We thank CSIR-IICB animal facility. G. D. thanks ICMR, J. K. and V. G. thank DST Inspire, and D. M. thanks DBT, India for their fellowships. S. G. kindly acknowledges SERB (EMR/2015/002230) India for providing financial support.

All experimental procedures involving animal were approved by the Institutional Animal Ethics Committee of CSIR-Indian Institute of Chemical Biology (IICB/AEC/Meeting/Apr/2018/1).
1. Reagent and media preparation
<ol>
	<li>Poly-D-lysine (PDL) solution: prepare PDL solutions at concentrations of 0.1 mg/mL in deionized water and store in 4 &#176;C until use.</li>
	<li>Dissociation medium: To 1 L of sterile, filtered deionized water, combine the following components in the respective concentrations: sodium chloride (8 mg/mL), potassium chloride (0.4 mg/mL), potassium phosphate monobasic (0.06 mg/mL), D-glucose (1 mg/mL), sodium phosphate dibasic (0.479 mg/mL), and 1 M HEPES [4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; 10 mM]. Vortex all the components to aid proper mixing and store in 4 &#176;C until use. 
	NOTE: Use the dissociation medium in ice-cold form during dissociation but at room temperature (RT) for washing and other purposes.</li>
	<li>Plating medium: plating medium consists of the following: minimum essential medium (MEM) Eagle&#39;s with Earle&#39;s Balanced Salt Solution (BSS; 88.4%), D-glucose (0.6%), horse serum (10%), and penicillin/streptomycin (1%). Combine the components in the respective ratios and perform the procedure inside a hood under sterile conditions. 
	NOTE: Always use freshly prepared plating medium to avoid degradation of any component.</li>
	<li>Maintenance medium: prepare the maintenance medium by combining the following in the respective ratios: neurobasal medium (97%), 0.5 mM commercially obtained glutamine sample, B27 serum-free supplement (2%), and penicillin/streptomycin (1%). Combine the components in the respective ratios and perform the procedure inside a hood under sterile conditions. Ensure that all components are freshly prepared.</li>
</ol>
2. Preparation of coverslips
<ol>
	<li>Take a 12 mm diameter round glass coverslip and soak it in 1 M hydrochloric acid (HCl) for 4 h.</li>
	<li>Transfer the coverslips in distilled water using a pair of forceps and swirl it gently to get rid of the acid completely.</li>
	<li>Transfer the washed coverslips for an additional round of cleaning in a beaker containing 100% ethanol.</li>
	<li>Before using the coverslips, dry them well in the laminar hood by keeping them on tissue paper.</li>
</ol>
3. Preparation of poly-D-lysine coated plates for neuron culture
<ol>
	<li>Take two 24 well plates: one for high density plating and another for low density plating. Open the sterile packets only inside the laminar hood.</li>
	<li>Transfer the 12 mm of sterile glass coverslips in the 24 well plates.</li>
	<li>Pour 300 &#181;L of PDL solution (0.1 mg/mL in deionized water) in each well so that it fully covers the surface of the coverslips.</li>
	<li>Wrap the plates with aluminum foil to prevent drying and keep it in the CO2 incubator overnight.</li>
	<li>The next day (before plating), aspirate the PDL solution and wash properly with 300 &#181;L of sterile deionized water two to three times.</li>
	<li>Add 200 &#181;L of freshly prepared plating medium and return the plates to the incubator until plating.</li>
</ol>
4. Removal and decapitation of the fetus
NOTE: Sterilize all surgical instruments packed in aluminum foil in an autoclave at 121 &#176;C (15 psi) for 30 min. This includes a pair of blunt-end scissors, forceps, fine forceps, two fine scissors, and one artery forceps for the entire procedure.
<ol>
	<li>For generating neurons and neurospheres, use a timed-pregnant Sprague Dawley rat and mark the day with vaginal plug detection as E0. 
	&#8203;NOTE: The culture must be performed between E14-E16.</li>
	<li>On the day of culture, place a sterile glass Petri plate on ice and fill it with cold Hank&#39;s Balanced Salt Solution (HBSS).</li>
	<li>Anesthetize an E14-E16 pregnant rat with an intraperitoneal (i.p.) injection of 90 mg ketamine/kg of body weight and 10 mg xylazine/kg, then sacrifice by performing cervical dislocation. 
	NOTE: Rats can also be euthanized by an overdose of pentobarbital or overdose of ketamine with xylazine or diazepam.</li>
	<li>Sterilize the dam&#39;s abdomen by spraying 70% ethanol and make a V-shaped cut in the abdominal area using sterile forceps and a pair of blunt-end scissors.</li>
	<li>Take the embryonic sacs carefully on the Petri plate with cold HBSS solution. 
	NOTE: Do not use the same forceps and scissors that were just used for the skin, as this will contaminate the internal organs. Use a different set of scissors/forceps for the internal organs.</li>
	<li>Take the embryos out of the embryonic sacs in fresh, cold HBSS.</li>
	<li>Decapitate the head with sterile scissors.</li>
</ol>
5. Removal of brain and dissection of the cortex with hippocampus
<ol>
	<li>Before starting, fill 90 mm sterile Petri dishes with cold, sterile HBSS.</li>
	<li>Transfer the heads in the sterile dishes using sterile, blunt-ended dressing forceps.</li>
	<li>Under the stereomicroscope, hold the head from the snout region with sterile, serrated forceps and remove the brain by cutting the skin and skull open.</li>
