Name: coculture of axotomized rat retinal ganglion neurons with olfactory ensheathing glia, as an in vitro model of adult axonal regeneration
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Description: Watch this Scientific Journal Video about Coculture of Axotomized Rat Retinal Ganglion Neurons with Olfactory Ensheathing Glia, as an In Vitro Model of Adult Axonal Regeneration at JoVE.com

This work was financially supported by project SAF2017-82736-C2-1-R from Ministerio de Ciencia e Innovaci&#243;n to MTM-F and by Fundaci&#243;n Universidad Francisco de Vitoria to JS.

NOTE: Animal experimentation was approved by national and institutional bioethics committees.
1. ihOEG (Ts12 and Ts14) culture
NOTE: This procedure is done under sterile conditions in a tissue culture biosafety cabinet.
<ol>
	<li>Prepare 50 mL ME10 OEG culture medium as provided in Table 1.</li>
	<li>Prepare 5 mL of DMEM/F12-FBS, as provided in Table 1, in a 15 mL conical tube.</li>
	<li>Warm both media at 37 &#176;C in a clean wa...

<ol>
	<li>Kanno, H., Pearse, D. D., Ozawa, H., Itoi, E., Bunge, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schwann+cell+transplantation+for+spinal+cord+injury+repair:+Its+significant+therapeutic+potential+and+prospectus.">Schwann cell transplantation for spinal cord injury repair: Its significant therapeutic potential and prospectus.</a> Reviews in the Neurosciences. 26 (2), 121-128 (2015).</li><li>Assinck, P., Duncan, G. J., Hilton, B. J., Plemel, J. R., Tetzlaff, 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+transplantation+therapy+for+spinal+cord+injury.">Cell transplantation therapy for spinal cord injury.</a> Nature Neuroscience. 20 (5), 637-647 (2017).</li><li>Lindsay, S. L., Toft, A., Griffin, J., Emraja, A. M. M., Barnett, S. C., Riddell, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+olfactory+mesenchymal+stromal+cell+transplants+promote+remyelination+and+earlier+improvement+in+gait+coordination+after+spinal+cord+injury.">Human olfactory mesenchymal stromal cell transplants promote remyelination and earlier improvement in gait coordination after spinal cord injury.</a> Glia. 65 (4), 639-656 (2017).</li><li>Moreno-Flores, M. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+clonal+cell+line+from+immortalized+olfactory+ensheathing+glia+promotes+functional+recovery+in+the+injured+spinal+cord.">A clonal cell line from immortalized olfactory ensheathing glia promotes functional recovery in the injured spinal cord.</a> Molecular Therapy. 13 (3), 598-608 (2006).</li><li>Gilmour, A. D., Reshamwala, R., Wright, A. A., Ekberg, J. A. K., St. John, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optimizing+olfactory+ensheathing+cell+transplantation+for+spinal+cord+injury+repair.">Optimizing olfactory ensheathing cell transplantation for spinal cord injury repair.</a> Journal of Neurotrauma. 37 (5), 817-829 (2020).</li><li>Barraud, P., 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=Neural+crest+origin+of+olfactory+ensheathing+glia.">Neural crest origin of olfactory ensheathing glia.</a> Proceedings of the National Academy of Sciences of the United States of America. 107, 21040-21045 (2010).</li><li>Su, Z., He, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olfactory+ensheathing+cells:+biology+in+neural+development+and+regeneration.">Olfactory ensheathing cells: biology in neural development and regeneration.</a> Progress in Neurobiology. 92 (4), 517-532 (2010).</li><li>Yao, R., 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=Olfactory+ensheathing+cells+for+spinal+cord+injury:+sniffing+out+the+issues.">Olfactory ensheathing cells for spinal cord injury: sniffing out the issues.</a> Cell Transplant. 27 (6), 879-889 (2018).</li><li>G&#243;mez, R. 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=Cell+therapy+for+spinal+cord+injury+with+olfactory+ensheathing+glia+cells+(OECs).">Cell therapy for spinal cord injury with olfactory ensheathing glia cells (OECs).</a> Glia. 66 (7), 1267-1301 (2018).</li><li>Plant, G. W., Harvey, A. R., Leaver, S. G., Lee, S. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olfactory+ensheathing+glia:+repairing+injury+to+the+mammalian+visual+system.">Olfactory ensheathing glia: repairing injury to the mammalian visual system.</a> Experimental Neurology. 229 (1), 99-108 (2011).</li><li>Xue, L., 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=Transplanted+olfactory+ensheathing+cells+restore+retinal+function+in+a+rat+model+of+light-induced+retinal+damage+by+inhibiting+oxidative+stress.">Transplanted olfactory ensheathing cells restore retinal function in a rat model of light-induced retinal damage by inhibiting oxidative stress.</a> Oncotarget. 8 (54), 93087-93102 (2017).