Abstract
Purpose: :
Adult human Müller stem cells constitute a potential source of cells for use in cell-based therapies to treat retinal degenerative diseases. This study investigated the anatomical and functional effects of photoreceptors derived from Müller stem cells in vitro upon transplantation into a rodent model of photoreceptor degeneration.
Methods: :
Human Müller stem cells were differentiated into an enriched photoreceptor cell population upon culture on extracellular matrix proteins in the presence of various growth factors. Enriched populations of cells expressing photoreceptor markers were transplanted into the subretinal space of three week old P23-H rhodopsin knockout rats (n=5). These animals undergo a slow photoreceptor loss due to a rhodopsin mutation similar to that seen in human retinitis pigmentosa. Unoperated eyes (n=11), transplantation with untreated Müller stem cells (n=6) and transplantation with human tenons fibroblasts (n=5) were used as controls. Electroretinography to assess photoreceptor function and immunohistochemistry with confocal microscopy to examine localisation of the transplanted cells were performed at 3 weeks following transplantation. A wave amplitudes were compared by 2 way ANOVA with Bonferroni post-testing.
Results: :
Animals transplanted with enriched populations of photoreceptor cells showed a significantly greater A-wave amplitude when compared to animals transplanted with undifferentiated Müller stem cells (p<0.01) or unoperated eyes (p<0.001). Confocal microscopy analysis of immunostained retinal sections showed that grafted photoreceptors had migrated and integrated into the host outer nuclear layer where they expressed markers of mature photoreceptors including rhodopsin.
Conclusions: :
These observations strongly suggest that Müller stem cells isolated from the adult human retina have the ability to differentiate into photoreceptors with the potential to restore photoreceptor function in vivo. Taking into consideration that Müller stem cells can be easily sourced from the adult human retina, these cells may constitute a valuable tool for the design of cell based therapies to treat human retinal degenerative conditions affecting photoreceptors.
Keywords: transplantation • Muller cells • photoreceptors: visual performance