Characterization of ES Cell-derived Cortical Radial Precursor Differentiation

Murine neural precursor cells have been a well studied model for neural cell fate determination and stem cell function both in vivo and in primary culture. However, factors such as cell number, the presence of multiple cell populations and of niche intrinsic factors made it difficult to dissect the mechanisms regulating cortical development. To overcome this issue, we have developed a culture system where mouse embryonic stem cells (ES) are differentiated to cortical radial precursors through retinoic acid treatment of embryoid bodies. One day after plating in neural differentiation conditions, ~70% of cells in the culture are cortical radial precursors (RPs) as indicated by the definitive cortical marker Emx1, and over 8 days in culture, these RPs differentiate to pyramidal glutamatergic neurons of the cortex mimicking in vivo development. Astrocyte differentiation can be observed later as the culture progresses, which again mimics the typical timed genesis of cells in the cortex. The stem cell properties and cell fate of these RPs can be manipulated with growth factors in culture as they are in vivo. In particular, FGF2 promotes proliferation and survival, while ciliary neurotrophic factor (CNTF) induces precocious astrocyte formation. Thus, our ES-derived cortical RP cultures can serve as an alternate and complementary in vitro model to examine neural precursor biology during early development.MAS