	<li>Collect all the embryo brains in the same manner in the HBSS solution.</li>
	<li>Remove all meninges from the hemispheres and midbrain by holding the brainstem.</li>
	<li>Carefully remove the intact hemispheres resembling mushroom caps that contain the hippocampus and cortex.</li>
	<li>Collect the hemispheres containing cortex and intact hippocampus in a 15 mL conical tube containing 10 mL of dissociation medium.</li>
</ol>
6. Dissociation of cortical and hippocampal tissue into single neurons
<ol>
	<li>Allow the collected tissues to settle down and aspirate the dissociation medium, leaving 5%-10% of medium in it.</li>
	<li>Add 10 mL of fresh dissociation medium to the tissue, and repeat step 6.1 twice.</li>
	<li>Add 4.5 mL of dissociation medium and 0.5 mL of 0.25% (1x) trypsin EDTA (ethylene diamine tetraacetate) solution.</li>
	<li>Keep the tissue in the incubator at 37 &#176;C for 20 min for the digestion to proceed.</li>
	<li>Aspirate the medium and add 10 mL of dissociation and plating medium consecutively to the digested tissues.</li>
	<li>Allow the digested tissues to settle down and aspirate the dissociation medium. Add 2.5 mL of plating medium and pour into the base of a 90 mm sterile dish.</li>
	<li>Triturate the digested tissues in the corner base of the dish using a 1,000 &#181;L pipette tip to occupy the minimal volume.</li>
	<li>Pass the obtained cell suspension through the 70 &#181;m cell strainer, excluding any chunks of tissue.</li>
	<li>Determine the density of viable cells using the trypan blue dye exclusion method and count the number of cells in an automated cell counter.
	<ol>
		<li>For trypan blue dye exclusion method, take 10 &#181;L of the cell suspension and 10 &#181;L of 0.4% trypan blue stain, mix thoroughly, and add 10 &#181;L of the mixture in one of the two enclosed chambers of the disposable chamber slides.</li>
		<li>Insert the slide containing the mixture into the cell counter and obtain the reading. 
		NOTE: The trypan blue dye exclusion method is based on the principle that live cells (due to their intact membranes) will exclude trypan blue dye and will hence show a clear cytoplasm, compared to a non-viable cell that will easily take up trypan blue and appear blue in color15.</li>
	</ol>
	</li>
	<li>Dilute the number of cells obtained to plate 1.5 x 105 cells/mL for high density and 20,000 cells/mL for low density in two separate tubes containing 30 mL each of the plating medium.</li>
	<li>Aspirate the previously added plating medium from each well and plate 500 &#181;L of cells dispersed in plating medium in each well.</li>
	<li>After that return the plates to the incubator at 37 &#176;C and 5% CO2 for 4 h.</li>
	<li>Examine the cells for adherence under the microscope 4 h after plating.</li>
	<li>If there is proper adherence of the cells in both plates, replace the medium in each well with 500 &#181;L of fresh maintenance medium and incubate at 37 &#176;C.</li>
	<li>Culture these neurons grown at low density for 30 days by changing the maintenance medium 2x per week.</li>
	<li>Culture the neurospheres obtained from the high-density plated neurons in the same maintenance medium by transferring them to the ultra-low attachment plates.</li>
	<li>Characterize the neurons and the neurospheres by immunostaining them with important markers. For immunocytochemistry, first fix the cells/neurospheres using 4% formaldehyde for 30 min on the plate itself, then permeabilize the cells with 0.1% non-ionic detergent for 10 min.</li>
	<li>Add primary antibodies for both neurons (anti-Tuj1, GFAP, O4, tau) and neurospheres (anti-Nestin, GFAP, Tuj1) in phosphate-buffered saline (PBS) at 1:300 concentrations and incubate overnight at 4 &#176;C16. 
	NOTE: The Tuj1 (class III &#946;-tubulin) and tau are positive markers for the primary neurons, while GFAP (glial fibrillary acidic protein) and O4 (oligodendrocyte marker) are negative markers for primary neurons17,18. In the case of neurospheres, Tuj1, GFAP, and Nestin all&#160;serve as positive markers19,20.</li>
	<li>The next day, wash the cells with PBS once or twice and add appropriate secondary antibodies in PBS at 1:600 concentrations at RT for 2 h. 
	NOTE: The anti-Mouse or anti-Rabbit secondary antibodies are selected depending on the host species of the primary antibody added. It should be kept in mind that the secondary antibodies must be conjugated to fluorescence derivatives suitable for fluorescence microscopy purposes.</li>
	<li>Wash the cells again with PBS once or twice.
	<ol>
		<li>Perform nuclear staining of the cells with Hoechst 33258 (1 mg/mL stock solution in deionized water). Prepare 0.1% Hoechst solution in PBS from the stock solution and add it to the cells.</li>
		<li>Incubate the cells with 0.1% Hoechst solution for 30 min, then wash again with PBS.</li>
	</ol>
	</li>
	<li>Add 20 &#181;L PBS (or mounting medium) on the slide and slowly mount the coverslip containing the stained cells over the area of the slide containing PBS. Seal the margins of the coverslip with dibutylphthalate polystyrene xylene (DPX).</li>
	<li>Perform imaging of the fixed cells under a microscope at 10x and 40x magnification.</li>
</ol>

