Induction of neuroepithelial stem cells from mouse embryonic stem cells treated with retinoic acid.

Embryonic stem cells can be applicable for neural cell transplantation. Here we differentiated mouse embryonic stem cells into neuroepithelial stem cells with tertiary structures in floating cell aggregates. We first cultured ES cells with 0.5μM retinoic acid to induce neural differentiation. RT-PCR and immunostainning studies showed most of the RA treated cells at day 8 differentiated into Nestin expressing neural stem cells without tertiary structures. About 80% of the treated cells become panNCAM+ neural cells by FACS analysis. The findings indicated the RA treatment successfully induced neural stem cells from ES cells. The RA treated cells at day 8 were recovered and were cultured in FCS depleted medium consisted of DMEM/F 12, N 2 supplement and fibronectin on nontreated dishes for additional 6-8 days. The cell aggregates contained a cluster of pseudostratified Nestin+ neuroepithelial stem cells surrounded by the Masson staining+ basement membrane, whereas mature neural cells located outside of the structures. Thus, we have generated neuroepithelial stem cells from ES cells. These findings may get access to induce purposive and transplantable neurons for several diseases and get a cue to resolve inaccessible problems of neurogenesis.