</li><li>Pastrana, 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=Genes+associated+with+adult+axon+regeneration+promoted+by+olfactory+ensheathing+cells:+a+new+role+for+matrix+metalloproteinase+2.">Genes associated with adult axon regeneration promoted by olfactory ensheathing cells: a new role for matrix metalloproteinase 2.</a> The Journal of Neuroscience. 26, 5347-5359 (2006).</li><li>Pastrana, 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=BDNF+production+by+olfactory+ensheathing+cells+contributes+to+axonal+regeneration+of+cultured+adult+CNS+neurons.">BDNF production by olfactory ensheathing cells contributes to axonal regeneration of cultured adult CNS neurons.</a> Neurochemistry International. 50, 491-498 (2007).</li><li>Sim&#243;n, D., 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=Expression+of+plasminogen+activator+inhibitor-1+by+olfactory+ensheathing+glia+promotes+axonal+regeneration.">Expression of plasminogen activator inhibitor-1 by olfactory ensheathing glia promotes axonal regeneration.</a> Glia. 59, 1458-1471 (2011).</li><li>Lim, F., 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=Reversibly+immortalized+human+olfactory+ensheathing+glia+from+an+elderly+donor+maintain+neuroregenerative+capacity.">Reversibly immortalized human olfactory ensheathing glia from an elderly donor maintain neuroregenerative capacity.</a> Glia. 58, 546-558 (2010).</li><li>Garc&#237;a-Escudero, V., 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=Prevention+of+senescence+progression+in+reversibly+immortalized+human+ensheathing+glia+permits+their+survival+after+deimmortalization.">Prevention of senescence progression in reversibly immortalized human ensheathing glia permits their survival after deimmortalization.</a> Molecular Therapy. 18, 394-403 (2010).</li><li>Garc&#237;a-Escudero, V., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+neuroregenerative+human+ensheathing+glia+cell+line+with+conditional+rapid+growth.">A neuroregenerative human ensheathing glia cell line with conditional rapid growth.</a> Cell Transplant. 20, 153-166 (2011).</li><li>Plaza, N., Sim&#243;n, D., Sierra, J., Moreno-Flores, M. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transduction+of+an+immortalized+olfactory+ensheathing+glia+cell+line+with+the+green+fluorescent+protein+(GFP)+gene:+Evaluation+of+its+neuroregenerative+capacity+as+a+proof+of+concept.">Transduction of an immortalized olfactory ensheathing glia cell line with the green fluorescent protein (GFP) gene: Evaluation of its neuroregenerative capacity as a proof of concept.</a> Neuroscience Letters. 612, 25-31 (2016).</li><li>Deumens, R., 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=Alignment+of+glial+cells+stimulates+directional+neurite+growth+of+CNS+neurons+in+vitro.">Alignment of glial cells stimulates directional neurite growth of CNS neurons in vitro.</a> Neuroscience. 125 (3), 591-604 (2004).</li><li>Chung, R. 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=Olfactory+ensheathing+cells+promote+neurite+sprouting+of+injured+axons+in+vitro+by+direct+cellular+contact+and+secretion+of+soluble+factors.">Olfactory ensheathing cells promote neurite sprouting of injured axons in vitro by direct cellular contact and secretion of soluble factors.</a> Cell and Molecular Life Sciences. 61 (10), 1238-1245 (2004).</li><li>Leaver, S. G., Harvey, A. R., Plant, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+olfactory+ensheathing+glia+promote+the+long-distance+growth+of+adult+retinal+ganglion+cell+neurites+in+vitro.">Adult olfactory ensheathing glia promote the long-distance growth of adult retinal ganglion cell neurites in vitro.</a> Glia. 53 (5), 467-476 (2006).</li><li>Pellitteri, R., Spatuzza, M., Russo, A., Stanzani, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olfactory+ensheathing+cells+exert+a+trophic+effect+on+the+hypothalamic+neurons+in+vitro.">Olfactory ensheathing cells exert a trophic effect on the hypothalamic neurons in vitro.</a> Neuroscience Letters. 417 (1), 24-29 (2007).</li><li>Pellitteri, R., Spatuzza, M., Russo, A., Zaccheo, D., Stanzani, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olfactory+ensheathing+cells+represent+an+optimal+substrate+for+hippocampal+neurons:+an+in+vitro+study.">Olfactory ensheathing cells represent an optimal substrate for hippocampal neurons: an in vitro study.</a> International Journal of Developmental Neuroscience. 27 (5), 453-458 (2009).</li><li>Runyan, S. A., Phelps, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+olfactory+ensheathing+glia+enhance+axon+outgrowth+on+a+myelin+substrate+in+vitro.">Mouse olfactory ensheathing glia enhance axon outgrowth on a myelin substrate in vitro.</a> Experimental Neurology. 216 (1), 95-104 (2009).</li><li>Witheford, M., Westendorf, K., Roskams, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olfactory+ensheathing+cells+promote+corticospinal+axonal+outgrowth+by+a+L1+CAM-dependent+mechanism.">Olfactory ensheathing cells promote corticospinal axonal outgrowth by a L1 CAM-dependent mechanism.