Transcranial Optogenetic Seizure Inhibition in Pre-clinical Models of Epilepsy
Abstract number :
1.522
Submission category :
2. Translational Research / 2B. Devices, Technologies, Stem Cells
Year :
2024
Submission ID :
1532
Source :
www.aesnet.org
Presentation date :
12/7/2024 12:00:00 AM
Published date :
Authors :
Evyatar Swisa, PhD – Modulight Bio
Carmel Asch, PhD – Modulight Bio
Karni Bar-Or, MS – Modulight Bio
Yoav Kfir, PhD – Modulight Bio
Ofer Yizhar, PhD – Weizmann Institute of Science
Ofir Levi, PhD – Modulight Bio
Presenting Author: Yotam Eldar, MD – Modulight Bio
Rationale: Approximately one-third of epilepsy patients have seizures that cannot be controlled by anti-seizure medications, resulting in drug-resistant epilepsy (DRE). Surgical intervention and/or electrical neuromodulation are not an option for many of these patients due to challenges in localizing the seizure focus or involvement of eloquent cortex areas. To address this need, we are developing an optogenetic platform using the novel G/i-coupled rhodopsin eOPN3. Compared to other inhibitory opsins, eOPN3 is ultrasensitive, red-shifted, and capable of inhibiting both somatic and synaptic activity, overcoming many challenges in translating optogenetics to clinical applications. We demonstrate the efficacy of using transcranial light to activate eOPN3 and disrupt seizures in pre-clinical models of epilepsy. We also show the feasibility of activating eOPN3 in a large-animal brain through computational modeling of red-light penetration through the brain.
Methods: In the first study, we induced focal seizures in Sprague Dawley rats via intra-hippocampal injection of 4-aminopyridine (4AP). Animals were injected with 1 µL of either AAV5-CaMKII-eOPN3-mScarlet or the control construct AAV5-hSyn-EGFP at three locations within the hippocampus, and implanted with EEG screws connected to a wireless transmitter. After 6 weeks we unilaterally injected 4AP into the hippocampus under ketamine anesthesia, and delivered 623 nm light transcranially through a fiber positioned above the injection site. Light was delivered on-demand following online seizure detection. In the second study, we induced chronic seizures in SD rats using unilateral intra-hippocampal kainic acid injections. Two months after the KA injection, we injected eOPN3 or control virus into the hippocampus, as described in Study 1, and implanted microwires in the hippocampus and cortex alongside a red LED array above the skull. We recorded electrographic activity both with and without transcranial red-light illumination (1-second pulses every 5 seconds repeatedly for iterating blocks of 30 minutes). Two video cameras continuously monitored behavior, and an expert reviewer assessed seizure severity using Racine’s scale.
Results: In Study 1 (acute model), red light delivery resulted in shorter seizure durations compared to seizures without light illumination when tested within each animal, with no significant differences observed between light-on and light-off in the control group. In Study 2 (chronic model), red light illumination in eOPN3-expressing cohort reduced both seizure severity and duration, while light stimulation had no significant effects on seizures in the control group.
Conclusions: Our results demonstrate that transcranial illumination of eOPN3-expressing hippocampal excitatory neurons significantly reduces seizure frequency and/or duration in both acute and chronic epilepsy models. Moreover, through light penetration assessments in large-animal brains and computational modeling, we demonstrate the feasibility of delivering safe light doses to human brain targets. Our findings highlight the potential of an eOPN3-based optogenetic therapeutic platform for treating neurological disorders characterized by hyperactivity.
Funding: None
Translational Research