Retinitis pigmentosa is an inherited form of slow degenerative blindness, in which essential retinal cells accumulate defects due to one or more mutated genes. Generating replacement, properly formed retinal cells to treat this condition is one of the longer-running initiatives in the stem cell research community; if you look back in the Longevity Meme archives, you'll see it mentioned in 2004, for example. It appears that researchers have now succeeded in restoring sight in mice:
An international research team led by Columbia University Medical Center successfully used mouse embryonic stem cells to replace diseased retinal cells and restore sight in a mouse model of retinitis pigmentosa.
In Dr. Tsang's study, sight was restored in one-fourth of the mice that received the stem cells. However, complications of benign tumors and retinal detachments were seen in some of the mice, so Dr. Tsang and colleagues will optimize techniques to decrease the incidence of these complications in human embryonic stem cells before testing in human patients can begin. "Once the complication issues are addressed, we believe this technique could become a new therapeutic approach for not only retinitis pigmentosa, but age-related macular degeneration, Stargardt disease, and other forms of retinal disease that also feature loss of retinal cells," said Dr. Tsang.
As noted, a viable source of replacement retinal cells has much broader application than just retinitis pigmentosa. In the context of the wider picture, it is heartening to see steady progress being made towards the ultimate end goal of a general repair kit for human beings - the biotechnological capabilities and medical community capable of replacing any damaged or diseased tissue safely and at reasonable cost. While the years seem to flicker by for those of us keeping an eye on this field of research, significant progress is taking place.
As a parting note, you might take a look at the actual paper, if you're interested. The website of the publishing journal, Transplantation, is well worth browsing if you'd like to get a sense of what the tissue engineering community is presently working on. It is a very energetic field, and what filters through to the popular science press is a fraction of what's going on in the labs.
Wang, Nan-Kai, Tosi, Joaquin, Kasanuki, Jennifer Mie, Chou, Chai Lin, Kong, Jian, Parmalee, Nancy, Wert, Katherine J., Allikmets, Rando, Lai, Chi-Chun, Chien, Chung-Liang, Nagasaki, Takayuki, Lin, Chyuan-Sheng, & Tsang, Stephen H. (2010). Transplantation of Reprogrammed Embryonic Stem Cells Improves Visual Function in a Mouse Model for Retinitis Pigmentosa Transplantation, 89 (5) : 10.1097/TP.0b013e3181d45a61