Abstract Electromagnetic stimulation has been shown as an effective strategy to enhance neural cells regeneration. The use of electrically conductive materials including polymer nanocomposites for the construction of scaffolds with potential to repair the injured nervous system has attracted great attentions. In the present study, attempts have been made to fabricate nanostructured fibrous scaffolds based on flexible thermoplastic polyurethane (TPU) and surface functionalized multiwalled carbon nanotubes (MWNT) via electrospinning process in order to examine and highlight the influence of state of electrical conductivity of scaffolds upon neural cells proliferation and differentiation. For this purpose, various scaffolds comprising different wt.% of MWNTs were prepared and their electrical conductivity, microstructural and mechanical characteristics were studied using two probe electrometer, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and tensile measurements. Cellular behavior, proliferation and neural differentiation of rat mesenchymal stem cells (RMSC) seeded on the fabricated scaffolds with different state of conductivity were investigated both in the presence and absence of an external electromagnetic stimulation. Results revealed a linear correlation between electrical conductivity and cell signaling as well as neural gene expression. It is demonstrated that MWNT particles are encapsulated by the TPU and mostly oriented along the nanofibers axis by the electric field imposed on the jetted fibers during electrospinning process. Reinforcement of both bulk and surface modulus was exhibited by MWNT loaded scaffolds, indicating intensification of the interface between TPU and surface modified MWNT partices. Electrical conductivity of scaffolds versus MWNT wt% showed to follow percolation model with a threshold around 2.5 wt% of MWNTs, implying the involvement of both tunneling and conduction mechanisms for the passage of the electron current throughout the scaffolds upon stimulation. RMSCs cultured on MWNT loaded nanofibrous scaffolds with conductivity above threshold exhibited enhanced neural differentiation, suggesting the crucial role of state of electrical conductivity of the scaffolds for directing the proliferation and differentiation of stem cells towards the neural tissues.

中文翻译：

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基于热塑性聚氨酯 (TPU) 的碳纳米管负载电纺支架，增强大鼠间充质干细胞的增殖和神经分化：导电状态的作用

摘要 电磁刺激已被证明是一种促进神经细胞再生的有效策略。使用包括聚合物纳米复合材料在内的导电材料来构建具有修复受损神经系统潜力的支架已经引起了人们的极大关注。在本研究中，已尝试通过静电纺丝工艺制造基于柔性热塑性聚氨酯 (TPU) 和表面功能化多壁碳纳米管 (MWNT) 的纳米结构纤维支架，以检查和突出支架导电状态对神经细胞增殖和分化。为此，制备了包含不同重量百分比 MWNT 的各种支架及其导电性，使用两个探针静电计、扫描电子显微镜 (SEM)、透射电子显微镜 (TEM)、原子力显微镜 (AFM) 和拉伸测量来研究微观结构和机械特性。在存在和不存在外部电磁刺激的情况下，研究了接种在具有不同导电状态的制造支架上的大鼠间充质干细胞 (RMSC) 的细胞行为、增殖和神经分化。结果显示电导率与细胞信号传导以及神经基因表达之间存在线性相关性。结果表明，MWNT 颗粒被 TPU 包裹，并且在静电纺丝过程中施加在喷射纤维上的电场主要沿纳米纤维轴取向。装载 MWNT 的支架表现出体积和表面模量的增强，表明 TPU 和表面改性 MWNT 颗粒之间的界面增强。支架的电导率与 MWNT wt% 显示遵循渗透模型，阈值约为 MWNT 的 2.5 wt%，这意味着在刺激时电子电流通过支架的隧道和传导机制都参与其中。在 MWNT 负载的纳米纤维支架上培养的 RMSCs 具有高于阈值的电导率，表现出增强的神经分化，表明支架的电导率状态在指导干细胞向神经组织增殖和分化方面起着至关重要的作用。表明 TPU 和表面改性 MWNT 颗粒之间界面的强化。支架的电导率与 MWNT wt% 显示遵循渗透模型，阈值约为 MWNT 的 2.5 wt%，这意味着在刺激时电子电流通过支架的隧道和传导机制都参与其中。在 MWNT 负载的纳米纤维支架上培养的 RMSCs 具有高于阈值的电导率，表现出增强的神经分化，表明支架的电导率状态在指导干细胞向神经组织增殖和分化方面起着至关重要的作用。表明 TPU 和表面改性 MWNT 颗粒之间界面的强化。支架的电导率与 MWNT wt% 显示遵循渗透模型，MWNT 的阈值约为 2.5 wt%，这意味着在刺激时电子电流通过支架的隧道和传导机制都参与其中。在 MWNT 负载的纳米纤维支架上培养的 RMSCs 具有高于阈值的电导率，表现出增强的神经分化，表明支架的电导率状态在指导干细胞向神经组织增殖和分化方面起着至关重要的作用。这意味着在刺激时电子流通过支架的隧道和传导机制都参与其中。在 MWNT 负载的纳米纤维支架上培养的 RMSCs 具有高于阈值的电导率，表现出增强的神经分化，表明支架的电导率状态在指导干细胞向神经组织增殖和分化方面起着至关重要的作用。这意味着在刺激时电子流通过支架的隧道和传导机制都参与其中。在 MWNT 负载的纳米纤维支架上培养的 RMSCs 具有高于阈值的电导率，表现出增强的神经分化，表明支架的电导率状态在指导干细胞向神经组织增殖和分化方面起着至关重要的作用。