Department of Orthopaedics , The First Affiliated Hospital of Soochow University , Suzhou 215006 , China.
Orthopaedic Institute, Medical College , Soochow University , Suzhou 215007 , China.
ACS Appl Mater Interfaces. 2019 Feb 20;11(7):6867-6880. doi: 10.1021/acsami.9b00293. Epub 2019 Feb 6.
Electrospun uniaxially aligned ultrafine fibers show great promise in constructing vascular grafts mimicking the anisotropic architecture of native blood vessels. However, understanding how the stiffness of aligned fibers would impose influences on the functionality of vascular cells has yet to be explored. The present study aimed to explore the stiffness effects of electrospun aligned fibrous substrates (AFSs) on phenotypic modulation in vascular smooth muscle cells (SMCs). A stable jet coaxial electrospinning (SJCES) method was employed to generate highly aligned ultrafine fibers of poly(l-lactide- co-caprolactone)/poly(l-lactic acid) (PLCL/PLLA) in shell-core configuration with a remarkably varying stiffness region from 0.09 to 13.18 N/mm. We found that increasing AFS stiffness had no significant influence on the cellular shape and orientation along the fiber direction with the cultured human umbilical artery SMCs (huaSMCs) but inhibited the cell adhesion rate, promoted cell proliferation and migration, and especially enhanced the F-actin fiber assembly in the huaSMCs. Notably, higher fiber stiffness resulted in significant downregulation of contractile markers like alpha-smooth muscle actin (α-SMA), smooth muscle myosin heavy chain, calponin, and desmin, whereas upregulated the gene expression of pathosis-associated osteopontin ( OPN) in the huaSMCs. These results allude to the phenotype of huaSMCs on stiffer AFSs being miserably modulated into a proliferative and pathological state. Consequently, it adversely affected the proliferation and migration behavior of human umbilical vein endothelial cells as well. Moreover, stiffer AFSs also revealed to incur significant upregulation of inflammatory gene expression, such as interleukin-6 ( IL-6), monocyte chemoattractant protein-1 ( MCP-1), and intercellular adhesion molecule-1 ( ICAM-1), in the huaSMCs. This study stresses that although electrospun aligned fibers are capable of modulating native-like oriented cell morphology and even desired phenotype realization or transition, they might not always direct cells into correct functionality. The integrated fiber stiffness underlying is thereby a critical parameter to consider in engineering structurally anisotropic tissue-engineered vascular grafts to ultimately achieve long-term patency.
静电纺单轴定向超细纤维在构建模仿天然血管各向异性结构的血管移植物方面具有广阔的前景。然而，了解定向纤维的刚度如何对血管细胞的功能产生影响尚未得到探索。本研究旨在探索静电纺单轴定向纤维支架（AFS）的刚度对血管平滑肌细胞（SMCs）表型调节的影响。采用稳定射流同轴静电纺丝（SJCES）方法，以壳核结构制备具有显著变化的刚度区域（0.09-13.18 N/mm）的聚（L-丙交酯-共-己内酯）/聚（L-乳酸）（PLCL/PLLA）高度定向超细纤维。我们发现，随着培养的人脐动脉平滑肌细胞（huaSMCs）沿纤维方向的细胞形状和取向，AFS 刚度的增加没有显著影响，但抑制了细胞黏附率，促进了细胞增殖和迁移，特别是增强了 huaSMCs 中的 F-肌动蛋白纤维组装。值得注意的是，较高的纤维刚度导致收缩标志物如α-平滑肌肌动蛋白（α-SMA）、平滑肌肌球蛋白重链、钙调蛋白和结蛋白的表达显著下调，而与疾病相关的骨桥蛋白（OPN）的基因表达上调。这些结果表明，huaSMCs 在较硬的 AFS 上的表型被悲惨地调节为增殖和病理性状态。因此，它也对人脐静脉内皮细胞的增殖和迁移行为产生不利影响。此外，较硬的 AFS 还显示出炎症基因表达的显著上调，如白细胞介素 6（IL-6）、单核细胞趋化蛋白 1（MCP-1）和细胞间黏附分子 1（ICAM-1）在 huaSMCs 中。这项研究强调，尽管静电纺单轴定向纤维能够调节类似天然的定向细胞形态，甚至实现或转变所需的表型，但它们并不总是能引导细胞进入正确的功能状态。因此，纤维的综合刚度是在工程结构各向异性组织工程血管移植物中考虑的一个关键参数，以最终实现长期通畅。