<ol>
	<li>Lorsch, J. R., Collins, F. S., Lippincott-Schwartz, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fixing+problems+with+cell+lines.">Fixing problems with cell lines.</a> Science. 346 (6216), 1452-1453 (2014).</li><li>Masters, J. R. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cell+line+misidentification:+the+beginning+of+the+end.">Cell line misidentification: the beginning of the end.</a> Nature Reviews Cancer. 10 (6), 441-448 (2010).</li><li>Banker, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Culturing Nerve Cells, 2nd edition. , 339-370 (1998).</li><li>Geschwind, D. H., Konopka, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroscience+in+the+era+of+functional+genomics+and+systems+biology.">Neuroscience in the era of functional genomics and systems biology.</a> Nature. 461 (7266), 908-915 (2009).</li><li>Kaech, S., Banker, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culturing+hippocampal+neurons.">Culturing hippocampal neurons.</a> Nature Protocol. 1, 2406-2415 (2006).</li><li>Lu, Z. M., Piechowicz, M., Qiu, S. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Simplified+Method+for+Ultra-Low+Density,+Long-Term+Primary+Hippocampal+Neuron+Culture.">A Simplified Method for Ultra-Low Density, Long-Term Primary Hippocampal Neuron Culture.</a> Journal of Visual Experiments. 109, e53797 (2016).</li><li>Kaneko, A., Sankai, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Long-Term+Culture+of+Rat+Hippocampal+Neurons+at+Low+Density+in+Serum-Free+Medium:+Combination+of+the+Sandwich+Culture+Technique+with+the+Three-Dimensional+Nanofibrous+Hydrogel+PuraMatrix.">Long-Term Culture of Rat Hippocampal Neurons at Low Density in Serum-Free Medium: Combination of the Sandwich Culture Technique with the Three-Dimensional Nanofibrous Hydrogel PuraMatrix.</a> PLoS ONE. 9 (7), e102703 (2014).</li><li>Banker, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trophic+interactions+between+astroglial+cells+and+hippocampal+neurons+in+culture.">Trophic interactions between astroglial cells and hippocampal neurons in culture.</a> Science. 209 (4458), 809-810 (1980).</li><li>Dotti, C. G., Sullivan, C. A., Banker, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+establishment+of+polarity+by+hippocampal+neurons+in+culture.">The establishment of polarity by hippocampal neurons in culture.</a> Journal of Neuroscience. 8 (4), 1454-1468 (1988).</li><li>Piret, G., Perez, M. T., Prinz, C. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Support+of+Neuronal+Growth+Over+Glial+Growth+and+Guidance+of+Optic+Nerve+Axons+by+Vertical+Nanowire+Arrays.">Support of Neuronal Growth Over Glial Growth and Guidance of Optic Nerve Axons by Vertical Nanowire Arrays.</a> ACS Applied Materials &amp; Interfaces. 7 (34), 18944-18948 (2015).</li><li>Campos, L. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neurospheres:+Insights+biology+into+neural+stem+cell+biology.">Neurospheres: Insights biology into neural stem cell biology.</a> Journal of Neuroscience Research. 78 (6), 761-769 (2004).</li><li>Ahmed, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Culture+of+Neural+Stem+Cells.">The Culture of Neural Stem Cells.</a> Journal of Cellular Biochemistry. 106, 1-6 (2009).</li><li>Reynolds, B. A., Weiss, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generation+of+neurons+and+astrocytes+from+isolated+cells+of+the+adult+mammalian+central+nervous+system.">Generation of neurons and astrocytes from isolated cells of the adult mammalian central nervous system.</a> Science. 255, 1707-1710 (1992).</li><li>Jensen, J. B., Parmar, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Strengths+and+limitations+of+the+neurosphere+culture+system.">Strengths and limitations of the neurosphere culture system.</a> Molecular Neurobiology. 34 (3), 153-161 (2006).</li><li>Strober, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Trypan+blue+exclusion+test+of+cell+viability.">Trypan blue exclusion test of cell viability.</a> Current Protocols in Immunology. 111, A3.B.1-A3.B.3 (2015).</li><li>Pradhan, K., 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=Neuro-Regenerative+Choline-Functionalized+Injectable+Graphene+Oxide+Hydrogel+Repairs+Focal+Brain+Injury.">Neuro-Regenerative Choline-Functionalized Injectable Graphene Oxide Hydrogel Repairs Focal Brain Injury.</a> ACS Chemical Neuroscience. 10 (3), 1535-1543 (2019).</li><li>Ray, B., Bailey, J. A., Sarkar, S., Lahiri, D. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+and+immunocytochemical+characterization+of+primary+neuronal+cultures+from+adult+rat+brain:+Differential+expression+of+neuronal+and+glial+protein+markers.">Molecular and immunocytochemical characterization of primary neuronal cultures from adult rat brain: Differential expression of neuronal and glial protein markers.</a> Journal of Neuroscience Methods. 184 (2), 294-302 (2009).</li><li>Robinson, A. P., Rodgers, J. M., Goings, G. E., Miller, S. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Oligodendroglial+Populations+in+Mouse+Demyelinating+Disease+Using+Flow+Cytometry:+Clues+for+MS+Pathogenesis.">Characterization of Oligodendroglial Populations in Mouse Demyelinating Disease Using Flow Cytometry: Clues for MS Pathogenesis.</a> PLoS ONE. 9 (9), (2014).</li><li>Osterberg, N., Roussa, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+primary+neurospheres+generated+from+mouse+ventral+rostral+hindbrain.">Characterization of primary neurospheres generated from mouse ventral rostral hindbrain.</a> Cell and Tissue Research. 336 (1), 11-20 (2009).</li><li>Bernal, A., Arranz, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nestin-expressing+progenitor+cells:+function,+identity+and+therapeutic+implications.">Nestin-expressing progenitor cells: function, identity and therapeutic implications.</a> Cellular and Molecular Life Sciences. 75 (12), 2177-2195 (2018).</li><li>Qu, Q. H., 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=High-efficiency+motor+neuron+differentiation+from+human+pluripotent+stem+cells+and+the+function+of+Islet-1.">High-efficiency motor neuron differentiation from human pluripotent stem cells and the function of Islet-1.</a> Nature Communications. 5, 3449 (2014).</li><li>Bradke, F., Dotti, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiated+neurons+retain+the+capacity+to+generate+axons+from+dendrites.">Differentiated neurons retain the capacity to generate axons from dendrites.</a> Current Biology. 10 (22), 1467-1470 (2000).</li><li>Theocharatos, S., 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=Regulation+of+Progenitor+Cell+Proliferation+and+Neuronal+Differentiation+in+Enteric+Nervous+System+Neurospheres.">Regulation of Progenitor Cell Proliferation and Neuronal Differentiation in Enteric Nervous System Neurospheres.</a> PLoS ONE. 8 (1), (2013).</li><li>Binder, E., 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=Enteric+Neurospheres+Are+Not+Specific+to+Neural+Crest+Cultures:+Implications+for+Neural+Stem+Cell+Therapies.">Enteric Neurospheres Are Not Specific to Neural Crest Cultures: Implications for Neural Stem Cell Therapies.</a> PLoS ONE. 10 (3), e0119467 (2015).</li><li>Cordey, M., Limacher, M., Kobel, S., Taylor, V., Lutolf, M. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Enhancing+the+Reliability+and+Throughput+of+Neurosphere+Culture+on+Hydrogel+Microwell+Arrays.">Enhancing the Reliability and Throughput of Neurosphere Culture on Hydrogel Microwell Arrays.</a> Stem Cells. 26 (10), 2586-2594 (2008).</li><li>Ladiwala, U., Basu, H., Mathur, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assembling+Neurospheres:+Dynamics+of+Neural+Progenitor/Stem+Cell+Aggregation+Probed+Using+an+Optical+Trap.">Assembling Neurospheres: Dynamics of Neural Progenitor/Stem Cell Aggregation Probed Using an Optical Trap.</a> PLoS ONE. 7 (6), (2012).</li></ol>

