Abstract
Purpose: :
A number of reports have shown that it is possible to derive an array of retinal cell types from human embryonic stem cells (hESCs), including photoreceptor precursors and retinal pigmented epithelium. The key factors which promote the production of each cellular phenotype during retinal histogenesis in vivo are continually being revealed, however the efficiency of replicating this process in vitro from pluripotent cell types remains limited and requires extensive periods for cell differentiation. This work aims to optimise the generation of photoreceptor cells from human pluripotent stem cells in vitro.
Methods: :
We have developed an in vitro photoreceptor differentiation protocol, which enables the rapid and efficient derivation of enriched populations of photoreceptor precursors from hESCs using defined and stage-specific culture and growth factor conditions. This acts to promote ventral neural specification in differentiating cultures, followed by the retinal field and then photoreceptor fate. Our current work extends this by assessing the efficacy of our retinal induction protocol on additional human pluripotent cell lines.
Results: :
Initial work demonstrated this regime to be a successful approach in hESC cultures, where after 30 days of differentiation up to 30% of the population expressed the postmitotic photoreceptor marker CRX. Our recent results now demonstrate that the directed differentiation of induced pluripotent stem cells (iPSCs) under our regime generates expandable populations of retinal progenitors, which also give rise to photoreceptor precursors and cells which express mature photoreceptor markers including OPN1SW and RHODOPSIN, with a similar efficiency to hESCs.
Conclusions: :
Our results indicate that, in addition to hESCs, the directed differentiation of iPSCs can yield enriched populations of photoreceptor precursors. The optimisation of such protocols is key, not only for cell replacement strategies directed towards the treatment of various forms of blindness, but for the development of clinically relevant in vitro models of photoreceptor development and disease.
Keywords: differentiation • photoreceptors • age-related macular degeneration