Another look at “Stem cell fate dictated solely by altered nanotube dimension”
Another look at “Stem cell fate dictated solely by altered nanotube dimension”
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DOI：
10.1073/pnas.0903663106
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发表时间：
2009-06
期刊：
影响因子：
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通讯作者：
K. von der Mark;S. Bauer;Jung Park;P. Schmuki
中科院分区：
文献类型：
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作者：
K. von der Mark;S. Bauer;Jung Park;P. Schmuki
Oh等人(1)在他们的文章中报道，仅通过改变纳米管直径就可以控制干细胞在TiO2纳米管上的行为。在直径为30 ~ 100 nm的纳米管上培养人间充质干细胞（MSCs），细胞拉伸和成骨分化标志物的表达在100 nm纳米管上最高，而细胞粘附率随着管直径的减小而增加，在30 nm时达到最大值。这一发现尤其引人注目，因为之前的相反报告显示，MSCs向成骨细胞的纳米级依赖性分化遵循相反的方向（2,3）。在这些研究中，数据显示大鼠骨髓间充质干细胞的粘附、增殖和迁移以及成骨分化在15纳米纳米管上最高，而在70和100纳米纳米管上急剧下降。15 nm的纳米间距与纳米管网格上直径≈10 nm的整合素簇的最佳支持是一致的（2,4,5）。此外，Arnold等人(6)已经表明，纳米间距bbbb73 nm可显著减少细胞扩散和灶性粘连的形成。这种差异令人不安，可能没有引起Oh等人的注意。相反，他们提出的假设是，在70 nm而不是30 nm TiO2纳米管上观察到的MSCs中细胞拉伸和应力纤维的形成促进了成骨细胞的分化，而没有考虑到整合素聚集和局部接触形成对细胞分化的关键作用。为了解决这一明显的冲突，有必要进行进一步的讨论和实验。
In their article, Oh et al. (1) reported that stem cell behavior on TiO2 nanotubes can be controlled solely by altering nanotube diameter. Culturing human mesenchymal stem cells (MSCs) on a range of nanotubes with diameters between 30 and 100 nm, cell stretching and expression of osteogenic differentiation markers was highest on 100-nm nanotubes, whereas cell-adhesion rates increased with decreasing tube diameter, with a maximum at 30 nm. This finding is particularly striking in light of previous contrary reports showing that nanoscale-dependent differentiation of MSCs to osteoblasts followed in the opposite direction (2, 3). In these studies, data were presented showing that not only adhesion, proliferation, and migration, but also osteogenic differentiation of rat bone marrow MSCs were highest on 15-nm nanotubes and decreased dramatically on 70- and 100-nm nanotubes. A nanospacing of 15 nm is consistent with an optimal support of clustering of integrins, which are ≈10 nm in diameter, on the nanotube grid (2, 4, 5). Also, Arnold et al. (6) have shown that nanospacing >73 nm dramatically reduced cell spreading and the formation of focal adhesions. This discrepancy is disturbing and may have escaped the attention of Oh et al. In contrast, they presented the hypothesis that cell stretching and formation of stress fibers in MSCs observed on 70-nm but not on 30-nm TiO2 nanotubes promoted differentiation into osteogenic cells, not taking into account the critical role of integrin clustering and focal-contact formation for cell differentiation. Further discussion and experimentation will be necessary to resolve this apparent conflict.