Li Qiang, Liu Rui, Zhao Jianmin, Lu Quanli
Department of Orthopedics, the Affiliated Hospital of Inner Mongolia Medical University, China.
J Toxicol Sci. 2016;41(5):701-9. doi: 10.2131/jts.41.701.
Ischemic-hypoxic condition for local osteoblasts and bone mesenchymal stem cells during bone fracture inhibits bone repairing. N-methyl pyrrolidone (NMP) has been approved as a safe and biologically inactive small chemical molecule, and might be useful for bone fracture repairing. In the present study, we investigated the effect of NMP on the hypoxia-reduced cellular viability and the expression of differentiation-associated markers, such as bone morphogenetic protein 2 (BMP-2), propeptide of type I procollagen I (PINP), alkaline phosphatase (ALP) or runt-related transcription factor 2 (Runx2) in the osteoblasts, and then we examined the molecular mechanism underlining such effect in the human osteoblastic hFOB 1.19 cells. Our results demonstrated that NMP significantly blocked the hypoxia-induced cell viability reduction and inhibited the hypoxia-caused expression downregulation of BMP-2, PINP, ALP and Runx2 in hFOB 1.19 cells. Then we confirmed the involvement of nuclear factor κB (NF-κB) pathway in the regulation by NMP on the hypoxia-mediated the reduction of osteoblast differentiation. The upregulated expression and transcriptional activity of NF-κB, while the downregulated inhibitory κB expression by the hypoxia treatment was reversed by the treatment with 10 mM NMP. In conclusion, our study found a protective role of NMP in osteoblast differentiation in response to hypoxia, and such protection was through inhibiting the NF-κB signaling. This suggests that NMP might be a protective agent in bone fracture repairing.
骨折期间局部成骨细胞和骨间充质干细胞的缺血缺氧状态会抑制骨修复。N-甲基吡咯烷酮（NMP）已被批准为一种安全且无生物活性的小分子化学物质，可能对骨折修复有用。在本研究中，我们研究了NMP对缺氧降低的细胞活力以及成骨细胞中分化相关标志物（如骨形态发生蛋白2（BMP-2）、I型前胶原I前肽（PINP）、碱性磷酸酶（ALP）或 runt相关转录因子2（Runx2））表达的影响，然后我们研究了人成骨细胞hFOB 1.19细胞中这种作用的分子机制。我们的结果表明，NMP显著阻止了缺氧诱导的细胞活力降低，并抑制了缺氧导致的hFOB 1.19细胞中BMP-2、PINP、ALP和Runx2的表达下调。然后我们证实了核因子κB（NF-κB）通路参与了NMP对缺氧介导的成骨细胞分化降低的调节。缺氧处理上调了NF-κB的表达和转录活性，而下调的抑制性κB表达通过10 mM NMP处理得以逆转。总之，我们的研究发现NMP在缺氧反应中成骨细胞分化中具有保护作用，且这种保护作用是通过抑制NF-κB信号实现的。这表明NMP可能是骨折修复中的一种保护剂。
