Retinal degeneration represents a group of blinding diseases that are increasingly impacting the health and well-being of affected patients. More than 150 genes are known and more being discovered causing retinal disorders upon mutation. About 45 million people are blind worldwide (Europe 10 million, Germany 0.1 million). It is estimated that by 2020, over 76 million (www.vision2020.org) will suffer from vision loss or blindness due to age-related macular degen eration (AMD), the most common cause of retinal degeneration in the elderly. In Germany 1 million patients already suffer from high vision loss and about 2 million people have been diagnosed with AMD (1:10 above age 60). AMD is anticipated to be epidemic by increasing 6-fold until 2025 (NIH, USA; BMBF Roadmap 2007). Although loss of photoreceptors is the major reason for vision loss, in other retinal diseases, like glaucoma (ganglion cell loss), damage of other neurons is causative. Development of various therapies targeting prevention, progression and repair is thus pressing and will not only contribute to maintain mobility, life quality and indepen dence, but also to reduce the social annual cost due to vision loss (>500 million € in Germany today).
Frontiers of retinal research: Fortunately recent research provided remarkable proof-of-principle evidence on neuronal regeneration, retinal tissue engineering as well as neuronal replacement by cell transplantation in the retina opening up a new field of basic science of regenerative medicine. In the retina of adult mice a limited amount of neuronal regeneration by endogenous de-novo neurogenesis could be stimulated after neuron loss in vivo. Further, protocols for deriving retinal progenitor from human stem cell lines have been developed and derived photoreceptors integrate into adult mouse retina after transplantation.
