Today, cell therapy is being considered for a large number of retinal and optic nerve diseases that have resulted in cell loss that is considered irreversible. These include glaucoma and the need to regenerate ganglion cells, as well as the loss of photoreceptors and pigment epithelium in retinopathy pigmentosa and age-related macular degeneration.
In these conditions, the aim is to replace photoreceptor and pigment epithelium cells. Endogenous repair had been envisaged for some fifteen years, based on the demonstration, first in fish and chicken, of proliferation starting from the marginal zone, and preliminary work in 2000 raising hopes that these approaches could eventually be applied to mammalian retinas. However, this strategy has yet to confirm its promise. Another approach aims to use Muller's glial cells to regenerate retinal cells, an approach which has proved valid in fish and chicken, but has yet to demonstrate its relevance in mammals.
Today, the repair or replacement of photoreceptor cells and pigment epithelium relies mainly on strategies involving the administration of exogenous cells. Two main sources are currently being considered: embryonic stem cells and induced pluripotent reprogrammed cells.