</a> Glia. 61 (11), 1873-1889 (2013).</li><li>Roloff, F., Ziege, S., Baumg&#228;rtner, W., Wewetzer, K., Bicker, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Schwann+cell-free+adult+canine+olfactory+ensheathing+cell+preparations+from+olfactory+bulb+and+mucosa+display+differential+migratory+and+neurite+growth-promoting+properties+in+vitro.">Schwann cell-free adult canine olfactory ensheathing cell preparations from olfactory bulb and mucosa display differential migratory and neurite growth-promoting properties in vitro.</a> BMC Neuroscience. 14, 141 (2013).</li><li>Khankan, R. R., Wanner, I. B., Phelps, P. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Olfactory+ensheathing+cell-neurite+alignment+enhances+neurite+outgrowth+in+scar-like+cultures.">Olfactory ensheathing cell-neurite alignment enhances neurite outgrowth in scar-like cultures.</a> Experimental Neurology. 269, 93-101 (2015).</li><li>Wigley, C. B., Berry, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Regeneration+of+adult+rat+retinal+ganglion+cell+processes+in+monolayer+culture:+comparisons+between+cultures+of+adult+and+neonatal+neurons.">Regeneration of adult rat retinal ganglion cell processes in monolayer culture: comparisons between cultures of adult and neonatal neurons.</a> Brain Research. 470 (1), 85-98 (1988).</li><li>Sonigra, R. J., Brighton, P. C., Jacoby, J., Hall, S., Wigley, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Adult+rat+olfactory+nerve+ensheathing+cells+are+effective+promoters+of+adult+central+nervous+system+neurite+outgrowth+in+coculture.">Adult rat olfactory nerve ensheathing cells are effective promoters of adult central nervous system neurite outgrowth in coculture.</a> Glia. 25 (3), 256-269 (1999).</li><li>Hayat, S., Thomas, A., Afshar, F., Sonigra, R., Wigley, C. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Manipulation+of+olfactory+ensheathing+cell+signaling+mechanisms:+effects+on+their+support+for+neurite+regrowth+from+adult+CNS+neurons+in+coculture.">Manipulation of olfactory ensheathing cell signaling mechanisms: effects on their support for neurite regrowth from adult CNS neurons in coculture.</a> Glia. 44 (3), 232-241 (2003).</li><li>Kumar, R., Hayat, S., Felts, P., Bunting, S., Wigley, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+differences+and+interactions+between+phenotypic+subpopulations+of+olfactory+ensheathing+cells+in+promoting+CNS+axonal+regeneration.">Functional differences and interactions between phenotypic subpopulations of olfactory ensheathing cells in promoting CNS axonal regeneration.</a> Glia. 50 (1), 12-20 (2005).</li><li>Moreno-Flores, M. T., Lim, F., Mart&#237;n-Bermejo, M. J., D&#237;az-Nido, J., Avila, J., Wandosell, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immortalized+olfactory+ensheathing+glia+promote+axonal+regeneration+of+rat+retinal+ganglion+neurons.">Immortalized olfactory ensheathing glia promote axonal regeneration of rat retinal ganglion neurons.</a> Journal of Neurochemistry. 85 (4), 861-871 (2003).</li><li>Garc&#237;a-Escudero, V., 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=Patient-derived+olfactory+mucosa+cells+but+not+lung+or+skin+fibroblasts+mediate+axonal+regeneration+of+retinal+ganglion+neurons.">Patient-derived olfactory mucosa cells but not lung or skin fibroblasts mediate axonal regeneration of retinal ganglion neurons.</a> Neuroscience Letters. 509 (1), 27-32 (2012).</li><li>Sternberger, L. A., Sternberger, N. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Monoclonal+antibodies+distinguish+phosphorylated+and+nonphosphorylated+forms+of+neurofilaments+in+situ.">Monoclonal antibodies distinguish phosphorylated and nonphosphorylated forms of neurofilaments in situ.</a> Proceedings of the National Academy of Sciences of the United States of America. 80 (19), 6126-6130 (1983).</li><li>S&#225;nchez Martin, C., D&#237;az-Nido, J., Avila, J. <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+a+site-specific+phosphorylation+of+the+microtubule-associated+protein+2+during+the+development+of+cultured+neurons.">Regulation of a site-specific phosphorylation of the microtubule-associated protein 2 during the development of cultured neurons.</a> Neuroscience. 87 (4), 861-870 (1998).</li><li>Reshamwala, R., Shah, M., Belt, L., Ekberg, J. A. K., St. John, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reliable+cell+purification+and+determination+of+cell+purity:+crucial+aspects+of+olfactory+ensheathing+cell+transplantation+for+spinal+cord+repair.">Reliable cell purification and determination of cell purity: crucial aspects of olfactory ensheathing cell transplantation for spinal cord repair.</a> Neural Regeneration Research. 15 (11), 2016-2026 (2020).</li></ol>

