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sindhu velmurugan, Tsung-Han Chou, Jeremy D. Eastwood, Diego Alba, Vittorio Porciatti, John Guy, Hong Yu; A new mode of gene therapy to subdue the limitations of the allotopic method: an analytic approach. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2830 – A0346.
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© ARVO (1962-2015); The Authors (2016-present)
To compare the efficacy of gene therapy using mito-targeted and allotopic expression strategies to treat LHON in mice.
Adult DBA/1J mice (N=30) were randomly split into three groups and were injected with mitochondria-targeted AAV carrying mutant human ND4 gene (hND4G11778A) to induce LHON. We rescued them at a two-day interval using 1) mito-targeted strategy with MTSAAVs carrying- a) mCherry(n=10), b) wtND4(n=10), naïve (mCherry-mCherry) (n=10) and 2) allotopic strategy (n=20) with MTSAAV carrying a) mCherry (n=10), b) wtND4 (n=10) into both eyes. The rescue of the optic nerve and retina atrophy was evaluated using PERG and TEM.
Our main hypothesis is that the mito-targeted strategy will likely result in a higher delivery efficacy than the allotopic approach making it a quicker and an efficient treatment option for LHON. PERG was performed and mice treated with mito-targeted wildtype hND4 showed a PERG amplitude increase by 34% (p=0.150), 46% (p=0.035), and 83% (p=0.093) respectively at 3, 6, and 12 months after injection, whereas mice treated with allotopic expressed wildtype hND4 increased PERG amplitude by 12% (p=0.594), 21% (p=0.357), 43% (p= 0.012), and 33% (p=0.087).The time course of age-related PERG changes was different between the 2 groups (Interaction age x treatment, P=0.003) (Fig.1A), indicating the efficiency of mito-targeted rescue over allotopic where no significant effect of age (P=0.55) but an overall effect of group on PERG amplitude between the rescued and unrescued mice(P=0.043) was observed (Fig.1B). The significance in amplitude difference (control vs rescue) for mice in mito-targeted strategy (OD, P=0.006; OS, P=0.023) indicates that the rescue efficacy with mito-targeted ND4 compared to allotopic.TEM revealed that MTND4-rescued mice displayed a shift towards small axons showing that the mito-targeted hND4 efficiently prevented the demise of small axons that are lost in human LHON.
Our data showed that the severe visual loss induced by a mitochondrial disease may be reversed using both mito-targeted and allotopic expressed gene therapy,but mito-targeted therapy likely mediates a quicker and more efficient rescue than the allotopic strategy making it a promising option to treat LHON.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
Mean of PERG amplitudes of all mice tested in allotopic (A) group.
Mean of PERG amplitudes of all mice tested in mito-targeted(B) group.
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