The authors would like to acknowledge Dr. Steve Heap (BVSc, CertVOphthal) for his assistance in establishing this protocol and performing the injections described by Murray et&#160;al.15. The authors also acknowledge funding from CureKids New Zealand, the Canterbury Medical Research Foundation, Neurogene Inc, and the Batten Disease Support and Research Association.

All experimental protocols were approved by the Lincoln University Animal Ethics committee and are in line with the US National Institutes of Health guidelines for the care and use of animals in research and the New Zealand Animal Welfare Act (1999). Borderdale sheep were diagnosed at birth14 and maintained at Lincoln University research farms. Three 3-month-old homozygous (CLN5-/-) ewes received a single IVT injection to the left eye, with the untreated right eye acting as an internal ...

<ol>
	<li>Himawan, 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=Drug+delivery+to+retinal+photoreceptors.">Drug delivery to retinal photoreceptors.</a> Drug Discovery Today. 24 (8), 1637-1643 (2019).</li><li>Murray, S. J., Mitchell, N. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ocular+therapies+for+neuronal+ceroid+lipofuscinoses:+More+than+meets+the+eye.">Ocular therapies for neuronal ceroid lipofuscinoses: More than meets the eye.</a> Neural Regeneration Research. 17 (8), 1755-1756 (2022).</li><li>Bishop, P. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structural+macromolecules+and+supramolecular+organisation+of+the+vitreous+gel.">Structural macromolecules and supramolecular organisation of the vitreous gel.</a> Progress in Retinal and Eye Research. 19 (3), 323-344 (2000).</li><li>Grzybowski, 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=update+on+intravitreal+injections:+Euretina+expert+consensus+recommendations.">update on intravitreal injections: Euretina expert consensus recommendations.</a> Ophthalmologica. 239 (4), 181-193 (2018).</li><li>Pavlou, 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+AAV+capsids+for+intravitreal+gene+therapy+of+photoreceptor+disorders.">Novel AAV capsids for intravitreal gene therapy of photoreceptor disorders.</a> EMBO Molecular Medicine. 13 (4), 13392 (2021).</li><li>Kousi, M., Lehesjoki, A. -. E., Mole, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Update+of+the+mutation+spectrum+and+clinical+correlations+of+over+360+mutations+in+eight+genes+that+underlie+the+neuronal+ceroid+lipofuscinoses.">Update of the mutation spectrum and clinical correlations of over 360 mutations in eight genes that underlie the neuronal ceroid lipofuscinoses.</a> Human Mutation. 33 (1), 42-63 (2012).</li><li>Wibbeler, 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=Cerliponase+alfa+for+the+treatment+of+atypical+phenotypes+of+CLN2+disease:+A+retrospective+case+series.">Cerliponase alfa for the treatment of atypical phenotypes of CLN2 disease: A retrospective case series.</a> Journal of Child Neurology. 36 (6), 468-474 (2021).</li><li>Schulz, 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=Study+of+intraventricular+cerliponase+alfa+for+CLN2+disease.">Study of intraventricular cerliponase alfa for CLN2 disease.</a> The New England Journal of Medicine. 378 (20), 1898-1907 (2018).</li><li>Mitchell, N. 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=Longitudinal+in+vivo+monitoring+of+the+CNS+demonstrates+the+efficacy+of+gene+therapy+in+a+sheep+model+of+CLN5+Batten+disease.">Longitudinal in vivo monitoring of the CNS demonstrates the efficacy of gene therapy in a sheep model of CLN5 Batten disease.</a> Molecular Therapy. 26 (10), 2366-2378 (2018).</li><li>Murray, S. J., Mitchell, N. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+history+of+retinal+degeneration+in+ovine+models+of+CLN5+and+CLN6+neuronal+ceroid+lipofuscinoses.">Natural history of retinal degeneration in ovine models of CLN5 and CLN6 neuronal ceroid lipofuscinoses.</a> Scientific Reports. 12 (1), 3670 (2022).</li><li>Russell, K. N., Mitchell, N. L., Wellby, M. P., Barrell, G. K., Palmer, D. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electroretinography+data+from+ovine+models+of+CLN5+and+CLN6+neuronal+ceroid+lipofuscinoses.">Electroretinography data from ovine models of CLN5 and CLN6 neuronal ceroid lipofuscinoses.</a> Data in Brief. 37, 107188 (2021).</li><li>Shafiee, A., McIntire, G. L., Sidebotham, L. C., Ward, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Experimental+determination+and+allometric+prediction+of+vitreous+volume,+and+retina+and+lens+weights+in+G&#246;ttingen+minipigs.">Experimental determination and allometric prediction of vitreous volume, and retina and lens weights in G&#246;ttingen minipigs.</a> Veterinary Ophthalmology. 11 (3), 193-196 (2008).</li><li>Shinozaki, A., Hosaka, Y., Imagawa, T., Uehara, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Topography+of+ganglion+cells+and+photoreceptors+in+the+sheep+retina.">Topography of ganglion cells and photoreceptors in the sheep retina.</a> The Journal of Comparative Neurology. 518 (12), 2305-2315 (2010).</li><li>Frugier, 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+new+large+animal+model+of+CLN5+neuronal+ceroid+lipofuscinosis+in+Borderdale+sheep+is+caused+by+a+nucleotide+substitution+at+a+consensus+splice+site+(c.571+1G&gt;A)+leading+to+excision+of+exon+3.">A new large animal model of CLN5 neuronal ceroid lipofuscinosis in Borderdale sheep is caused by a nucleotide substitution at a consensus splice site (c.571+1G&gt;A) leading to excision of exon 3.</a> Neurobiology of Disease. 29 (2), 306-315 (2008).</li><li>Murray, S. 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=Intravitreal+gene+therapy+protects+against+retinal+dysfunction+and+degeneration+in+sheep+with+CLN5+Batten+disease.">Intravitreal gene therapy protects against retinal dysfunction and degeneration in sheep with CLN5 Batten disease.