Establishment of Culture System Capable of Inducing Neural Crest Cells from ES Cells

小鼠胚胎干细胞（ES）是一种多能的、原始的、类似外胚层的细胞，来源于3、5天大的囊胚内细胞团。作为黑素细胞分化的体外模型，我们开发了从全能ES细胞系诱导黑素细胞的培养系统。当未分化的胚胎干细胞与骨髓来源的基质细胞系共培养时，可再生产生非常少但数量显著的黑色素细胞。在培养物中加入地塞米松后，这一过程大大增强，并严格依赖于c-Kit信号和内皮素3信号。在这项研究中，我们发现尾化因子维甲酸提高了这种培养中黑素细胞诱导的效率。黑素细胞的早期前体经过几次传代后克隆增殖，在培养中被有效地诱导，内皮素3和维甲酸的加入刺激了它们的自我更新。这些结果表明，在该培养体系中，神经嵴细胞是经过相应的体内发育而诱导形成的。

Mouse embryonic stem (ES) cells are totipotent, primitive, ectodermal-like cells derived from inner cell mass of 3,5 day blastocysts. As an in vitro model for melanocyte differentiation, we have developed the culture system to induce melanocytes from totipotent ES cell line. When undifferentiated ES cells were co-cultured with a bone marrow-derived stromal cell line, a very small but significant number of melanocytes were reproducibly generated. This process was greatly enhanced by addition of dexamethasone to the culture and strictly depended on the c-Kit signaling and endothelin 3 signaling. In this study, we found that caudalizing factor retinoic acid enhanced the efficiency of melanocyte induction in this culture. The early precursors for melanocytes, which proliferate clonally after several passages, were efficiently induced in the culture and their self-renew was stimulated by the addition of endothelin 3 and also by retinoic acid. These results suggests that neural crest cells are induced in this culture system upon corresponding in vivo development.