The authors declare no competing financial interests.

This protocol describes that how by altering the&#160;cell plating densities of primary neurons, two variable neuronal platforms&#160;are obtained. Though this is a simple method, each step must be meticulously performed to achieve the desired results. Other previous methods have either reported long-term primary neuron cultures or neurosphere cultures. Most primary neuron culture protocols have involved the culturing of hippocampal neurons for 3-5 weeks, but most have failed, as the neurons die and wither away due to lo...

The brain is an intricate circuitry of neuronal and non-neuronal cells. For years, scientists have been trying to gain insight into this complex machinery. To do so, neuroscientists initially resorted to various transformed nerve-based cell lines for investigations. However, the inability of these clonal cell lines to form strong synaptic connections and proper axons or dendrites have shifted scientific interest to primary neuron cultures1,2. The most exciting aspect of primary neuron culture is that it creates an opportunity to observe and manipulate living neurons3. Moreover, it is less complex compared to neural tissue, which makes it an ideal candidate for studying the function and transport of various neuronal proteins. Recently, several developments in the fields of microscopy, genomics, and proteomics have generated new opportunities for neuroscientists to exploit neuron cultures4.
Primary cultures have allowed neuroscientists to explore the molecular mechanisms behind neural development, analyze various neural signaling pathways, and develop a more coherent understanding of synapsis. Though a number of methods have reported cultures from primary neurons (mostly from the hippocampal origin5,6,7), a unified protocol with a chemically defined medium that enables long-term culture of neurons is still needed. However, neurons plated at a low density are most often observed, which do not survive long-term, likely due to the lack of trophic support8 that is provided by the adjacent neurons and glial cells. Some methods have even suggested co-culturing of the primary neurons with glial cells, wherein the glial cells are used as a feeder layer9. However, glial cells pose a lot of problems due to their overgrowth, which sometimes override the neuronal growth10. Hence, considering the problems above, a simpler and more cost-effective primary neural culture protocol is required, which can be used by both neurobiologists and neurochemists for investigations.
A primary neuron culture is essentially a form of 2D culture and does not represent the plasticity, spatial integrity, or heterogeneity of the brain. This has given rise to the need for a more believable 3D model called neurospheres11,12.&#160;Neurospheres present a novel platform to neuroscientists, with a closer resemblance to the real, in vivo brain13. Neurospheres are non-adherent 3D clusters of cells that are rich in neural stem cells (NSCs), neural progenitor cells (NPCs), neurons, and astrocytes. They are an excellent source for the isolation of neural stem cells and neural progenitor cells, which can be used to study differentiation into various neuronal and non-neuronal lineages. Again, variability within neurosphere cultures produced using the previously reported protocols presents a barrier to the formulation of a unified neurosphere culture protocol14.
This manuscript presents a protocol in which it is possible to generate both 2D and 3D platforms by alternating cell plating densities from a mixed cortical and hippocampal culture. It is observed that within 7 days free-floating neurospheres are obtained from&#160;high-density plated neurons isolated from E14-E16 Sprague Dawley rat embryo, which upon further culture, form bridges and interconnections through radial glial-like extensions. Similarly, in the low density plated neurons, a primary neuron culture that can be maintained for up to 30 days is obtained by changing the maintenance medium twice per week.

