Name: ex vivo oculomotor slice culture from embryonic gfp-expressing mice for time-lapse imaging of oculomotor nerve outgrowth
Uploaded: 2019-07-16T15:00:00
Description: Watch this Scientific Journal Video about Ex Vivo Oculomotor Slice Culture from Embryonic GFP-Expressing Mice for Time-Lapse Imaging of Oculomotor Nerve Outgrowth at JoVE.com

Funding provided by the National Eye Institute [5K08EY027850], National Institute of Child Health and Development [U54HD090255], Harvard-Vision Clinical Scientist Development Program [5K12EY016335], the Knights Templar Eye Foundation [Career Starter Grant], and the Children&#8217;s Hospital Ophthalmology Foundation [Faculty Discovery Award]. ECE is a Howard Hughes Medical Institute investigator.

All animal work described here was approved and performed in compliance with the Boston Children&#39;s Hospital Institutional Animal Care and Use Committee (IACUC) protocols.
1. Timed matings
<ol>
	<li>Place ISLMN:GFP (Islet Motor Neuron Green Fluorescent Protein; MGI: J:132726; Jax Tg(Isl-EGFP*)1Slp/J Stock No:&#160;017952) male and female mice together overnight. Weigh the females and record weights prior to mating. 
	NOTE: ISL...

<ol>
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J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuropilin-2+is+required+in+vivo+for+selective+axon+guidance+responses+to+secreted+semaphorins.">Neuropilin-2 is required in vivo for selective axon guidance responses to secreted semaphorins.</a> Neuron. 25 (1), 29-41 (2000).</li><li>Chen, 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=Neuropilin-2+regulates+the+development+of+selective+cranial+and+sensory+nerves+and+hippocampal+mossy+fiber+projections.">Neuropilin-2 regulates the development of selective cranial and sensory nerves and hippocampal mossy fiber projections.</a> Neuron. 25 (1), 43-56 (2000).</li><li>Lerner, O., 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=Stromal+cell-derived+factor-1+and+hepatocyte+growth+factor+guide+axon+projections+to+the+extraocular+muscles.">Stromal cell-derived factor-1 and hepatocyte growth factor guide axon projections to the extraocular muscles.</a> Developmental Neurobiology. 70 (8), 549-564 (2010).</li><li>Cheng, 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=Human+CFEOM1+mutations+attenuate+KIF21A+autoinhibition+and+cause+oculomotor+axon+stalling.">Human CFEOM1 mutations attenuate KIF21A autoinhibition and cause oculomotor axon stalling.</a> Neuron. 82 (2), 334-349 (2014).</li><li>Tischfield, M. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+TUBB3+mutations+perturb+microtubule+dynamics,+kinesin+interactions,+and+axon+guidance.">Human TUBB3 mutations perturb microtubule dynamics, kinesin interactions, and axon guidance.</a> Cell. 140 (1), 74-87 (2010).</li><li>Kim, 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=Motor+neuron+cell+bodies+are+actively+positioned+by+Slit/Robo+repulsion+and+Netrin/DCC+attraction.">Motor neuron cell bodies are actively positioned by Slit/Robo repulsion and Netrin/DCC attraction.</a> Developmental Biology. 399 (1), 68-79 (2015).</li><li>Montague, K., Guthrie, S., Poparic, I. <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+and+In+Vitro+Knockdown+Approaches+in+the+Avian+Embryo+as+a+Means+to+Study+Semaphorin+Signaling.">In Vivo and In Vitro Knockdown Approaches in the Avian Embryo as a Means to Study Semaphorin Signaling.</a> Methods in molecular biology. 1493, 403-416 (2017).</li><li>Clark, C., Austen, O., Poparic, I., Guthrie, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=alpha2-Chimaerin+regulates+a+key+axon+guidance+transition+during+development+of+the+oculomotor+projection.">alpha2-Chimaerin regulates a key axon guidance transition during development of the oculomotor projection.</a> The Journal of neuroscience : the official journal of the Society for Neuroscience. 33 (42), 16540-16551 (2013).</li><li>Ferrario, J. 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This ex vivo slice culture protocol provides significant advantages over traditional axon guidance assays23. The size of each cranial motor nucleus is not a limiting factor, and no difficult dissection is necessary. The endogenous microenvironment through which the axons travel is maintained, allowing modification of one signaling pathway while maintaining other signaling pathways. Additionally, effects can be assessed at different points along the axon trajectory. Since axon guidance requires mul...

