This study was supported by the National Key Research and Development Program of China (Grant No. 2017YFA0104703), the National Natural Foundation of China (Grant No. 31500927).

This study was carried out in accordance with the Institutional Animal Care Guidelines of Nantong University. All the procedures including the animal subjects were ethically approved by the Administration Committee of Experimental Animals, Jiangsu Province, China.
1. Isolation and culture of motor and sensory nerve fibroblasts and SCs
<ol>
	<li>Use seven-day-old Sprague-Dawley (SD) rats (n=4) provided by the Experimental Animal Center of Nantong University of China. Place the rats in a tank containing 5% isoflurane for 2-3 minutes, allow the animals to breath slowly and have no independent activity, and then sanitize using 75% ethanol prior to decapitation.</li>
	<li>Use scissors to cut the back skin for about 3 cm and remove the spinal column. Open the vertebral canal carefully to expose the spinal cord.</li>
	<li>Maintain the spinal cord in a 60 mm Petri dish with 2-3 mL of ice-cold D-Hanks&#39; balanced salt solution (HBSS).</li>
	<li>Based on the anatomical structure, excise the ventral root (motor nerve) and then the dorsal root (sensory nerve) under a dissecting microscope. Next, place them in an ice-cold D-Hanks&#39; balanced salt solution (HBSS).</li>
	<li>After removing the HBSS, slice the nerves into 3-5 mm pieces with scissors and digest with 1 mL of 0.25% (w/v) trypsin at 37 &#176;C for 18-20 min. Next, supplement with 3-4 mL of DMEM containing 10% fetal bovine serum (FBS) to stop the digestion.</li>
	<li>Pipette the mixture up and down gently about 10 times and centrifuge at 800 x g for 5 min. After that, discard the supernatant and suspend the precipitate in 2-3 mL of DMEM supplemented with 10% FBS.</li>
	<li>Filter the cell suspension using a 400 mesh filter, and then inoculate the cells in 60 mm Petri dish and culture at 37 &#176;C in the presence of 5% CO2. After 4-5 days of culturing, isolate the passage 0 (p0) fibroblasts and SCs after reaching 90% confluence.</li>
	<li>Isolation and culture of SCs (Figure 1)
	<ol>
		<li>Wash the cells once using 1x PBS. Add 1 mL of 0.25% (w/v) trypsin (37 &#176;C) per 60 mm Petri dish to digest the cells for 8-10 s at room temperature. After that, add 3 mL of DMEM supplemented with 10% FBS to stop the digestion.</li>
		<li>Gently blow the mixture to detach the SCs with a pipette. Then collect and centrifuge the SCs at 800 x g for 5 min.</li>
		<li>Discard the supernatant and suspend the precipitate in 3 mL of DMEM with 10% FBS, 1% penicillin/streptomycin, 2 &#181;M forskolin and 10 ng/mL HRG, and then inoculate the cells in uncoated 60 mm Petri dish. After culturing at 37 &#176;C for 30-45 min, the fibroblasts (a few number of fibroblasts are digested with SCs) attach to the bottom of the dish.</li>
		<li>Transfer the supernatant (including the SCs) to another poly-L-lysine (PLL)-coated medium dish and culture at 37 &#176;C for 2 days.</li>
	</ol>
	</li>
	<li>Isolation and culture of fibroblasts (Figure 1)
	<ol>
		<li>After removing the SCs (as shown in step 1.8), wash the remaining fibroblasts in the dishes with 1x PBS and then add 1 mL of 0.25% (w/v) trypsin to digest the fibroblasts for 2 min at 37 &#176;C.</li>
		<li>Add DMEM supplemented with 10% FBS to end the digestion. Blow the fibroblasts using a pipette, and then collect and centrifuge them at 800 x g for 5 min.</li>
