Cell-based Therapy In A Mouse Model Of Leber Congenital Amaurosis

Abstract

Purpose: : Mutations in CEP290 are responsible for almost 25% of Leber congenital amaurosis (LCA). We have recently described the rd16/Nrl^-/- mouse model that exhibits similarity to patients with CEP290-LCA (Cideciyan et al. Hum Mol Genet. 20:1411-1423, 2011). The goal of this project is to investigate the therapeutic effect of retinal cells transplanted into the degenerating retina from this cone-only mouse model.

Methods: : Cells were dissociated from whole retina of the wild-type Nrl-GFP mice at postnatal day 3-5, and then transplanted into the cone-only degenerating retina of rd16/Nrl^-/- mice at P14 by subretinal injection. Fundus photography, histology, immunohistochemistry and electroretinogram (ERG) were used for assessing the morphology and retinal function.

Results: : White dots on the retina and pseudorosettes (whorls) on the histology were characteristics of cones in rd16/Nrl^-/- mice. They appeared at 2 weeks of age and reached the peak at 1 month. However, these cones underwent degeneration, as evidenced by retinal hyperpigmentation since 1.5 months of age followed by vascular attenuation. ERG recordings showed progressively decreasing responses (25% at 2 months and 15% at 3 months), compared with those at 1 month. When the transplantation was done at P14, donor rod cells (as marked by GFP expression) 2 weeks later showed morphological changes, including outer segment development (or neurite outgrowth) and integration. The donor cells survived at 2 months after transplantation. ERG recordings showed improvement of the scotopic a-wave amplitude.

Conclusions: : Retinal cell replacement may be helpful for preserving the retinal function. Meticulous procedures are mandatory for a successful transplantation. The rd16/Nrl^-/- mouse retina can serve as a model for understanding the preservation of cones in foveal region of patients with CEP290 (or other) mutations and for optimizing the protocols for cell-based therapy.

Keywords: transplantation • retinal degenerations: hereditary • electroretinography: non-clinical