<table border="0" cellpadding="0" cellspacing="0" style="width:812px;" width="812">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Anti-GFAP</td>
			<td style="width:183px;">Abcam</td>
			<td style="width:174px;">AB7260</td>
			<td style="width:249px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Anti- Nestin</td>
			<td style="width:183px;">Abcam</td>
			<td style="width:174px;">AB92391</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Anti-O4</td>
			<td style="width:183px;">Millipore</td>
			<td style="width:174px;">MAB345</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Anti-Tau</td>
			<td style="width:183px;">Abcam</td>
			<td style="width:174px;">AB76128</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Anti-Tuj1</td>
			<td style="width:183px;">Millipore</td>
			<td style="width:174px;">MAB1637</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">B27 Serum Free Supplement&#160;</td>
			<td style="width:183px;">Gibco</td>
			<td style="width:174px;">17504-044</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Cell Counter</td>
			<td style="width:183px;">Life technologies</td>
			<td style="width:174px;">Countess II FL</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">CO2 Incubator</td>
			<td style="width:183px;">Eppendorf</td>
			<td style="width:174px;">Galaxy 170 R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">D-glucose&#160;</td>
			<td style="width:183px;">SDFCL</td>
			<td style="width:174px;">38450-K05</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Ethanol</td>
			<td style="width:183px;">Merck Millipore</td>
			<td style="width:174px;">100983</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Fluorescence Microscope</td>
			<td style="width:183px;">Olympus</td>
			<td style="width:174px;">IX83 Model</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Formaldehyde</td>
			<td style="width:183px;">Sigma Aldrich</td>
			<td style="width:174px;">47608</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">GlutaMax-I Supplement</td>
			<td style="width:183px;">Gibco</td>
			<td style="width:174px;">35050-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">GtXMs IgG Fluor</td>
			<td style="width:183px;">Millipore</td>
			<td style="width:174px;">AP1814</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">GtXMs IgG (H+L)</td>
			<td style="width:183px;">Millipore</td>
			<td style="width:174px;">AP124C</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">HEPES</td>
			<td style="width:183px;">SRL</td>
			<td style="width:174px;">16826</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Hoechst 33258</td>
			<td style="width:183px;">Calbiochem</td>
			<td style="width:174px;">382061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Horse Serum&#160;</td>
			<td style="width:183px;">HiMedia</td>
			<td style="width:174px;">RM10674</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Hydrochloric Acid</td>
			<td style="width:183px;">Rankem</td>
			<td style="width:174px;">H0100</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Laminar Hood</td>
			<td style="width:183px;">BioBase</td>
			<td style="width:174px;">BBS-V1800</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">MEM Eagle&#8217;s with Earle&#8217;s BSS&#160;</td>
			<td style="width:183px;">Sigma Aldrich</td>
			<td style="width:174px;">M-2279</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Microscope</td>
			<td style="width:183px;">Dewinter</td>
			<td style="width:174px;">Victory Model</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Neurobasal Medium&#160;</td>
			<td style="width:183px;">Gibco</td>
			<td style="width:174px;">21103-049</td>
			<td></td>
		</tr>
		<tr height="62">
			<td height="62" style="height:63px;width:207px;">Plasticware (24 well plate, cell strainers, and low adherence plates)</td>
			<td style="width:183px;">BD Falcon</td>
			<td style="width:174px;">353047, 352350 and 3471</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">90 mm Petridishes</td>
			<td style="width:183px;">Himedia</td>
			<td style="width:174px;">PW001</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Penicillin/Streptomycin&#160;</td>
			<td style="width:183px;">Gibco</td>
			<td style="width:174px;">15140-122</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Poly-D-Lysine</td>
			<td style="width:183px;">Millipore</td>
			<td style="width:174px;">A.003.E</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium Chloride&#160;</td>
			<td style="width:183px;">Fisher Scientific</td>
			<td style="width:174px;">BP366-500</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potassium Phosphate Monobasic&#160;</td>
			<td style="width:183px;">Merck</td>
			<td style="width:174px;">MI6M562401</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium Chloride&#160;</td>
			<td style="width:183px;">Qualigem</td>
			<td style="width:174px;">15918</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sodium Phosphate Dibasic&#160;</td>
			<td style="width:183px;">Merck</td>
			<td style="width:174px;">MI6M562328</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Stereomicrosope</td>
			<td style="width:183px;">Dewinter</td>
			<td style="width:174px;">Zoomstar Model</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Triton-X 100</td>
			<td style="width:183px;">SRL</td>
			<td style="width:174px;">2020130</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">Trypan Blue Solution</td>
			<td style="width:183px;">Gibco</td>
			<td style="width:174px;">15250-061</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:207px;">0.25 % Trypsin-EDTA</td>
			<td style="width:183px;">Gibco</td>
			<td style="width:174px;">25200-072</td>
			<td></td>
		</tr>
	</tbody>
</table>

generation of neurospheres from mixed primary hippocampal and cortical neurons isolated from e14-e16 sprague dawley rat embryo

Primary neuron culture is an essential technique in the field of neuroscience. To gain deeper mechanistic insights into the brain, it is essential to have a robust in vitro model that can be exploited for various neurobiology studies. Though primary neuron cultures (i.e., long-term hippocampal cultures) have provided scientists with models, it does not yet represent the complexity of brain network completely. In the wake of these limitations, a new model has emerged using neurospheres, which bears a closer resemblance to the brain tissue. The present protocol describes the plating of high and low densities of mixed cortical and hippocampal neurons isolated from the embryo of embryonic day 14-16 Sprague Dawley rats. This allows for the generation of neurospheres and long-term primary neuron culture as two independent platforms to conduct further studies. This process is extremely simple and cost-effective, as it minimizes several steps and reagents previously deemed essential for neuron culture. This is a robust protocol with minimal requirements that can be performed with achievable results and further used for a diversity of studies related to neuroscience.

In this protocol, a simple strategy has been elucidated in which variable cell plating densities from two different neural screening platforms are obtained. Figure 1A,B illustrates the adherence of cells after 4 h of plating the neurons in high and low density plated cells, respectively. On observing the proper adherence of the neurons as shown in Figure 1, the plating medium was replaced by maintenance medium in...

Watch this Scientific Journal Video about Generation of Neurospheres from Mixed Primary Hippocampal and Cortical Neurons Isolated from E14-E16 Sprague Dawley Rat Embryo at JoVE.com

Generation of Neurospheres from Mixed Primary Hippocampal and Cortical Neurons Isolated from E14-E16 Sprague Dawley Rat Embryo

Presented here is a protocol for the spontaneous generation of neurospheres enriched in neural progenitor cells from high density plated neurons. During the same experiment, when neurons are plated at a lower density, the protocol also results in prolonged primary rat neuron cultures.

