activated neural stem cell via increasingly committed intermediate progenitor subtypes. Each of these subtypes expresses a set of specific molecular markers that, together with specific morphological criteria, can be used for their identification. Typically, immunofluorescent techniques are applied involving subtype-specific antibodies in combination with exo- or endogenous proliferation markers. We herein describe immunolabeling methods for the detection and quantification of all stages of adult hippocampal neurogenesis. These comprise the application of thymidine analogs, transcardial perfusion, tissue processing, heat-induced epitope retrieval, ABC immunohistochemistry, multiple indirect immunofluorescence, confocal microscopy and cell quantification. Furthermore we present&#160;a sequential multiple immunofluorescence protocol which circumvents problems usually arising from the need of using primary antibodies raised in the same host species. It allows an accurate identification of all hippocampal progenitor subtypes together with a proliferation marker within a single section. These techniques are a powerful tool to study the regulation of different progenitor subtypes in parallel, their involvement in brain pathologies and their role in specific brain functions.

This video article illustrates a comprehensive protocol to detect and quantify all stages of adult hippocampal neurogenesis within the same tissue section. We elaborated a method to overcome the limitations of indirect multiple immunofluorescence that arise when suitable antibodies from different host species are unavailable.

Adult neurogenesis is a highly regulated, multi-stage process in which new neurons are generated from an activated neural stem cell via increasingly ...

Derivation of Adult Human Fibroblasts and their Direct Conversion into Expandable Neural Progenitor Cells

Generation of&#160;induced pluripotent stem cell (iPSCs) from adult skin fibroblasts and subsequent differentiation into somatic cells provides fascinating prospects for the derivation of autologous transplants that circumvent histocompatibility barriers. However, progression through a pluripotent state and subsequent complete differentiation into desired lineages remains a roadblock for the clinical translation of iPSC technology because of the associated neoplastic potential and genomic instability. Recently, we and others showed that somatic cells cannot only be converted into iPSCs but also into different types of multipotent somatic stem cells by using defined factors, thereby circumventing progression through the pluripotent state. In particular, the direct conversion of human fibroblasts into induced neural progenitor cells (iNPCs) heralds the possibility of a novel autologous cell source for various applications such as cell replacement, disease modeling and drug screening. Here, we describe the isolation of adult human primary fibroblasts by skin biopsy and their efficient direct conversion into iNPCs by timely restricted expression of Oct4, Sox2, Klf4, as well as c-Myc. Sox2-positive neuroepithelial colonies appear after 17 days of induction and iNPC lines can be established efficiently by monoclonal isolation and expansion. Precise adjustment of viral multiplicity of infection and supplementation of leukemia inhibitory factor during the induction phase represent critical factors to achieve conversion efficiencies of up to 0.2%. Thus far, patient-specific iNPC lines could be expanded for more than 12 passages and uniformly display morphological and molecular features of neural stem/progenitor cells, such as the expression of Nestin and Sox2. The iNPC lines can be differentiated into neurons and astrocytes as judged by staining against TUJ1 and GFAP, respectively. In conclusion, we report a robust protocol for the derivation and direct conversion of human fibroblasts into stably expandable neural progenitor cells that might provide a cellular source for biomedical applications such as autologous neural cell replacement and disease modeling.

Generation of induced pluripotent stem cells provides fascinating prospects for the derivation of autologous transplants. However, progression through a pluripotent state and laborious re-differentiation still hinders clinical translation. Here we describe the derivation of adult human fibroblasts and their direct conversion into induced neural progenitor cells and the subsequent differentiation into neural lineages.

Generation of&#160;induced pluripotent stem cell (iPSCs) from adult skin fibroblasts and subsequent differentiation into somatic cells provides ...

Preparation of Acute Brain Slices Using an Optimized N-Methyl-D-glucamine Protective Recovery Method

This protocol is a practical guide to the N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. Numerous recent studies have validated the utility of this method for enhancing neuronal preservation and overall brain slice viability. The implementation of this technique by early adopters has facilitated detailed investigations into brain function using diverse experimental applications and spanning a wide range of animal ages, brain regions, and cell types. Steps are outlined for carrying out the protective recovery brain slice technique using an optimized NMDG artificial cerebrospinal fluid (aCSF) media formulation and enhanced procedure to reliably obtain healthy brain slices for patch clamp electrophysiology. With this updated approach, a substantial improvement is observed in the speed and reliability of gigaohm seal formation during targeted patch clamp recording experiments while maintaining excellent neuronal preservation, thereby facilitating challenging experimental applications. Representative results are provided from multi-neuron patch clamp recording experiments to assay synaptic connectivity in neocortical brain slices prepared from young adult transgenic mice and mature adult human neurosurgical specimens. Furthermore, the optimized NMDG protective recovery method of brain slicing is compatible with both juvenile and adult animals, thus resolving a limitation of the original methodology. In summary, a single media formulation and brain slicing procedure can be implemented across various species and ages to achieve excellent viability and tissue preservation.

Preparation of Acute Brain Slices Using an Optimized N-Methyl-D-glucamine Protective Recovery Method

This protocol demonstrates the implementation of an optimized N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. A single media formulation is used to reliably obtain healthy brain slices from animals of any age and for diverse experimental applications.

This protocol is a practical guide to the N-methyl-D-glucamine (NMDG) protective recovery method of brain slice preparation. Numerous recent studies have ...

Assessing Primary Neurogenesis in Xenopus Embryos Using Immunostaining

Primary neurogenesis is a dynamic and complex process during embryonic development that sets up the initial layout of the central nervous system. During this process, a portion of neural stem cells undergo differentiation and give rise to the first populations of differentiated primary neurons within the nascent central nervous system. Several vertebrate model organisms have been used to explore the mechanisms of neural cell fate specification, patterning, and differentiation. Among these is the African clawed frog, Xenopus, which provides a powerful system for investigating the molecular and cellular mechanisms responsible for primary neurogenesis due to its rapid and accessible development and ease of embryological and molecular manipulations. Here, we present a convenient and rapid method to observe the different populations of neuronal cells within Xenopus central nervous system. Using antibody staining and immunofluorescence on sections of Xenopus embryos, we are able to observe the locations of neural stem cells and differentiated primary neurons during primary neurogenesis.

Assessing Primary Neurogenesis in Xenopus Embryos Using Immunostaining

This article presents a convenient and rapid method for visualizing different neuronal cell populations in the central nervous system of Xenopus embryos using immunofluorescent staining on sections.

Primary neurogenesis is a dynamic and complex process during embryonic development that sets up the initial layout of the central nervous system. During ...