The pCAG-gapEGFP plasmid was a gift from Dr. S. McConnell (Stanford, CA). pCAG-tdTomato plasmid was a gift from Dr. M. Feller (Berkeley, CA). We thank Dr. Edward Ruthazer for suggesting the use of a two-plasmid strategy for single cell labeling and Anne Schohl (Montreal, QC) for validating the two-plasmid Cre/loxP strategy in pilot studies and Crair lab members for technical support. Supported by R01 MH62639 (MC), NIH R01 EY015788 (MC) and NIH P30 EY000785 (MC).

1. Equipment Set-up for Electroporation
<ol>
 <li>Electrodes: We modified Dumont #5 forceps to use as electrodes.
 <ol>
 <li>Separate and break apart the forceps.</li>
 <li>Solder a wire at the wider end of each prong. Wrap the wire attached and prongs with insulation tape leaving approximately 25-30 mm of the tip of the prongs exposed.</li>
 <li>Put the modified forceps back together with any suitable plastic spacer (e.g a button) between the two prongs to provide spring action.</li>
 </...

<ol>
	<li>Huberman, A. D., Feller, M. B., Chapman, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanisms+underlying+development+of+visual+maps+and+receptive+fields.">Mechanisms underlying development of visual maps and receptive fields.</a> Annu Rev Neurosci. 31, 479-509 (2008).</li><li>McLaughlin, T., Torborg, C. L., Feller, M. B., O'Leary, D. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinotopic+map+refinement+requires+spontaneous+retinal+waves+during+a+brief+critical+period+of+development.">Retinotopic map refinement requires spontaneous retinal waves during a brief critical period of development.</a> Neuron. 40, 1147-1160 (2003).</li><li>Godement, P., Salaun, J., Imbert, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prenatal+and+postnatal+development+of+retinogeniculate+and+retinocollicular+projections+in+the+mouse.">Prenatal and postnatal development of retinogeniculate and retinocollicular projections in the mouse.</a> J Comp Neurol. 230, 552-575 (1984).</li><li>Jaubert-Miazza, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+and+functional+composition+of+the+developing+retinogeniculate+pathway+in+the+mouse.">Structural and functional composition of the developing retinogeniculate pathway in the mouse.</a> Vis Neurosci. 22, 661-676 (2005).</li><li>Garcia-Frigola, C., Carreres, M. I., Vegar, C., Herrera, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+delivery+into+mouse+retinal+ganglion+cells+by+in+utero+electroporation.">Gene delivery into mouse retinal ganglion cells by in utero electroporation.</a> BMC Dev Biol. 7, 103-103 (2007).</li><li>Matsuda, T., Cepko, C. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analysis+of+gene+function+in+the+retina.">Analysis of gene function in the retina.</a> Methods Mol Biol. 423, 259-278 (2008).</li><li>Petros, T. J., Rebsam, A., Mason, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+utero+and+ex+vivo+electroporation+for+gene+expression+in+mouse+retinal+ganglion+cells.">In utero and ex vivo electroporation for gene expression in mouse retinal ganglion cells.</a> J Vis Exp. , (2009).</li><li>Ishikawa, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+GDNF+gene+transfer+into+axotomized+retinal+ganglion+cells+using+in+vivo+electroporation+with+a+contact+lens-type+electrode.">Effect of GDNF gene transfer into axotomized retinal ganglion cells using in vivo electroporation with a contact lens-type electrode.</a> Gene Ther. 12, 289-298 (2005).</li><li>Hewapathirane, D. S., Haas, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single+cell+electroporation+in+vivo+within+the+intact+developing+brain.">Single cell electroporation in vivo within the intact developing brain.</a> J Vis Exp. , (2008).</li><li>Ruthazer, E. S., Haas, K., Javaherian, A., Jensen, K., Sin, W. C., Cline, H. T., Yuste, R., Konnerth, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vivo+time-+lapse+imaging+of+neuronal+development.">In vivo time- lapse imaging of neuronal development.</a> Imaging in Neuroscience and Development: A Laboratory Manual. , 191-204 .</li><li>Kachi, S., Oshima, Y., Esumi, N., Kachi, M., Rogers, B., Zack, D. J., Campochiaro, P. 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In this video we demonstrate an in vivo electroporation protocol that results in labeling of single or small clusters of retinal neurons in postnatal mice with DNA constructs encoding fluorescent proteins. Small clusters of fluorescently labeled RGC projections to the dLGN and SC reproduced similar projection patterns as previous studies using RGC labeling with lipophilic dyes, indicating that electroporation did not interfere with normal RGC axon arbor refinement. We have utilized this protocol to analyze the r...

