Possible sources of neuroprotection following subretinal silicon chip implantation in RCS rats

J Neural Eng. 2005 Mar;2(1):S39-47. doi: 10.1088/1741-2560/2/1/006. Epub 2005 Feb 22.

Abstract

Current retinal prosthetics are designed to stimulate existing neural circuits in diseased retinas to create a visual signal. However, implantation of retinal prosthetics may create a neurotrophic environment that also leads to improvements in visual function. Possible sources of increased neuroprotective effects on the retina may arise from electrical activity generated by the prosthetic, mechanical injury due to surgical implantation, and/or presence of a chronic foreign body. This study evaluates these three neuroprotective sources by implanting Royal College of Surgeons (RCS) rats, a model of retinitis pigmentosa, with a subretinal implant at an early stage of photoreceptor degeneration. Treatment groups included rats implanted with active and inactive devices, as well as sham-operated. These groups were compared to unoperated controls. Evaluation of retinal function throughout an 18 week post-implantation period demonstrated transient functional improvements in eyes implanted with an inactive device at 6, 12 and 14 weeks post-implantation. However, the number of photoreceptors located directly over or around the implant or sham incision was significantly increased in eyes implanted with an active or inactive device or sham-operated. These results indicate that in the RCS rat localized neuroprotection of photoreceptors from mechanical injury or a chronic foreign body may provide similar results to subretinal electrical stimulation at the current output evaluated here.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Electric Stimulation / instrumentation*
  • Electric Stimulation / methods
  • Foreign-Body Reaction / pathology
  • Foreign-Body Reaction / physiopathology*
  • Neuronal Plasticity / physiology*
  • Photoreceptor Cells, Vertebrate / cytology
  • Photoreceptor Cells, Vertebrate / physiology*
  • Prostheses and Implants*
  • Rats
  • Recovery of Function / physiology*
  • Retinitis Pigmentosa / pathology*
  • Retinitis Pigmentosa / physiopathology
  • Silicon

Substances

  • Silicon