</a> Experimental Eye Research. 207, 108600 (2021).</li><li>Ross, 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=Outer+retinal+transduction+by+AAV2-7m8+following+intravitreal+injection+in+a+sheep+model+of+CNGA3+achromatopsia.">Outer retinal transduction by AAV2-7m8 following intravitreal injection in a sheep model of CNGA3 achromatopsia.</a> Gene Therapy. , (2021).</li><li>Boyd, R. 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=Photoreceptor-targeted+gene+delivery+using+intravitreally+administered+AAV+vectors+in+dogs.">Photoreceptor-targeted gene delivery using intravitreally administered AAV vectors in dogs.</a> Gene Therapy. 23 (2), 223-230 (2016).</li><li>Dalkara, 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=In+vivo-directed+evolution+of+a+new+adeno-associated+virus+for+therapeutic+outer+retinal+gene+delivery+from+the+vitreous.">In vivo-directed evolution of a new adeno-associated virus for therapeutic outer retinal gene delivery from the vitreous.</a> Science Translational Medicine. 5 (189), (2013).</li><li>Gearhart, P. M., Gearhart, C., Thompson, D. A., Petersen-Jones, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improvement+of+visual+performance+with+intravitreal+administration+of+9-cis-retinal+in+Rpe65-mutant+dogs.">Improvement of visual performance with intravitreal administration of 9-cis-retinal in Rpe65-mutant dogs.</a> Archives of Ophthalmology. 128 (11), 1442-1448 (2010).</li><li>Ross, 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=Evaluation+of+photoreceptor+transduction+efficacy+of+capsid-modified+adeno-associated+viral+vectors+following+intravitreal+and+subretinal+delivery+in+sheep.">Evaluation of photoreceptor transduction efficacy of capsid-modified adeno-associated viral vectors following intravitreal and subretinal delivery in sheep.</a> Human Gene Therapy. 31 (13-14), 719-729 (2020).</li><li>Kotterman, 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=Antibody+neutralization+poses+a+barrier+to+intravitreal+adeno-associated+viral+vector+gene+delivery+to+non-human+primates.">Antibody neutralization poses a barrier to intravitreal adeno-associated viral vector gene delivery to non-human primates.</a> Gene Therapy. 22 (2), 116-126 (2015).</li><li>Whitehead, M., Osborne, A., Yu-Wai-Man, P., Martin, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Humoral+immune+responses+to+AAV+gene+therapy+in+the+ocular+compartment.">Humoral immune responses to AAV gene therapy in the ocular compartment.</a> Biological Reviews. 96 (4), 1616-1644 (2021).</li><li>Yun, C., Oh, J., Hwang, S. -. Y., Kim, S. -. 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L., Mueller, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraocular+pressure+and+injection+forces+during+intravitreal+injection+into+enucleated+porcine+eyes.">Intraocular pressure and injection forces during intravitreal injection into enucleated porcine eyes.</a> European Journal of Pharmaceutics and Biopharmaceutics. 166, 87-93 (2021).</li><li>Ross, M., Ofri, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+future+of+retinal+gene+therapy:+Evolving+from+subretinal+to+intravitreal+vector+delivery.">The future of retinal gene therapy: Evolving from subretinal to intravitreal vector delivery.</a> Neural Regeneration Research. 16 (9), 1751-1759 (2021).</li><li>Henein, C., 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=Hydrodynamics+of+intravitreal+injections+into+liquid+vitreous+substitutes.">Hydrodynamics of intravitreal injections into liquid vitreous substitutes.</a> Pharmaceutics. 11 (8), 371 (2019).</li><li>Park, I., Park, H. S., Kim, H. K., Chung, W. K., Kim, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+measurement+of+intraocular+pressure+variation+during+automatic+intravitreal+injections:+An+ex-vivo+experimental+study+using+porcine+eyes.">Real-time measurement of intraocular pressure variation during automatic intravitreal injections: An ex-vivo experimental study using porcine eyes.</a> PloS One. 16 (8), 0256344 (2021).</li><li>Willekens, 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=Intravitreally+injected+fluid+dispersion:+Importance+of+injection+technique.">Intravitreally injected fluid dispersion: Importance of injection technique.</a> Investigative Ophthalmology &amp; Visual Science. 58 (3), 1434-1441 (2017).</li><li>Peynshaert, K., Devoldere, J., De Smedt, S. C., Remaut, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+and+ex+vivo+models+to+study+drug+delivery+barriers+in+the+posterior+segment+of+the+eye.">In vitro and ex vivo models to study drug delivery barriers in the posterior segment of the eye.</a> Advanced Drug Delivery Reviews. 126, 44-57 (2018).</li><li>Kiss, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vector+Considerations+for+Ocular+Gene+Therapy.+Adeno-associated+virus+vectors+offer+a+safe+and+effective+tool+for+gene+delivery.">Vector Considerations for Ocular Gene Therapy. Adeno-associated virus vectors offer a safe and effective tool for gene delivery.</a> Retinal Physician. 17, 40-45 (2020).</li><li>Kleine Holthaus, S. -. 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=Gene+therapy+targeting+the+inner+retina+rescues+the+retinal+phenotype+in+a+mouse+model+of+CLN3+Batten+disease.">Gene therapy targeting the inner retina rescues the retinal phenotype in a mouse model of CLN3 Batten disease.</a> Human Gene Therapy. 31 (13-14), 709-718 (2020).</li><li>Kleine Holthaus, S. -. 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=Neonatal+brain-directed+gene+therapy+rescues+a+mouse+model+of+neurodegenerative+CLN6+Batten+disease.">Neonatal brain-directed gene therapy rescues a mouse model of neurodegenerative CLN6 Batten disease.</a> Human Molecular Genetics. 28 (23), 3867-3879 (2019).</li></ol>