		<li>Discard the supernatant, suspend the precipitate with 2 mL of DMEM containing 10% FBS, and then inoculate the cells in uncoated 60 mm Petri dish. The fibroblasts after culturing for 30-45 min at 37 &#176;C attach to the bottom of the dish. Discard the supernatant (including a few numbers of SCs). Then add 3 mL of DMEM supplemented with 10% FBS into the fibroblasts dish and culture at 37 &#176;C for 2 days.</li>
	</ol>
	</li>
	<li>Passage the p1 cells until they reached 90% confluence. Then purify them by differential digestion and differential adherence again as described in sections 1.8 and 1.9.</li>
	<li>Digest the p2 fibroblasts and SCs after culturing for 2 days, and then collect the cells, count and inoculate in 1 x 105 numbers/well on PLL-coated slides for immunocytochemistry (ICC).</li>
</ol>
2. ICC for identification of cell purity
<ol>
	<li>Culture the cells for 24 h at 37 &#176;C and perform ICC staining after differential digestion and differential adherence of motor and sensory fibroblasts and SCs.</li>
	<li>Wash the motor and sensory fibroblasts and SCs with 1x PBS and fix them in 200 &#181;L/well of 4% paraformaldehyde (pH 7.4) for 18 min at room temperature.</li>
	<li>Block the sample SCs with blocking buffer (0.1% Triton X-100 in 0.01 M PBS containing 5% goat serum) and block the sample fibroblasts with blocking buffer (0.01 M PBS containing 5% goat serum) for 45 min at 37 &#176;C after washing them with PBS thrice.</li>
	<li>Remove the blocking buffer, and incubate with the following primary antibodies: mouse monoclonal anti-CD90 antibody (a specific marker for fibroblasts) (1:1000) for fibroblasts and mouse anti-S100 antibody (a specific marker for SCs) (1:400) for SCs at 4 &#176;C overnight.</li>
	<li>Discard the primary antibodies, wash with PBS thrice, and incubate with the following secondary antibodies: Alexa Fluor 594 goat anti-mouse IgG (1:400) for fibroblasts and 488-conjugated goat anti-mouse IgG (1:400) for SCs at room temperature for 1.5 h.</li>
	<li>Wash the samples thrice with PBS, and stain the nuclei with 5 &#181;g/mL Hoechst 33342 dye for 10 min at room temperature. Wash the sample with 1x PBS thrice and mount them using the mounting medium (20 &#181;L/slide) on the glass slide.</li>
	<li>Take the cell photographs by confocal laser scanning microscope in three random fields for each well. Evaluate the total number of nuclei and CD90-positive cells, S100-positive cells and then calculate the percentage of CD90-positive cells and S100-positive cells, respectively. Perform the staining in triplicate.</li>
</ol>
3. Flow cytometry analysis (FCA) for identification of cell purity
<ol>
	<li>Evaluate the purity of motor and sensory fibroblasts and SCs as described previously by FCA16. Briefly, digest the p2 motor and sensory fibroblasts and SCs with 0.25% (w/v) trypsin, resuspend the cell pellets and incubate them in fixation medium at room temperature for 15 min.</li>
	<li>Incubate the cells with permeabilization medium and probe using mouse monoclonal anti-CD90 antibody (0.1 &#181;g/106 cells, 200 &#181;L) for fibroblasts and mouse anti-S100 antibody (1:400, 200 &#181;L) for SCs at room temperature for 30 min, respectively.</li>
	<li>Incubate the cells with 488-conjugated goat anti-mouse IgG for 30 min. Use FACS caliber to perform flow cytometry, and analyze the data using Cell Quest software.</li>
	<li>Incubate the cells only with 488-conjugated goat anti-mouse IgG (fibroblasts Group) and mouse IgG1 kappa [MOPC-21] (FITC) - Isotype control (SCs group), which serves as negative control.</li>
</ol>
4. Statistical analysis
<ol>
	<li>Present all data as means &#177; SEM. Assess statistical differences in the data by unpaired t-test using GraphPad Prism 6.0. Set statistical significance at p&#60;0.05. Perform all assays in triplicate.</li>
</ol>