OEG transplantation at CNS injury sites is considered a promising therapy for CNS injury due to its constitutive pro-neuroregenerative properties7,8,9. However, depending on the tissue source&#8212;olfactory mucosa (OM-OEG) versus olfactory bulb (OB-OEG)&#8212;or the age of the donor, considerable variation exists in such capacity26,31,33</su...

Adult central nervous system (CNS) neurons have limited regenerative capacity after injury or disease. A common strategy to promote CNS regeneration is transplantation, at the injury site, of cell types that induce axonal growth such as stem cells, Schwann cells, astrocytes or olfactory ensheathing glia (OEG) cells1,2,3,4,5.
OEG derives from the neural crest6 and locates in the olfactory mucosa and in the olfactory bulb. In the adult, olfactory sensory neurons die regularly as the result of environmental exposure and they are replaced by newly differentiated neurons. OEG surrounds and guides these new olfactory axons to enter the olfactory bulb and to establish new synapses with their targets in the CNS7. Due to these physiological attributes, OEG has been used in models of CNS injury such as spinal cord or optic nerve injury and its neuroregenerative and neuroprotective properties become proven8,9,10,11. Several factors have been identified as responsible of the pro-regenerative characteristics of these cells, including extracellular matrix proteases production or secretion of neurotrophic and axonal growth factors12,13,14.
Given the technical limitations to expand primary OEG cells, we previously established and characterized reversible immortalized human OEG (ihOEG) clonal lines, which provide an unlimited supply of homogeneous OEG. These ihOEG cells derive from primary cultures, prepared from olfactory bulbs obtained in autopsies. They were immortalized by transduction of the telomerase catalytic subunit (TERT) and the oncogene Bmi-1 and modified with the SV40 virus large T antigen15,16,17,18. Two of these ihOEG cell lines are Ts14, which maintains the regenerative capacity of the original cultures and Ts12, a low regenerative line that is used as a low regeneration control in these experiments18.
To assess OEG capacity to foster axonal regeneration after neural injury, several in vitro models have been implemented. In these models, OEG is applied to cultures of different neuronal origin and neurite formation and elongation&#8212;in response to glial coculture&#8212;are assayed. Examples of such neuronal sources are neonatal rat cortical neurons19, scratch wounds performed on rat embryonic neurons from cortical tissue20, rat retinal explants21, rat hypothalamic or hippocampal postnatal neurons22,23, postnatal rat dorsal root ganglion neurons24, postnatal mouse corticospinal tract neurons25, human NT2 neurons26, or postnatal cerebral cortical neurons on reactive astrocyte scar-like cultures27.
In these models, however, the regeneration assay relies on embryonic or postnatal neurons, which have an intrinsic plasticity that is absent in injured adult neurons. To overcome this drawback, we present a model of adult axonal regeneration in cocultures of OEG lines with adult retinal ganglion neurons (RGNs), based on the one originally developed by Wigley et al.28,29,30,31 and modified and used by our group12,13,14,15,16,17,18,32,33. Briefly, retinal tissue is extracted from adult rats and digested with papain. Retinal cell suspension is then plated on either polylysine-treated coverslips or onto Ts14 and Ts12 monolayers. Cultures are maintained for 96 h before they are fixed and then immunofluorescence for axonal (MAP1B and NF-H proteins)34 and somatodendritic (MAP2A and B)35 markers is performed. Axonal regeneration is quantified as a percentage of neurons with axon, with respect to the total population of RGNs and axonal regeneration index is calculated as the mean axonal length per neuron. This protocol is not only useful for assessing the neuroregenerative potential of ihOEG but can be extended to different sources of OEG or other glial cells.

<table>
	<tbody>
		<tr>
			<td>antibody 514</td>
			<td>Reference 34</td>
			<td></td>
			<td>Rabbit polyclonal antiserum, which recognizes MAP2A and B.</td>
		</tr>
		<tr>
			<td>antibody SMI-31</td>
			<td>BioLegend</td>
			<td>801601</td>
			<td>Monoclonal antibody against MAP1B and NF-H proteins</td>
		</tr>
		<tr>
			<td>anti-mouse Alexa Fluor 488 antibody</td>
			<td>ThermoFisher</td>
			<td>A-21202</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-rabbit Alexa Fluor 594 antibody</td>
			<td>ThermoFisher</td>
			<td>A-21207</td>
			<td></td>
		</tr>
		<tr>
			<td>B-27 Supplement</td>
			<td>Gibco</td>
			<td>17504044</td>
			<td></td>
		</tr>
		<tr>
			<td>D,L-2-amino-5-phosphonovaleric acid</td>
			<td>Sigma</td>
			<td>283967</td>
			<td>NMDA receptor inhibitor</td>
		</tr>
		<tr>
			<td>DAPI</td>
			<td>Sigma</td>
			<td>D9542</td>
			<td>Nuclei fluorescent stain</td>
		</tr>
		<tr>
			<td>DMEM-F12</td>
			<td>Gibco</td>
			<td>11320033</td>
			<td>Cell culture medium</td>
		</tr>
		<tr>
			<td>FBS</td>
			<td>Gibco</td>
			<td>11573397</td>
			<td>Fetal bovine serum</td>
		</tr>
		<tr>
			<td>FBS-Hyclone</td>
			<td>Fisher Scientific</td>
			<td>16291082</td>
			<td>Fetal bovine serum</td>
		</tr>
		<tr>
			<td>Fluoromount</td>
			<td>Southern Biotech</td>
			<td>0100-01</td>
			<td>Mounting medium</td>
		</tr>
		<tr>
			<td>ImageJ</td>
			<td>National Institutes of Health (NIH-USA)</td>
			<td></td>
			<td>Image software</td>
		</tr>
		<tr>
			<td>L-Glutamine</td>
			<td>Lonza</td>
			<td>BE17-605F</td>
			<td></td>
		</tr>
		<tr>
			<td>Neurobasal Medium</td>
			<td>Gibco</td>
			<td>21103049</td>
			<td>Neuronal cells culture medium</td>
		</tr>
		<tr>
			<td>Papain Dissociation System</td>
			<td>Worthington Biochemical Corporation</td>
			<td>LK003150</td>
			<td>For use in neural cell isolation</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Home made</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>PBS-EDTA</td>
			<td>Lonza</td>
			<td>H3BE02-017F</td>
			<td></td>
		</tr>
		<tr>
			<td>Penicillin/Streptomycin/Amphotericin B</td>
			<td>Lonza</td>
			<td>17-745E</td>
			<td>Bacteriostatic and bactericidal</td>
		</tr>
		<tr>
			<td>Pituitary extract</td>
			<td>Gibco</td>
			<td>13028014</td>
			<td>Bovine pituitary extract</td>
		</tr>
		<tr>
			<td>Poly -L- lysine (PLL)</td>
			<td>Sigma</td>
			<td>A-003-M</td>
			<td></td>
		</tr>
	</tbody>
</table>

coculture of axotomized rat retinal ganglion neurons with olfactory ensheathing glia, as an in vitro model of adult axonal regeneration

