Department of Materials, Institute of Biomedical Engineering, Imperial College London, London, UK.
Eur Cell Mater. 2012 Sep 24;24:211-23. doi: 10.22203/ecm.v024a15.
Pluripotent cells, such as embryonic stem cells (ESCs), divide indefinitely and can differentiate to form mineralised nodules in response to osteogenic supplements. This suggests that they may be used as a cell source for bone replacement strategies. Here, we related the expression of osteogenic and chondrogenic genes in cultures of murine ESCs, marrow stromal cells (MSCs) and calvarial osteoblasts (OBs) cultured under osteogenic conditions to the biochemical composition and quantity of mineral formed. Mineralisation, measured by calcium sequestration, was >2-fold greater in ESC cultures than in either MSCs or OBs. Micro-Raman spectroscopy and spectral mapping revealed a lower mineral-to-matrix ratio and confirmed a more diffuse pattern of mineralisation in ESCs compared to MSCs and OBs. Baseline expression of chondrogenic and osteogenic genes was between 1 and 4 orders of magnitude greater in MSCs and OBs than in ESCs. Osteogenic culture of MSCs and OBs was accompanied by increases in osteogenic gene expression by factors of ~100 compared to only ~10 in ESCs. Consequentially, peak expression of osteogenic and chondrogenic genes was greater in MSCs and OBs than ESCs by factors of 100-1000, despite the fact that mineralisation was more extensive in ESCs than either MSCs or OBs. We also observed significant cell death in ESC nodules. We conclude that the mineralised material observed in cultures of murine ESCs during osteogenic differentiation may accumulate non-specifically, perhaps in necrotic cell layers, and that thorough characterisation of the tissue formed by ESCs must be achieved before these cells can be considered as a cell source for clinical applications.
多能细胞，如胚胎干细胞（ESCs），可以无限分裂，并能分化为矿化结节，以响应成骨补充剂。这表明它们可能被用作骨替代策略的细胞来源。在这里，我们将小鼠 ESC、骨髓基质细胞（MSCs）和颅骨成骨细胞（OBs）在成骨条件下培养的成骨和软骨基因的表达与形成的矿物质的生化组成和数量相关联。通过钙螯合测量的矿化在 ESC 培养物中比 MSC 或 OB 高 2 倍以上。微拉曼光谱和光谱映射显示出更低的矿物质与基质比，并证实了 ESC 中矿物质矿化的模式比 MSC 和 OB 更扩散。MSC 和 OB 中的软骨和成骨基因的基线表达比 ESC 高 1 到 4 个数量级。与 ESC 中仅增加约 10 相比，MSC 和 OB 的成骨培养伴随着成骨基因表达增加约 100 倍。因此，尽管 ESC 中的矿化比 MSC 或 OB 更广泛，但 MSC 和 OB 中成骨和软骨基因的峰值表达比 ESC 高 100-1000 倍。我们还观察到 ESC 结节中的明显细胞死亡。我们得出结论，在成骨分化过程中观察到的 ESC 培养物中的矿化物质可能是非特异性地积累的，也许在坏死的细胞层中，并且必须对 ESC 形成的组织进行彻底的特征描述，然后才能将这些细胞视为临床应用的细胞来源。