Primary neuron culture is an essential technique in the field of neuroscience. To gain deeper mechanistic insights into the brain, it is essential to have ...

generation-neurospheres-from-mixed-primary-hippocampal-cortical

Research

JoVE Journal

Neuroscience

8.7K Views.  CSIR-Indian Institute of Chemical Biology. Presented here is a protocol for the spontaneous generation of neurospheres enriched in neural progenitor cells from high density plated neurons. During the same experiment, when neurons are plated at a lower density, the protocol also results in prolonged primary rat neuron cultures.

Video: Generation of Neurospheres from Mixed Primary Hippocampal and Cortical Neurons Isolated from E14-E16 Sprague Dawley Rat Embryo

Nucleofection and Primary Culture of Embryonic Mouse Hippocampal and Cortical Neurons

Hippocampal and cortical neurons have been used extensively to study central nervous system (CNS) neuronal polarization, axon/dendrite outgrowth, and synapse formation and function. An advantage of culturing these neurons is that they readily polarize, forming distinctive axons and dendrites, on a two dimensional substrate at very low densities. This property has made them extremely useful for determining many aspects of neuronal development. Furthermore, by providing glial conditioning for these neurons they will continue to develop, forming functional synaptic connections and surviving for several months in culture. In this protocol we outline a technique to dissect, culture and transfect embryonic mouse hippocampal and cortical neurons. Transfection is accomplished by electroporating DNA into the neurons before plating via nucleofection. This protocol has the advantage of expressing fluorescently-tagged fusion proteins early in development (~4-8hrs after plating) to study the dynamics and function of proteins during polarization, axon outgrowth and branching. We have also discovered that this single transfection before plating maintains fluorescently-tagged fusion protein expression at levels appropriate for imaging throughout the lifetime of the neuron (&gt; 2 months in culture). Thus, this methodology is useful for studying protein localization and function throughout CNS development with little or no disruption of neuronal function.

This protocol outlines the steps required to dissect, transfect via electroporation and culture mouse hippocampal and cortical neurons. Short-term cultures may be used for studies of axon outgrowth and guidance, while long-term cultures can be used for studies of synaptogenesis and dendritic spine analysis.

Hippocampal and cortical neurons have been used extensively to study central nervous system (CNS) neuronal polarization, axon/dendrite outgrowth, and ...

Generation of Neural Stem Cells from Discarded Human Fetal Cortical Tissue

Neural stem cells (NSCs) reside along the ventricular zone neuroepithelium during the development of the cortical plate. These early progenitors ultimately give rise to intermediate progenitors and later, the various neuronal and glial cell subtypes that form the cerebral cortex. The capacity to generate and expand human NSCs (so called neurospheres) from discarded normal fetal tissue provides a means with which to directly study the functional aspects of normal human NSC development 1-5. This approach can also be directed toward the generation of NSCs from known neurological disorders, thereby affording the opportunity to identify disease processes that alter progenitor proliferation, migration and differentiation 6-9. We have focused on identifying pathological mechanisms in human Down syndrome NSCs that might contribute to the accelerated Alzheimer's disease phenotype 10,11. Neither in vivo nor in vitro mouse models can replicate the identical repertoire of genes located on human chromosome 21. 
Here we use a simple and reliable method to isolate Down syndrome NSCs from aborted human fetal cortices and grow them in culture. The methodology provides specific aspects of harvesting the tissue, dissection with limited anatomical landmarks, cell sorting, plating and passaging of human NSCs. We also provide some basic protocols for inducing differentiation of human NSCs into more selective cell subtypes.

A simple and reliable method on isolation and culture of neural stem cells from discarded human fetal cortical tissue is described. Cultures derived from known human neurological disorders can be used for characterization of pathological cellular and molecular processes, as well as provide a platform to assess pharmacological efficacy.

Neural stem cells (NSCs) reside along the ventricular zone neuroepithelium during the development of the cortical plate. These early progenitors ...

Bilaminar Co-culture of Primary Rat Cortical Neurons and Glia

This video will guide you through the process of culturing rat cortical neurons in the presence of a glial feeder layer, a system known as a bilaminar or co-culture model. This system is suitable for a variety of experimental needs requiring either a glass or plastic growth substrate and can also be used for culture of other types of neurons.
Rat cortical neurons obtained from the late embryonic stage (E17) are plated on glass coverslips or tissue culture dishes facing a feeder layer of glia grown on dishes or plastic coverslips (known as Thermanox), respectively. The choice between the two configurations depends on the specific experimental technique used, which may require, or not, that neurons are grown on glass (e.g. calcium imaging versus Western blot). The glial feeder layer, an astroglia-enriched secondary culture of mixed glia, is separately prepared from the cortices of newborn rat pups (P2-4) prior to the neuronal dissection.
A major advantage of this culture system as compared to a culture of neurons only is the support of neuronal growth, survival, and differentiation provided by trophic factors secreted from the glial feeder layer, which more accurately resembles the brain environment in vivo. Furthermore, the co-culture can be used to study neuronal-glial interactions1.
At the same time, glia contamination in the neuronal layer is prevented by different means (low density culture, addition of mitotic inhibitors, lack of serum and use of optimized culture medium) leading to a virtually pure neuronal layer, comparable to other established methods1-3. Neurons can be easily separated from the glial layer at any time during culture and used for different experimental applications ranging from electrophysiology4, cellular and molecular biology5-8, biochemistry5, imaging and microscopy4,6,7,9,10. The primary neurons extend axons and dendrites to form functional synapses11, a process which is not observed in neuronal cell lines, although some cell lines do extend processes.
A detailed protocol of culturing rat hippocampal neurons using this co-culture system has been described previously4,12,13. Here we detail a modified protocol suited for cortical neurons. As approximately 20x106 cells are recovered from each rat embryo, this method is particularly useful for experiments requiring large numbers of neurons (but not concerned about a highly homogenous neuronal population). The preparation of neurons and glia needs to be planned in a time-specific manner. We will provide the step-by-step protocol for culturing rat cortical neurons as well as culturing glial cells to support the neurons.