<table border="1">
 <tbody>
 <tr>
 <th>Materials</th>
 <th>Company</th>
 <th>Catalog number</th>
 </tr>
 <tr>
 <td>Dumont #5 Forceps</td>
 <td>Fine Science Tools</td>
 <td>11252-20</td>
 </tr>
 <tr>
 <td>Electrical Stimulator</td>
 <td>Grass Instruments</td>
 <td>Model S4</td>
 </tr>
 <tr>
 <td>Oscilloscope</td>
 <td>Agilent</td>
 <td>Model 54621A</td>
 </tr>
 <tr>
 <td>Audio monitor</td>
 <td>Grass Instruments</td>
 <td>Model AM8B</td>
 </tr>
 <tr>
 <td>Puller</td>
 <td>Sutter Instruments</td>
 <td>Model P-97</td>
 </tr>
 <tr>
 <td>Vannas Scissors a</td>
 <td>World Precision Instruments</td>
 <td>14003</td>
 </tr>
 <tr>
 <td>Micro Scissors b</td>
 <td>Ted Pella</td>
 <td>1347</td>
 </tr>
 <tr>
 <td>Dumont AA Forceps c</td>
 <td>Fine Science Tools</td>
 <td>11210-20</td>
 </tr>
 <tr>
 <td>Nanoinject II System</td>
 <td>Drummond Scientific</td>
 <td>3-000-204</td>
 </tr>
 <tr>
 <td>Glass Pipettes</td>
 <td>Drummond Scientific</td>
 <td>3-000-203-G/X</td>
 </tr>
 <tr>
 <td>Foot pedal</td>
 <td>Drummond Scientific</td>
 <td>3-000-026</td>
 </tr>
 <tr>
 <td>Mineral Oil</td>
 <td>Sigma-Aldrich</td>
 <td>M3516</td>
 </tr>
 <tr>
 <td>DiI</td>
 <td>Invitrogen</td>
 <td>D-383</td>
 </tr>
 <tr>
 <td>N,N-Dimethylformamide</td>
 <td>Sigma</td>
 <td>D4551</td>
 </tr>
 </tbody>
</table>

transfection of mouse retinal ganglion cells by in vivo electroporation

The targeting and refinement of RGC projections to the midbrain is a popular and powerful model system for studying how precise patterns of neural connectivity form during development. In mice, retinofugal projections are arranged in a topographic manner and form eye-specific layers in the Lateral Geniculate Nucleus (dLGN) of the thalamus and the Superior Colliculus (SC). The development of these precise patterns of retinofugal projections has typically been studied by labeling populations of RGCs with fluorescent dyes and tracers, such as horseradish peroxidase1-4. However, these methods are too coarse to provide insight into developmental changes in individual RGC axonal arbor morphology that are the basis of retinotopic map formation. They also do not allow for the genetic manipulation of RGCs.
Recently, electroporation has become an effective method for providing precise spatial and temporal control for delivery of charged molecules into the retina5-11. Current retinal electroporation protocols do not allow for genetic manipulation and tracing of retinofugal projections of a single or small cluster of RGCs in postnatal mice. It has been argued that postnatal in vivo electroporation is not a viable method for transfecting RGCs since the labeling efficiency is extremely low and hence requires targeting at embryonic ages when RGC progenitors are undergoing differentiation and proliferation6. 
In this video we describe an in vivo electroporation protocol for targeted delivery of genes, shRNA, and fluorescent dextrans to murine RGCs postnatally. This technique provides a cost effective, fast and relatively easy platform for efficient screening of candidate genes involved in several aspects of neural development including axon retraction, branching, lamination, regeneration and synapse formation at various stages of circuit development. In summary we describe here a valuable tool which will provide further insights into the molecular mechanisms underlying sensory map development.

Watch this Scientific Journal Video about Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation at JoVE.com

Transfection of Mouse Retinal Ganglion Cells by in vivo Electroporation

We demonstrate an in vivo electroporation protocol for transfecting single or small clusters of retinal ganglion cells (RGCs) and other retinal cell types in postnatal mice over a wide range of ages. The ability to label and genetically manipulate postnatal RGCs in vivo is a powerful tool for developmental studies.