Olfactory ensheathing glia (OEG) cells are localized all the way from the olfactory mucosa to and into the olfactory nerve layer (ONL) of the olfactory bulb. Throughout adult life, they are key for axonal growing of newly generated olfactory neurons, from the lamina propria to the ONL. Due to their pro-regenerative properties, these cells have been used to foster axonal regeneration in spinal cord or optic nerve injury models.
We present an in vitro model to assay and measure OEG neuroregenerative capacity after neural injury. In this model, reversibly immortalized human OEG (ihOEG) is cultured as a monolayer, retinas are extracted from adult rats and retinal ganglion neurons (RGN) are cocultured onto the OEG monolayer. After 96 h, axonal and somatodendritic markers in RGNs are analyzed by immunofluorescence and the number of RGNs with axon and the mean axonal length/neuron are quantified.
This protocol has the advantage over other in vitro assays that rely on embryonic or postnatal neurons, that it evaluates OEG neuroregenerative properties in adult tissue. Also, it is not only useful for assessing the neuroregenerative potential of ihOEG but can be extended to different sources of OEG or other glial cells.

In this protocol, we present an in vitro model to assay OEG neuroregenerative capacity after neuronal injury. As shown in Figure 1, the OEG source is a reversible immortalized human OEG clonal cell line -Ts14 and Ts12-, which derives from primary cultures, prepared from olfactory bulbs obtained in autopsies15,17,18. Retinal tissue is extracted from adult rats, digested, and retinal ganglion neurons ...

Watch this Scientific Journal Video about Coculture of Axotomized Rat Retinal Ganglion Neurons with Olfactory Ensheathing Glia, as an In Vitro Model of Adult Axonal Regeneration at JoVE.com

Coculture of Axotomized Rat Retinal Ganglion Neurons with Olfactory Ensheathing Glia, as an In Vitro Model of Adult Axonal Regeneration

We present an in vitro model to assess olfactory ensheathing glia (OEG) neuroregenerative capacity, after neural injury. It is based on a coculture of axotomized adult retinal ganglion neurons (RGN) on OEG monolayers and subsequent study of axonal regeneration, by analyzing RGN axonal and somatodendritic markers.

Olfactory ensheathing glia (OEG) cells are localized all the way from the olfactory mucosa to and into the olfactory nerve layer (ONL) of the olfactory ...

Our protocol is a simple and reproducible model to assess olfactory ensheathing capacity to foster adult axonal regeneration This is a quantitative technique that allows the evaluation of olfactory ensheathing glia regenerative capacity that can also be extended to other glial cell types. This technique is the first step to study olfactory ensheathing glia as a candidate for cell therapy in nervous system injuries before translation to in vivo or clinical studies. Demonstrating the procedure will be Maria Portela, a PhD student from our laboratory.To begin, prepare all the required media as described in the text manuscript. After sacrificing the rat, place its head in a 100 milliliter Petri dish and spray it with 70%ethanol before placing it in a laminar flow hood. Cut the rat's whiskers with scissors so they do not interfere with the eye manipulation.Grip the optic nerve with forceps to pull out the eyeball enough to be able to make an incision across the eye with a scalpel. Remove the lens and vitreous humor and pull out the retina, keeping the remaining layers of the eye inside. Place the retina in a previously prepared P60 cell culture dish with five milliliters of cold EBSS, then transfer it to a P60 cell culture dish with reconstituted papain plus 50 microliters of APV and 250 microliters of DNAs plus five microliters of APV.Cut the retina into small pieces with a scalpel. Transfer the pieces to a 15 milliliter plastic tube and incubate them for 30 minutes in a humidified incubator at 37 degrees Celsius under 5%carbon dioxide, agitating every 10 minutes. Dissociate cell clumps by pipetting up and down with a glass pasture pipette.Then centrifuge the cell suspension at 200 times G for five minutes. Discard supernatant and re-suspend the cell pellet in albumin OVO mucoid protease inhibitor with 150 microliters of DNAs and 30 microliters of APV. Carefully add the cell suspension on five milliliters of albumin OVO mucoid protease inhibitor and repeat the centrifugation.While centrifuging, completely remove the EMI 10 medium from an OEG 24 well plate and replace it with 500 microliters of NBB 27 medium per well. Discard the supernatant and re-suspend the cells in two milliliters of NB B27 medium. Plate 100 microliters of retinal cell suspension into each well of the M 24 plate onto PLL-treated or OEG monolayer cover slips.Maintain cultures at 37 degrees Celsius with 5%carbon dioxide for 96 hours in NB B27 medium. After 96 hours, fix the cells for 10 minutes by adding the same volume of 4%PFA in PBS to the culture medium. Discard the fixing solution and wash the cells three times with PBS for five minutes per wash, then block with PBS TS for 30 to 40 minutes.Prepare the primary antibodies in PBS TS buffer as described in the text manuscript and add them to the cocultures. Incubate the cells overnight at four degrees Celsius. On the next day, discard the antibodies and wash the cover slips three times with PBS for five minutes per wash.Add the corresponding fluorescent secondary antibodies and incubate the cover slips for one hour at room temperature in the dark. Then wash the cover slips three times with PBS for five minutes per wash in the dark. Mount the cover slips with mounting medium and keep them at four degrees Celsius.Use a 40 times objective of an epi fluorescence microscope to quantify axonal regeneration. Quantify the percentage of neurons with axons relative to the total population of retinal ganglion neurons. Use the neuron J plugin in image J to quantify the axonal regeneration index or mean Ono length, which is the sum of the lengths of all identified axons divided by the total number of counted neurons, whether they presented in axon or not.After opening the image, click on analyze and set scale according to microscope settings, working in pixels per micrometer. Select add tracings to begin axon tracking then track the axons from the soma to the end. Click on measure tracings, display tracing measurements, and run.Neuroregenerative capacity of olfactory ensheathing glia after neuronal injury was investigated using a reversible immortalized human OEG clonal cell line. TS14 OEG identity was assessed by immunostaining within sheath and glioma markers, such as S 100 beta and vimentin. GFAP expression was also analyzed to discard astrocyte contamination.In the axonal regeneration assay, TS14 regenerative capacity was compared to TS12 in RGN OEG cocultures using PLL substrate as a negative control. Representative images show a lack of capacity of RGN to regenerate their axons over PLL or TS12 cells. Well TS14 stimulates the outgrowth of axons in RGN.Both the percentage of cells with axons, as well as the average length of the regenerated axons were significantly higher in neurons cocultured on TS14 monolayers compared to neurons plated on either TS12 cells or PLL. This protocol can be used to elucidate the molecular mechanisms responsible of the neuroregenerative capacities of olfactory ensheathing glia.

