This study was supported by the Seoul National University Research Grant (800-20140542), the Pioneer Research Program of NRF/MEST (2012-0009544), and the Bio-Signal Analysis Technology Innovation Program of NRF/MEST (2009-0090895),&#160;and&#160;the Grant of NRF/MEST (2015M3A9E6028949).

All experiments on animals were performed in accordance with the Association for Research in Vision and Ophthalmology Statement for the Use of Animals in Ophthalmic and Vision Research, and the guidelines and regulations set forth by the Seoul National University Institutional Animal Care and Use Committee and Seoul National University Hospital Biosafety Committee.
1. Preparing Injection Kit and Viral Vectors
<ol>
	<li>Prepare the microliter syringe equipped with a 33 G blunt needle sterilized using ethylene oxide gas. Dilute the viral vectors in PBS for the adequate titer in the micro tube (i.e., 1 x 106 TU/&#181;l). Flush the syringe several times with viral vectors to remove any dead space in the syringe.</li>
</ol>
2. Subretinal Injection of Viral Vectors
<ol>
	<li>Anesthetize the adult mice (i.e., 6 - 8 weeks old) with an intraperitoneal injection of the mixture of tiletamine and zolazepam (1:1, 2.25 mg/kg body weight) and xylazine hydrochloride (0.7 mg/kg body weight) or an alternative suitable anesthesia regime.</li>
	<li>Dilate pupils with an eye drop of phenylephrine 0.5% and tropicamide 0.5%.</li>
	<li>Prepare the microliter syringe by loading with 1.5 - 2 &#181;l of viral vectors.</li>
	<li>Open the eyelid and protrude the eye to expose the equator for convenient injection and focus on under the operating microscope. Maintain the protruded eye position until finishing the injection, or displacement of the needle can occur during the injection. To hold the eyeball firmly, place the fingers outside the orbital rim.</li>
	<li>Apply a drop of ophthalmic viscoelastic solution to the corneal surface.</li>
	<li>Place a small round cover slide on the top of the cornea to visualize the retina.</li>
	<li>Puncture a small hole at slight posterior to the limbus using a sterile 30&#160;G 1/2 needle for the further subretinal injection. Make the hole inferior for the right eye, and superior for the left eye for the convenience. 
	NOTE: If the hole is made at temporal or nasal, it&#8217;s hard to be covered by the eyelid after the injection. &#160;Initial puncture should be made slightly posterior to the limbus to avoid the limbal vessels which run along the limbus and can be easily recognized.&#160;&#160;Be careful to avoid hitting the lens with needle while making the initial puncture. Do not insert the entire bevel of the needle to avoid lens puncture.</li>
	<li>Place the 33 G blunt needle of microliter syringe through the pre-punctured hole and approach the needle into the subretinal space until the point when mild resistance is felt. 
	NOTE: For the subretinal injection, the best approach angle of the needle is about 45 degrees against iris plane, and the blunt needle should be pushed posteriorly toward peripapillary area. Dotted square indicated the suggested needle pathway across the vitreous cavity for the subretinal injection in Figure 1. 
	NOTE: There will be no resistance felt when piercing (or passing) the retinal layers as they are very soft. Thus, the first feeling of mild resistance indicates that the needle has already touched the RPE layer and the insertion of the needle should be stopped. Be careful not to penetrate scleral tissue with excessive pressure because the needle should be placed in the potential subretinal space. If the needle punctures the scleral tissue by excessive power, it enters into the extraocular orbital spaces without resistance. (This step is critical)</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/53030/53030fig1.jpg" /> 
Figure 1.&#160;Schematic Diagram of the Subretinal Injection.&#160;H&#38;E stained cross section of the mouse eye depicting the structures with a needle pathway for the subretinal injection marked (a dotted square). Magnification:40X, Scale bar: 500 &#181;m. <a href="https://www.jove.com/files/ftp_upload/53030/53030fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="9">
	<li>Inject the viral vectors (i.e.,&#160;1 x 106 TU/&#181;l) gently into the subretinal space without tremor to avoid unwanted tissue damage and withdraw the needle gently. Hold the eyeball firmly during the injection as described in 2.4.</li>
	<li>Observe the formation of subretinal bleb after the injection under operating microscope to make sure there is no retinal bleeding.</li>
</ol>
<img alt="Figure 2" src="/files/ftp_upload/53030/53030fig2.jpg" /> 
Figure 2. Subretinal Belb Formation without Retinal Hemorrhage.&#160;Microscopic view of subretinal belb after the subretinal injection under operating microscope shows successful bleb formation without retinal hemorrhage. <a href="https://www.jove.com/files/ftp_upload/53030/53030fig2large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="11">
	<li>Gently close the eyelid to cover the injection site for self-sealing.&#160;Return the mice to home cage and keep alive until the evaluation. 
	NOTE: After the researchers get used to the procedures, they can get the repeatable results with rapid procedures by skipping these steps (2.5, 6, and 10)</li>