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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=STAT3+Controls+the+Long-Term+Survival+and+Phenotype+of+Repair+Schwann+Cells+during+Nerve+Regeneration.">STAT3 Controls the Long-Term Survival and Phenotype of Repair Schwann Cells during Nerve Regeneration.</a> Journal of Neuroscience Research. 37 (16), 4255-4269 (2017).</li><li>Zhang, Z. J., Jiang, B. C., Gao, Y. 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E., Wu, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+3,+Unit+17:+Isolation+and+purification+of+primary+Schwann+cells.">Chapter 3, Unit 17: Isolation and purification of primary Schwann cells.</a> Current Protocols in Neuroscience. , (2001).</li><li>Palomo Irigoyen, 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=Isolation+and+Purification+of+Primary+Rodent+Schwann+Cells.">Isolation and Purification of Primary Rodent Schwann Cells.</a> Methods in Molecular Biology. 1791, 81-93 (2018).</li><li>Cheng, L., Khan, M., Mudge, A. 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The authors have nothing to disclose.

The two major cell populations of peripheral nerves included SCs and fibroblasts. The primarily cultured fibroblasts and SCs can accurately assist in modeling the physiology of fibroblasts and SCs during peripheral nerve development and regeneration. The study showed that P7 rat sciatic nerve cells contained about 85% of S100-positive SCs, 13% of OX7-positive fibroblasts and only 1.5% of OX42-positive macrophages13. Although the number of fibroblasts is less than SCs, the initial proliferation rat...

