Abstract
Purpose :
Previous studies have suggested that C57BL/6J mice are more resistant to optic nerve injury than CD1 mice, though the reasons for this are unclear. Comparing retinal ganglion cell (RGC) susceptibility to cell death in different injury contexts could help identify the mediating factors. Here we compare RGC death rates in axotomized organotypic retinal explants derived from C57BL/6J versus CD1 mice.
Methods :
Retinal explants were isolated from 8-week-old mice from CD1 and C57BL/6J mice and cultured for 0, 7, and 14 days according to a well-characterized protocol. Flatmounted tissue was processed for immunofluorescent labeling of RGCs using RBPMS and ß-III-Tubulin (B3T) specific antibodies and imaged with confocal microscopy. RGCs were quantified in four 0.0505 mm2 fields per retinal quadrant, sampling evenly from near the optic nerve head to the periphery.
Results :
At day 0, the RGC density by B3T staining was 2185.6 cells/mm2 for CD1 and 2422.8 cells/mm2 for C57BL/6J mice; RBPMS density was 2407.5 cells/mm2 for CD1 and 2742 cells/mm2 for C57BL/6J mice. At day 7 of culture, B3T density decreased to 1205.6 cells/mm2 for CD1 and 1241.9 cells/mm2 for C57BL/6J mice; RBPMS density was 1224 cells/mm2 for CD1 and 1147.1 cells/mm2 for C57BL/6J mice. At day 14 of culture, B3T density decreased to 695.19 cells/mm2 for CD1 and 532.52 cells/mm2 for C57BL/6J mice; RBPMS density was 747.76 cells/mm2 for CD1 and 528.19 cells/mm2 for C57BL/6J mice. By two-way ANOVA, there was a statistically significant association between RGC survival and time (p<0.001), but not RGC survival and mouse strain (p>0.05).
Conclusions :
The loss of RGCs over time that occurs in cultured organotypic retinal explants following axotomy is similar between the CD1 and C57BL/6J strains. Previously identified differences in RGC survival among these strains due to experimental ocular hypertension may indicate that strain differences are related to ocular response to intraocular pressure changes rather than intrinsic RGC susceptibility to death.
This is a 2020 ARVO Annual Meeting abstract.