AAV-mediated and pharmacological induction of Hsp70 expression stimulates survival of retinal ganglion cells following axonal injury

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We evaluated the effect of AAV2- and 17-AAG (17-N-allylamino-17-demethoxygeldanamycin)-mediated upregulation of Hsp70 expression on the survival of retinal ganglion cells (RGCs) injured by optic nerve crush (ONC). AAV2-Hsp70 expression in the retina was primarily observed in the ganglion cell layer. Approximately 75% of all transfected cells were RGCs. RGC survival in AAV2-Hsp70-injected animals was increased by an average of 110% 2 weeks after the axonal injury compared with the control. The increase in cell numbers was not even across the retinas with a maximum effect of approximately 306% observed in the inferior quadrant. 17-AAG-mediated induction of Hsp70 expression has been associated with cell protection in various models of neurodegenerative diseases. We show here that a single intravitreal injection of 17-AAG (0.2 ug ul−1) results in an increased survival of ONC-injured RGCs by approximately 49% compared with the vehicle-treated animals. Expression of Hsp70 in retinas of 17-AAG-treated animals was upregulated approximately by twofold compared with control animals. Our data support the idea that the upregulation of Hsp70 has a beneficial effect on the survival of injured RGCs, and the induction of this protein could be viewed as a potential neuroprotective strategy for optic neuropathies.

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This work was supported by the National Institutes of Health (NIH) Grant EY018644 (NP) and Research to Prevent Blindness (JC). WWH acknowledges NIH grants P30EY021721 and R01EY17549 and grants from the Macular Vision Research Foundation, Foundation Fighting Blindness, Usher3 Initiative, Overstreet Fund and Research to Prevent Blindness, Inc. for partial support of this work.

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Correspondence to N Piri.

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Competing interests

WWH and the University of Florida have a financial interest in the use of AAV therapies, and own equity in a company (AGTC Inc.) that might, in the future, commercialize some aspects of this work. The remaining authors declare no conflict of interest.

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Kwong, J., Gu, L., Nassiri, N. et al. AAV-mediated and pharmacological induction of Hsp70 expression stimulates survival of retinal ganglion cells following axonal injury. Gene Ther 22, 138–145 (2015) doi:10.1038/gt.2014.105

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