</ol>
3. Evaluation of the Efficacy of Gene Delivery in Retinal Pigment Epithelium
<ol start="1">
	<li>Sacrifice the mice in the CO2 chamber. Enucleate the eyes using scissors.</li>
	<li>Fix the eyes in the 4% paraformaldehyde solution at 4&#160;&#176;C&#160;for a minimum 1 hr&#160;to few days.</li>
	<li>Grab the cornea with fine forceps and puncture the cornea with micro-scissors. Remove the cornea after scissoring along the limbus. Remove the lens with forceps.</li>
	<li>Trim the ciliary body with micro-scissors allowing retinal detachment. Gently pull the whole retina from the RPE/choroid/sclera complex. Cut the RPE/choroid/scleral complex radially from the periphery to the center near optic nerve several times to make 4 to 8 leaves for flat mounting.</li>
	<li>Flip the RPE/choroid/scleral complex to make RPE side down, and trim all the remaining tissues at the scleral side including muscles, conjunctiva and optic nerve. This step is important to make a flat RPE/choroid/scleral complex because any remaining tissue makes the complex uneven.</li>
	<li>Incubate the complex with primary and secondary antibody for your specific research purposes (optional, see the references for detailed methods). Flat-mount the RPE/choroid/scleral complexes on the glass slide and absorb the PBS with an absorbent sponge.</li>
	<li>Add 30 &#181;l&#160;of mounting solution and place the cover slide. Observe the sample for the efficacy of vector delivery under fluorescein microscope. Keep the samples in the refrigerator for further observation.</li>
</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=Preclinical+potency+and+safety+studies+of+an+AAV2-mediated+gene+therapy+vector+for+the+treatment+of+MERTK+associated+retinitis+pigmentosa.">Preclinical potency and safety studies of an AAV2-mediated gene therapy vector for the treatment of MERTK associated retinitis pigmentosa.</a> Hum Gene Ther Clin Dev. 24 (1), 23-28 (2013).</li><li>MacLaren, R. 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M., Bennett, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraocular+delivery+of+recombinant+virus.">Intraocular delivery of recombinant virus.</a> Methods Mol Med. 47, 125-139 (2001).</li><li>Peyman, G. A., Lad, E. M., Moshfeghi, D. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intravitreal+injection+of+therapeutic+agents.">Intravitreal injection of therapeutic agents.</a> Retina. 29 (7), 875-912 (2009).</li><li>Matsumoto, H., Miller, J. W., Vavvas, D. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+detachment+model+in+rodents+by+subretinal+injection+of+sodium+hyaluronate.">Retinal detachment model in rodents by subretinal injection of sodium hyaluronate.</a> J Vis Exp. (79), (2013).</li><li>Wert, K. J., Skeie, J. M., Davis, R. J., Tsang, S. H., Mahajan, V. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subretinal+injection+of+gene+therapy+vectors+and+stem+cells+in+the+perinatal+mouse+eye.">Subretinal injection of gene therapy vectors and stem cells in the perinatal mouse eye.</a> J Vis Exp. (69), (2012).</li><li>Eberle, D., Santos-Ferreira, T., Grahl, S., Ader, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Subretinal+transplantation+of+MACS+purified+photoreceptor+precursor+cells+into+the+adult+mouse+retina.">Subretinal transplantation of MACS purified photoreceptor precursor cells into the adult mouse retina.</a> J Vis Exp. (84), e50932 (2014).</li><li>Sahel, J. A., Roska, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+therapy+for+blindness.">Gene therapy for blindness.</a> Annu Rev Neurosci. 36, 467-488 (2013).</li><li>Allocca, 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=Novel+adeno-associated+virus+serotypes+efficiently+transduce+murine+photoreceptors.">Novel adeno-associated virus serotypes efficiently transduce murine photoreceptors.</a> J Virol. 81 (20), 11372-11380 (2007).</li><li>Takahashi, 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=Sustained+transduction+of+ocular+cells+with+a+bovine+immunodeficiency+viral+vector.">Sustained transduction of ocular cells with a bovine immunodeficiency viral vector.</a> Hum Gene Ther. 13 (11), 1305-1316 (2002).</li><li>Rolling, 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=Gene+therapeutic+prospects+in+early+onset+of+severe+retinal+dystrophy:+restoration+of+vision+in+RPE65+Briard+dogs+using+an+AAV+serotype+4+vector+that+specifically+targets+the+retinal+pigmented+epithelium.">Gene therapeutic prospects in early onset of severe retinal dystrophy: restoration of vision in RPE65 Briard dogs using an AAV serotype 4 vector that specifically targets the retinal pigmented epithelium.</a> Bull Mem Acad R Med Belg. 161 (10-12), 497-508 (2006).</li><li>Le Meur, G., 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=Restoration+of+vision+in+RPE65-deficient+Briard+dogs+using+an+AAV+serotype+4+vector+that+specifically+targets+the+retinal+pigmented+epithelium.">Restoration of vision in RPE65-deficient Briard dogs using an AAV serotype 4 vector that specifically targets the retinal pigmented epithelium.</a> Gene Ther. 14 (4), 292-303 (2007).</li><li>Alexander, J. 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The authors have nothing to disclose.

