National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China; Institute of Life Sciences, Chongqing Medical University, Chongqing, 400016, China.
National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China.
Acta Biomater. 2021 Jul 15;129:293-308. doi: 10.1016/j.actbio.2021.05.026. Epub 2021 Jun 1.
Porous biphasic calcium phosphate bioceramic (BCP) possesses osteoinductivity to induce the osteoblastic commitment of mesenchymal stem cells (MSCs) and ectopic bone formation. However, the underlying mechanism remains enigmatic. We performed a gene array analysis of MSCs cocultured with BCP to screen for candidate osteoinductive modulators. Na, K-ATPase (NKA), an ion transporter, therefore was identified as a crucial ion transporter in regulating the osteogenesis of the cells. NKA activator, a polyclonal antibody, enriched the cytomembrane abundance of NKA and lead to an enhanced osteogenic effect of BCP. As indicated in gene array analysis and suggested by co-immunoprecipitation assay, protein phosphatase 2A (PP2A) was elevated by BCP to dephosphorylate NKA and prevent its endocytosis. The inhibition of NKA by ouabain resulted in an adverse effect on osteoinductivity of BCP. We further altered NKA activity in mice implanted with BCP and found that the intensity and incidence of osteoinduction was increased by the NKA activator. We went one step further by investigating the potential of targeting NKA in osteoporotic bone regeneration. Activating NKA upregulated osteogenic gene expression and calcium deposition ability of osteoporotic osteoblasts. Furthermore, activation of NKA in mice ameliorated estrogen-deficiency induced bone loss, in terms of increased bone mass and improved bending strength. With this osteoinductive bioceramic derived ion transporter target, we demonstrate that the activation of NKA has significant potential to revolutionize the regeneration of bone. STATEMENT OF SIGNIFICANCE: In this study, we identified an important role of Na, K-ATPase (NKA) have played in osteoinductivity of biphasic calcium phosphate bioceramic (BCP). Furthermore, we demonstrated the therapeutic potential of targeting NKA in osteoporotic bone regeneration. Numerous gene and protein targets to treat osteoporosis were discovered every year, mainly obtained by genomic and proteomic screenings of a large population. In contrast, our study identified an unrevealed bone regenerating target from the upregulated genes induced by an osteoinductive biomaterial. The approach was cost-saving since it did not require a large sample pool. Furthermore, the target derived from this approach was proven to be anabolic. Identification of an anabolic agent holds significant value since most of the current anti-osteoporotic therapies are antiresorptive.
多孔双相磷酸钙生物陶瓷（BCP）具有成骨诱导性，可诱导间充质干细胞（MSCs）的成骨细胞分化和异位骨形成。然而，其潜在机制仍不清楚。我们对与 BCP 共培养的 MSC 进行了基因芯片分析，以筛选候选的成骨诱导调节剂。因此，Na+，K+-ATPase（NKA），一种离子转运体，被鉴定为调节细胞成骨作用的关键离子转运体。NKA 激活剂，一种多克隆抗体，富集了 NKA 的细胞质膜丰度，并增强了 BCP 的成骨作用。正如基因芯片分析所示，并通过共免疫沉淀实验提示，BCP 上调蛋白磷酸酶 2A（PP2A）以去磷酸化 NKA 并防止其内吞。哇巴因抑制 NKA 会对 BCP 的成骨诱导作用产生不良影响。我们进一步改变了植入 BCP 的小鼠中的 NKA 活性，发现 NKA 激活剂增加了成骨诱导的强度和发生率。我们更进一步研究了靶向 NKA 在骨质疏松性骨再生中的潜力。激活 NKA 上调了成骨基因的表达和骨质疏松性成骨细胞的钙沉积能力。此外，在小鼠中激活 NKA 可改善雌激素缺乏引起的骨丢失，增加骨量并提高弯曲强度。通过这种具有成骨诱导作用的生物陶瓷衍生的离子转运体靶标，我们证明了激活 NKA 具有显著潜力来革新骨再生。
在这项研究中，我们确定了 Na+，K+-ATPase（NKA）在双相磷酸钙生物陶瓷（BCP）的成骨诱导性中发挥了重要作用。此外，我们证明了靶向 NKA 在骨质疏松性骨再生中的治疗潜力。每年都有大量治疗骨质疏松症的基因和蛋白质靶点被发现，主要是通过对大量人群的基因组和蛋白质组筛选获得的。相比之下，我们的研究从成骨诱导生物材料诱导的上调基因中确定了一个未被揭示的骨再生靶标。这种方法具有成本效益，因为它不需要大量的样本库。此外，该方法衍生的靶标被证明具有合成代谢作用。鉴定合成代谢剂具有重要意义，因为大多数当前的抗骨质疏松症疗法都是抗吸收的。
