Abstract
Purpose :
Cell transplantation into the mouse retina has been shown to result in the transfer of cytoplasmic material between donor and host photoreceptors. Here we assessed whether material transfer can also occur between endogenous photoreceptors in a horizontal fashion under normal physiological conditions.
Methods :
Retinal wholemounts and sections of cone-specific GFP reporter mice, wild-type mice and primary human retinas were used for immunohistochemistry using cone- (cone arrestin; PNA) and rod- (Nr2e3) specific antibodies. GFP signals and immunostainings were imaged using structured illumination-, spinning disc-, confocal- or stochastic optical reconstruction (STORM) microscopy. By computational estimation the distance between cone axonal processes and rod cell bodies was assessed.
Results :
In retinas of cone-GFP mice, approximately 2000 GFP+ cells/retina with rod-specific morphology, location and marker expression were detected in close proximity to GFP+ cone axons. Quantification of the distance between the cell bodies of GFP+ rods and GFP+ cone axons revealed an average distance of approximately 1.1μm, which is significantly lower than the distance that would be expected given a random distribution of rods in relation to cones (ca. 4.24 µm). Indications for thin protrusions formed between the cell body of GFP+ rods and GFP+ cone axons were observed by spinning disk microscopy within retinal wholemounts. The presence of GFP+ nanotube-like connections between rods and cones could be confirmed on retinal sections by STORM super resolution microscopy. Expression of cone-specific markers could be further observed in distinct rod cell-bodies in wild-type mice and human retinal sections.
Conclusions :
Using cone-specific reporter mice and super-resolution microscopy, we identified previously undescribed direct cell-cell connections presumably mediating the horizontal transfer of cytoplasmic material between rod and cone photoreceptors. The extent of cellular material exchange and its biological significance remains to be explored in further studies.
This is a 2021 ARVO Annual Meeting abstract.