We previously demonstrated that mouse embryonic stem cell (mESC)-derived retinal epithelium self-forms an optic cup-like structure. In the developing retina, the dorsal and ventral sides differ in terms of local gene expression and morphological features. This aspect has not yet been shown in vitro. Here we demonstrate that mESC-derived retinal tissue spontaneously acquires polarity reminiscent of the dorsal-ventral (D-V) patterning of the embryonic retina. Tbx5 and Vax2 were expressed in a mutually exclusive manner, as seen in vivo. Three-dimensional morphometric analysis showed that the in vitro-formed optic cup often contains cleft structures resembling the embryonic optic fissure. To elucidate the mechanisms underlying the spontaneous D-V polarization of mESC-derived retina, we examined the effects of patterning factors, and found that endogenous BMP signaling plays a predominant role in the dorsal specification. Further analysis revealed canonical Wnt signaling that was spontaneously activated at the proximal region acted upstream of BMP signaling for the dorsal specification. These observations suggest that D-V polarity could be formed within the self-formed retinal neuroepithelium by intrinsic mechanisms involving the spatiotemporal regulation of canonical Wnt and BMP signals.
- Received December 28, 2015.
- Accepted September 1, 2016.