Here we provide a protocol for culturing rat cortical neurons in the presence of a glial feeder layer. The cultured neurons establish polarity and create synapses, and can be separated from the glia for use in various applications, such as electrophysiology, calcium imaging, cell survival assays, immunocytochemistry, and RNA/DNA/protein isolation.

This video will guide you through the process of culturing rat cortical neurons in the presence of a glial feeder layer, a system known as a bilaminar or ...

Isolation and Culture of Hippocampal Neurons from Prenatal Mice

Primary cultures of rat and murine hippocampal neurons are widely used to reveal cellular mechanisms in neurobiology. By isolating and growing individual neurons, researchers are able to analyze properties related to cellular trafficking, cellular structure and individual protein localization using a variety of biochemical techniques. Results from such experiments are critical for testing theories addressing the neural basis of memory and learning. However, unambiguous results from these forms of experiments are predicated on the ability to grow neuronal cultures with minimum contamination by other brain cell types. In this protocol, we use specific media designed for neuron growth and careful dissection of embryonic hippocampal tissue to optimize growth of healthy neurons while minimizing contaminating cell types (i.e. astrocytes). Embryonic mouse hippocampal tissue can be more difficult to isolate than similar rodent tissue due to the size of the sample for dissection. We show detailed dissection techniques of hippocampus from embryonic day 19 (E19) mouse pups. Once hippocampal tissue is isolated, gentle dissociation of neuronal cells is achieved with a dilute concentration of trypsin and mechanical disruption designed to separate cells from connective tissue while providing minimum damage to individual cells. A detailed description of how to prepare pipettes to be used in the disruption is included. Optimal plating densities are provided for immuno-fluorescence protocols to maximize successful cell culture. The protocol provides a fast (approximately 2 hr) and efficient technique for the culture of neuronal cells from mouse hippocampal tissue.

We provide a protocol for the culture of highly purified hippocampal neurons from prenatal mouse brains without the use of a feeder glial cell layer.

Primary cultures of rat and murine hippocampal neurons are widely used to reveal cellular mechanisms in neurobiology. By isolating and growing individual ...

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 ...

Imaging Dendritic Spines of Rat Primary Hippocampal Neurons using Structured Illumination Microscopy

Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. Technological advances have identified these structures as key elements in neuron connectivity and synaptic plasticity. The quantitative analysis of spine morphology using light microscopy remains an essential problem due to technical limitations associated with light's intrinsic refraction limit. Dendritic spines can be readily identified by confocal laser-scanning fluorescence microscopy. However, measuring subtle changes in the shape and size of spines is difficult because spine dimensions other than length are usually smaller than conventional optical resolution fixed by light microscopy's theoretical resolution limit of 200 nm.
Several recently developed super resolution techniques have been used to image cellular structures smaller than the 200 nm, including dendritic spines. These techniques are based on classical far-field operations and therefore allow the use of existing sample preparation methods and to image beyond the surface of a specimen. Described here is a working protocol to apply super resolution structured illumination microscopy (SIM) to the imaging of dendritic spines in primary hippocampal neuron cultures. Possible applications of SIM overlap with those of confocal microscopy. However, the two techniques present different applicability. SIM offers higher effective lateral resolution, while confocal microscopy, due to the usage of a physical pinhole, achieves resolution improvement at the expense of removal of out of focus light. In this protocol, primary neurons are cultured on glass coverslips using a standard protocol, transfected with DNA plasmids encoding fluorescent proteins and imaged using SIM. The whole protocol described herein takes approximately 2 weeks, because dendritic spines are imaged after 16-17 days in vitro, when dendritic development is optimal. After completion of the protocol, dendritic spines can be reconstructed in 3D from series of SIM image stacks using specialized software.

This article describes a working protocol to image dendritic spines from hippocampal neurons in vitro using Structured Illumination Microscopy (SIM). Super-resolution microscopy using SIM provides image resolution significantly beyond the light diffraction limit in all three spatial dimensions, allowing the imaging of individual dendritic spines with improved detail.

Dendritic spines are protrusions emerging from the dendrite of a neuron and represent the primary postsynaptic targets of excitatory inputs in the brain. ...

A Method of Nodose Ganglia Injection in Sprague-Dawley Rat

Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located in the organs of the abdomen and thorax. The vagus nerve communicates information from stimuli such as heart rate, blood pressure, bronchopulmonary irritation, and gastrointestinal distension to the nucleus of solitary tract of the medulla. The cell bodies of the vagus nerve are located in the nodose and petrosal ganglia, of which the majority are located in the former. The nodose ganglia contain a wealth of receptors for amino acids, monoamines, neuropeptides, and other neurochemicals that can modify afferent vagus nerve activity. Modifying vagal afferents through systemic peripheral drug treatments targeted at the receptors on nodose ganglia has the potential of treating diseases such as sleep apnea, gastroesophageal reflux disease, or chronic cough. The protocol here describes a method of injection neurochemicals directly into the nodose ganglion. Injecting neurochemicals directly into the nodose ganglia allows study of effects solely on cell bodies that modulate afferent nerve activity, and prevents the complication of involving the central nervous system as seen in systemic neurochemical treatment. Using readily available and inexpensive equipment, intranodose ganglia injections are easily done in anesthetized Sprague-Dawley rats.