In the peripheral nervous system, the nerve fibers mainly consists of axons, Schwann cells (SCs), and fibroblasts, and also contains a small number of macrophages, microvascular endothelial cells, and immune cells1. SCs wrap the axons in a 1:1 ratio and are enclosed by a connective tissue layer called the endoneurium. The axons are then bundled together to form groups called fascicles, and each fascicle is wrapped in a connective tissue layer known as the perineurium. Finally, the whole nerve fiber is wrapped in a layer of connective tissue, which is termed as the epineurium. In the endoneurium, the whole cell population is comprised of 48% SCs, and a substantial portion of the remaining cells involves fibroblasts2. Furthermore, fibroblasts are important components of all nerve compartments, including the epineurium, the perineurium, and the endoneurium3. Many studies have indicated that SCs and fibroblasts play a crucial role in the regeneration process after peripheral nerve injuries4,5,6. After transection of the peripheral nerve, the perineurial fibroblasts regulate cell sorting via the ephrin-B/EphB2 signaling pathway between SCs and fibroblasts, further guiding the axonal regrowth through wounds5. Peripheral nerve fibroblasts secrete tenascin-C protein and enhance the migration of SCs during nerve regeneration through &#946;1-integrin signaling pathway7. However, the SCs and fibroblasts used in the above studies were derived from the sciatic nerve, which includes both sensory and motor nerves.
In the peripheral nervous system, the sensory nerves (afferent nerves) conduct sensory signaling from the receptors to the central nervous system (CNS), while the motor nerves (efferent nerves) conduct signals from the CNS to the muscles. Previous studies have indicated that SCs express distinct motor and sensory phenotypes and secrete neurotrophic factors to support peripheral nerve regeneration8,9. According to a recent study, fibroblasts also express different motor and sensory phenotypes and affect the migration of SCs10. Thus, the exploration of differences between motor and sensory nerve fibroblasts/SCs allows us to study the complicated underlying molecular mechanisms of peripheral nerve specific regeneration.
At present, there are many ways to purify SCs and fibroblasts, including the application of antimitotic agents, antibody-mediated cytolysis11,12, sequential immunopanning13 and laminin substratum14. However, all the above methods remove fibroblasts and preserve only the SCs. Highly purified SCs and fibroblasts can be obtained by flow cytometry sorting technology15, but it is a time-consuming and costly technique. Hence, in this study, a simple differential digestion and differential adherence method for purifying and isolating sensory and motor nerve fibroblasts and SCs was developed in order to obtain a large number of fibroblasts and SCs more rapidly.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Alexa Fluor 594 Goat Anti-Mouse IgG(H+L)</td>
			<td>Life Technologies</td>
			<td>A11005</td>
			<td>Dilution: 1:400</td>
		</tr>
		<tr>
			<td>CoraLite488-conjugated Affinipure Goat Anti-Mouse IgG(H+L)</td>
			<td>Proteintech</td>
			<td>SA00013-1</td>
			<td>Dilution: 1:400</td>
		</tr>
		<tr>
			<td>Confocal laser scanning microscope</td>
			<td>Leica Microsystems</td>
			<td>TCS SP5</td>
			<td></td>
		</tr>
		<tr>
			<td>Cell Quest software</td>
			<td>Becton Dickinson Biosciences</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>D-Hank&#39;s balanced salt solution</td>
			<td>Gibco</td>
			<td>14170112</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM</td>
			<td>Corning</td>
			<td>10-013-CV</td>
			<td></td>
		</tr>
		<tr>
			<td>Dissecting microscope</td>
			<td>Olympus</td>
			<td>SZ2-ILST</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum (FBS)</td>
			<td>Gibco</td>
			<td>10099-141C</td>
			<td></td>
		</tr>
		<tr>
			<td>Forskolin</td>
			<td>Sigma</td>
			<td>F6886-10MG</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluoroshield Mounting Medium</td>
			<td>Abcam</td>
			<td>ab104135</td>
			<td></td>
		</tr>
		<tr>
			<td>Fixation medium/Permeabilization medium</td>
			<td>Multi Sciences (LIANKE) Biotech, Co., LTD</td>
			<td>GAS005</td>
			<td></td>
		</tr>
		<tr>
			<td>Flow cytometry</td>
			<td>Becton Dickinson Biosciences</td>
			<td>FACS Calibur</td>
			<td></td>
		</tr>
		<tr>
			<td>Mouse IgG1 kappa [MOPC-21] (FITC) - Isotype Control</td>
			<td>Abcam</td>
			<td>ab106163</td>
			<td>Dilution: 1:400</td>
		</tr>
		<tr>
			<td>Mouse monoclonal anti-CD90 antibody</td>
			<td>Abcam</td>
			<td>ab225</td>
			<td>Dilution: 1:1000 for ICC, 0.1 &#181;g for 106 cells for Flow Cyt</td>
		</tr>
		<tr>
			<td>Mouse anti-S100 antibody</td>
			<td>Abcam</td>
			<td>ab212816</td>
			<td>Dilution: 1:400</td>
		</tr>
		<tr>
			<td>Polylysine (PLL)</td>
			<td>Sigma</td>
			<td>P4832</td>
			<td></td>
		</tr>
		<tr>
			<td>Recombinant Human NRG1-beta 1/HRG1-beta 1 EGF Domain Protein</td>
			<td>R&#38;D Systems</td>
			<td>396-HB-050</td>
			<td></td>
		</tr>
		<tr>
			<td>0.25% (w/v) trypsin</td>
			<td>Gibco</td>
			<td>25200-072</td>
			<td></td>
		</tr>
	</tbody>
</table>

purification of fibroblasts and schwann cells from sensory and motor nerves in vitro

The principal cells in the peripheral nervous system are the Schwann cells (SCs) and the fibroblasts. Both these cells distinctly express the sensory and motor phenotypes involved in different patterns of neurotrophic factor gene expression and other biological processes, affecting nerve regeneration. The present study has established a protocol to obtain highly purified rat sensory and motor SCs and fibroblasts more rapidly. The ventral root (motor nerve) and the dorsal root (sensory nerve) of neonatal rats (7-days-old) were dissociated and the cells were cultured for 4-5 days, followed by isolation of sensory and motor fibroblasts and SCs by combining differential digestion and differential adherence methods sequentially. The results of immunocytochemistry and flow cytometry analyses showed that the purity of the sensory and motor SCs and fibroblasts were &#62;90%. This protocol can be used to obtain a large number of sensory and motor fibroblasts/SCs more rapidly, contributing to the exploration of sensory and motor nerve regeneration.