coculture-axotomized-rat-retinal-ganglion-neurons-with-olfactory

Research

JoVE Journal

Neuroscience

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 ...

Genetic Study of Axon Regeneration with Cultured Adult Dorsal Root Ganglion Neurons

It is well known that mature neurons in the central nervous system (CNS) cannot regenerate their axons after injuries due to diminished intrinsic ability to support axon growth and a hostile environment in the mature CNS1,2. In contrast, mature neurons in the peripheral nervous system (PNS) regenerate readily after injuries3. Adult dorsal root ganglion (DRG) neurons are well known to regenerate robustly after peripheral nerve injuries. Each DRG neuron grows one axon from the cell soma, which branches into two axonal branches: a peripheral branch innervating peripheral targets and a central branch extending into the spinal cord. Injury of the DRG peripheral axons results in substantial axon regeneration, whereas central axons in the spinal cord regenerate poorly after the injury. However, if the peripheral axonal injury occurs prior to the spinal cord injury (a process called the conditioning lesion), regeneration of central axons is greatly improved4. Moreover, the central axons of DRG neurons share the same hostile environment as descending corticospinal axons in the spinal cord. Together, it is hypothesized that the molecular mechanisms controlling axon regeneration of adult DRG neurons can be harnessed to enhance CNS axon regeneration. As a result, adult DRG neurons are now widely used as a model system to study regenerative axon growth5-7.
Here we describe a method of adult DRG neuron culture that can be used for genetic study of axon regeneration in vitro. In this model adult DRG neurons are genetically manipulated via electroporation-mediated gene transfection6,8. By transfecting neurons with DNA plasmid or si/shRNA, this approach enables both gain- and loss-of-function experiments to investigate the role of any gene-of-interest in axon growth from adult DRG neurons. When neurons are transfected with si/shRNA, the targeted endogenous protein is usually depleted after 3-4 days in culture, during which time robust axon growth has already occurred, making the loss-of-function studies less effective. To solve this problem, the method described here includes a re-suspension and re-plating step after transfection, which allows axons to re-grow from neurons in the absence of the targeted protein. Finally, we provide an example of using this in vitro model to study the role of an axon regeneration-associated gene, c-Jun, in mediating axon growth from adult DRG neurons9.

An in vitro model for genetic study of axon regeneration using cultured adult mouse dorsal root ganglion neurons is described. The method includes a re-suspension/re-plating step to allow axon re-growth from neurons undergoing genetic manipulation. This approach is especially useful for loss-of-function studies of axon regeneration using RNAi-based protein knockdown.

It is well known that mature neurons in the central nervous system (CNS) cannot regenerate their axons after injuries due to diminished intrinsic ability ...

