Imreh M P, Gertow K, Cedervall J, Unger C, Holmberg K, Szöke K, Csöregh L, Fried G, Dilber S, Blennow E, Ahrlund-Richter L
Department of Laboratory Medicine, Clinical Research Centre, Karolinska University Hospital, Karolinska Institutet, Stockholm, Sweden.
J Cell Biochem. 2006 Oct 1;99(2):508-16. doi: 10.1002/jcb.20897.
Previous studies in several laboratories have demonstrated inadvertent chromosomal abnormalities in long-term cultured human embryonic stem cells (HESC). Here, using a two-step selection process we report a functional adaptation of a HESC line, HS181, towards a decreased dependence of extra cellular matrix (ECM) for in vitro survival, that is for growth directly onto a plastic surface. Successful adaptation was paralleled with a karyotype change in 100% of the cells to 47,XX,del(7)(q11.2),+i(12)(p10). The resulting adapted population showed increased survival and growth on plastic and also maintained expression of HESC markers, but showed a decreased pluripotency, as demonstrated by results from embryoid body (EB) formation in vitro. The finding of reduced pluripotency may not be totally unexpected since the variant cells were selected for self-renewal and proliferation, not differentiation during the adaptation to growth on plastic. In the light of recent models of a germ cell origin of HESC it is of particular interest that similar to many of the reported spontaneous HESC mutants, one of the identified specific chromosome abnormalities, i(12p), has also been strongly implicated for human germ cell cancer. However, the mutated HESC variant carrying this mutation failed to grow as a xeno-graft in a mouse model in vivo. This is surprising and needs a further mechanistic analysis for its explanation. Increased knowledge of genetic integrity of HESC may have significance on the understanding of mechanisms for tumor progression and thus strategy for treatments, particularly for tumors occurring in early life.
此前多个实验室的研究已证明，长期培养的人类胚胎干细胞（HESC）存在意外的染色体异常。在此，我们通过两步筛选过程报告了HESC系HS181的一种功能适应性变化，即其对细胞外基质（ECM）的体外存活依赖性降低，能够直接在塑料表面生长。成功的适应性变化与100%的细胞发生核型改变至47,XX,del(7)(q11.2),+i(12)(p10)同时出现。由此产生的适应性细胞群体在塑料表面的存活和生长能力增强，并且维持了HESC标志物的表达，但多能性降低，体外胚状体（EB）形成结果证明了这一点。多能性降低这一发现可能并非完全出乎意料，因为在适应于在塑料表面生长的过程中，变异细胞是为自我更新和增殖而非分化而被选择的。鉴于最近有关HESC起源于生殖细胞的模型，特别值得关注的是，与许多已报道的自发HESC突变体类似，所鉴定出的特定染色体异常之一i(12p)，也与人类生殖细胞癌密切相关。然而，携带这种突变的突变型HESC变体在体内小鼠模型中未能作为异种移植物生长。这一结果令人惊讶，需要进一步进行机制分析来解释。对HESC遗传完整性的深入了解可能对理解肿瘤进展机制以及治疗策略具有重要意义，特别是对于早期发生的肿瘤。
