The hereditary or acquired retinal degenerations are the leading causes of legal blindness in the industrialized world. All forms of degenerative retina have a common pathophysiology that leads to cell death. The photoreceptor cell degeneration starts from the photoreceptor outer segment and then spread to the inner segment. Replacing the cells dead could be, in theory, able to restore vision.
Another way to slow or stop the progression of retinal degeneration may be to implant the retinal pigmented epithelium cells. These cells reside in close contact with the outer segments of the photoreceptors. The retinal pigment epithelial function is to regulate the normal turnover of outer segments of the photoreceptors.
First success of transplantation of retinal cells
It has recently been demonstrated in the laboratory that fetal photoreceptor cells can be successfully implanted in the adult retina. These photoreceptors have been shown to make synaptic connections and improve visual functions in adult mice in which the retina had been previously damaged. The studies have emerged, as interesting knowledge, that makes possible the function and viability of the photoreceptors only if they have been implanted with the right orientation (the outer segments facing the retinal pigment epithelium and the inner segments facing the bipolar cells). The main challenge is actually related to the immune response to the cells of the retinal pigment epithelium.
These researches are conducted in various Centers across the world, such as the Moorfields Eye Hospital in London, the Univesrity College London, the University of Washington, the University of Louisville, Columbia University, the Karolinska Institute in Stockholm Eye, etc.