Transplantation of Olfactory Ensheathing Cells to Evaluate Functional Recovery after Peripheral Nerve Injury

Olfactory ensheathing cells (OECs) are neural crest cells which allow growth and regrowth of the primary olfactory neurons. Indeed, the primary olfactory system is characterized by its ability to give rise to new neurons even in adult animals. This particular ability is partly due to the presence of OECs which create a favorable microenvironment for neurogenesis. This property of OECs has been used for cellular transplantation such as in spinal cord injury models. Although the peripheral nervous system has a greater capacity to regenerate after nerve injury than the central nervous system, complete sections induce misrouting during axonal regrowth in particular after facial of laryngeal nerve transection. Specifically, full sectioning of the recurrent laryngeal nerve (RLN) induces aberrant axonal regrowth resulting in synkinesis of the vocal cords. In this specific model, we showed that OECs transplantation efficiently increases axonal regrowth.
OECs are constituted of several subpopulations present in both the olfactory mucosa (OM-OECs) and the olfactory bulbs (OB-OECs). We present here a model of cellular transplantation based on the use of these different subpopulations of OECs in a RLN injury model. Using this paradigm, primary cultures of OB-OECs and OM-OECs were transplanted in Matrigel after section and anastomosis of the RLN. Two months after surgery, we evaluated transplanted animals by complementary analyses based on videolaryngoscopy, electromyography (EMG), and histological studies. First, videolaryngoscopy allowed us to evaluate laryngeal functions, in particular muscular cocontractions phenomena. Then, EMG analyses demonstrated richness and synchronization of muscular activities. Finally, histological studies based on toluidine blue staining allowed the quantification of the number and profile of myelinated fibers.
All together, we describe here how to isolate, culture, identify and transplant OECs from OM and OB after RLN section-anastomosis and how to evaluate and analyze the efficiency of these transplanted cells on axonal regrowth and laryngeal functions.

Olfactory ensheathing cells (OECs) are neural crest cells which allow growth of the primary olfactory neurons. This specific property can be used for cellular transplantation. We present here a model of cellular transplantation based on the use of OECs in a laryngeal nerve injury model.

Olfactory ensheathing cells (OECs) are neural crest cells which allow growth and regrowth of the primary olfactory neurons. Indeed, the primary olfactory ...

An In-vitro Preparation of Isolated Enteric Neurons and Glia from the Myenteric Plexus of the Adult Mouse

The enteric nervous system is a vast network of neurons and glia running the length of the gastrointestinal tract that functionally controls gastrointestinal motility. A procedure for the isolation and culture of a mixed population of neurons and glia from the myenteric plexus is described. The primary cultures can be maintained for over 7 days, with connections developing among the neurons and glia. The longitudinal muscle strip with the attached myenteric plexus is stripped from the underlying circular muscle of the mouse ileum or colon and subjected to enzymatic digestion. In sterile conditions, the isolated neuronal and glia population are preserved within the pellet following centrifugation and plated on coverslips. Within 24-48 hr, neurite outgrowth occurs and neurons can be identified by pan-neuronal markers. After two days in culture, isolated neurons fire action potentials as observed by patch clamp studies. Furthermore, enteric glia can also be identified by GFAP staining. A network of neurons and glia in close apposition forms within 5 - 7 days. Enteric neurons can be individually and directly studied using methods such as immunohistochemistry, electrophysiology, calcium imaging, and single-cell PCR. Furthermore, this procedure can be performed in genetically modified animals. This methodology is simple to perform and inexpensive. Overall, this protocol exposes the components of the enteric nervous system in an easily manipulated manner so that we may better discover the functionality of the ENS in normal and disease states.

An In-vitro Preparation of Isolated Enteric Neurons and Glia from the Myenteric Plexus of the Adult Mouse

We demonstrate a cell culture protocol for the direct study of neuronal and glial components of the enteric nervous system. A neuron/glia mixed culture on coverslips is prepared from the myenteric plexus of adult mouse providing the ability to examine individual neuron and glia function by electrophysiology, immunohistochemical, etc.

The enteric nervous system is a vast network of neurons and glia running the length of the gastrointestinal tract that functionally controls ...

Retrograde Labeling of Retinal Ganglion Cells in Adult Zebrafish with Fluorescent Dyes

As retrograde labeling retinal ganglion cells (RGCs) can isolate RGCs somata from dying sites, it has become the gold standard for counting RGCs in RGCs survival and regeneration experiments. Many studies have been performed in mammalian animals to research RGCs survival after optic nerve injury. However, retrograde labeling of RGCs in adult zebrafish has not yet been reported, though some alternative methods can count cell numbers in retinal ganglion cell layers (RGCL). Considering the small size of the adult zebrafish skull and the high risk of death after drilling on the skull, we open the skull with the help of acid-etching and seal the hole with a light curing bond, which could significantly improve the survival rate. After absorbing the dyes for 5 days, almost all the RGCs are labeled. As this method does not need to transect the optic nerve, it is irreplaceable in the research of RGCs survival after optic nerve crush in adult zebrafish. Here, we introduce this method step by step and provide representative results.

We introduce an efficient method to retrograde label retinal ganglion cells (RGCs) in adult zebrafish.

As retrograde labeling retinal ganglion cells (RGCs) can isolate RGCs somata from dying sites, it has become the gold standard for counting RGCs in RGCs ...

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

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

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

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

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

The Indirect Neuron-astrocyte Coculture Assay: An In Vitro Set-up for the Detailed Investigation of Neuron-glia Interactions

Proper neuronal development and function is the prerequisite of the developing and the adult brain. However, the mechanisms underlying the highly controlled formation and maintenance of complex neuronal networks are not completely understood thus far. The open questions concerning neurons in health and disease are diverse and reaching from understanding the basic development to investigating human related pathologies, e.g.,&#160;Alzheimer&#39;s disease and&#160;Schizophrenia. The most detailed analysis of neurons can be performed in vitro. However, neurons are demanding cells and need the additional support of astrocytes for their long-term survival. This cellular heterogeneity is in conflict with the aim to dissect the analysis of neurons and astrocytes. We present here a cell-culture assay that allows for the long-term cocultivation of pure primary neurons and astrocytes, which share the same chemically defined medium, while being physically separated. In this setup, the cultures survive for up to four weeks and the assay is suitable for a diversity of investigations concerning neuron-glia interaction.