In this video article, we described the limbal-approach subretinal injection technique in detail with representative results of RPE/choroid/scleral flat-mount. This is an easy and convenient technique for subretinal injection of viral vectors into RPE. Direct visualization of bleb formation during the injection is an important step for accurate delivery for the beginners. There are some subretinal injection techniques introduced in Journal of Visualized Experiments8-10. Subretinal space is the potential space ...

In ophthalmology, gene therapy has emerged as the treatment modality in monogenic inherited retinopathies. There are inherited retinopathies associated with genes in retinal pigment epithelium (RPE) including Leber congenital amurosis1,2, retinitis pigmentosa3, and choroideremia4. The research field of gene therapy is expanding in both preclinical studies and clinical trials using viral vectors such as adeno-associated virus (AAV), lentivirus (LV) and adenovirus (Ad)5. Different viral vectors have different tropism in the retina. For a safe and effective gene therapy, viral vectors should be carefully selected according to target cells and target genes.
The route of gene delivery is also important for effective gene delivery to target cells, thus, it should be carefully chosen as well. The two most common methods for intraocular delivery of viral vectors are subretinal injection and intravitreal injection6. The latter, intravitreal injection, has been widely used for drug delivery to treat choroidal neovascularization in wet age-related macular degeneration (AMD) and macular edema in diabetic retinopathy7. Intravitreal route provides exposure of viral vectors to vitreous and inner&#160;retina, but the diffusion of the vectors to outer retina is limited. On the other hand, the subretinal route provides direct delivery of viral vectors to the potential space between retina and RPE, inducing a localized bleb. Therefore, subretinal injection is currently considered a more efficient route for targeting photoreceptor cells and RPE. In terms of surgical approach, pars plana is chosen as a safe area for intravitreal injection to avoid retinal damage in human patients. By simply modifying this approach to mice, we could inject viral vectors subretinally or intravireally via limbal approach.
In this video article, we demonstrate an easy and convenient method of subretinal injection of viral vectors into mice RPE. After single puncture at posterior to limbus with a 30 G 1/2 needle, a 33 G blunt needle equipped microliter syringe is inserted into the subretinal space via the limbal puncture site. The viral vectors of 1.5 - 2 &#181;l volume are injected to the potential space between retina and RPE inducing subretinal blebs. This procedure can be performed under direct visualization using surgical microscope. Repeated practice will guarantee replicable results even without direct visualization of the bleb formation. This will help the researchers to perform accurate and timesaving experiments for subretinal gene delivery in mice RPE.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>TWEEZERS DUMONT #5 11cm DUMOSTAR 0.1 x 0.06 mm TIPS</td>
			<td>WPI</td>
			<td>500233</td>
			<td></td>
		</tr>
		<tr>
			<td>VANNAS Scissors S/S, 105mm</td>
			<td>WPI</td>
			<td>555583S</td>
			<td></td>
		</tr>
		<tr>
			<td>33G Blunt needle</td>
			<td>WPI</td>
			<td>NF33BL-2</td>
