Department of Oral Biology, University of Pittsburgh, Pittsburgh, PA, USA; The Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA, USA; The McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
Department of Oral Biology, University of Pittsburgh, Pittsburgh, PA, USA; The Center for Craniofacial Regeneration, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA; The McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA.
Acta Biomater. 2014 Jun;10(6):2834-42. doi: 10.1016/j.actbio.2014.02.002. Epub 2014 Feb 7.
Magnesium alloys are being investigated for load-bearing bone fixation devices due to their initial mechanical strength, modulus similar to native bone, biocompatibility and ability to degrade in vivo. Previous studies have found Mg alloys to support bone regeneration in vivo, but the mechanisms have not been investigated in detail. In this study, we analyzed the effects of Mg(2+) stimulation on intracellular signaling mechanisms of human bone marrow stromal cells (hBMSCs). hBMSCs were cultured in medium containing 0.8, 5, 10, 20 and 100mM MgSO4, either with or without osteogenic induction factors. After 3weeks, mineralization of extracellular matrix (ECM) was analyzed by Alizarin red staining, and gene expression was analyzed by quantitative polymerase chain reaction array. Mineralization of ECM was enhanced at 5 and 10mM MgSO4, and collagen type X mRNA (COL10A1, an ECM protein deposited during bone healing) expression was increased at 10mM MgSO4 both with and without osteogenic factors. We also confirmed the increased production of collagen type X protein by Western blotting. Next, we investigated the mechanisms of intracellular signaling by analyzing the protein production of hypoxia-inducible factor (HIF)-1α and 2α (transcription factors of COL10A1), vascular endothelial growth factor (VEGF) (activated by HIF-2α) and peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α (transcription coactivator of VEGF). We observed that 10mM MgSO4 stimulation enhanced COL10A1 and VEGF expression, possibly via HIF-2α in undifferentiated hBMSCs and via PGC-1α in osteogenic cells. These data suggest possible ECM proteins and transcription factors affected by Mg(2+) that are responsible for the enhanced bone regeneration observed around degradable Mg orthopedic/craniofacial devices.
镁合金因其初始机械强度、与天然骨相似的模量、生物相容性以及在体内降解的能力而被用于承重骨固定装置。先前的研究发现镁合金能够支持体内骨再生，但这些机制尚未得到详细研究。在这项研究中，我们分析了镁（Mg）刺激对人骨髓基质细胞（hBMSCs）细胞内信号转导机制的影响。hBMSCs 在含有 0.8、5、10、20 和 100mM MgSO4 的培养基中培养，有或没有成骨诱导因子。3 周后，通过茜素红染色分析细胞外基质（ECM）的矿化，通过定量聚合酶链反应（PCR）分析基因表达。在 5mM 和 10mM MgSO4 中增强了 ECM 的矿化，并且在有或没有成骨因子的情况下，COL10A1（骨愈合过程中沉积的 ECM 蛋白）mRNA 的表达在 10mM MgSO4 中增加。我们还通过 Western blot 证实了 COL10A1 蛋白的产量增加。接下来，我们通过分析缺氧诱导因子（HIF）-1α 和 2α（COL10A1 的转录因子）、血管内皮生长因子（VEGF）（由 HIF-2α 激活）和过氧化物酶体增殖物激活受体γ共激活剂（PGC）-1α（VEGF 的转录共激活因子）的蛋白质产量来研究细胞内信号转导的机制。我们观察到 10mM MgSO4 刺激增强了 COL10A1 和 VEGF 的表达，这可能是通过未分化的 hBMSCs 中的 HIF-2α 和成骨细胞中的 PGC-1α 实现的。这些数据表明，Mg（2+）可能影响到 COL10A1 和 VEGF 等 ECM 蛋白和转录因子，从而导致可降解镁骨科/颅面设备周围观察到的增强的骨再生。
