Neuronal induction and regional identity by co-culture of adherent human embryonic stem cells with chicken notochords and somites.

The role of somites and notochords in neuroectoderm differentiation from the embryonic ectoderm and its subsequent patterning into regional compartments along rostro-caudal and dorso-ventral axes, especially in humans, remains elusive. Here, we demonstrate the co-culture effect of somites and notochords isolated from chicken embryos on the neuronal differentiation and regional identity of an adherent culture of human embryonic stem cells (hESCs). Notochord increased the efficiency and speed of neuronal induction, whereas somites had a weak neuronal inducing effect on hESCs. However, a synergistic effect was not observed when notochords and somites were used together. Moreover, in somite and notochord co-culture groups, hESCs-derived neuronal cells expressed HOXB4, OTX2, IRX3 and PAX6, indicative of dorsal hindbrain and ventral anterior identities, respectively. Our results reveal the influence of embryonic notochord and somite co-culture in providing neuronal induction as well as rostro-caudal and dorso-ventral regional identity of hESCs-derived neuronal cells. This study provides a model through which in vivo neuronal induction events may be imitated.