Afferent vagal signaling transmits important information to central nervous system from receptors located in organs of the abdomen and thorax. The nodose ganglia of vagus nerves contain many types of receptors that modulate vagal activity. This protocol describes a method of local injections of neurochemicals into the nodose ganglia.

Afferent signaling via the vagus nerve transmits important general visceral information to the central nervous system from many diverse receptors located ...

Quantification of Filamentous Actin (F-actin) Puncta in Rat Cortical Neurons

Filamentous actin protein (F-actin) plays a major role in spinogenesis, synaptic plasticity, and synaptic stability. Changes in dendritic F-actin rich structures suggest alterations in synaptic integrity and connectivity. Here we provide a detailed protocol for culturing primary rat cortical neurons, Phalloidin staining for F-actin puncta, and subsequent quantification techniques. First, the frontal cortex of E18 rat embryos are dissociated into low-density cell culture, then the neurons grown in vitro for at least 12-14 days. Following experimental treatment, the cortical neurons are stained with AlexaFluor 488 Phalloidin (to label the dendritic F-actin puncta) and microtubule-associated protein 2 (MAP2; to validate the neuronal cells and dendritic integrity). Finally, specialized software is used to analyze and quantify randomly selected neuronal dendrites. F-actin rich structures are identified on second order dendritic branches (length range 25-75 &#181;m) with continuous MAP2 immunofluorescence. The protocol presented here will be a useful method for investigating changes in dendritic synapse structures subsequent to experimental treatments.

Quantification of Filamentous Actin F-actin Puncta in Rat Cortical Neurons

Filamentous actin (F-actin) plays an important role in spinogenesis, synaptic plasticity, and synaptic stability. Quantification of F-actin puncta is therefore a useful tool to study the integrity of synaptic structures. This protocol describes the procedures of quantifying F-actin puncta labeled with Phalloidin in low-density primary cortical neuronal cultures.

Filamentous actin protein (F-actin) plays a major role in spinogenesis, synaptic plasticity, and synaptic stability. Changes in dendritic F-actin rich ...

Preparation of Primary Mixed Glial Cultures from Adult Mouse Spinal Cord Tissue

It has been well-accepted that spinal cord glial responses contribute significantly to the development of neuropathic pain. Tremendous information regarding glial activities at the cellular and molecular levels has been obtained through in vitro cell culture systems. The in vitro systems utilized, mainly include primary glia derived from neonatal brain cortical tissue and immortalized cell lines. However, these systems may not reflect the characteristics of spinal cord glial cells in vivo. In order to further investigate the roles of spinal cord glial cells in the development of peripheral nerve injury-induced neuropathic pain using a culture system that better reflects the in vivo condition, our laboratory has developed a method to establish primary spinal cord mixed glial cultures from adult mice. Briefly, spinal cords are collected from adult mice and processed through papain digestion followed by myelin removal with a density-gradient medium. Single cell suspensions are cultured in complete Dulbecco&#39;s modified Eagle media (cDMEM) supplemented with 2-mercaptoethanol (2-ME) at 35.9 oC. These culture conditions were optimized specifically for the growth of mixed glial cells. Under these conditions, cells are ready to be used for experimentation between 12 - 14 d&#160;(cells are usually in log phase during this time) after the establishment of the culture (D 0) and can be kept in culture conditions up to D 21. This culture system can be used to investigate the responses of spinal cord glial cells upon stimulation with various substances and agents. Besides neuropathic pain, this system can be used to study glial responses in other diseases that involve pathological changes of spinal cord glial cells.

The development of neuropathic pain involves pathological changes of spinal cord glial cells. A reliable glial culture system derived from adult spinal cord tissue and designed for studying these cells in vitro is lacking. Therefore, we show here how&#160;to establish primary mixed glial cultures from adult mouse spinal cord tissue.

It has been well-accepted that spinal cord glial responses contribute significantly to the development of neuropathic pain. Tremendous information ...

A Simple and Reproducible Method to Prepare Membrane Samples from Freshly Isolated Rat Brain Microvessels

The blood-brain barrier (BBB) is a dynamic barrier tissue that responds to various pathophysiological and pharmacological stimuli. Such changes resulting from these stimuli can greatly modulate drug delivery to the brain and, by extension, cause considerable challenges in the treatment of central nervous system (CNS) diseases. Many BBB changes that affect pharmacotherapy, involve proteins that are localized and expressed at the level of endothelial cells. Indeed, such knowledge on BBB physiology in health and disease has sparked considerable interest in the study of these membrane proteins. From a basic science research standpoint, this implies a requirement for a simple but robust and reproducible method for isolation of microvessels from brain tissue harvested from experimental animals. In order to prepare membrane samples from freshly isolated microvessels, it is essential that sample preparations be enriched in endothelial cells but limited in the presence of other cell types of the neurovascular unit (i.e., astrocytes, microglia, neurons, pericytes). An added benefit is the ability to prepare samples from individual animals in order to capture the true variability of protein expression in an experimental population. In this manuscript, details regarding a method that is utilized for isolation of rat brain microvessels and preparation of membrane samples are provided. Microvessel enrichment, from samples derived, is achieved by using four centrifugation steps where dextran is included in the sample buffer. This protocol can easily be adapted by other laboratories for their own specific applications. Samples generated from this protocol have been shown to yield robust experimental data from protein analysis experiments that can greatly aid the understanding of BBB responses to physiological, pathophysiological, and pharmacological stimuli.

Here, a method for isolation of rat brain microvessels and for the preparation of membrane samples is described. This protocol has the clear advantage of producing enriched microvessel samples with acceptable protein yield from individual animals. Samples can then be used for robust protein analyses at the brain microvascular endothelium.

The blood-brain barrier (BBB) is a dynamic barrier tissue that responds to various pathophysiological and pharmacological stimuli. Such changes resulting ...