The ocular motor system provides an elegant system for investigating axon guidance mechanisms. It is relatively uncomplicated, consisting of three cranial nerves innervating six extraocular muscles (EOMs) which move the eye, and the levator palpebrae superioris (LPS) which lifts the eyelid. The oculomotor nerve innervates the LPS and four EOMs - the inferior oblique and the medial, inferior, and superior rectus muscles. The other two nerves, the trochlear and abducens, each only innervate one muscle, the superior oblique and lateral rectus muscle, respectively. Eye movements provide an easy readout, showing if innervation was appropriate, missing, or aberrant. Additionally, there are human eye movement disorders that result from deficits in neuronal development or axon guidance, collectively termed the congenital cranial disinnervation disorders (CCDDs)1.
Despite these advantages, the ocular motor system is rarely used in axon guidance studies2,3,4,5,6,7,8,9,10, due to technical drawbacks. In vitro axon guidance assays have many disadvantages11. Co-culture assays, in which neuronal explants are cultured together with explants of target tissue12 or transfected cells13, depend on both symmetry of the explant and precise positioning between the explant and target tissue. Stripe assays14,15, in which two cues are laid down in alternating stripes and axons are assessed for preferential growth on one stripe, only indicate that one substrate is preferable to the other, not that either is attractive or repulsive, or physiologically relevant. Microfluidics chambers can form precise chemical gradients, but subject growing axons to shear stress16,17,18, which can affect their growth. Moreover, in each of these approaches, collecting explants or dissociated cells requires that outgrowing axons be axotomized and thus these assays actually examine axon regeneration, rather than initial axon outgrowth. Finally, these in vitro approaches remove the microenvironment that influences axons and their responses to cues along different points of their course, and traditionally only test one cue in isolation. Compounding these disadvantages, the small size of each nucleus in the ocular motor system makes dissection technically challenging for either explants or dissociated cultures. Additionally, primary cultures of ocular motor neurons are usually heterogeneous, have significant cell death, and are density dependent, requiring pooling of cells from multiple embryos (Ryosuki Fujiki, personal communication). In vivo methods, however, including knockout mouse models, are inappropriate to use for screening, given the time and expense required.
Methods developed to culture whole embryos19 allow labeling of migrating cells20 or blockade of specific molecules21, but whole embryo cultures require incubation in roller bottles which precludes real-time imaging of labeled structures. Surgical techniques that allow manipulation of the embryo and then subsequent further development either in the uterus or in the abdomen of the mother (maintaining the placental connection)22 are also possible, but these also do not allow time-lapse imaging.
To overcome the obstacles of in vitro assays and allow rapid screening of signaling pathways, an ex vivo embryonic slice culture technique was developed23, adapted from a previously published protocol for peripheral nerve outgrowth24. Using this protocol, the developing oculomotor nerve can be imaged over time in the presence of many of the surrounding structures along its trajectory, including EOM targets. By adding small molecule inhibitors, growth factors, or guidance cues to the culture media, we can assess guidance perturbations at multiple points along the axon trajectory, allowing more rapid assessment of potential growth and guidance factors.

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			<td height="40" style="height:40px;width:359px;">24-Well Tissue Culture Plate</td>
			<td style="width:163px;">Genesee Scientific</td>
			<td style="width:344px;">25-107</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">6-Well Tissue Culture Plate</td>
			<td>Genesee Scientific</td>
			<td>25-105</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Disposable Pasteur Pipet (Flint Glass)</td>
			<td>VWR</td>
			<td>14672-200</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Fine Forceps</td>
			<td>Fine Science Tools</td>
			<td>11412-11</td>
			<td style="width:331px;"></td>
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		<tr height="40">
			<td height="40" style="height:40px;">Fluorobrite DMEM</td>
			<td>Thermo Fisher Scientific</td>
			<td>A1896701</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Glucose (200 g/L)</td>
			<td>Thermo Fisher Scientific</td>
			<td>A2494001</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Hank&#39;s Balanced Salt Solution (1X)</td>
			<td>Thermo Fisher Scientific</td>
			<td>14175-095</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Heat Inactivated Fetal Bovine Serum</td>
			<td>Atlanta Biologicals</td>
			<td>S11550H</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">HEPES Buffer Solution (1M)</td>
			<td>Thermo Fisher Scientific</td>
			<td>15630106</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">L-Glutamine (250 nM)</td>
			<td>Thermo Fisher Scientific</td>
			<td>25030081</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Loctite Superglue</td>
			<td>Loctite</td>
			<td></td>
			<td style="width:331px;"></td>
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		<tr height="40">
			<td height="40" style="height:40px;">Low Melting Point Agarose</td>
			<td>Thermo Fisher Scientific</td>
			<td>16520050</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Millicell Cell Culture Insert (30mm, hydrophilic PTFE, 0.4 um)</td>
			<td>Millipore Sigma</td>
			<td>PICM03050</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Moria Mini Perforated Spoon</td>
			<td>Fine Science Tools</td>
			<td>10370-19</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Penicillin/Streptomycin (10,000 U/mL)</td>
			<td>Thermo Fisher Scientific</td>
			<td>15140122&#160;</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Petri Dish (100 x 15mm)</td>
			<td>Genesee Scientific</td>
			<td>32-107G</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Phosphate Buffered Saline (1X, pH 7.4)</td>
			<td>Thermo Fisher Scientific</td>
			<td>10010049</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Razor Blades</td>
			<td>VWR</td>
			<td>55411-050</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Surgical Scissors - Blunt</td>
			<td>Fine Science Tools</td>
			<td>14000-12</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Ti Eclipse Perfect Focus with TIRF</td>
			<td>Nikon</td>
			<td></td>
			<td style="width:331px;"></td>
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		<tr height="21">
			<td height="21" style="height:21px;">Vibratome (VT 1200S)</td>
			<td>Leica</td>
			<td>1491200S001</td>
			<td style="width:331px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vibratome Blades (Double Edge, Stainless Steel)</td>
			<td>Ted Pella, Inc.</td>
			<td>121-6</td>
			<td style="width:331px;"></td>
		</tr>
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ex vivo oculomotor slice culture from embryonic gfp-expressing mice for time-lapse imaging of oculomotor nerve outgrowth