Intravitreal injections are one of the most common surgical procedures in human ophthalmology and have proven effective in delivering AAV-mediated gene therapies to the retina of sheep. We had previously demonstrated the efficacy of AAV9.CLN5 gene therapy delivered intravitreally in attenuating retinal dysfunction and degeneration in sheep with CLN5 NCL15. It is hoped that the translation of this route of administration to human NCL patients will also prove beneficial.
...

Several methods can be used to deliver therapeutic agents to the retina, including intravitreal (IVT), subretinal, suprachoroidal, periocular, or topical administration. Each route of administration involves overcoming barriers such as the blood-retina barrier or the inner and outer limiting membranes and has varying rates of efficacy depending on the drug being delivered and the specific retinal target1,2.
IVT drug delivery involves an injection into the vitreous humor of the eye, a gelatinous substance that occupies the posterior chamber of the eye. The primary function of the vitreous humor is to maintain the shape of the eye globe and keep ocular tissues, such as the lens and retina, in place. The vitreous humor is composed largely of water, with small amounts of collagen, hyaluronic acid, and other noncollagenous proteins3. IVT injection is a simple and common procedure used routinely to treat a wide&#160;range of ocular conditions, including age-related macular degeneration, diabetic macular edema, diabetic retinopathy, retinal vein occlusion, and several inherited retinal dystrophies4,5.
Neuronal ceroid lipofuscinoses (NCL; Batten disease) are a group of fatal lysosomal storage diseases that cause severe degeneration of the brain and retina. There are currently 13 known variants of NCL resulting from mutations in different genes (CLN1-8, CLN10-14) that predominantly affect children but have varying ages of onset and disease severity6. The NCLs share common progressive symptoms, including cognitive and motor decline, seizures, and loss of vision. There is no cure for NCL; however, brain-directed enzyme-replacement therapy is currently in clinical trials for CLN2 disease7,8, and AAV-mediated gene therapy has shown great promise in preclinical studies, with a clinical trial for CLN5 gene therapy expected to begin in 20229,10.
Many other species develop naturally occurring forms of NCL, including cats, dogs, sheep, and cows. Two ovine models of NCL are currently under active study in New Zealand: a CLN5 disease model in Borderdale sheep and a CLN6 disease model in South Hampshire sheep. Affected sheep exhibit many of the clinical and pathological features of the human disease, including retinal atrophy and loss of vision10,11. Although brain-directed CLN5 gene therapy in sheep with CLN5 disease can prevent or halt brain atrophy and clinical decline, the treated sheep do still lose their vision9. This highlighted the need to treat the retina to preserve vision and maintain a better quality of life, leading to the establishment of a protocol for ocular gene therapy in sheep.
The sheep eye represents a good model of the human eye due to its similarity in eye globe dimensions, vitreous volume, and retinal structure10,12,13. This paper details the surgical protocol for IVT delivery of a small volume (&#8804;100 &#181;L) of therapeutic viral vector to the ovine eye.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1 mL low dead-space safety syringe with permanently attached 0.5 inch needle</td>
			<td>Fisher Scientific, Auckland, New Zealand</td>
			<td>05-561-28</td>
			<td>Covidien Monoject Tuberculin Safety syringe or similar</td>
		</tr>
		<tr>
			<td>1.5 mL microcentrifuge tube</td>
			<td>Sigma Aldrich</td>
			<td>HS4323</td>
			<td>Autoclave tubes to sterilise prior to use</td>
		</tr>
		<tr>
			<td>Anesthesia machine with gas bench and monitor&#160;</td>
			<td>Hyvet Anesthesia, Christchurch, New Zealand</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Antibiotic eye drops&#160;</td>
			<td>Teva Pharma Ltd, Auckland, New Zealand</td>
			<td></td>
			<td>Commercial name: Chlorafast (0.5% chloramphenicol)</td>
		</tr>
		<tr>
			<td>BrightMount plus anti-fade mounting medium</td>
			<td>Abcam, Cambridge, United Kingdom</td>
			<td>ab103748</td>
			<td></td>
		</tr>
		<tr>
			<td>DAPI (4&#8242; ,6-diamidino-2-phenylindole dihydrochloride)</td>
