Authors: Andrzej T. Foik, Georgina A. Lean, Leo R. Scholl, Bryce T. McLelland, Anuradha Mathur, Robert B. Aramant, Magdalene J. Seiler, David C. Lyon
Summary: To combat retinal degeneration, healthy fetal retinal sheets have been successfully transplanted into both rodent models and humans, with synaptic connectivity between transplant and degenerated host retina having been confirmed. In rodent studies transplants have been shown to restore responses to flashes of light in a region of the superior colliculus corresponding to the location of the transplant in the host retina. To determine the quality and detail of visual information provided by the transplant, visual responsivity was studied here at the level of visual cortex where higher visual perception is processed. For our model, we used the transgenic Rho-S334ter line-3 rat (both sexes) which loses photoreceptors at an early age and is effectively blind at post-natal day 30. These rats received fetal retinal sheet transplants in one eye between 24-40 days of age. Three to ten months following surgery, visually responsive neurons were found in regions of primary visual cortex (V1) matching the transplanted region of the retina that were as highly selective as normal rat to stimulus orientation, size, contrast, and spatial and temporal frequencies. Conversely, we found that selective response properties were largely absent in non-transplanted line-3 rats. Our data show that fetal retinal sheet transplants can result in remarkably normal visual function in visual cortex of rats with a degenerated host retina and represents a critical step towards developing an effective remedy for the visually impaired human population.
Source: The Journal of Neuroscience, 2018; 1279-18