A Robust Method to Generate Mechanically Anisotropic Vascular Smooth Muscle Cell Sheets for Vascular Tissue Engineering

摘要

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. Here, we developed a thermo-responsive cell culture platform for growing aligned vascular smooth muscle cell sheets by photo-grafting N-isopropylacrylamide (NIPAAm) onto micro-patterned PDMS. We experimentally and computationally optimized the grafting process to produce PNIPAAm-PDMS substrates optimal for vascular smooth muscle cell (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 (APTES) yielding a robust, thermo-responsive cell culture platform for culturing VSMC sheets. VSMC cell sheets cultured on patterned thermo-responsive substrates exhibit cellular and collagen alignment in the direction of the micro-pattern. Mechanical characterization of patterned, single-layer VSMC sheets reveals increased stiffness in the aligned direction compared to the perpendicular direction whereas non-patterned cell sheets exhibit no directional dependence. Structural and mechanical anisotropy of aligned, single-layer VSMC sheets makes this platform an attractive micro-structural building block for engineering a vascular graft to match the in vivo mechanical properties of native arterial tissue.