Abstract: A microfluidic device is provided that incorporates a highly organized co-culture of live cells within a microengineered platform, by which the architecture and cellular constituents of an organ or other native tissue environment may be modeled over a long period of culture for biological and/or pharmacological studies. Vertical posts (e.g., microposts) may be used to induce alignment of hydrogel-encapsulated tissues in a cell suspension region of a microfluidic device. Such a device can complement animal studies in recapitulating pathophysiological characteristics of disease. When populated with cardiac cells, such a device provides a three-dimensional (3D) biomimetic human cardiac tissue model that enables the study of pathophysiological events involved in the transition of healthy to diseased cardiac tissue, to better inform therapeutic strategies and functional outcomes in cardiac-based therapies. Other types of cells may be used in certain embodiments.