Hi ev-wee-body. I have just had a tawk wiff a Siwwy Wabbit about Retinal Pigment Epithelium ( didn't think I could pwonounce that, huh?)
RPE is a Dark Pigment that filters out light from the retina.
Wead this from Wikipaedia
Retinal pigment epithelium
RPE was known in the 18th and 19th centuries as the pigmentum nigrum, referring to the observation that the RPE is dark (black in many animals, brown in humans); and as the tapetum nigrum.
The RPE shields the retina from excess incoming light. It supplies omega-3 fatty acids and glucose, the former for building photoreceptive membranes, the latter for energy. Retinal is supplied by the visual vitamin A cycle. Water is removed from the retinal side to the choroid side, at a rate of 1.4-11 microliters per square centimeter per hour. It maintains balance of pH, and routinely phagocytoses the oldest outer segment discs of the photoreceptors. It has a self-contained immune system, which is connected with the immune system proper to either shut down interactions when healthy, and when there is disease, it teams up with the main immune controls. Finally, it secretes substances to help build and sustain the choroid and retina.
Bugs tewws me you can get the same wesults from eating cawwots.
In macular degeneration, rods&cones are gone. RPE is not going to replace them.
Anyone know why we should stay invested in this?
ellmerrfudd, the wabbit Busgs miswinformed you when he swed:
"In macular degeneration, rods&cones are gone."
Some of the rods and cones are not necessarily gone but are still struggling along though not really functioning. Some of them, apparently in some cases, can revive. Plus, beyond that happening, as you, yourself, point out, the RPE shields the retina from incoming light. That is a function that does, by itself, improve vision. Thus, you can see (pardon the expression) that merely rebuilding the RPE layer can, alone, help improve vision to some extent, as well.
Now get back out there and let that wabbit get a gander at your big, powerful shotgun, west he tell you any more wies.
Per ACTC website, also reiterated in your quoted 'wikipedia reference'
Atrophic (dry) AMD, the most prevalent form accounting for 90% of all cases, is characterized by the degeneration of the retinal pigment epithelium (RPE) and the neuroretina. End stage AMD occurs when the RPE completely degenerates, which further induces secondary cell death of macular rod and cones.
The RPE cells are a necessary scaffold to maintain the integrity and function of the neuroretina (rods and cones). Without the RPE cells, the rods and cones do not survive/ RPE cells are like the nursemaids to the rods.cones.
Restoring RPE cells may therefore prevent progression of AMD and maybe even help restore functional status of the neuroretina. But you may be right about those already with severe AMD and loss of rod.cone cells. These may not be reversible.