Hierarchical Topography with Tunable Micro- and Nanoarchitectonics for Highly Enhanced Cardiomyocyte Maturation via Multi-Scale Mechanotransduction.

Enhancing cardiomyocyte (CM) maturation by topographical cues is a critical issue in cardiac tissue engineering. Thus far, single-scale topographies with a broad range of feature shapes and dimensions have been utilized including grooves, pillars, and fibers. This study reports for the first time a hierarchical structure composed of nano-pillars (nPs) on micro-wrinkles (µWs) for effective maturation of CMs. Through capillary force lithography followed by a wrinkling process, vast size ranges of topographies are fabricated, and the responses of CMs are systematically investigated. Maturation of CMs on the hierarchical structures is highly enhanced compared to a single-scale topography: cardiac differentiation of H9C2s (rat cardiomyocytes) on the hierarchical topography is ≈ 2.8 and ≈ 1.9 times higher than those consisting of single-scale µWs and nPs. Both nPs and µWs have important roles in cardiac maturation, and the aspect ratio (height/diameter) of the nPs and the wavelength of the µWs are important in CM maturation. This enhancement is caused by strong focal adhesion and nucleus mediated mechanotransduction of CMs from the confinement effects of the different wavelengths of µWs and the cellular membrane protrusion on the nPs. This study demonstrates how a large family of hierarchical structures is used for cardiac maturation.