Abstract
Purpose: :
To compare the potential of in vitro expanded retinal stem cells (RSCs) versus primary retinal cells to integrate into the outer nuclear layer (ONL) and differentiate into photoreceptors following transplantation into the retina of adult mice.
Methods: :
Expandable RSCs were generated by cultivating cell suspensions isolated from the retina of enhanced green fluorescence protein (EGFP) positive mice at postnatal (P) 0/1 in defined medium containing epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF-2). Primary retinal cells were harvested from developing EGFP-positive retinas at P4. Expanded RSCs or primary retinal cells were transplanted into the subretinal space of adult mice. Experimental retinas were fixed after 1-10 weeks and analysed for integrated and differentiated donor cells using fluorescence microscopy.
Results: :
RSCs were expanded for up to 30 passages and the majority of cells expressed markers specific for undifferentiated, proliferating neural cells. Following differentiation in vitro cells were immuno-positive for neuronal or glial specific markers. Although transplanted RSCs survived for up to 10 weeks in the host tissue and differentiated into neuronal and glial cell-types, integration into the ONL was rare and differentiation into photoreceptors was not observed. In contrast, a subfraction of transplanted primary retinal cells integrated into the ONL, developed a photoreceptor-like morphology and expressed photoreceptor-specific markers.
Keywords: transplantation • retinal culture • differentiation