Measurement and control of mechanics of cardiac trabeculae secured by light-curable hydrogel

Isolated cardiac trabeculae are small heart muscle tissue preparations, which have been widely used in in vitro studies of mechanics and energetics function of cardiac muscle. Current instruments for such experimentation often (1) involve delicate mounting of the muscle, (2) constrain investigations to one muscle at a time, and thus (3) limit experimental throughput. Here, we present a novel device that allows trabeculae to be secured by a visible-light photo-crosslinked hydrogel, manipulated via a robust motor-driven stainless steel cantilever, and their shortening and force production to be measured and controlled using feedback from real-time imaging. The device has multiple wells, making it amenable to high-throughput testing of muscle. We use our robust, accurate image registration techniques to measure cantilever and gel deformation during trabecula contraction and thereby provide a measure of trabecula shortening and force production during twitches. We apply methods to allow the trabecula to contract either isometrically or isotonically. The methods used in this device can be widely applied to the study of the mechanics of cardiac muscle samples in laboratories with available light microscopic systems.