Transcriptional factors involved in photoreceptor differentiation.

Regenerative medicine constitutes a potentially promising therapy for blind people suffering from retinal degenerative diseases such as retinitis pigmentosa and age-related macular degeneration. For the realization of retinal regeneration, it is necessary to establish 1) a method to produce functional photoreceptor cells in vitro and 2) successful transplantation of the donor cells to connect their axons to the recipient secondary neurons so that they can function properly. The results of experimental transplantation of human retinal photoreceptor cells from cadaveric eyes or of fetal retinal cells into the retina of RP patients have not been satisfactory, but encouraging enough to indicate that the transplantation of developing retinal cells may have beneficial results. Recently, attempts have been made to generate photoreceptor-like cells from stem cells, but it remains to be seen whether they are in fact photoreceptor cells. It is therefore important to fully understand the mechanisms involved in the development of these cells, and to characterize them not only by transcriptome but also by functional analysis.