Intervertebral fusion is the most common surgery to treat lumbar degenerative disease (LDD). And the graft material used in the operation is derived from the iliac crest to promote fusion. However, autografts possess the fatal disadvantage of lack of source. Therefore, economical and practical bone substitutes are urgently needed to be developed. Sinusoidal electromagnetic fields (EMF) combined with tissue engineering techniques may be an appropriate way to promote intervertebral fusion. In this research, porous scaffolds made of polycaprolactone (PCL) and nano-hydroxyapatite (nHA) were used as cell carriers. Then, the scaffolds loaded with bone marrow mesenchymal stem cells (BMSCs) were treated with sinusoidal electromagnetic field and the osteogenic capability of BMSCs was tested later. In addition, an intervertebral disc of the tail vertebra of the rat was removed to construct a spinal intervertebral fusion model with a cell-scaffold implanted. The intervertebral fusion was observed and analyzed by X-ray, micro-CT, and histological methods. BMSCs stimulated by EMF possess splendid osteogenic capability under an osteogenic medium (OM) in vitro. And the conditioned medium of BMSCs treated with EMF can further promote osteogenic differentiation of the primitive BMSCs. Mechanistically, EMF regulates BMSCs via BMP/Smad and mitogen-activated protein kinase (MAPK)-associated p38 signaling pathways. In vivo experiments revealed that the scaffold loaded with BMSCs stimulated by EMF accelerated intervertebral fusion successfully. In summary, EMF accelerated intervertebral fusion by improving the osteogenic capacity of BMSCs seeded on scaffolds and might boost the paracrine function of BMSCs to promote osteogenic differentiation of the homing BMSCs at the injured site. EMF combined with tissue engineering techniques may become a new clinical treatment for LDD.

中文翻译：

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低频电磁场结合组织工程技术可加速椎间融合

椎间融合术是治疗腰椎退行性疾病（LDD）的最常见手术。手术中使用的移植物材料来自rest，以促进融合。然而，自体移植具有缺乏来源的致命缺点。因此，迫切需要开发经济实用的骨替代物。正弦波电磁场（EMF）结合组织工程技术可能是促进椎间融合的一种合适方法。在这项研究中，聚己内酯（PCL）和纳米羟基磷灰石（nHA）制成的多孔支架用作细胞载体。然后，用正弦波电磁场处理装有骨髓间充质干细胞（BMSCs）的支架，然后测试其的成骨能力。此外，去除大鼠尾椎的椎间盘，以构建植入了细胞支架的脊椎椎间融合模型。通过X射线，显微CT和组织学方法观察和分析椎间融合。EMF刺激的BMSC在成骨培养基（OM）下具有出色的成骨能力。EMF处理过的BMSCs的条件培养基可以进一步促进原始BMSCs的成骨分化。从机理上讲，EMF通过BMP / Smad和有丝分裂原激活的蛋白激酶（MAPK）相关的p38信号通路调节BMSC。体内实验表明，EMF刺激的BMSCs支架能够成功地促进椎间融合。总之，EMF通过改善接种在支架上的BMSC的成骨能力来加速椎间融合，并可能增强BMSC的旁分泌功能以促进损伤部位归巢BMSC的成骨分化。EMF与组织工程技术相结合可能成为LDD的一种新的临床治疗方法。