The Indirect Neuron-astrocyte Coculture Assay: An In Vitro Set-up for the Detailed Investigation of Neuron-glia Interactions

This protocol describes the indirect neuron-astrocyte coculture for compartmentalized analysis of neuron-glia interactions.

Proper neuronal development and function is the prerequisite of the developing and the adult brain. However, the mechanisms underlying the highly ...

M&#252;ller Glia Cell Activation in a Laser-induced Retinal Degeneration and Regeneration Model in Zebrafish

A fascinating difference between teleost and mammals is the lifelong potential of the teleost retina for retinal neurogenesis and regeneration after severe damage. Investigating the regeneration pathways in zebrafish might bring new insights to develop innovative strategies for the treatment of retinal degenerative diseases in mammals. Herein, we focused on the induction of a focal lesion to the outer retina in adult zebrafish by means of a 532 nm diode laser. A localized injury allows investigating biological processes that take place during retinal degeneration and regeneration directly at the area of damage. Using non-invasive optical coherence tomography (OCT), we were able to define the location of the damaged area and monitor subsequent regeneration in vivo. Indeed, OCT imaging produces high-resolution, cross-sectional images of the zebrafish retina, providing information which was previously only available with histological analyses. In order to confirm the data from real-time OCT, histological sections were performed and regenerative response after the induction of the retinal injury was investigated by immunohistochemistry.

The zebrafish is a popular animal model to study mechanisms of retinal degeneration/regeneration in vertebrates. This protocol describes a method to induce localized injury disrupting the outer retina with minimal damage to the inner retina. Subsequently, we monitor in vivo the retinal morphology and the M&#252;ller glia response throughout retinal regeneration.

A fascinating difference between teleost and mammals is the lifelong potential of the teleost retina for retinal neurogenesis and regeneration after ...

Investigating Mammalian Axon Regeneration: In Vivo Electroporation of Adult Mouse Dorsal Root Ganglion

Electroporation is an essential non-viral gene transfection approach to introduce DNA plasmids or small RNA molecules into cells. A sensory neuron in the dorsal root ganglion (DRGs) extends a single axon with two branches. One branch goes to the peripheral nerve (peripheral branch), and the other branch enters the spinal cord through the dorsal root (central branch). After the neural injury, the peripheral branch regenerates robustly whereas the central branch does not regenerate. Due to the high regenerative capacity, sensory axon regeneration has been widely used as a model system to study mammalian axon regeneration in both the peripheral nervous system (PNS) and the central nervous system (CNS). Here, we describe a previously established approach protocol to manipulate gene expression in mature sensory neurons in vivo via electroporation. Based on transfection with plasmids or small RNA oligos (siRNAs or microRNAs), the approach allows for both loss- and gain-of-function experiments to study the roles of genes-of-interests or microRNAs in regulation of axon regeneration in vivo. In addition, the manipulation of gene expression in vivo can be controlled both spatially and temporally within a relatively short time course. This model system provides a unique tool to investigate the molecular mechanisms by which mammalian axon regeneration is regulated in vivo.

Investigating Mammalian Axon Regeneration: In Vivo Electroporation of Adult Mouse Dorsal Root Ganglion

Electroporation is an effective approach to deliver genes of interests into cells. By applying this approach in vivo on the neurons of adult mouse dorsal root ganglion (DRG), we describe a model to study axon regeneration in vivo.

Electroporation is an essential non-viral gene transfection approach to introduce DNA plasmids or small RNA molecules into cells. A sensory neuron in the ...

Facial Nerve Surgery in the Rat Model to Study Axonal Inhibition and Regeneration

This protocol describes consistent and reproducible methods to study axonal regeneration and inhibition in a rat facial nerve injury model. The facial nerve can be manipulated along its entire length, from its intracranial segment to its extratemporal course. There are three primary types of nerve injury used for the experimental study of regenerative properties: nerve crush, transection, and nerve gap. The range of possible interventions is vast, including surgical manipulation of the nerve, delivery of neuroactive reagents or cells, and either central or end-organ manipulations. Advantages of this model for studying nerve regeneration include simplicity, reproducibility, interspecies consistency, reliable survival rates of the rat, and an increased anatomic size relative to murine models. Its limitations involve a more limited genetic manipulation versus the mouse model and the superlative regenerative capability of the rat, such that the facial nerve scientist must carefully assess time points for recovery and whether to translate results to higher animals and human studies. The rat model for facial nerve injury allows for functional, electrophysiological, and histomorphometric parameters for the interpretation and comparison of nerve regeneration. It thereby boasts tremendous potential toward furthering the understanding and treatment of the devastating consequences of facial nerve injury in human patients.

This protocol describes a reproducible approach to facial nerve surgery in the rat model, including descriptions of various inducible patterns of injury.

This protocol describes consistent and reproducible methods to study axonal regeneration and inhibition in a rat facial nerve injury model. The facial ...