不同培养体系可逆改变人类胚胎干细胞的分化倾向

背景：人类胚胎干细胞可以在饲养细胞依赖性培养体系和化学限定性培养体系下维持未分化状态，能够在体内外诱导分化成三胚层来源的细胞类型。 目的：比较饲养细胞和化学限定性培养体系对人类胚胎干细胞特性的影响。 方法：将在饲养细胞培养体系下培养27代的人类胚胎干细胞转入到化学限定性培养基体系中培养56代，然后再将其转回到饲养细胞培养体系中，将3种培养条件下的人类胚胎干细胞(饲养细胞培养体系培养70代、化学限定性培养体系培养56代、化学限定性培养体系下培养70代后转回饲养细胞培养体系下培养13代和20代)进行多能性分子标记SSEA4流式分析等检测分析，同时对3种培养条件下人类胚胎干细胞经拟胚体诱导分化后分别检测多能性基因和三胚层分化基因的表达。 结果与结论：人类胚胎干细胞在饲养细胞和化学限定性培养体系下表现出不同的诱导分化倾向，在化学限定性培养体系下表现出向神经诱导分化抑制，这种不同的诱导分化倾向可发生可逆性转换，当人类胚胎干细胞由化学限定性培养体系转回到饲养细胞培养体系时，诱导分化倾向表现出与其在饲养细胞下诱导分化一致的模式。在拟胚体分化中，多能性基因Nanog高可能对诱导分化倾向起着重要作用。与此同时，人类胚胎干细胞SSEA4细胞亚群发生相应的变化，人类胚胎干细胞在饲养细胞和化学限定下培养体系下表现的分化倾向与人类胚胎干细胞亚群所占的比例存在关联。

Differentiation inclination of human embryonic stem cells reversibly affected by different culture systems

BACKGROUND: Human embryonic stem cells (hESCs) can be maintained in feeder dependent and chemical defined culture systems, and have the capacity to differentiate into three germ layers derived cells. OBJECTIVE: To compare the effects of feeder cells and chemical defined culture system on characteristics of hESCs. METHODS: hESCs in feeder dependent culture system (passage 27) were transferred to chemical defined culture system for 56 passages and returned back to feeder culture system. hESCs in three culture conditions (feeder dependent culture system for 70 passages, chemical defined culture system for 56 passages or the condition hESCs transferred from chemical defined culture system to feeder dependent culture system for 13 passages and 20 passages) were analyzed by flow cytometry for SSEA4. Expression of multipotency gene and differentiation gene in three embryonic layers was determined following hESCs were induced to differentiate under three culture conditions. RESULTS AND CONCLUSION: hESCs exhibited different differentiation inclinations in embryonic bodies conditions in feeder dependent and chemical defined culture systems, and the differentiation inclinations can be converted reciprocally. In chemical defined culture system, hESCs showed anti-differentiation to neural ectoderm cells, and this anti-differentiation can be rescued when hESCs were transferred back to feeder dependent culture system. The gene expression of Nanog may have an important role in embryonic bodies differentiation. At the same time, SSEA4 subpopulations hESCs showed the similar pattern. There may be some relationships between the SSEA4 subpopulations and differentiation inclination in feeder dependent and chemical defined culture systems.