Abstract
Purpose :
The ability to generate new neurons through life has been widely described in the retina of fish, birds, and amphibians, but it has never been demonstrated in mammals. In this work, we aimed to study and characterize the presence of adult neurogenesis in the peripheral human retina.
Methods :
Four human retinas from donors of 10, 20, 30 and 40 years old were fixed, dissected and subjected to immunohistochemistry protocols in retinal cryosections and wholemounts. Antibodies against adult retinal cells (recoverin, PKC, parvalbumin, synaptophysin, etc), retinal stem cells (Pax6, Chx10, Sox2, Rx) and proliferation markers (Ki67) were used and images were taken using confocal microscopy.
Results :
Ki67 positive cells were identified in the retina of all four studied subjects. Many of them also co-expressed some progenitor cell markers like Pax6, Chx10 or Sox2, indicating that they are proliferating neural cells. In addition, cells in the peripheral non-laminated retina expressed adult retinal markers but displayed an immature and undifferentiated morphology, that became gradually more mature towards the center. In the same region, many cells co-expressed retinal progenitor markers (i. e. Pax6+Chx10+Rx), while these were differentially expressed by distinct cell populations in the central retina: Pax6 in amacrine cells, Chx10 in bipolar cells and Rx in photoreceptors.
Conclusions :
The existence of a population of cells that proliferate in vivo and coexpress progenitor markers, together with the existence of a gradual morphological maturation process, suggest that this region may be a niche of neural stem cells and that adult neurogenesis occurs in the human retina. The characterization of this neurogenesis process would be of special interest for the development of new treatments to stimulate retinal regeneration in neurodegenerative diseases.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.