Light microscopic observation 
The SCs and fibroblasts are the two main cell populations obtained in the primary cell culture from nerve tissues. After inoculation for 1 h, most of the cells adhered to the bottom of the dish, and the cell morphology changed from round to oval. After culturing for 24 h, the SCs exhibited a bipolar or tripolar morphology and the length of these ranged from 100 to 200 &#181;m. After 48 h, aggregation and proliferation of cells occurred,...

Watch this Scientific Journal Video about Purification of Fibroblasts and Schwann Cells from Sensory and Motor Nerves in Vitro at JoVE.com

Purification of Fibroblasts and Schwann Cells from Sensory and Motor Nerves in Vitro

Here, we present a method to purify fibroblasts and Schwann cells from sensory and motor nerves in vitro.

The principal cells in the peripheral nervous system are the Schwann cells (SCs) and the fibroblasts. Both these cells distinctly express the sensory and ...

purification-fibroblasts-schwann-cells-from-sensory-motor-nerves

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Neuroscience

7.0K Views.  Nantong University. Here, we present a method to purify fibroblasts and Schwann cells from sensory and motor nerves in vitro.

Video: Purification of Fibroblasts and Schwann Cells from Sensory and Motor Nerves in Vitro

The Culture of Primary Motor and Sensory Neurons in Defined Media on Electrospun Poly-L-lactide Nanofiber Scaffolds

Electrospinning is a technique for producing micro- to nano-scale fibers. Fibers can be electrospun with varying degrees of alignment, from highly aligned to completely random. In addition, fibers can be spun from a variety of materials, including biodegradable polymers such as poly-L-lactic acid (PLLA). These characteristics make electrospun fibers suitable for a variety of scaffolding applications in tissue engineering. Our focus is on the use of aligned electrospun fibers for nerve regeneration. We have previously shown that aligned electrospun PLLA fibers direct the outgrowth of both primary sensory and motor neurons in vitro. We maintain that the use of a primary cell culture system is essential when evaluating biomaterials to model real neurons found in vivo as closely as possible. Here, we describe techniques used in our laboratory to electrospin fibrous scaffolds and culture dorsal root ganglia explants, as well as dissociated sensory and motor neurons, on electrospun scaffolds. However, the electrospinning and/or culture techniques presented here are easily adapted for use in other applications.

Aligned electrospun fibers direct the growth of neurons in vitro and are a potential component of nerve regeneration scaffolds. We describe a procedure for preparing electrospun fiber substrates and the serum-free culture of primary rat E15 sensory (DRG) and motor neurons. Visualization of neurons by immunocytochemistry is also included.

Electrospinning is a technique for producing micro- to nano-scale fibers. Fibers can be electrospun with varying degrees of alignment, from highly aligned ...

Live-imaging of PKC Translocation in Sf9 Cells and in Aplysia Sensory Neurons

Protein kinase Cs (PKCs) are serine threonine kinases that play a central role in regulating a wide variety of cellular processes such as cell growth and learning and memory. There are four known families of PKC isoforms in vertebrates: classical PKCs (&alpha;, &beta;I, &beta;II and &gamma;), novel type I PKCs (&#949; and &eta;), novel type II PKCs (&delta; and &theta;), and atypical PKCs (&zeta; and &iota;). The classical PKCs are activated by Ca2+ and diacylclycerol (DAG), while the novel PKCs are activated by DAG, but are Ca2+-independent. The atypical PKCs are activated by neither Ca2+ nor DAG. In Aplysia californica, our model system to study memory formation, there are three nervous system specific PKC isoforms one from each major class, namely the conventional PKC Apl I, the novel type I PKC Apl II and the atypical PKC Apl III. PKCs are lipid-activated kinases and thus activation of classical and novel PKCs in response to extracellular signals has been frequently correlated with PKC translocation from the cytoplasm to the plasma membrane. Therefore, visualizing PKC translocation in real time in live cells has become an invaluable tool for elucidating the signal transduction pathways that lead to PKC activation. For instance, this technique has allowed for us to establish that different isoforms of PKC translocate under different conditions to mediate distinct types of synaptic plasticity and that serotonin (5HT) activation of PKC Apl II requires production of both DAG and phosphatidic acid (PA) for translocation 1-2. Importantly, the ability to visualize the same neuron repeatedly has allowed us, for example, to measure desensitization of the PKC response in exquisite detail 3. In this video, we demonstrate each step of preparing Sf9 cell cultures, cultures of Aplysia sensory neurons have been described in another video article 4, expressing fluorescently tagged PKCs in Sf9 cells and in Aplysia sensory neurons and live-imaging of PKC translocation in response to different activators using laser-scanning microscopy.

