Contents Introduction
Engineered heart tissue (EHT) models have demonstrated valuable potential to reproduce the (patho)physiology of human cardiac tissue in vitro [1]. They are composed of cardiomyocytes (CMs) and non-cardiomyocyte cells within an extracellular matrix (ECM), which self-assemble into tissue-like constructs around two or multiple elastic anchoring points, here called (micro)pillars. For a platform meant to culture EHTs, the design of substrate, the shape and number of elastic pillars, and their mechanical properties are crucial for tissue formation. In our previous miniature EHT platform based on polydimethylsiloxane (PDMS) [2], the cell-gel mixture self-assembled into a tissue-like construct around a pair of micropillars with uniform, rectangular cross-section within an elliptic microwell. However, tests showed that such straight pillar geometry is not optimal for long-term tissue culture, as tissues tend in time to increase the contraction force and move upwards towards the pillars' tip, eventually jumping off and detaching from the pillars in extreme cases. Variation in tissues' adherence position along the pillars hampers precise and consistent measurements of tissue contractile parameters. To address this issue, herein we introduce a tailored tapering in pillar design to constrain the tissue on a precisely defined position along the pillars' length.