			<td>Sigma Aldrich, St. Louis, Missouri, United States</td>
			<td>10236276001</td>
			<td></td>
		</tr>
		<tr>
			<td>Diazepam sedative</td>
			<td>Ilium, Troy Laboratories Pty Ltd, Tauranga, New Zealand</td>
			<td></td>
			<td>5 mg/mL</td>
		</tr>
		<tr>
			<td>Endotracheal tubes</td>
			<td>Flexicare Medical Ltd, Mountain Ash, United Kingdom</td>
			<td></td>
			<td>Standard, cuffed. Sizes 7, 7.5, or 8 depending on sheep size</td>
		</tr>
		<tr>
			<td>Eye speculum</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>KP151/14</td>
			<td>Nopa Barraquer-Colibri (10 mm)</td>
		</tr>
		<tr>
			<td>Fenestrated surgical drape</td>
			<td>Amtech Medical Ltd, Whanganui, New Zealand</td>
			<td>DI583</td>
			<td>Or similar&#160;</td>
		</tr>
		<tr>
			<td>Filter Tips</td>
			<td>Interlab, Auckland, New Zealand</td>
			<td></td>
			<td>10, 200, and 1,000 &#181;L&#160;</td>
		</tr>
		<tr>
			<td>Formaldehyde solution (37%)</td>
			<td>Fisher Scientific, Auckland, New Zealand</td>
			<td>AJA809-2.5PL</td>
			<td>Make up to 10% in distilled water with 0.9% NaCl</td>
		</tr>
		<tr>
			<td>Goat anti-rabbit Alexa Fluor 594</td>
			<td>Invitrogen Carlsbad, CA, USA</td>
			<td>&#160;A-11012</td>
			<td>Use at a dilution of 1:500</td>
		</tr>
		<tr>
			<td>Isoflurane anesthetic</td>
			<td>Attane, Bayer Animal Health, Auckland, New Zealand</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Ketamine HCl anesthetic/analgesic</td>
			<td>PhoenixPharm Distributors Ltd, Auckland, New Zealand</td>
			<td></td>
			<td>100 mg/mL</td>
		</tr>
		<tr>
			<td>Laryngoscope (veterinary)</td>
			<td>KaWe Medical, Denmark</td>
			<td></td>
			<td>Miller C blade, size 2</td>
		</tr>
		<tr>
			<td>Needles&#160;</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>302025</td>
			<td>BD Hypodermic Needles, or similar</td>
		</tr>
		<tr>
			<td>Non-steroidal anti-inflammatory</td>
			<td>Boehringer Ingelheim (NZ) Ltd, Auckland, New Zealand</td>
			<td>49402/008</td>
			<td>Commercial name: Metacam 20 (20 mg/mL meloxicam)</td>
		</tr>
		<tr>
			<td>Non-toothed forceps</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>AB864/16</td>
			<td>Or similar&#160;</td>
		</tr>
		<tr>
			<td>Non-toothed hemostat</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>AA150/12</td>
			<td>Or similar&#160;</td>
		</tr>
		<tr>
			<td>Normal goat serum</td>
			<td>Thermo Fisher Scientific, Christchurch, New Zealand</td>
			<td>16210072</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen (medical)</td>
			<td>BOC Gas, Christchurch, New Zealand</td>
			<td></td>
			<td>D2 cylinder, gas code 180</td>
		</tr>
		<tr>
			<td>Phosphate buffered saline&#160;</td>
			<td>Thermo Fisher Scientific, Christchurch, New Zealand</td>
			<td>10010023</td>
			<td>Sterile, filtered</td>
		</tr>
		<tr>
			<td>Povidone-Iodine solution</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>005835</td>
			<td>Commercial name: Betadine (10% povidone-iodine)</td>
		</tr>
		<tr>
			<td>Rabbit anti-cow glial fibrillary acidic protein (GFAP)</td>
			<td>Dako, Glostrup, Denmark</td>
			<td>Z0334</td>
			<td>Use at a dilution of 1:2,500</td>
		</tr>
		<tr>
			<td>Self-complementary adeno-associated virus serotype 9, containing the chicken beta action (CBh) promoter and codon-optimized ovine CLN5</td>
			<td>University of North Carolina Vector Core, NC, USA.</td>
			<td>scAAV9/CBh-oCLN5opt</td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium Chloride 0.9% IV Solution</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>AHB1322</td>
			<td>Commercial name: Saline solution&#160;</td>
		</tr>
		<tr>
			<td>Subcutaneous antibiotics</td>
			<td>Intervet Schering Plough Animal Health Ltd, Wellington, New Zealand</td>
			<td></td>
			<td>Commercial name: Duplocillin LA (150,000 IU/mL procaine penicillin and 115,000 IU/mL benzathine penicillin)</td>
		</tr>
		<tr>
			<td>Surgical sharp blunt curved scissors&#160;</td>
			<td>Capes Medical Ltd, Tauranga, New Zealand</td>
			<td>SSSHBLC130</td>
			<td></td>
		</tr>
		<tr>
			<td>Terumo Syringe Luer Lock</td>
			<td>Amtech Medical Ltd, Whanganui, New Zealand</td>
			<td>SH159/SH160</td>
			<td>Sterile syringes; 10 mL for drawing up induction drugs, 20 mL for drawing up saline</td>
		</tr>
		<tr>
			<td>Virkon Disinfectant Powder</td>
			<td>EBOS Group Ltd, Christchurch, NZ</td>
			<td>28461115</td>
			<td></td>
		</tr>
	</tbody>
</table>

