Specification of Region-Specific Neurons Including Forebrain Glutamatergic Neurons from Human Induced Pluripotent Stem Cells

BackgroundDirected differentiation of human induced pluripotent stem cells (hiPSC) into functional, region-specific neural cells is a key step to realizing their therapeutic promise to treat various neural disorders, which awaits detailed elucidation.
Methodology/Principal FindingsWe analyzed neural differentiation from various hiPSC lines generated by others and ourselves. Although heterogeneity in efficiency of neuroepithelial (NE) cell differentiation was observed among different hiPSC lines, the NE differentiation process resembles that from human embryonic stem cells (hESC) in morphology, timing, transcriptional profile, and requirement for FGF signaling. NE cells differentiated from hiPSC, like those from hESC, can also form rostral phenotypes by default, and form the midbrain or spinal progenitors upon caudalization by morphogens. The rostrocaudal neural progenitors can further mature to develop forebrain glutamatergic projection neurons, midbrain dopaminergic neurons, and spinal motor neurons, respectively. Typical ion channels and action potentials were recorded in the hiPSC-derived neurons.
Conclusions/SignificanceOur results demonstrate that hiPSC, regardless of how they were derived, can differentiate into a spectrum of rostrocaudal neurons with functionality, which supports the considerable value of hiPSC for study and treatment of patient-specific neural disorders.

背景
将人类诱导多能干细胞（human induced pluripotent stem cells, hiPSC）定向分化为具有功能的区域特异性神经细胞，是实现其治疗各类神经疾病的治疗前景的关键环节，该过程的详细机制仍有待进一步阐明。
方法/主要结果
我们对他人及本研究团队构建的多株hiPSC的神经分化过程展开了分析。尽管不同hiPSC株的神经上皮细胞（neuroepithelial cell, NE）分化效率存在显著异质性，但其NE分化过程在形态特征、时间进程、转录谱以及对成纤维细胞生长因子（fibroblast growth factor, FGF）信号通路的依赖特性上，均与人类胚胎干细胞（human embryonic stem cells, hESC）的神经上皮分化过程高度相似。由hiPSC诱导得到的NE细胞，与hESC来源的NE细胞类似，可通过默认途径形成吻侧表型；经形态发生因子诱导尾侧化后，则可分化为中脑或脊髓前体细胞。上述沿吻尾轴分布的神经前体细胞可进一步成熟，分别分化为前脑谷氨酸能投射神经元、中脑多巴胺能神经元及脊髓运动神经元。对hiPSC来源的神经元进行电生理记录，可检测到典型的离子通道电流与动作电位。
结论与意义
本研究结果证实，无论采用何种重编程方式获取的hiPSC，均可分化为一系列具备功能的沿吻尾轴分布的神经元，这为hiPSC在患者特异性神经疾病的研究与临床治疗中的应用提供了重要的理论支撑。