			<td></td>
		</tr>
		<tr>
			<td>NanoFil Syringe, 10 microliter&#160;</td>
			<td>WPI</td>
			<td>NANOFIL</td>
			<td></td>
		</tr>
		<tr>
			<td>RPE-KIT</td>
			<td>WPI</td>
			<td>RPE-KIT</td>
			<td>For easy one hand injection</td>
		</tr>
		<tr>
			<td>30Gx1/2 (0.3mmx 13mm) BD PrecisionGlideTM Needle</td>
			<td>BD</td>
			<td>305107</td>
			<td>Initial puncture for subretinal injection</td>
		</tr>
		<tr>
			<td>Microscope Cover Glasses (No. 1 3 mm diameter)</td>
			<td>Warner Instruments</td>
			<td>64-0720&#160; (CS-3R)</td>
			<td></td>
		</tr>
		<tr>
			<td>Leica operating microscope</td>
			<td>Leica</td>
			<td>LM M80</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluoresecein microscope</td>
			<td>Nikon</td>
			<td>Eclipse 80i</td>
			<td></td>
		</tr>
		<tr>
			<td>Lentivirus</td>
			<td>Thermo scientific</td>
			<td>TMO.LV-Ctr</td>
			<td>Used to dilute vectors</td>
		</tr>
		<tr>
			<td>PBS</td>
			<td>Gibco</td>
			<td>10010-015</td>
			<td>Used to dilute vectors</td>
		</tr>
		<tr>
			<td>Troperin (Phenylephrin 0.5%-Tropicamide 0.5%)</td>
			<td>Hanmi</td>
			<td></td>
			<td>For dilation</td>
		</tr>
		<tr>
			<td>Proparacaine Hydrochloride Ophthalmic Solution USP, 0.5% (Sterile)</td>
			<td>Bausch&#38;Lomb</td>
			<td></td>
			<td>For topical anesthesia</td>
		</tr>
		<tr>
			<td>Healon GV OVD</td>
			<td>Abbott Medical Optics Inc.</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Zoletil 50 (tiletamine hypochloride and zolazepam hypochloride)</td>
			<td>Virbac</td>
			<td></td>
			<td>For general anesthesia</td>
		</tr>
		<tr>
			<td>Rompun&#174; injection (Xylazine HCl)</td>
			<td>Bayer</td>
			<td></td>
			<td>For general anesthesia</td>
		</tr>
	</tbody>
</table>

limbal approach-subretinal injection of viral vectors for gene therapy in mice retinal pigment epithelium

The eye is a small and enclosed organ which makes it an ideal target for gene therapy. Recently various strategies have been applied to gene therapy in retinopathies using non-viral and viral gene delivery to the retina and retinal pigment epithelium (RPE). Subretinal injection is the best approach to deliver viral vectors directly to RPE cells. Before the clinical trial of a gene therapy, it is inevitable to validate the efficacy of the therapy in animal models of various retinopathies. Thus, subretinal injection in mice becomes a fundamental technique for an ocular gene therapy. In this protocol, we provide the easy and replicable technique for subretinal injection of viral vectors to experimental mice. This technique is modified from the intravitreal injection, which is widely used technique in ophthalmology clinics. The representative results of RPE/choroid/scleral complex flat-mount will help to understand the efficacy of this technique and adjust the volume and titer of viral vectors for the extent of gene transduction.

To evaluate the efficacy of the subretinal injection on viral gene transduction by this protocol, we used commercially available LV vectors with CMV promoter expressing both GFP and RFP for the indicator. Eyes were enucleated after the appropriate time period according to the research purpose. For the representative results, eyes were enucleated 10 weeks and 20 weeks after subretinal injection. After complete removal of the retina using the method described above, the flat mount of RPE/choroid/sclera complex was evaluate...