intravitreal injections in the ovine eye

There are several methods for the delivery of therapeutic agents to the retina, including intravitreal (IVT), subretinal, suprachoroidal, periocular, or topical administration. IVT drug delivery involves an injection into the vitreous humor of the eye, a gelatinous substance that fills the posterior chamber of the eye and maintains the shape of the eye globe. Although the IVT route is less specifically targeted than subretinal delivery, it is much less invasive and is widely used in clinical settings for a range of ocular diseases. 
We previously demonstrated the efficacy of intravitreal delivery of an adeno-associated virus (AAV)-mediated gene therapy product (AAV9.CLN5) in sheep with a naturally occurring CLN5 form of neuronal ceroid lipofuscinosis (NCL). Affected sheep received IVT gene therapy in one eye, with the other untreated eye serving as an internal control. Retinal structure and function were maintained in the treated eye up to 15 months after treatment, while the untreated eye displayed progressively declining function and severe atrophy during postmortem examination. Based on the sheep studies, the CLN5 gene therapy product was cleared as a candidate investigational new drug (IND) by the United States Food and Drug Administration in September 2021. This paper details the surgical protocol for IVT delivery of a therapeutic viral vector to the ovine eye.

The efficacy of IVT delivery of a CLN5 gene therapy vector in attenuating retinal dysfunction and degeneration in sheep with CLN5 NCL has previously been demonstrated by this research group15. Affected sheep received a single 100 &#181;L IVT injection of CLN5 packaged in an AAV serotype 9 (AAV9) vector (AAV9.CLN5) into one eye, with the contralateral eye serving as an untreated internal control. Vision was assessed monthly from the age at injection (3 months) to end-stage disease (18 months). Post...

Watch this Scientific Journal Video about Intravitreal Injections in the Ovine Eye at JoVE.com

Intravitreal Injections in the Ovine Eye

Intravitreal injections were performed in the sheep eye with the aim of delivering viral-mediated gene therapy to the retina.

There are several methods for the delivery of therapeutic agents to the retina, including intravitreal (IVT), subretinal, suprachoroidal, periocular, or ...

Intravitreal injections can be used to deliver therapeutic agents to the retina. A protocol for intravitreal injections into the sheep eye, as a model of the human eye, is presented here. Intravitreal injections are much less invasive than other ocular injections.Intravitreal injections can be successfully used to deliver a gene therapy product and treat retinal degeneration in sheep with naturally-occurring neuronal ceroid lipofuscinoses. Once the sheep is anesthetized, start aseptically disinfecting the eye to be injected by irrigating it with 1 to 5%povidone iodine solution using a 20-milliliter syringe. Then, position a sterile, fenestrated surgical drape over the eye.Fit an eye speculum to the eyelids to hold the eye open. Grasp the bulbar conjunctiva on the dorsal lateral aspect of the eye with forceps and rotate the eye globe ventromedially. Insert the needle approximately seven-millimeter posterior to the sclera on the lateral aspect of the eye, and angled posteriorly to avoid the lens.Administer the single injection of 100 microliters as a bolus, as close to the retina as possible, without disturbing the retinal surface. Rinse the eye with approximately 10 to 15 milliliters of 1 to 5%povidone iodine solution followed by 10 milliliters of saline, before removal of the speculum and drape. Electroretinography analysis demonstrated preserved retinal function in the treated eye while the untreated eye declined in a similar manner to CLN5-affected animals.Retinal histology was near normalized in the treated eye with a total retinal thickness comparable to healthy control animals in the central retina. In contrast, the thickness of the untreated retina was comparable to CLN5-affected animals. The expression of the glial fibrillary acidic protein, or GFAP, a marker of retinal stress and astroglia, was lower in treated eyes than the untreated eyes, indicating that disease-associated inflammation was attenuated following treatment.With the establishment of a protocol for intravitreal injections into the sheep eye, sheep could now be used to test the safety and efficacy of many intravitreally-delivered therapeutic agents.