In this video, we demonstrate visualization of PKC translocation in living cells using fluorescently tagged PKCs.

Protein kinase Cs (PKCs) are serine threonine kinases that play a central role in regulating a wide variety of cellular processes such as cell growth and ...

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 ...

Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells

Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in communication with the epidermal cells they innervate and thus their analysis benefits from in situ visualization of both neuronally and epidermally expressed proteins by immunofluorescence. Traditional methods of preparing larval fillets for immunofluorescence experiments leave intact the muscle tissue that covers most of the body wall, presenting several challenges to imaging neuronal and epidermal proteins. Here we describe a method for removing muscle tissue from Drosophila larval fillets. This protocol enables imaging of proteins that are otherwise obscured by muscle tissue, improves signal to noise ratio, and facilitates the use of super-resolution microscopy to study da neuron development.

Removal of Drosophila Muscle Tissue from Larval Fillets for Immunofluorescence Analysis of Sensory Neurons and Epidermal Cells

Studies of neuronal morphogenesis using Drosophila larval dendritic arborization (da) neurons benefit from in situ visualization of neuronal and epidermal proteins by immunofluorescence. We describe a procedure that improves immunofluorescence analysis of da neurons and surrounding epidermal cells by removing muscle tissue from the larval body wall.

Drosophila larval dendritic arborization (da) neurons are a popular model for investigating mechanisms of neuronal morphogenesis. Da neurons develop in ...

Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog (Rana catesbeiana)

The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American bullfrog, has become a mainstay of auditory and vestibular research. Studies of this organ have revealed how sensory cells hair can actively detect signals from the environment. Because of these studies, we now better understand the mechanical gating and localization of a hair cell&#39;s transduction channels, calcium&#39;s role in mechanical adaptation, and the identity of hair cell currents. This highly accessible organ continues to provide insight into the workings of hair cells. Here we describe the preparation of the bullfrog&#39;s sacculus for biophysical studies on its hair cells. We include the complete dissection procedure and provide specific protocols for the preparation of the sacculus in specific contexts. We additionally include representative results using this preparation, including the calculation of a hair bundle&#39;s instantaneous force-displacement relation and measurement of a bundle&#39;s spontaneous oscillation.

Physiological Preparation of Hair Cells from the Sacculus of the American Bullfrog Rana catesbeiana

The American bullfrog&#39;s (Rana catesbeiana) sacculus permits direct examination of hair-cell physiology. Here the dissection and preparation of the bullfrog&#39;s sacculus for biophysical studies is described. We show representative experiments from these hair cells, including the calculation of a bundle&#39;s force-displacement relation and measurement of its unforced motion.

The study of hearing and balance rests upon insights drawn from biophysical studies of model systems. One such model, the sacculus of the American ...

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

Zebrafish, first introduced as a developmental model, have gained popularity in many other fields. The ease of rearing large numbers of rapidly developing organisms, combined with the embryonic optical clarity, served as initial compelling attributes of this model. Over the past two decades, the success of this model has been further propelled by its amenability to large-scale mutagenesis screens and by the ease of transgenesis. More recently, gene-editing approaches have extended the power of the model.
For neurodevelopmental studies, the zebrafish embryo and larva provide a model to which multiple methods can be applied. Here, we focus on methods that allow the study of an essential property of neurons, electrical excitability. Our preparation for the electrophysiological study of zebrafish spinal neurons involves the use of veterinarian suture glue to secure the preparation to a recording chamber. Alternative methods for recording from zebrafish embryos and larvae involve the attachment of the preparation to the chamber using a fine tungsten pin1,2,3,4,5. A tungsten pin is most often used to mount the preparation in a lateral orientation, although it has been used to mount larvae dorsal-side up4. The suture glue has been used to mount embryos and larvae in both orientations. Using the glue, a minimal dissection can be performed, allowing access to spinal neurons without the use of an enzymatic treatment, thereby avoiding any resultant damage. However, for larvae, it is necessary to apply a brief enzyme treatment to remove the muscle tissue surrounding the spinal cord. The methods described here have been used to study the intrinsic electrical properties of motor neurons, interneurons, and sensory neurons at several developmental stages6,7,8,9.