Accurate eye movements are crucial for vision, but the development of the ocular motor system, especially the molecular pathways controlling axon guidance, has not been fully elucidated. This is partly due to technical limitations of traditional axon guidance assays. To identify additional axon guidance cues influencing the oculomotor nerve, an ex vivo slice assay to image the oculomotor nerve in real-time as it grows towards the eye was developed. E10.5 IslMN-GFP embryos are used to generate ex vivo slices by embedding them in agarose, slicing on a vibratome, then growing them in a microscope stage-top incubator with time-lapse photomicroscopy for 24-72 h. Control slices recapitulate the in vivo timing of outgrowth of axons from the nucleus to the orbit. Small molecule inhibitors or recombinant proteins can be added to the culture media to assess the role of different axon guidance pathways. This method has the advantages of maintaining more of the local microenvironment through which axons traverse, not axotomizing the growing axons, and assessing the axons at multiple points along their trajectory. It can also identify effects on specific subsets of axons. For example, inhibition of CXCR4 causes axons still within the midbrain to grow dorsally rather than ventrally, but axons that have already exited ventrally are not affected.

Normal Results: Figure 1 provides a schematic of the experiment. Starting as early as E9.5 in mouse, the first axons begin to emerge from the oculomotor nucleus26. By E10.5, a fasciculated oculomotor nerve, which contains the early pioneer neurons, can be seen in the mesenchyme. There is significant variability between embryos at E10.5 (even within the same litter) in how far the nerve has progressed towards the orbit, likely due to developmental differences of a few ...

Watch this Scientific Journal Video about Ex Vivo Oculomotor Slice Culture from Embryonic GFP-Expressing Mice for Time-Lapse Imaging of Oculomotor Nerve Outgrowth at JoVE.com

Ex Vivo Oculomotor Slice Culture from Embryonic GFP-Expressing Mice for Time-Lapse Imaging of Oculomotor Nerve Outgrowth

An ex vivo slice assay allows oculomotor nerve outgrowth to be imaged in real time. Slices are generated by embedding E10.5 IslMN:GFP embryos in agarose, slicing on a vibratome, and growing in a stage-top incubator. The role of axon guidance pathways is assessed by adding inhibitors to the culture media.

Accurate eye movements are crucial for vision, but the development of the ocular motor system, especially the molecular pathways controlling axon ...

Research

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Neuroscience

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For many purposes, the cultivation of mouse embryos ex vivo as organotypic slices is desirable. For example, we employ a transgenic mouse line (tauGFP) in ...

An Organotypic Slice Assay for High-Resolution Time-Lapse Imaging of Neuronal Migration in the Postnatal Brain

Neurogenesis in the postnatal brain depends on maintenance of three biological events: proliferation of progenitor cells, migration of neuroblasts, as ...

VisualEyes: A Modular Software System for Oculomotor Experimentation

Eye movement studies have provided a strong foundation forming an understanding of how the brain acquires visual information in both the normal and ...

Electrophysiological Characterization of GFP-Expressing Cell Populations in the Intact Retina

Studying the physiological properties and synaptic connections of specific neurons in the intact tissue is a challenge for those cells that lack ...

VisioTracker, an Innovative Automated Approach to Oculomotor Analysis

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, ...

Motor Nerve Transection and Time-lapse Imaging of Glial Cell Behaviors in Live Zebrafish

The  nervous system is often described as a hard-wired component of the body even  though it is a considerably fluid organ system that reacts to external ...

In vivo Postnatal Electroporation and Time-lapse Imaging of Neuroblast Migration in Mouse Acute Brain Slices

In vivo Postnatal Electroporation and Time-lapse Imaging of Neuroblast Migration in Mouse Acute Brain Slices

The subventricular zone (SVZ) is one of the main neurogenic niches in the postnatal brain. Here, neural progenitors proliferate and give rise to ...

In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice

In vivo Imaging of Optic Nerve Fiber Integrity by Contrast-Enhanced MRI in Mice

The rodent visual system encompasses retinal ganglion cells and their axons that form the optic nerve to enter thalamic and midbrain centers, and ...

Long-term Time Lapse Imaging of Mouse Cochlear Explants

Here we present a method for long-term time-lapse imaging of live embryonic mouse cochlear explants. The developmental program responsible for building ...

Time-lapse Confocal Imaging of Migrating Neurons in Organotypic Slice Culture of Embryonic Mouse Brain Using In Utero Electroporation

Time-lapse Confocal Imaging of Migrating Neurons in Organotypic Slice Culture of Embryonic Mouse Brain Using In Utero Electroporation

In utero electroporation is a rapid and powerful approach to study the process of radial migration in the cerebral cortex of developing mouse embryos. It ...