Abstract
Purpose :
Nerve fibers in the adult mammalian central nervous system (CNS) do not regeneration after damage, such as optic nerve degeneration in glaucoma patients. Electrical activity is important for neuronal survival and axonal growth. The goal of my research is exciting retinal ganglion cells (RGCs) after injury using optogenetic approaches to protect RGCs from apoptosis, promote axon regeneration and hopefully achieve functional recovery.
Methods :
The Thy1-Chr2-EFYP mice were separated into the optogenetically stimulated and control group after crush. RGC survival rate was calculated based on the confocal laser scanning ophthalmoscopy (CLSO) and whole mount retinal immunostaining results. Nerve fiber layer thickness change was quantified by the optical coherence tomography while optic nerve regeneration was observed in optic nerve frozen section immunostaining images. And last pattern electroretinogram (PERG) was used to detect RGC function specifically.
Results :
No significant difference of RGC density between the stimulated and control group was observed at 7 days post crush. However, 25 days after crush, mice in stimulated group preserved more Thy1+ RGCs compared to the mice in the control group based on CSLO images. The survival rate of RGCs in stimulated group is significantly higher than that in control group based on either GFP or RBPMS counting from retina whole mount stainning results (Figure1).
The optogenetically stimulated group demonstrates a significantly larger number of regenerated axons and they run a much longer distance distal from the crush site compared to the control non-stimulated group. The quantification of NFL thickness change showed that the decrease of NFL thickness in the control group from 7 days to 28 days after crush was much greater than that of mice in the optogenetically stimulated group (Figure2).
The PERG amplitude of mice in the control group sharply dropped and lost their normal PERG wave form shape while mice in stimulated group preserved normal PERG wave shape after crush. In terms of the PERG amplitude, stimulated group demonstrated significantly higher averaged PERG amplitudes than control group at one month after crush (Figure2).
Conclusions :
To conclude, optogenetic stimulation can increase RGC survival rate, protect NFL thickness, promote axon regeneration and preserve RGC function after crush.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.