Zebrafish In Situ Spinal Cord Preparation for Electrophysiological Recordings from Spinal Sensory and Motor Neurons

This manuscript describes methods for electrophysiological recordings from spinal neurons of zebrafish embryos and larvae. The preparation maintains neurons in situ and often involves minimum dissection. These methods allow for the electrophysiological study of a variety of spinal neurons, from the initial electrical excitability acquisition through the early larval stages.

Zebrafish, first introduced as a developmental model, have gained popularity in many other fields. The ease of rearing large numbers of rapidly developing ...

Analysis of Immune Cells in Single Sciatic Nerves and Dorsal Root Ganglion from a Single Mouse Using Flow Cytometry

Nerve-resident immune cells in the peripheral nervous system (PNS) are essential to maintaining neuronal integrity in a healthy nerve. The immune cells of the PNS are affected by injury and disease, affecting the nerve function and the capacity for regeneration. Neuronal immune cells are commonly analyzed by immunofluorescence (IF). While IF is essential for determining the location of the immune cells in the nerve, IF is only semi-quantitative and the method is limited to the number of markers that can be analyzed simultaneously and the degree of surface expression. In this study, flow cytometry was used for quantitative analysis of leukocyte infiltration into sciatic nerves or dorsal root ganglions (DRGs) of individual mice. Single cell analysis was performed using DAPI and several proteins were analyzed simultaneously for either surface or intracellular expression. Both sciatic nerves from one mouse that were treated according to this protocol generated &#8805; 30,000 single nucleated events. The proportion of leukocytes in the sciatic nerves, determined by expression of CD45, was approximately 5% of total cell content in the sciatic nerve and approximately 5-10% in the DRG. Although this protocol focuses primarily on the immune cell population within the PNS, the flexibility of flow cytometry to measure a number of markers simultaneously means that the other cells populations present within the nerve, such as Schwann cells, pericytes, fibroblasts, and endothelial cells, can also be analyzed using this method. This method therefore provides a new means for studying systemic effects on the PNS, such as neurotoxicology and genetic models of neuropathy or in chronic diseases, such as diabetes.

Quantitative analysis of cell content within the murine sciatic nerve is difficult due to the scarcity of the tissue. This protocol describes a method for tissue digestion and preparation that provides sufficient cells for flow cytometry analysis of immune cell populations from nerves of individual mice.

Nerve-resident immune cells in the peripheral nervous system (PNS) are essential to maintaining neuronal integrity in a healthy nerve. The immune cells of ...

Ocular Kinematics Measured by In Vitro Stimulation of the Cranial Nerves in the Turtle

After animals are euthanized, their tissues begin to die. Turtles offer an advantage because of a longer survival time of their tissues, especially when compared to warm-blooded vertebrates. Because of this, in vitro experiments in turtles can be performed for extended periods of time to investigate the neural signals and control of their target actions. Using an isolated head preparation, we measured the kinematics of eye movements in turtles, and their modulation by electrical signals carried by cranial nerves. After the brain was removed from the skull, leaving the cranial nerves intact, the dissected head was placed in a gimbal to calibrate eye movements. Glass electrodes were attached to cranial nerves (oculomotor, trochlear, and abducens) and stimulated with currents to evoke eye movements. We monitored eye movements with an infrared video tracking system and quantified rotations of the eyes. Current pulses with a range of amplitudes, frequencies, and train durations were used to observe effects on responses. Because the preparation is separated from the brain, the efferent pathway going to muscle targets can be examined in isolation to investigate neural signaling in the absence of centrally processed sensory information.

