Backman Daniel E, LeSavage Bauer L, Shah Shivem B, Wong Joyce Y
Department of Biomedical Engineering, Boston University, 44 Cummington Mall, Boston, MA, 02215, USA.
Division of Materials Science and Engineering, Boston University, 15 Saint Mary's Street, Boston, MA, 02215, USA.
Macromol Biosci. 2017 Jun;17(6). doi: 10.1002/mabi.201600434. Epub 2017 Feb 16.
In arterial tissue engineering, mimicking native structure and mechanical properties is essential because compliance mismatch can lead to graft failure and further disease. With bottom-up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve the necessary macroscale properties in the final implant. This study develops a thermoresponsive cell culture platform for growing aligned vascular smooth muscle cell (VSMC) sheets by photografting N-isopropylacrylamide (NIPAAm) onto micropatterned poly(dimethysiloxane) (PDMS). The grafting process is experimentally and computationally optimized to produce PNIPAAm-PDMS substrates optimal for VSMC attachment. To allow long-term VSMC sheet culture and increase the rate of VSMC sheet formation, PNIPAAm-PDMS surfaces were further modified with 3-aminopropyltriethoxysilane yielding a robust, thermoresponsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermoresponsive substrates exhibit cellular and collagen alignment in the direction of the micropattern. Mechanical characterization of patterned, single-layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas nonpatterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single-layer VSMC sheets makes this platform an attractive microstructural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.
在动脉组织工程中，模仿天然结构和力学性能至关重要，因为顺应性不匹配会导致移植物失败及引发进一步的疾病。采用自下而上的组织工程方法时，设计具有适当微观力学性能的组织组件对于在最终植入物中实现所需的宏观性能至关重要。本研究开发了一种热响应性细胞培养平台，通过将N-异丙基丙烯酰胺（NIPAAm）光接枝到微图案化的聚二甲基硅氧烷（PDMS）上，来培养排列的血管平滑肌细胞（VSMC）片层。对接枝过程进行了实验和计算优化，以制备出最适合VSMC附着的PNIPAAm-PDMS底物。为了实现VSMC片层的长期培养并提高VSMC片层的形成速率，用3-氨丙基三乙氧基硅烷对PNIPAAm-PDMS表面进行了进一步修饰，从而产生了一个用于培养VSMC片层的坚固的热响应性细胞培养平台。在图案化的热响应性底物上培养的VSMC细胞片层在微图案方向上呈现细胞和胶原蛋白的排列。对图案化的单层VSMC片层的力学表征显示，与垂直方向相比，在排列方向上刚度增加，而非图案化的细胞片层则没有方向依赖性。排列的单层VSMC片层的结构和力学各向异性使得该平台成为一种有吸引力的微观结构构建块，可用于构建血管移植物以匹配天然动脉组织的体内力学性能。
