Abstract
Purpose:
Human pluripotent stem cells can be differentiated to yield all of the major cell types of the retina, with important implications for studies of retinogenesis as well as degenerative disorders affecting the retina. However, the precise mechanisms underlying the specification of certain retinal cell types over others has been largely ignored. Thus, efforts were undertaken to elucidate signaling pathways responsible for the directed differentiation of major retinal cell types.
Methods:
Human pluripotent stem cells were differentiated to a highly enriched retinal progenitor cell population following previously established protocols. The ability to influence the differentiation of these retinal progenitor cells was tested through the activation and inhibition of classical signaling pathways, and the effect of these signaling factors on retinal cell fate determination was assessed by immunocytochemistry and qRT-PCR. Differences in cell proliferation and differentiation toward specific retinal cell types was then assessed and quantified, and significant differences between treatment conditions determined.
Results:
Highly enriched populations of retinal progenitor cells could be derived from human pluripotent stem cells within a total of 30 days of differentiation, expressing progenitor markers including CHX10. By default, these progenitor cells are capable of giving rise to all of the major cell types of the retina, with retinal ganglion cells and photoreceptors the most abundant cell types generated by a total of 70 days of differentiation. Activation and/or inhibition of classical signaling pathways, including Wnt and Hedgehog pathways, demonstrated the ability to alter the differentiation of retinal progenitor cells, biasing their differentiation toward specific retinal neurons.
Conclusions:
The ability to influence the differentiation of human pluripotent stem cell-derived retinal progenitor cells allows for the unique ability to study critical events of human retinogenesis, yielding enriched populations of retinal neurons. Such an ability also has profound implications for the study of retinal degenerative disorders such as glaucoma or age-related macular degeneration, as enriched populations of specific retinal cell types will likely be required for the development of therapeutic strategies to combat the degenerative processes associated with these diseases.