Watch this Scientific Journal Video about Limbal Approach-Subretinal Injection of Viral Vectors for Gene Therapy in Mice Retinal Pigment Epithelium at JoVE.com

Limbal Approach-Subretinal Injection of Viral Vectors for Gene Therapy in Mice Retinal Pigment Epithelium

Subretinal injection is a surgical technique for effective gene delivery to retinal pigment epithelium in the mouse eye. Here we describe an easy and replicable method for subretinal injection of viral vectors to retinal pigment epithelium in experimental mice.

The eye is a small and enclosed organ which makes it an ideal target for gene therapy. Recently various strategies have been applied to gene therapy in ...

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21.0K Views.  Seoul National University College of Medicine. Subretinal injection is a surgical technique for effective gene delivery to retinal pigment epithelium in the mouse eye. Here we describe an easy and replicable method for subretinal injection of viral vectors to retinal pigment epithelium in experimental mice.

Video: Limbal Approach-Subretinal Injection of Viral Vectors for Gene Therapy in Mice Retinal Pigment Epithelium

Experimental Models for Study of Retinal Pigment Epithelial Physiology and Pathophysiology

We have developed a cell culture procedure that can produce large quantities of confluent monolayers of primary human fetal retinal pigment epithelium (hfRPE) cultures with morphological, physiological and genetic characteristics of native human RPE. These hfRPE cell cultures exhibit heavy pigmentation, and electron microscopy show extensive apical membrane microvilli. The junctional complexes were identified with immunofluorescence labeling of various tight junction proteins. Epithelial polarity and function of these easily reproducible primary cultures closely resemble previously studied mammalian models of native RPE, including human. These results were extended by the development of therapeutic interventions in several animal models of human eye disease. We have focused on strategies for the removal of abnormal fluid accumulation in the retina or subretinal space. The extracellular subretinal space separates the photoreceptor outer segments and the apical membrane of the RPE and is critical for maintenance of retinal attachments and a whole host of RPE/retina interactions.

We provide a reproducible method for culturing confluent monolayers of human fetal retinal pigment epithelial cells (hfRPE) cells that exhibit morphology, physiology, polarity, and protein and gene expression patterns of adult native tissue. This work has been extended to an animal model of several eye diseases.

We have developed a cell culture procedure that can produce large quantities of confluent monolayers of primary human fetal retinal pigment epithelium ...

Targeting of Deep Brain Structures with Microinjections for Delivery of Drugs, Viral Vectors, or Cell Transplants

Microinjections into the brain parenchyma are important procedures to deliver drugs, viral vectors or cell transplants.  The brain lesion that an injecting needle produces during its trajectory is a major concern especially in the mouse brain for not only the brain is small but also sometimes multiple injections are needed.  We show here a method to produce glass capillary needles with a 50-&mu;m lumen which significantly reduces the brain damage and allows a precise targeting into the rodent brain. This method allows a delivery of small volumes (from 20 to 100 nl), reduces bleeding risks, and minimizes passive diffusion of drugs into the brain parenchyma. By using different size of capillary glass tubes, or changing the needle lumen, several types of substances and cells can be injected. Microinjections with a glass capillary tube represent a significant improvement in injection techniques and deep brain targeting with minimal collateral damage in small rodents.

In this article, we show a method to make glass capillary needles with a 50-&mu;m lumen. This technique significantly reduces the brain damage, minimizes passive diffusion of drugs and allows a precise targeting into the rodent brain.

Microinjections into the brain parenchyma are important procedures to deliver drugs, viral vectors or cell transplants.  The brain lesion that an ...

Intracranial Injection of Adeno-associated Viral Vectors

Intracranial injection of viral vectors engineered to express a fluorescent protein is a versatile labeling technique for visualization of specific subsets of cells in different brain regions both in vivo and in brain sections. Unlike the injection of fluorescent dyes, viral labeling offers targeting of individual cell types and is less expensive and time consuming than establishing transgenic mouse lines. In this technique, an adeno-associated viral (AAV) vector is injected intracranially using stereotaxic coordinates, a micropipette and an automated pump for precise delivery of AAV to the desired area with minimal damage to the surrounding tissue. Injection parameters can be tailored to individual experiments by adjusting the animal age at injection, injection location, volume of injection, rate of injection, AAV serotype and the promoter driving gene expression. Depending on the conditions chosen, virally-induced transgene expression can allow visualization of groups of cells, individual cells or fine cellular processes, down to the level of dendritic spines. The experiment shown here depicts an injection of double-stranded AAV expressing green fluorescent protein for the labeling of neurons and glia in the mouse primary visual cortex.

