Lentiviral gene replacement therapy of retinas in a mouse model for Usher syndrome type 1B

Abstract

One of the most disabling forms of retinal degeneration occurs in Usher syndrome, since it affects patients who already suffer from deafness. Mutations in the myosin VIIa gene (MYO7A) cause a major subtype of Usher syndrome, type 1B. Owing to the loss of function nature of Usher 1B and the relatively large size of MYO7A, we investigated a lentiviral-based gene replacement therapy in the retinas of MYO7A-null mice. Among the different promoters tested, a CMV-MYO7A chimeric promoter produced wild-type levels of MYO7A in cultured RPE cells and retinas in vivo. Efficacy of the lentiviral therapy was tested by using cell-based assays to analyze the correction of previously defined, MYO7A-null phenotypes in the mouse retina. In vitro, defects in phagosome digestion and melanosome motility were rescued in primary cultures of RPE cells. In vivo, the normal apical location of melanosomes in RPE cells was restored, and the abnormal accumulation of opsin in the photoreceptor connecting cilium was corrected. These results demonstrate that a lentiviral vector can accommodate a large cDNA, such as MYO7A, and mediate correction of important cellular functions in the retina, a major site affected in the Usher syndrome. Therefore, a lentiviral-mediated gene replacement strategy for Usher 1B therapy in the retina appears feasible.

CNTF-mediated protection of photoreceptors requires initial activation of the cytokine receptor gp130 in Müller glial cells

“…LV-hCNTF was constructed by inserting the cDNA of a secreted form of human CNTF with S166D and G167H substitutions (25) between the CMV promoter and IRES-GFP cassette. The production, titer determination, and subretinal injection of lentiviruses were performed as previously described (56). Lentiviral stocks with titers of 1 × 10 7 CFU/mL were used for in vivo subretinal injections, unless otherwise specified.…”

C1q enhances cone photoreceptor survival in a mouse model of autosomal recessive retinitis pigmentosa

“…[3][4][5] In addition, therapeutic modalities have been demonstrated for other genetic subtypes of RP and LCA in a growing number of animal models, both of recessive and dominant forms of disease. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Notwithstanding such progress, the genetic complexity of this group of diseases represents a formidable logistic and economic hurdle in developing viable methods of prevention. Given this caveat, parameters effecting photoreceptor survival that are independent of the primary genetic lesion are critically important to identify.…”

Gene Therapy of Inherited Retinopathies: A Long and Successful Road from Viral Vectors to Patients

“…Notably, PR transduction by LVs is inversely correlated to PR differentiation (Miyoshi et al, 1997;Bainbridge et al, 2001;Pang et al, 2006;Nicoud et al, 2007). Consistent with these observations, the SR delivery of LVs to the adult retina was effective in rodent models of IR caused by mutations in genes expressed in the RPE (Vollrath et al, 2001;Bemelmans et al, 2006), whereas perinatal (Takahashi et al, 1999;Hashimoto et al, 2007;Kong et al, 2008) or in utero (Williams et al, 2006) deliveries were required to treat rodent models that bear mutations in genes expressed in PRs. These preclinical studies served as the basis to test the nonprimate equine infectious anemia virus in ongoing clinical trials to treat exudative age-related macular degeneration (NCT01301443), STGD (NCT01367444), and USH type IB (USH1B) (NCT01505062).…”