Retinal expression of Fgf2 in RCS rats with subretinal microphotodiode array

Area of Science:

• Ophthalmology and Visual Neuroscience
• Regenerative Medicine
• Molecular Biology

Background:

• Retinal degeneration in Royal College of Surgeons (RCS) rats serves as a model for inherited retinal dystrophies.
• Subretinal electrical stimulation is being explored as a therapeutic strategy for vision loss.
• The underlying molecular mechanisms, particularly the role of growth factors, require elucidation.

Purpose of the Study:

• To investigate the neuroprotective potential of subretinal electrical stimulation via a microphotodiode array (MPA) in RCS rats.
• To determine if MPA stimulation induces the expression of key neurotrophic factors, hypothesizing a role for growth factors in neuroprotection.

Main Methods:

• RCS rats received subretinal implantation of an active MPA, minimally active MPA, sham surgery, or no surgery.
• Electroretinograms (ERGs) were recorded at 1 and 4 weeks post-surgery to assess retinal function.
• Real-time RT-PCR quantified mRNA expression of growth factors (Bdnf, Fgf2, Fgf1, Cntf, Gdnf, Igf1) in retinal samples.

Main Results:

• Active MPA implantation significantly increased retinal fibroblast growth factor 2 (Fgf2) expression compared to control groups.
• No significant changes were observed in the expression of other tested growth factors (Bdnf, Cntf, Fgf1, Gdnf, Igf1).
• Active MPA treatment preserved ERG b-wave amplitude at 4 weeks post-implantation, indicating functional neuroprotection.

Conclusions:

• Subretinal implantation of an MPA selectively upregulates Fgf2 expression beyond that caused by surgical injury alone.
• The preservation of retinal function (ERG b-wave amplitude) correlates with elevated Fgf2 levels.
• These findings suggest that Fgf2 plays a crucial role in the neuroprotective effects mediated by subretinal electrical stimulation.