Here we present the intracranial injection of AAV vectors for fluorescent labeling of neurons and glia in the visual cortex.

Intracranial injection of viral vectors engineered to express a fluorescent protein is a versatile labeling technique for visualization of specific ...

Dissection of a Mouse Eye for a Whole Mount of the Retinal Pigment Epithelium

The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and cones). The RPE is a monolayer of pigmented cuboidal cells and associates closely with the neural retina just above it. This association makes the RPE of great interest to researchers studying retinal diseases. The RPE is also the site of an in vivo assay of homology-directed DNA repair, the pun assay. The mouse eye is particularly difficult to dissect due to its small size (about 3.5mm in diameter) and its spherical shape. This article demonstrates in detail a procedure for dissection of the eye resulting in a whole mount of the RPE. In this procedure, we show how to work with, rather than against, the spherical structure of the eye. Briefly, the connective tissue, muscle, and optic nerve are removed from the back of the eye. Then, the cornea and lens are removed. Next, strategic cuts are made that result in significant flattening of the remaining tissue. Finally, the neural retina is gently lifted off, revealing an intact RPE, which is still attached to the underlying choroid and sclera. This whole mount can be used to perform the pun assay or for immunohistochemistry or immunofluorescent assessment of the RPE tissue.

A formal demonstration of the dissection of a mouse eye, resulting in a whole mount of the retinal pigment epithelium.

The retinal pigment epithelium (RPE) lies at the back of the mammalian eye, just under the neural retina, which contains the photoreceptors (rods and ...

Expansion of Embryonic and Adult Neural Stem Cells by In Utero Electroporation or Viral Stereotaxic Injection

Somatic stem cells can divide to generate additional stem cells (expansion) or more differentiated cell types (differentiation), which is fundamental for tissue formation during embryonic development and tissue homeostasis during adulthood 1. Currently, great efforts are invested towards controlling the switch of somatic stem cells from expansion to differentiation because this is thought to be fundamental for developing novel strategies for regenerative medicine 1,2. However, a major challenge in the study and use of somatic stem cell is that their expansion has been proven very difficult to control.
Here we describe a system that allows the control of neural stem/progenitor cell (altogether referred to as NSC) expansion in the mouse embryonic cortex or the adult hippocampus by manipulating the expression of the cdk4/cyclinD1 complex, a major regulator of the G1 phase of the cell cycle and somatic stem cell differentiation 3,4. Specifically, two different approaches are described by which the cdk4/cyclinD1 complex is overexpressed in NSC in vivo. By the first approach, overexpression of the cell cycle regulators is obtained by injecting plasmids encoding for cdk4/cyclinD1 in the lumen of the mouse telencephalon followed by in utero electroporation to deliver them to NSC of the lateral cortex, thus, triggering episomal expression of the transgenes 5-8. By the second approach, highly concentrated HIV-derived viruses are stereotaxically injected in the dentate gyrus of the adult mouse hippocampus, thus, triggering constitutive expression of the cell cycle regulators after integration of the viral construct in the genome of infected cells 9. Both approaches, whose basic principles were already described by other video protocols 10-14, were here optimized to i) reduce tissue damage, ii) target wide portions of very specific brain regions, iii) obtain high numbers of manipulated cells within each region, and iv) trigger high expression levels of the transgenes within each cell. Transient overexpression of the transgenes using the two approaches is obtained by different means i.e. by natural dilution of the electroporated plasmids due to cell division or tamoxifen administration in Cre-expressing NSC infected with viruses carrying cdk4/cyclinD1 flanked by loxP sites, respectively 9,15.
These methods provide a very powerful platform to acutely and tissue-specifically manipulate the expression of any gene in the mouse brain. In particular, by manipulating the expression of the cdk4/cyclinD1 complex, our system allows the temporal control of NSC expansion and their switch to differentiation, thus, ultimately increasing the number of neurons generated in the mammalian brain. Our approach may be critically important for basic research and using somatic stem cells for therapy of the mammalian central nervous system while providing a better understanding of i) stem cell contribution to tissue formation during development, ii) tissue homeostasis during adulthood, iii) the role of adult neurogenesis in cognitive functions, and perhaps, iv) better using somatic stem cells in models of neurodegenerative diseases.