Ocular Kinematics Measured by In Vitro Stimulation of the Cranial Nerves in the Turtle

This protocol describes how to use an in vitro isolated turtle head preparation to measure the kinematics of their eye movements. After removal of the brain from the cranium, cranial nerves can be stimulated with currents to quantify rotations of the eye and changes in pupil sizes.

After animals are euthanized, their tissues begin to die. Turtles offer an advantage because of a longer survival time of their tissues, especially when ...

In Vivo Calcium Imaging of Lateral-line Hair Cells in Larval Zebrafish

Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory stimuli that mechanically deflect apical protrusions called hair bundles. Deflection opens mechanotransduction (MET) channels in hair bundles, leading to an influx of cations, including calcium. This cation influx depolarizes the cell and opens voltage-gated calcium channels located basally at the hair-cell presynapse. In mammals, hair cells are encased in bone, and it is challenging to functionally assess these activities in vivo. In contrast, larval zebrafish are transparent and possess an externally located lateral-line organ that contains hair cells. These hair cells are functionally and structurally similar to mammalian hair cells and can be functionally assessed in vivo. This article outlines a technique that utilizes a genetically encoded calcium indicator (GECI), GCaMP6s, to measure stimulus-evoked calcium signals in zebrafish lateral-line hair cells. GCaMP6s can be used, along with confocal imaging, to measure in vivo calcium signals at the apex and base of lateral-line hair cells. These signals provide a real-time, quantifiable readout of both mechanosensation- and presynapse-dependent calcium activities within these hair cells. These calcium signals also provide important functional information regarding how hair cells detect and transmit sensory stimuli. Overall, this technique generates useful data about relative changes in calcium activity in vivo. It is less well-suited for quantification of the absolute magnitude of calcium changes. This in vivo technique is sensitive to motion artifacts. A reasonable amount of practice and skill are required for proper positioning, immobilization, and stimulation of larvae. Ultimately, when properly executed, the protocol outlined in this article provides a powerful way to collect valuable information about the activity of hair-cells in their natural, fully integrated states within a live animal.

The zebrafish is a model system that has many valuable features including optical clarity, rapid external development, and, of particular importance to the field of hearing and balance, externally located sensory hair cells. This article outlines how transgenic zebrafish can be used to assay both hair-cell mechanosensation and presynaptic function in toto.

Sensory hair cells are mechanoreceptors found in the inner ear that are required for hearing and balance. Hair cells are activated in response to sensory ...

Purification of Prominin-1+ Stem Cells from Postnatal Mouse Cerebellum

Most cerebellar neurons arise from two embryonic stem niches: a rhombic lip niche, which generates all the cerebellar excitatory glutamatergic neurons, and a ventricular zone niche, which generates the inhibitory GABAergic Purkinje cells, which are neurons that constitute the deep cerebellar nuclei and Bergman glia. Recently, a third stem cell niche has been described that arises as a secondary germinal zone from the ventricular zone niche. The cells of this niche are defined by the cell surface marker prominin-1 and are localized to the developing white matter of the postnatal cerebellum. This niche accounts for the late born molecular layer GABAergic interneurons along with postnatally generated cerebellar astrocytes. In addition to their developmental role, this niche is gaining translational importance in regards to its involvement in neurodegeneration and tumorigenesis. The biology of these cells has been difficult to decipher because of a lack of efficient techniques for their purification. Demonstrated here are efficient methods to purify, culture, and differentiate these postnatal cerebellar stem cells.

Purification of Prominin-1+ Stem Cells from Postnatal Mouse Cerebellum

Demonstrated here is an efficient and cost-effective method to purify, culture, and differentiate white matter stem cells from postnatal mouse cerebellum.

Most cerebellar neurons arise from two embryonic stem niches: a rhombic lip niche, which generates all the cerebellar excitatory glutamatergic neurons, ...