Research

JoVE Journal

Medicine

Development of an Audio-based Virtual Gaming Environment to Assist with Navigation Skills in the Blind

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio based cues and set within the context of a video game metaphor, users gather relevant spatial information regarding a building's layout. This allows the user to develop an accurate spatial cognitive map of a large-scale three-dimensional space that can be manipulated for the purposes of a real indoor navigation task. After game play, participants are then assessed on their ability to navigate within the target physical building represented in the game. Preliminary results suggest that early blind users were able to acquire relevant information regarding the spatial layout of a previously unfamiliar building as indexed by their performance on a series of navigation tasks. These tasks included path finding through the virtual and physical building, as well as a series of drop off tasks. We find that the immersive and highly interactive nature of the AbES software appears to greatly engage the blind user to actively explore the virtual environment. Applications of this approach may extend to larger populations of visually impaired individuals.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind.

Audio-based Environment Simulator (AbES) is virtual environment software designed to improve real world navigation skills in the blind. Using only audio ...

Heterotopic Mucosal Engrafting Procedure for Direct Drug Delivery to the Brain in Mice

Delivery of therapeutics into the brain is impeded by the presence of the blood-brain barrier (BBB) which restricts the passage of polar and high molecular weight compounds from the bloodstream and into brain tissue. Some direct delivery success in humans has been achieved via implantation of transcranial catheters; however this method is highly invasive and associated with numerous complications. A less invasive alternative would be to dose the brain through a surgically implanted, semipermeable membrane such as the nasal mucosa that is used to repair skull base defects following endoscopic transnasal tumor removal surgery in humans. Drug transfer though this membrane would effectively bypass the BBB and diffuse directly into the brain and cerebrospinal fluid. Inspired by this approach, a surgical approach in mice was developed that uses a donor septal mucosal membrane engrafted over an extracranial surgical BBB defect. This model has been shown to effectively allow the passage of high molecular weight compounds into the brain. Since numerous drug candidates are incapable of crossing the BBB, this model is valuable for performing preclinical testing of novel therapies for neurological and psychiatric diseases.

A mouse model of human endoscopic skull base reconstruction has been developed that creates a semipermeable interface between the brain and nose using nasal mucosal grafts. This method allows researchers to study delivery to the central nervous system of high molecular weight therapeutics which are otherwise excluded by the blood-brain barrier when administered systemically.

Delivery of therapeutics into the brain is impeded by the presence of the blood-brain barrier (BBB) which restricts the passage of polar and high ...

Performing Subretinal Injections in Rodents to Deliver Retinal Pigment Epithelium Cells in Suspension

The conversion of light into electrical impulses occurs in the outer retina and is accomplished largely by rod and cone photoreceptors and retinal pigment epithelium (RPE) cells. RPE provide critical support for photoreceptors and death or dysfunction of RPE cells is characteristic of age-related macular degeneration (AMD), the leading cause of permanent vision loss in people age 55 and older. While no cure for AMD has been identified, implantation of healthy RPE in diseased eyes may prove to be an effective treatment, and large numbers of RPE cells can be readily generated from pluripotent stem cells. Several interesting questions regarding the safety and efficacy of RPE cell delivery can still be examined in animal models, and well-accepted protocols used to inject RPE have been developed. The technique described here has been used by multiple groups in various studies and involves first creating a hole in the eye with a sharp needle. Then a syringe with a blunt needle loaded with cells is inserted through the hole and passed through the vitreous until it gently touches the RPE. Using this injection method, which is relatively simple and requires minimal equipment, we achieve consistent and efficient integration of stem cell-derived RPE cells in between the host RPE that prevents significant amount of photoreceptor degeneration in animal models. While not part of the actual protocol, we also describe how to determine the extent of the trauma induced by the injection, and how to verify that the cells were injected into the subretinal space using in vivo imaging modalities. Finally, the use of this protocol is not limited to RPE cells; it may be used to inject any compound or cell into the subretinal space.

Here we present a community accepted protocol in multimedia format for subretinally injecting a bolus of RPE cells in rats and mice. This approach can be used for determining rescue potentials, safety profiles, and survival capacities of grafted RPE cells upon implantation in animal models of retinal degeneration.

The conversion of light into electrical impulses occurs in the outer retina and is accomplished largely by rod and cone photoreceptors and retinal pigment ...

Trabecular Meshwork Response to Pressure Elevation in the Living Human Eye

The mechanical characteristics of the trabecular meshwork (TM) are linked to outflow resistance and intraocular pressure (IOP) regulation. The rationale behind this technique is the direct observation of the mechanical response of the TM to acute IOP elevation. Prior to scanning, IOP is measured at baseline and during IOP elevation. The limbus is scanned by spectral-domain optical coherence tomography at baseline and during IOP elevation (ophthalmodynamometer (ODM) applied at 30 g force). Scans are processed to enhance visualization of the aqueous humor outflow pathway using ImageJ. Vascular landmarks are used to identify corresponding locations in baseline and IOP elevation scan volumes. Schlemm canal (SC) cross-sectional area (SC-CSA) and SC length from anterior to posterior along its long axis are measured manually at 10 locations within a 1 mm segment of SC. Mean inner to outer wall distance (short axis length) is calculated as the area of SC divided by its long axis length. To examine the contribution of adjacent tissues to the effect IOP elevations, measurements are repeated without and with smooth muscle relaxation with instillation of tropicamide. TM migration into SC is resisted by TM stiffness, but is enhanced by the support of its attachment to adjacent smooth muscle within the ciliary body. This technique is the first to measure the living human TM response to pressure elevation in situ under physiological conditions within the human eye.