Expansion of Embryonic and Adult Neural Stem Cells by In Utero Electroporation or Viral Stereotaxic Injection

Controlling the expansion of somatic stem cells is a major factor hampering their study and use in therapy. Here we describe a system to temporally control neural stem cells expansion during development and adulthood, which can be used to increase the number of neurons generated in the mouse brain.

Somatic stem cells can divide to generate additional stem cells (expansion) or more differentiated cell types (differentiation), which is fundamental for ...

Stereotaxic Injection of a Viral Vector for Conditional Gene Manipulation in the Mouse Spinal Cord

Intraparenchymal injection of a viral vector enables conditional gene manipulation in distinct populations of neurons or particular regions of the central nervous system. We demonstrate a stereotaxic injection technique that allows targeted gene expression or silencing in the dorsal horn of the mouse spinal cord. The surgical procedure is brief. It requires laminectomy of a single vertebra, providing for quick recovery of the animal and unimpaired motility of the spine. Controlled injection of a small vector suspension volume at low speed and use of a microsyringe with beveled glass cannula minimize the tissue lesion. The local immune response to the vector depends on the intrinsic properties of the virus employed; in our experience, it is minor and short-lived when a recombinant adeno-associated virus is used. A reporter gene such as enhanced green fluorescent protein facilitates monitoring spatial distribution of the vector, and the efficacy and cellular specificity of the transfection.

Viral vectors allow for targeted gene manipulation. We demonstrate a method for conditional gene expression or ablation in the mouse spinal cord, using stereotaxic injection of a viral vector into the dorsal horn, a prominent site of synaptic contact between primary somatosensory afferents and neurons of the central nervous system.

Intraparenchymal injection of a viral vector enables conditional gene manipulation in distinct populations of neurons or particular regions of the central ...

Intracerebroventricular Viral Injection of the Neonatal Mouse Brain for Persistent and Widespread Neuronal Transduction

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene expression in the mouse brain. Here we describe a technique first introduced by Passini and Wolfe for direct intracranial delivery of virally-encoded transgenes into the neonatal mouse brain. In its most basic form, the procedure requires only an ice bucket and a microliter syringe. However, the protocol can also be adapted for use with stereotaxic frames to improve consistency for researchers new to the technique. The method relies on the ability of adeno-associated virus (AAV) to move freely from the cerebral ventricles into the brain parenchyma while the ependymal lining is still immature during the first 12-24 hr after birth. Intraventricular injection of AAV at this age results in widespread transduction of neurons throughout the brain. Expression begins within days of injection and persists for the lifetime of the animal. Viral titer can be adjusted to control the density of transduced neurons, while co-expression of a fluorescent protein provides a vital label of transduced cells. With the rising availability of viral core facilities to provide both off-the-shelf, pre-packaged reagents and custom viral preparation, this approach offers a timely method for manipulating gene expression in the mouse brain that is fast, easy, and far less expensive than traditional germline engineering.

Here we demonstrate a technique for widespread neuronal transduction by intraventricular injection of adeno-associated virus into the neonatal mouse brain. This method provides a rapid and easy way to attain lifelong expression of virally-delivered transgenes.

With the pace of scientific advancement accelerating rapidly, new methods are needed for experimental neuroscience to quickly and easily manipulate gene ...

Development of a Refined Protocol for Trans-scleral Subretinal Transplantation of Human Retinal Pigment Epithelial Cells into Rat Eyes

Degenerative retinal diseases such as age-related macular degeneration (AMD) are the leading cause of irreversible vision loss worldwide. AMD is characterized by the degeneration of retinal pigment epithelial (RPE) cells, which are a monolayer of cells functionally supporting and anatomically wrapping around the neural retina. Current pharmacological treatments for the non-neovascular AMD (dry AMD) only slow down the disease progression but cannot restore vision, necessitating studies aimed at identifying novel therapeutic strategies. Replacing the degenerative RPE cells with healthy cells holds promise to treat dry AMD in the future. Extensive preclinical studies of stem cell replacement therapies for AMD involve the transplantation of stem cell-derived RPE cells into the subretinal space of animal models, in which the subretinal injection technique is applied. The approach most frequently used in these preclinical animal studies is through the trans-scleral route, which is made difficult by the lack of direct visualization of the needle end and can often result in retinal damage. An alternative approach through the vitreous allows for direct observation of the needle end position, but it carries a high risk of surgical traumas as more eye tissues are disturbed. We have developed a less risky and reproducible modified trans-scleral injection method that uses defined needle angles and depths to successfully and consistently deliver RPE cells into the rat subretinal space and avoid excessive retinal damage. Cells delivered in this manner have been previously demonstrated to be efficacious in the Royal College of Surgeons (RCS) rat for at least 2 months. This technique can be used not only for cell transplantation but also for delivery of small molecules or gene therapies.

