Update on the genetics of macular dystrophies

Engrafted Neural Progenitor Cells Express a Tissue-Restricted Reporter Gene Associated with Differentiated Retinal Photoreceptor Cells

Neural progenitor cells (NPCs) have shown ability to repair injured CNS, and might provide precursors to retinal neurons. NPCs were isolated from the brains of 14 day murine embryos of transgenic mice that express β-galactosidase (β-gal) on the arrestin promoter, which specifically directs expression to retinal photoreceptor cells. NPCs were transferred to adult, syngeneic mice via inoculation into the anterior chamber of the eye, the peritoneal cavity, or the brain. At 14 weeks postgrafting, tissues were collected and examined to determine if differentiated NPC progeny were present in retina based on histochemical detection of β-gal. Four of six anterior chamber-inoculated recipients showed Bluo-gal-stained cells in retina, indicating the presence of transferred NPCs or their progeny. Because the progenitor cells do not express β-gal, positive staining indicates differentiation leading to activation of the arrestin promoter. Two recipients inoculated by the intraperitoneal route also exhibited Bluo-gal staining in retina. The NPCs did not express β-gal if inoculated into brain, but survived and dispersed. Most recipients, regardless of inoculation route, were PCR positive for β-gal DNA in extraocular tissues, but no Bluo-gal staining was found outside of the retina. Injury to the retina promoted, but was not required, for progenitor cell engraftment. β-Gal-positive cells were concentrated in the outer layers of the retina. In summary, a reporter gene specifically expressed in differentiated retinal photoreceptor cells due to the activity of the arrestin promoter was expressed in recipient mouse retina following transfer of NPCs prepared from the β-gal transgenic mice. The presence of β-gal DNA, but not Bluo-gal staining, in spleen and other tissues revealed that the cells also migrated elsewhere and took up residence in other organs, but did not undergo differentiation that led to β-gal expression.

Gene therapy for retinal disease

Gene therapy strategies for the treatment of inherited retinal diseases have made major advances in recent years. This review focuses on adeno-associated viral (AAV) vector approaches to treat retinal degeneration and, thus, prevent or delay the onset of blindness. Data from human clinical trials of gene therapy for retinal disease show encouraging signs of safety and efficacy from AAV vectors. Recent progress in enhancing cell-specific targeting and transduction efficiency of the various retinal layers plus the use of AAV-delivered growth factors to augment the therapeutic effect and limit cell death suggest even greater success in future human trials is possible.

Did Edgar Degas Have an Inherited Retinal Degeneration?

OBJECTIVE

Retrospective analysis of the famous painter Edgar Degas' eye disease.

DESIGN

A historical review and analysis based on Degas' paintings and letters exchanged between the painter and his friends and family members, as well as on the chronicles of his associates. DeGas-Musson family papers at the Howard-Tilton Library of Tulane University are also reviewed.

RESULTS

Degas had an eye disease that was first noticed in 1870 and that progressed throughout his life. He suffered from progressive bilateral central visual loss and light sensitivity which was most acutely recognized while he was visiting his mother's side of the family in New Orleans where he could not paint outside because of the bright sun. Edgar's maternal first cousin, Estelle Musson, also suffered gradual bilateral visual loss, and was also known to have light sensitivity early in her life. Estelle became totally blind in her early 30s. Both Edgar and Estelle were otherwise healthy and lived long lives.

CONCLUSION

It is likely that Edgar Degas and his cousin Estelle Musson had a hereditary retinal degeneration primarily affecting their central vision. Degas' retinal disease undoubtedly affected his life and his art but did not prevent him from being one of the most admired painters of all times.