Three-dimensional imaging of developing photoreceptors transplanted in a mouse model of CEP290-Leber congenital amaurosis (LCA)

Abstract

Purpose: To investigate the maturation, migration and integration of transplanted photoreceptors in rd16/Nrl-/- mouse retina using three-dimensional imaging reconstruction.

Methods: Immature photoreceptors from postnatal day 5 retina of Nrl-GFP mice were dissociated and injected into the sub-retinal space of rd16/Nrl-/- mice, a CEP290 mutation model of Leber congenital amaurosis (LCA). Retinas were sectioned after 1 month, stained and scanned for serial confocal imaging. Three-dimensional structure was reconstructed.

Results: Transplanted photoreceptors developed outer segments with polarization toward the retinal pigment epithelial layer. During cellular migration, defects of tight junctions at the outer limiting membrane created the passage for transplanted cell bodies or processes. After reaching the outer nuclear layer, transplanted photoreceptors developed synapses, interacting with host bipolar cells in three different patterns. Typically, one synapse was derived from one photoreceptor interacting to one bipolar cell. At times, we observed two synapses derived from one inner segment or two inner segments from one photoreceptor.

Conclusions: Three-dimensional imaging technique was applied to photoreceptor transplantation, overcoming the limitations of conventional two-dimensional imaging. This allows better evaluation of structural changes in donor cells and host tissues. Our studies are expected to contribute to broader understanding of cell-based strategies for photoreceptor replacement in mouse models of human retinal degenerative diseases.

Keywords: 648 photoreceptors • 741 transplantation • 494 degenerations/dystrophies