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Elizabeth Crabtree, Liujiang Song, Telmo Llanga, Laura Conatser, Brian C Gilger, Matthew Hirsch; Efficient Corneal Gene Delivery Following Subconjunctival Administrations of AAV Vectors. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3380. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Ideal application of a potential gene therapeutic to the eye would preserve the patients’ blood ocular barriers while allowing efficient and targeted intraocular tissue transduction. One option for the deposition of AAV vectors is via the subconjunctival (SC) space. SC injections are simple, commonly used in the clinic, and are safe. The purpose of this work is to determine the transduction efficiency of periorbital and ocular tissues following the SC administration of different AAV serotypes. Preclinical investigations include the volume/dose relationship, systemic biodistribution, the humoral capsid response and efficiency of vector re-administration.
SC injections were performed in healthy WTB6 mice using a Hamilton syringe on a motorized pump and a 32G needle. Escalating doses of multiple serotypes of self-complementary (sc) CMV-GFP AAV were administered SC in different injection volumes of one eye. Ocular exams included pachymetry, tear production, vector genome shedding, and slit lamp examination. At 8weeks vector genome biodistribution and transduction efficiency were characterized using Q-PCR. Histological examinations included H&E and GFP immunofluorescence.
SC injection of AAV vectors was well tolerated at lower injection volumes; corneal ulceration was noted in 25% of subjects at the highest volume. AAV transduction was serotype dependent in the eyelid, conjunctiva, cornea, and periorbital tissue and muscle. Transgene derived cDNA in the cornea was highest for AAV6 and AAV8, however, their cellular tropism was significantly different; AAV6 specifically transduced the endothelium layer while AAV8 was restricted to the stromal layer. Systemic vector genome biodistribution demonstrated that the tested AAV serotypes were predominantly found in peri-orbital and ocular tissues, however, capsid-specific antibodies were generated in all cases.
SC injection of AAV vectors results in serotype-dependent gene delivery to multiple extraocular tissues that would be valid targets for therapeutic protein production. Efficient and distributed corneal transduction was noted. Unlike other injections routes, administration of vectors to the SC space does not cause mechanical ocular tissue destruction. Considering applications to diseased, or compromised states, SC administration may offer a safer route for AAV gene therapy while maintaining efficient gene delivery.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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