Abstract
Purpose: :
To determine the capacity of different induced pluripotent stem (iPS) cell lines to generate definitive retinal cell types in a developmentally appropriate manner. Human embryonic stem (hES) cells can be directed towards a primitive retinal fate through an anterior neuroepithelial pathway. However, it remains to be determined if iPS cells can acquire retinal phenotypes in a similar fashion.
Methods: :
Human iPS cells were differentiated towards a retinal lineage using a protocol that was previously established for hES cells. Initially, several lines of iPS cells were tested for their ability to generate primitive cell types of the developing eye field. iPS-derived cell populations were tested by quantitative and non-quantitative PCR, ICC and FACS analysis. Those lines that generated the highest proportion of cells with an eye field phenotype (Pax6+/Rx+) were further differentiated to assess their ability to generate definitive neural retinal progenitors and RPE.
Results: :
Upon differentiation, iPS cell lines displayed varying potentials for generating primitive eye field phenotypes. Among the more efficient lines, eye field transcription factors such as Rx, Otx2, Six3, and Lhx2 were expressed within the first 10 days of differentiation. Further maturation led to the expression of characteristics indicative of neural retinal progenitor cells or RPE. Cells resembling the RPE first appeared by 30 days of differentiation. Prolonged differentiation also yielded cell populations that expressed Mitf and Chx10, indicative of the optic cup stage of development.
Conclusions: :
Human iPS cells have the ability to approximate the sequence and timing of events that occurs during early human retinogenesis. However, the capacity to generate these phenotypes varies between iPS cell lines. Even so, the results presented here underscore the potential to produce disease- and patient-specific retinal cell types for in vitro and in vivo investigation.
Keywords: retinal development • differentiation • development