Trabecular meshwork (TM) migration into Schlemm&#8217;s canal space can be induced by acute pressure elevation by ophthalmodynamometer, and observed by spectral domain optical coherence tomography. The goal of this method is to quantify the morphometric response of the living outflow tract to acute pressure elevation in living tissues in situ.

The mechanical characteristics of the trabecular meshwork (TM) are linked to outflow resistance and intraocular pressure (IOP) regulation. The rationale ...

Fluorescent Dye Labeling of Erythrocytes and Leukocytes for Studying the Flow Dynamics in Mouse Retinal Circulation

The retinal and choroidal blood flow dynamics may provide insight into the pathophysiology and sequelae of various ocular diseases, such as glaucoma, diabetic retinopathy, age-related macular degeneration (AMD) and other ocular inflammatory conditions. It may also help to monitor the therapeutic responses in the eye. The proper labeling of the blood cells, coupled with live-cell imaging of the labeled cells, allows for the investigation of the flow dynamics in the retinal and choroidal circulation. Here, we describe the standardized protocols of 1.5% indocyanine green (ICG) and 1% sodium fluorescein labeling of mice erythrocytes and leukocytes, respectively. Scanning laser ophthalmoscopy (SLO) was applied to visualize the labeled cells in the retinal circulation of C57BL/6J mice (wild type). Both methods demonstrated distinct fluorescently labeled cells in the mouse retinal circulation. These labeling methods can have wider applications in various ocular disease models.

Live-cell imaging of the labeled blood cells in ocular circulation can provide information about inflammation and ischemia in diabetic retinopathy and age-related macular degeneration. A protocol to label blood cells and image the labeled cells in the retinal circulation is described.

The retinal and choroidal blood flow dynamics may provide insight into the pathophysiology and sequelae of various ocular diseases, such as glaucoma, ...

Transvaginal Mesh Insertion in the Ovine Model

This protocol describes mesh insertion into the rectovaginal septum in sheep using a single vaginal incision technique, with and without the trocar-guided insertion of anchoring arms. Parous sheep underwent the dissection of the rectovaginal septum, followed by the insertion of an implant with or without four anchoring arms, both designed to fit the ovine anatomy. The anchoring arms were put in place using a trocar and an "outside-in" technique. The cranial arms were passed through the obturator, gracilis, and adductor magnus muscles. The caudal arms were fixed near the sacrotuberous ligament, through the coccygeus muscles. This technique allows for the mimicking of surgical procedures performed in women suffering from pelvic organ prolapse. The anatomical spaces and elements are easily identified. The most critical part of the procedure is the insertion of the cranial trocar, which can easily penetrate the peritoneal cavity or the surrounding pelvic organs. This can be avoided by a more extensive retroperitoneal dissection and by guiding the trocar more laterally. This approach is designed only for experimental testing of novel implants in large animal models, as trocar-guided insertion is currently not used clinically.

This protocol describes mesh implantation in the ovine rectovaginal septum using a single vaginal incision technique, with and without the trocar-guided insertion of anchoring arms.

This protocol describes mesh insertion into the rectovaginal septum in sheep using a single vaginal incision technique, with and without the trocar-guided ...

Ovine Lumbar Intervertebral Disc Degeneration Model Utilizing a Lateral Retroperitoneal Drill Bit Injury

Intervertebral disc degeneration is a significant contributor to the development of back pain and the leading cause of disability worldwide. Numerous animal models of intervertebral disc degeneration have been developed. The ideal animal model should closely mimic the human intervertebral disc with regard to morphology, biomechanical properties and the absence of notochordal cells. The sheep lumbar intervertebral disc model fulfils these criteria. We present an ovine model of intervertebral disc degeneration utilizing a drill bit injury through a lateral retroperitoneal approach. The lateral approach significantly reduces the incision and potential morbidity associated with the traditional anterior approach to the ovine spine. Utilization of a drill-bit method of injury affords the ability to produce a consistent and reproducible injury, of precise dimensions, that initiates a consistent degree of intervertebral disc degeneration. The focal nature of the annular and nucleus pulposus defect more closely mimics the clinical condition of focal intervertebral disc herniation. Sheep recover rapidly following this procedure and are typically mobile and eating within the hour. Intervertebral disc degeneration ensues and sheep undergo necropsy and subsequent analysis at periods from eight weeks. We believe that the drill bit injury model of intervertebral disc degeneration offers advantages over more conventional annular injury models.

Intervertebral disc degeneration is a significant contributor to back pain and a leading cause of disability worldwide. Numerous animal models of intervertebral disc degeneration exist. We demonstrate an ovine model of intervertebral disc degeneration, utilizing a drill bit, which achieves a consistent disc injury and reproducible level of disc degeneration.

Intervertebral disc degeneration is a significant contributor to the development of back pain and the leading cause of disability worldwide. Numerous ...