Subretinal injection has been widely applied in preclinical studies of stem cell replacement therapy for age-related macular degeneration. In this visualized article, we describe a less risky, reproducible and precisely modified subretinal injection technique via the trans-scleral approach to deliver cells into rat eyes.

Degenerative retinal diseases such as age-related macular degeneration (AMD) are the leading cause of irreversible vision loss worldwide. AMD is ...

A Protocol for Transcranial Photobiomodulation Therapy in Mice

Transcranial photobiomodulation is a potential innovative noninvasive therapeutic approach for improving brain bioenergetics, brain function in a wide range of neurological and psychiatric disorders, and memory enhancement in age-related cognitive decline and neurodegenerative diseases. We describe a laboratory protocol for transcranial photobiomodulation therapy (PBMT) in mice. Aged BALB/c mice (18 months old) are treated with a 660 nm laser transcranially, once daily for 2 weeks. Laser transmittance data shows that approximately 1% of the incident red light on the scalp reaches a 1 mm depth from the cortical surface, penetrating the dorsal hippocampus. Treatment outcomes are assessed by two methods: a Barnes maze test, which is a hippocampus-dependent spatial learning and memory task evaluation, and measuring hippocampal ATP levels, which is used as a bioenergetics index. The results from the Barnes task show an enhancement of the spatial memory in laser-treated aged mice when compared with age-matched controls. Biochemical analysis after laser treatment indicates increased hippocampal ATP levels. We postulate that the enhancement of memory performance is potentially due to an improvement in hippocampal energy metabolism induced by the red laser treatment. The observations in mice could be extended to other animal models since this protocol could potentially be adapted to other species frequently used in translational neuroscience, such as rabbit, cat, dog, or monkey. Transcranial photobiomodulation is a safe and cost-effective modality which may be a promising therapeutic approach in age-related cognitive impairment.

Photobiomodulation therapy is an innovative noninvasive modality for the treatment of a wide range of neurological and psychiatric disorders and can also improve healthy brain function. This protocol includes a step-by-step guide to performing brain photobiomodulation in mice by transcranial light delivery, which can be adapted for use in other laboratory rodents.

Transcranial photobiomodulation is a potential innovative noninvasive therapeutic approach for improving brain bioenergetics, brain function in a wide ...

In Vivo Direct Reprogramming of Resident Glial Cells into Interneurons by Intracerebral Injection of Viral Vectors

Converting resident glia in the brain into functional and subtype-specific neurons in vivo provides a step forward towards the development of alternative cell replacement therapies while also creating tools to study cell fate in situ. To date, it has been possible to obtain neurons via in vivo reprogramming, but the precise phenotype of these neurons or how they mature has not been analyzed in detail. In this protocol, we describe a more efficient conversion and cell-specific identification of the in vivo reprogrammed neurons, using an AAV-based viral vector system. We also provide a protocol for functional assessment of the reprogrammed cells&#8217; neuronal maturation. By injecting flip-excision (FLEX) vectors, containing the reprogramming and synapsin-driven reporter genes&#160;to specific cell types in the brain that serve as the target for cell reprogramming. This technique allows for the easy identification of newly reprogrammed neurons. Results show that the obtained reprogrammed neurons functionally mature over time, receive synaptic contacts and show electrophysiological properties of different types of interneurons. Using the transcription factors Ascl1, Lmx1a and Nurr1, the majority of the reprogrammed cells have properties of fast-spiking, parvalbumin-containing interneurons.

This protocol aims at generating directly reprogrammed interneurons in vivo, using an AAV-based viral system in the brain and a FLEX synapsin-driven GFP reporter, which allows for cell identification and further analysis in vivo.

Converting resident glia in the brain into functional and subtype-specific neurons in vivo provides a step forward towards the development of alternative ...