Hypoxia promotes chondrogenesis in rat mesenchymal stem cells:: A role for AKT and hypoxia-inducible factor (HIF)-1α
Hypoxia promotes chondrogenesis in rat mesenchymal stem cells:: A role for AKT and hypoxia-inducible factor (HIF)-1α
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DOI：
10.1002/jcp.21446
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发表时间：
2008-09-01
影响因子：
5.6
通讯作者：
Campbell, Veronica A.
中科院分区：
文献类型：
--
作者：
Kanichai, Manoj;Ferguson, Damien;Campbell, Veronica A.
间充质干细胞（MSC）是能够沿着软骨形成、成骨和脂肪形成谱系发育的多能细胞。因此，它们作为组织工程策略的潜在细胞来源而受到关注。软骨是无血管组织，因此存在于氧张力降低的微环境中。本研究的目的是检查低氧环境对 MSC 沿软骨形成途径分化的影响。在暴露于软骨生长因子、转化生长因子-P和克塞米松的间充质干细胞中，在缺氧环境（2%氧气）下，胶原蛋白11表达和蛋白多糖沉积的诱导明显大于细胞在常氧（20%氧气）条件下暴露于软骨生长因子时观察到的情况。转录因子缺氧不敏感因子 1 α (HIF-1 α) 是细胞对缺氧反应的关键介质。 MSC 暴露于缺氧（2% 氧气）后，HIF-1 α 从细胞质转移到细胞核，并与其靶 DNA 共有序列结合。同样，缺氧会引起 AKT 和 p38 丝裂原激活蛋白激酶（HIF-1 α 激活上游）的磷酸化增加。此外，P13 激酶/AKT 抑制剂 LY294002 和 p38 抑制剂 SB 203580 可阻止缺氧介导的 HIF-1 α 稳定。评估 HIF-1 α 的作用。在缺氧引起的软骨形成增加中，我们采用了 siRNA 敲低方法。在暴露于 HIF-1 α siRNA 的细胞中，缺乏缺氧引起的软骨形成增强（胶原蛋白 11、sox-9 和蛋白聚糖沉积的上调所证明）。这为 HIF-1 α 是低氧环境对软骨形成有益影响的关键介质提供了证据。
Mesenchymal stem cells (MSCs) are multipotent cells capable of developing along the chondrogenic, osteogenic and adipogenic lineages. As such, they have received interest as a potential cell source for tissue engineering strategies. Cartilage is an avascular tissue and thus resides in a microenvironment with reduced oxygen tension. The aim of this study was to examine the effect of a low oxygen environment on MSC differentiation along the chondrogenic route. In MSCs exposed to chondrogenic growth factors, transforming growth factor-P and clexamethasone, in a hypoxic environment (2% oxygen), the induction of collagen 11 expression and proteoglygan deposition was significantly greater than that observed when cells were exposed to the chondrogenic growth factors under normoxic (20% oxygen) conditions. The transcription factor, hypoxia-inclucible factor-1 alpha (HIF-1 alpha), is a crucial mediator of the cellular response to hypoxia. Following exposure of MSCs to hypoxia (2% oxygen), HIF-1 alpha translocated from the cytosol to the nucleus and bound to its target DNA consensus sequence. Similarly, hypoxia evoked an increase in phosphorylation of both AKT and p38 mitogen activated protein kinase, upstream of HIF-1 alpha activation. Furthermore, the P13 kinase/AKT inhibitor, LY294002, and p38 inhibitor, SB 203580, prevented the hypoxia-mediated stabilisation of HIF-1 alpha. To assess the role of HIF-1 alpha. in the hypoxia-incluced increase in chondrogenesis, we employed an siRNA knockdown approach. In cells exposed to HIF-1 alpha siRNA, the hypoxia-incluced enhancement of chondrogenesis, as evidenced by upregulation of collagen 11, sox-9 and proteoglycan deposition, was absent. This provides evidence for HIF-1 alpha being a key mediator of the beneficial effect of a low oxygen environment on chondrogenesis.