Neural differentiation of mouse embryonic stem cells grown in monolayer.

To drive neural differentiation of mouse embryonic stem (ES) cells, various culture protocols have been previously developed that all require the formation of embryoid bodies, usually combined with a treatment by all-trans retinoic acid (aRA). Here, we investigated whether or not neural differentiation can also occur in a simplified monolayer culture. Mouse ES cells were plated in serum-containing DMEM media with and without aRA and grown under these conditions for 2 days. Then, the cells were transferred to fresh serum-containing DMEM media and/or to serum-free DMEM/F12 media supplemented with a mixture of insulin, transferrin, selenium, and fibronectin (ITSF) for further culture. The changes in cell morphology and in the expression of selected molecular markers were monitored. Generally, in contrast to all the others, the protocol consisting of a 2-day culture in serum-containing DMEM followed by continuous exposure to the ITSF supplement in DMEM/F12 drove a vast majority of ES cells to generate phenotypic signs of neural lineage. Altogether, neural differentiation can be achieved in vitro without the step involving the formation of embryoid bodies as well as the treatment by aRA.