September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Optogenetic visual restoration using ChrimsonR: Photoactivation below safety radiation limit in retinal ganglion cell populations from non-human primates
Author Affiliations & Notes
  • Gregory Gauvain
    Visual Information Processing, Institut de la Vision, Paris, France
  • Romain Caplette
    Visual Information Processing, Institut de la Vision, Paris, France
  • Céline Jaillard
    Institut de la Vision, Paris, France
  • Antoine J Chaffiol
    Visual Information Processing, Institut de la Vision, Paris, France
  • Melissa Desrosiers
    Therapeutics, Institut de la Vision, Paris, France
  • Olivier Marre
    Visual Information Processing, Institut de la Vision, Paris, France
  • Deniz Dalkara
    Therapeutics, Institut de la Vision, Paris, France
  • José-Alain Sahel
    Institut de la Vision, Paris, France
  • Anne Douar
    GenSight Biologics, Paris, France
  • Didier Pruneau
    GenSight Biologics, Paris, France
  • Serge A Picaud
    Visual Information Processing, Institut de la Vision, Paris, France
  • Footnotes
    Commercial Relationships   Gregory Gauvain, None; Romain Caplette, None; Céline Jaillard, None; Antoine Chaffiol, None; Melissa Desrosiers, None; Olivier Marre, None; Deniz Dalkara, GenSight Biologics (C), GenSight Biologics (P); José-Alain Sahel, Chronocam (C), Chronocam (I), Chronocam (P), GenSight Biologics (C), GenSight Biologics (I), GenSight Biologics (P), GenSight Biologics (F), Pixium (C), Pixium (I), Pixium (P); Anne Douar, GenSight Biologics (E), GenSight Biologics (I); Didier Pruneau, GenSight Biologics (E), GenSight Biologics (I); Serge Picaud, Chronocam (I), GenSight Biologics (C), GenSight Biologics (F), Pixium (C)
  • Footnotes
    Support  Banque publique d'Investissement, Foundation Fighting Blindness, LabEx LIFESENSES (ANR-10-LABX-65), Fondation de la recherche médicale, Gensight Biologics.
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 598. doi:
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      Gregory Gauvain, Romain Caplette, Céline Jaillard, Antoine J Chaffiol, Melissa Desrosiers, Olivier Marre, Deniz Dalkara, José-Alain Sahel, Anne Douar, Didier Pruneau, Serge A Picaud; Optogenetic visual restoration using ChrimsonR: Photoactivation below safety radiation limit in retinal ganglion cell populations from non-human primates. Invest. Ophthalmol. Vis. Sci. 2016;57(12):598.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : In a parallel study (see poster Caplette et al.), we have shown that ChrimsonR (ChrR), a red shifted opsin, can induce light activation of retinal ganglion cells (RGCs) in blind rodents. In this pre-clinical primate study, we assessed whether an intravitreal injection of AAV vectors driving expression of ChrR, or ChrR fused to the fluorescent protein tdTomato (ChrR-tdT), can result in sufficient optogenetic protein expression to allow direct photoactivatation of RGCs.

Methods : Cynomolgus macaques (Macaca fascicularis) were injected intravitreally with either ChrR or ChrR-tdT cDNAs under the control of CAG promoter and vectorized by AAV2 or AAV2.7m8 (5 x 1011 VG/eye). A total of 8 monkeys were injected 2 months before ex vivo recordings of RGCs electrical activity in flat-mounted retinas using a 256 multielectrode array (MEA). Natural light responses were blocked by a cocktail of synaptic blockers (L-AP4, CNQX, CPP), in order to assess photoactivity of optogenetically engineered RGCs .

Results : In vivo ophthalmic exams did not detect any anomaly at 2 months. Expression of tdT was confined to a peri-foveal ring. Only half of the macular area was used for MEA recording (the other half was used for patch clamp experiments, see poster Chaffiol et al.). A similar number of RGCs were recorded in all retinas. However, the number of cells responding to light was different according to the injected AAV vector. A greater number of light responsive cells was recorded for AAV2.7m8-ChrR-tdT, followed by AAV2-7m8-ChrR, and AAV2-ChrR-tdT. No light responsive cells were found for AAV2-ChrR. Light sensitivity was distributed in a similar fashion across the different constructs and light level requested to induce RGC firing was below radiation safety limit. Short flash durations (in a ms range) evoked instantaneous firing at high rate (>50Hz) in a majority of responsive cells.

Conclusions : We demonstrated here that the most efficient AAV vector to ontogenetically engineer RGCs in the non-human primate retina is AAV2-7m8 ChrimsonR-TdTomato. All response kinetics are compatible with an in vivo activation using an external device within the safety radiation limit. Our study indicates that this vector - named GS030 - is an excellent candidate for optogenetic therapy in patients affected by outer retinal degeneration.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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