Purpose:
Olfactory ensheathing cells (OEC) promote neural repair in spinal cord lesions. We previously demonstrated that OEC transplanted into rat eyes associate with retinal ganglion cell (RGC) axons and optic nerve. Here we investigate the effects of OEC on RGC in co-culture.
Methods:
Three different OEC/RGC co-culture models: primary rat OEC with 1) RGC-5 cell line, 2) primary rat RGC, 3) retinal explants, in different matrix environments (on glass, in and on Matrigel/collagen matrices). Immunohistochemistry. Epifluorescence and confocal microscopy.
Results:
1) OEC form localised cell-cell contacts with the cell body and extensions of RGC-5 cells, both in two- and three-dimensional culture conditions. 2) In co-culture with primary RGC, OEC extensions form localised contacts with RGC processes (top left figure; red: RGC, green: OEC). 3) OEC cluster around retinal explants embedded in Matrigel and form arborizing structures (top right figure). OEC (bottom left figure; green) promote outgrowth of neurites (red) from retinal explant (blue). In the absence of OEC, no outgrowth is observed. High-resolution reconstruction of confocal z-stack (bottom right) demonstrates how RGC neurites (red) extend along scaffolds formed by OEC (green).
Conclusions:
OEC exert a neurotrophic effect on primary RGC and the RGC-5 cell line in culture and promote neurite outgrowth. Transplantation studies will investigate whether these effects may protect RGC axons in vivo and promote optic nerve rescue and regeneration.
Keywords: retina: proximal (bipolar, amacrine, and ganglion cells) • neuroprotection • regeneration