Retinal Transplantation, Stem Cell and Gene Therapy in Retinitis Pigmentosa

Retinitis pigmentosa is the most common hereditary retinal dystrophy which has marked clinical and genetic heterogeneity. Common presentations among this disorder include night blindness, tunnel vision, and subsequent progression to complete blindness respectively. The known causative disease genes have a variety of developmental and functional roles, with mutations in more than 120 genes shown to be responsible for the phenotypes. In addition, mutations within the same gene have been shown to cause different disease phenotypes, even within the same family, highlighting further levels of complexity. In recent years significant advancements have been made in the understanding of the pathogenesis of the disease and stem cell and gene replacement treatments have been proposed as potentially efficacious therapies. This review summarizes the clinical development of retinal stem cell and gene therapy.

Retinitis pigmentosa associated with systemic light chain amyloidosis (AL amyloidosis)

Retinitis pigmentosa (RP) or hereditary retinal dystrophy is a rare disease that can be isolated (non-syndromic RP) or associated with other systemic signs (syndromic RP). Kidney damage is exceptionally reported in patients with RP, particularly in syndromic forms. Association with renal amyloidosis remains unusual with only one reported case of RP and hereditary gelsolin amyloidosis due to a G654A gelsolin mutation defining the new syndrome of Ardalan-Shoja-Kiuru. Apart from this publication, no case associating RP and AL amyloidosis has been found. We report an original case of renal damage revealing kappa-type systemic light chains amyloidosis (AL amyloidosis) in 35-year-old man with sporadic RP. Our observation is, to our knowledge, the first to report this association.

Diffuse Pigmented Lesions in the Outer Retina: An Unusual Fundus Appearance

Purpose: This report describes and provides a differential diagnosis for a patient with unusual bilateral retinal pigmented lesions. Methods: A 40-year-old woman was found to have multiple flat, gray lesions scattered across her fundi, becoming larger and more confluent toward the periphery. There were small drusenlike deposits in her foveae. The hyperpigmented lesions demonstrated hypoautofluorescence with thickening of the retinal pigment epithelium and disruption of the overlying layers on optical coherence tomography (OCT). Full-field electroretinography revealed generalized reduced a- and b-wave amplitudes. Results: Chest x-ray, breast ultrasound, mammography, and pelvic ultrasound findings were negative for malignant etiologic factors. Panel testing results for hereditary retinal dystrophy were negative. Conclusions: Although the clinical and OCT appearance of the lesions is similar to congenital grouped pigmentation, the symmetric and bilateral nature of ocular findings coupled with electroretinographic changes suggest a possible retinal dystrophy. This case adds to the phenotypic diversity of pigmented fundus lesions.

Choroidal Neovascularization in Hereditary Retinal Dystrophy

Hereditary retinal dystrophies have various inheritance patterns and varying degrees of impact on vision. Although uncommon, the retinal dystrophy may progress significantly over time and some patients might develop visual impairment due to atrophic changes or the development of a choroidal neovascular membrane at the macula. The purpose of this review is to outline the main retinal dystrophies that are associated with choroidal neovascularization.

Retinoschisin is linked to retinal Na/K-ATPase signaling and localization

Mutations in the RS1 gene cause X-linked juvenile retinoschisis (XLRS), a hereditary retinal dystrophy. We recently showed that retinoschisin, the protein encoded by RS1, regulates ERK signaling and apoptosis in retinal cells. In this study, we explored an influence of retinoschisin on the functionality of the Na/K-ATPase, its interaction partner at retinal plasma membranes. We show that retinoschisin binding requires the β2-subunit of the Na/K-ATPase, whereas the α-subunit is exchangeable. Our investigations revealed no effect of retinoschisin on Na/K-ATPase–mediated ATP hydrolysis and ion transport. However, we identified an influence of retinoschisin on Na/K-ATPase–regulated signaling cascades and Na/K-ATPase localization. In addition to the known ERK deactivation, retinoschisin treatment of retinoschisin-deficient (Rs1h-/Y) murine retinal explants decreased activation of Src, an initial transmitter in Na/K-ATPase signal transduction, and of Ca2+signaling marker Camk2. Immunohistochemistry on murine retinae revealed an overlap of the retinoschisin–Na/K-ATPase complex with proteins involved in Na/K-ATPase signaling, such as caveolin, phospholipase C, Src, and the IP3 receptor. Finally, retinoschisin treatment altered Na/K-ATPase localization in photoreceptors of Rs1h-/Yretinae. Taken together, our results suggest a regulatory effect of retinoschisin on Na/K-ATPase signaling and localization, whereas Na/K-ATPase-dysregulation caused by retinoschisin deficiency could represent an initial step in XLRS pathogenesis.