A new approach for gene delivery into retinal bipolar cells

To date, various approaches have been used to restore some visual functions in affected patients, primarily human derived retinal organoids and gene therapies. First directly administered Adeno-associated virus (AAV) based gene therapy approved by U.S. Food and Drug Administration (FDA), Luxturna, significantly improved the vision of patients with retinal dystrophy at low light levels. Nevertheless, there are still difficulties with restoring high-resolution vision that need to be overcome.This project aims to develop a novel proof-of-concept approach to therapeutic gene delivery using a modified Rabies virus as a vector specific to bipolar cells. We propose that specific targeting of the surviving cell population within the degenerated retina, especially bipolar cells (BC) by our modified Rabies virus (RV), pseudotyped with LRIT3 (RV-LRIT3), may constitute a new strategy of gene therapy in retinal diseases. We hypothesize that the proposed viral approach can reach many BCs thanks to the interactions with the TRPM1 channels and deliver high levels of light-gated opsins to restore vision. The main innovation of this project is use of the RV, which can transfect up to 4 genes. Therefore, it can deliver a few opsins with different excitation spectrums and increase overall light sensitivity. We suggest this technique will restore selective responses in the mice’s visual cortex and superior colliculus. We perform single-neuron recordings and behavioral visual discrimination tasks to estimate visual network selectivity in response to complex and moving stimuli.

Image: The strategy of the vision assessment after LRIT3-RV treatment. A. the whole mount retina shows cells infected with the RV-mCherry vector carrying three opsins Bar: 100 um. B. scheme of the simultaneous recordings from the Superior colliculus (SC) and the visual cortex (V1) with representative evoked potentials (VEP) in response to a flash of light. C. Two examples of cells expressing two contradictory opsins. Blue laser caused activation of the cell expressing channelrhodopsin. The second cell expressed the ArchT opsin causing suppression of the activity while yellow laser illumination. D, VEPs recorded in single healthy (black), treated Rd12 with gene therapy (green), and diseased Rd12 (magenta) mice.

Text: Andrzej Foik, PhD habil.

Team:

Andrzej Foik, PhD habil.

Jagoda Płaczkiewicz, PhD

Hubert Doleżyczek, PhD

Milena Gumkowska, MSc Eng.

Lucyna Piórkowska, MSc Eng.

Karolina Saran, MSc Eng.

Keywords: retina, bipolar cells, LRIT3, pseudotyped Rabies virus, congenital stationary night blindness (cCSNB)

Reference:

P. Węgrzyn, W. Kulesza, M. Wielgo, S. Tomczewski, A. Galińska, B. Bałamut, K. Kordecka, O. Cetinkaya, A. Foik, R. J. Zawadzki, D. Borycki, M. Wojtkowski, A. Curatolo “In vivo volumetric analysis of retinal vascular hemodynamics in mice with spatio-temporal optical coherence tomography” Neurophotonics. 11(4):0450031-4500322. (2024) https//doi: 10.1117/1.NPh.11.4.045003.