Kishan Alysha P, Robbins Andrew B, Mohiuddin Sahar F, Jiang Mingliang, Moreno Michael R, Cosgriff-Hernandez Elizabeth M
Department of Biomedical Engineering, Texas A&M University, College Station, TX 77843-3120, USA; Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843-3123, USA.
Acta Biomater. 2017 Jul 1;56:118-128. doi: 10.1016/j.actbio.2016.12.041. Epub 2016 Dec 22.
Although a variety of fabrication methods have been developed to generate electrospun meshes with gradient properties, no platform has yet to achieve fiber alignment in the direction of the gradient that mimics the native tendon-bone interface. In this study, we present a method combining in-line blending and air-gap electrospinning to address this limitation in the field. A custom collector with synced rotation permitted fiber collection with uniform mesh thickness and periodic copper wires were used to induce fiber alignment. Two poly(ester urethane ureas) with different hard segment contents (BPUR 50, BPUR 10) were used to generate compositional gradient meshes with and without fiber alignment. The compositional gradient across the length of the mesh was characterized using a fluorescent dye and the results indicated a continuous transition from the BPUR 50 to the BPUR 10. As expected, the fiber alignment of the gradient meshes induced a corresponding alignment of adherent cells in static culture. Tensile testing of the sectioned meshes confirmed a graded transition in mechanical properties and an increase in anisotropy with fiber alignment. Finite element modeling was utilized to illustrate the gradient mechanical properties across the full length of the mesh and lay the foundation for future computational development work. Overall, these results indicate that this electrospinning method permits the fabrication of macromolecular gradients in the direction of fiber alignment and demonstrate its potential for use in interfacial tissue engineering.
The native tendon-bone interface contains a gradient of properties that ensures stability of the joint. Without this transition, failure can occur due to stress concentration at the bone insertion site. Electrospinning is a method commonly used to produce fibrous grafts with gradient properties; however, no current method allows for gradients in the direction of fiber alignment. This work details a novel electrospinning method to produce gradients in the direction of fiber alignment in order to better mimic transitional zones and improve regeneration of the tendon-bone interface. In addition to the biomechanical gradients demonstrated here, this method may also be used to generate gradients of macromolecular, biochemical, and cellular cues with broad potential utility in tissue engineering.
尽管已经开发出多种制造方法来制备具有梯度特性的电纺网，但尚未有平台能够实现纤维在模仿天然肌腱-骨界面的梯度方向上排列。在本研究中，我们提出了一种结合在线共混和气隙电纺的方法来解决该领域的这一局限性。一个具有同步旋转功能的定制收集器允许收集具有均匀网厚的纤维，并使用周期性铜线诱导纤维排列。使用两种具有不同硬段含量的聚（酯脲脲）（BPUR 50、BPUR 10）来制备有和没有纤维排列的成分梯度网。使用荧光染料对网长度上的成分梯度进行表征，结果表明从BPUR 50到BPUR 10的连续过渡。正如预期的那样，梯度网的纤维排列在静态培养中诱导了贴壁细胞的相应排列。对切片网的拉伸测试证实了机械性能的梯度过渡以及随着纤维排列各向异性的增加。利用有限元建模来说明网全长上的梯度机械性能，并为未来的计算开发工作奠定基础。总体而言，这些结果表明这种电纺方法允许在纤维排列方向上制造大分子梯度，并证明了其在界面组织工程中的应用潜力。
天然肌腱-骨界面包含确保关节稳定性的特性梯度。没有这种过渡，由于骨插入部位的应力集中可能会发生失效。电纺是一种常用于生产具有梯度特性的纤维移植物的方法；然而，目前没有方法能够实现纤维排列方向上的梯度。这项工作详细介绍了一种新颖的电纺方法，以在纤维排列方向上产生梯度，以便更好地模仿过渡区并改善肌腱-骨界面的再生。除了这里展示的生物力学梯度外，该方法还可用于产生大分子、生化和细胞线索的梯度，在组织工程中具有广泛的潜在用途。
