Abstract
Purpose: :
Cell transplantation is a potentially attractive approach for restoration of damaged retina. A recent study used GFP-tagged and committed rod photoreceptor precursors (Akimoto et al. 2006) from immature mouse retinas for transplantation in mouse models of retinal degeneration (MacLaren et al. 2006). This study demonstrated the feasibility and potential of retinal cell replacement therapy. However, in order for retinal cell-based therapies to succeed, it is necessary to find a robust source of appropriately committed human cells for transplantation.
Methods: :
We have selected four different lines from NIH-maintained human embryonic stem cells (HESCs) to examine their differentiation into retinal neurons and ability to integrate into retina. We are also utilizing Otx2, Rx and Nrl bacterial artificial chromosome (BAC)-derived fluorescent reporters to monitor the retinal differentiation of HESCs as well as to achieve efficient selection of retinal progenitors for transplantation using fluorescent-activated cell sorting. The expression profiles of those cells will be characterized to isolate surface markers for further non-fluorescence-mediated magnetic sorting of retinal cells from differentiating HESC cultures.
Results: :
We achieved successful efficient neuralization of all four HESC lines using noggin in adherent monolayer culture, and, following the formation of neural rosettes, induced them to retinal fate with Dkk-1 and IGF-1 (Lamba et al., 2006) and transplanted into subretinal space. The surviving grafts display early neuronal profile, low mitotic index and abundance of migrating cells at 3 weeks postgrafting time. We will present the results of long term graft monitoring, which may better reveal the potential of such cells to integrate into retina and become postmitotic photoreceptors.
Conclusions: :
The data is expected to uncover the variability of different HESC lines to be converted to photoreceptor precursors and integrate into retina.
Keywords: retina • retinal development • transplantation