Ultrahigh Resolution Mouse Optical Coherence Tomography to Aid Intraocular Injection in Retinal Gene Therapy Research

HR-SD-OCT is utilized to monitor the progression of photoreceptor degeneration in live mouse models, assess the delivery of therapeutic agents into the subretinal space, and to evaluate toxicity and efficacy in vivo. HR-SD-OCT uses near infrared light (800-880 nm) and has optics specifically designed for the unique optics of the mouse eye with sub-2-micron axial resolution. Transgenic mouse models of outer retinal (photoreceptor) degeneration and controls were imaged to assess the disease progression. Pulled glass microneedles were used to deliver sub retinal injections of adeno-associated virus (AAV) or nanoparticles (NP) via a trans-scleral and trans-choroidal approach. Careful positioning of the needle into the subretinal space was required prior to a calibrated pressure injection, which delivers fluid into the sub retinal space. Real time subretinal surgery was conducted on our retinal imaging system (RIS). HR-SD-OCT demonstrated progressive uniform retinal degeneration due to expression of a toxic mutant human mutant rhodopsin (P347S) (RHOP347S) transgene in mice. HR-SD-OCT allows rigorous quantification of all the retinal layers. Outer nuclear layer (ONL) thickness and photoreceptor outer segment length (OSL) measurements correlate with photoreceptor vitality, degeneration, or rescue. The RIS delivery system allows real-time visualization of subretinal injections in neonatal (~P10-14) or adult mice, and HR-SD-OCT immediately determines success of delivery and maps areal extent. HR-SD-OCT is a powerful tool that can evaluate the success of subretinal surgery in mice, in addition to measuring vitality of photoreceptors in vivo. HR-SD-OCT can also be used to identify uniform animal cohorts to evaluate the extent of retinal degeneration, toxicity, and therapeutic rescue in preclinical gene therapy research studies.

Here we demonstrate a novel approach to using high resolution spectral-domain optical coherence tomography (HR-SD-OCT) to assist delivery of gene therapy agents into the subretinal space, assess its areal coverage, and characterize photoreceptor vitality.

HR-SD-OCT is utilized to monitor the progression of photoreceptor degeneration in live mouse models, assess the delivery of therapeutic agents into the ...

Mechanical and Controlled PRP Injections in Patients Affected by Androgenetic Alopecia

23 patients (18 male and 5 female) aged 21-70 years who displayed male pattern hair loss (MPHL) in Stage 1 to Stage 5 as determined by the Norwood-Hamilton classification scale, and female pattern hair loss (FPHL) in Stage 1 to Stage 2 as determined by the Ludwig classification scale, were treated with non-activated autologous platelet-rich plasma (A-PRP). Autologous blood (55 mL) was harvested using sodium citrate as an anticoagulant. A-PRP (23 mL) was produced for all cases using a closed system according to the transfusion service protocol. Following centrifugation (260 x g for 10 min) the A-PRP was inserted in a laser light selector device, and after the centrifugation, 9 mL of A-PRP was collected.
The scalp of the patients affected by androgenetic alopecia (AGA) was divided into four areas (frontal, parietal, vertex, and occipital); local anesthesia was not performed. Interfollicular A-PRP injections (0.2 mL x cm2) were performed by controlled and mechanical injections scheduled at a depth of 5 mm using a medical injector gun. Treatment sessions were performed with a 30-day interval. For each patient, three treatment sessions were performed.
PRP was injected in the androgen-related areas of scalp affected by hair loss. Placebo (normal saline solution) was loaded in another syringe (10 mL) and injected on the adjacent side in a similar fashion.

This paper aims to describe the interfollicular autologous platelet-rich plasma injections (0.20 mL x cm2) in the scalp of 23 patients affected by androgenetic alopecia at a depth of 5 mm using a medical injector gun equipped with a 30 gauge needle, in three sessions.

23 patients (18 male and 5 female) aged 21-70 years who displayed male pattern hair loss (MPHL) in Stage 1 to Stage 5 as determined by the ...

A New Best Practice for Validating Tail Vein Injections in Rat with Near-infrared-Labeled Agents

Intravenous (IV) administration of agents into the tail vein of rats can be both difficult and inconsistent. Optimizing tail vein injections is a key part of many experimental procedures where reagents need to be introduced directly into the bloodstream. Unwittingly, the injection can be subcutaneous, possibly altering the scientific outcomes. Utilizing a nanoemulsion-based biological probe with an incorporated near-infrared fluorescent (NIRF) dye, this method offers the capability of imaging a successful tail vein injection in vivo. With the use of a NIRF imager, images are taken before and after the injection of the agent. An acceptable IV injection is then qualitatively or quantitatively determined based on the intensity of the NIRF signal at the site of injection.

Here we present a method to validate tail vein injections in rats by utilizing near-infrared fluorescence imaging data from dyes incorporated into agents or biological probes. The tail is imaged before and after the injection, the fluorescent signal is quantified, and an assessment of the injection quality is made.

Intravenous (IV) administration of agents into the tail vein of rats can be both difficult and inconsistent. Optimizing tail vein injections is a key part ...