Monitoring Visual Cortical Activity using Functional Bioluminescence imaging

Abstract

Purpose : To develop a method for monitoring cortical activity using bioluminescence imaging for the potential treatment of visual diseases (such as Retinitis Pigmentosa) using opsin-based resensitization.

Methods : Using the rd10 model (a Retinitis Pigmentosa model), we quantified visual cortical activity during progression of retinal degeneration and subsequent sensitization of remaining retinal architecture. We transfected visual cortices in wild type and rd10 mice with AAV viruses packaged with a Ca²⁺-responsive bioluminescence reporter (with an associated opsin, ~1.23x10¹³) . Changes in cortical bioluminescence due to visual stimulation were used to monitor degeneration. These changes were correlated with ERG signals and retinal thickness measurement via Optical Coherence Tomography. After complete degeneration (8 weeks), mice were intravitreally injected with AAV bearing multi-characteristic 0psin (MCO) and visual cortical activity was monitored over time.

Results : Bioluminescence imaging showed an expected progressive decrease in activity. This was confirmed with the loss of signals in ERG readings from the rd10 mice and thinning of the retina. After delivery of MCO into the left retina, reliable bioluminescence signals were once again observed in the visual cortices of rd10 mice reaching ~27% of their prior recorded maximum. Partial restoration of photoreceptor function was found with ERG at 12 and 14 weeks post injection in the injected eye.

Conclusions : This study establishes the use of Ca²⁺-bioluminescence monitoring as an alternate assay to characterize retinal degeneration. It also establishes the value of MCO for sensitization of remaining retinal structures for the restoration of visual signaling. The disease monitoring and treatment potential shown in this study can be applied to other diseases involving the loss of photoreceptors (e.g. Dry-AMD).

This is a 2020 ARVO Annual Meeting abstract.

 

Figure 1: Time-lapse of Ca²⁺-bioluminescence response after visual stimulation at 6 weeks post-transfection.

 

Figure 2: Longitudinal studies of bioluminescence in visual cortices of wt & rd10 mice. A) Fractional Intensity change in wt mice after exposure to visual stimuli. B & C) Average Fractional intensity change in rd10 mice during degeneration and post injection.