Cellular differentiation hierarchies in normal and culture-adapted human embryonic stem cells
Cellular differentiation hierarchies in normal and culture-adapted human embryonic stem cells
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DOI：
10.1093/hmg/ddi345
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发表时间：
2005-11-01
影响因子：
3.5
通讯作者：
Andrews, PW
中科院分区：
文献类型：
--
作者：
Enver, T;Soneji, S;Andrews, PW
人类胚胎干细胞（HESC）系的特性和行为各不相同，这不仅是因为它们来自遗传上的近亲繁殖群体，而且还因为它们可能在体外长期培养过程中逐渐适应。这种适应可能反映了变异的选择与改变的生存倾向和保留未分化的表型。阐明所涉及的机制对于理解正常的自我更新和对分化的承诺以及验证基于hesc的治疗的安全性非常重要。我们通过比较单个HESC细胞系H7的早期传代（正常）和晚期传代（适应）亚系，在细胞和分子水平上研究了这一适应过程。为了解释HESC培养中发生的自发分化，我们对细胞进行了SSEA3分类，这标志着未分化的HESC。我们发现适应细胞的基因表达程序部分反映了它们的异常核型，但也源于x失活的失败，强调了核型沉默表观遗传变化在适应中的重要性。基于生长潜力、重新启动ES培养的能力和全球转录谱，我们提出了HESC维持培养的细胞分化层次：正常SSEA3+细胞代表多能干细胞。正常的SSEA3-细胞已退出此区室，但仍保留多系分化潜能。然而，适应的SSEA3+和SSEA3-细胞在干细胞领域内共同分离，这意味着适应反映了自我更新和分化之间平衡的改变。由于这种平衡也是癌症的基本特征，培养适应的机制可能反映了肿瘤发生和肿瘤进展的机制。
Human embryonic stem cell (HESC) lines vary in their characteristics and behaviour not only because they are derived from genetically outbred populations, but also because they may undergo progressive adaptation upon long-term culture in vitro. Such adaptation may reflect selection of variants with altered propensity for survival and retention of an undifferentiated phenotype. Elucidating the mechanisms involved will be important for understanding normal self-renewal and commitment to differentiation and for validating the safety of HESC-based therapy. We have investigated this process of adaptation at the cellular and molecular levels through a comparison of early passage (normal) and late passage (adapted) sublines of a single HESC line, H7. To account for spontaneous differentiation that occurs in HESC cultures, we sorted cells for SSEA3, which marks undifferentiated HESC. We show that the gene expression programmes of the adapted cells partially reflected their aberrant karyotype, but also resulted from a failure in X-inactivation, emphasizing the importance in adaptation of karyotypically silent epigenetic changes. On the basis of growth potential, ability to re-initiate ES cultures and global transcription profiles, we propose a cellular differentiation hierarchy for maintenance cultures of HESC: normal SSEA3+ cells represent pluripotent stem cells. Normal SSEA3- cells have exited this compartment, but retain multilineage differentiation potential. However, adapted SSEA3+ and SSEA3- cells co-segregate within the stem cell territory, implying that adaptation reflects an alteration in the balance between self-renewal and differentiation. As this balance is also an essential feature of cancer, the mechanisms of culture adaptation may mirror those of oncogenesis and tumour progression.