Cardiovascular disease remains a pervasive and significant clinical problem, making it the target of extensive research for novel therapeutic strategies. In this report, we focus on describing the methods for the fabrication of cardiac strands with donor inserts and the application of this assay to test the ability of a few selected donor cell types to bridge and propagate electrical impulses from one cardiomyocyte area to another. We showed a set of reproducible, well-controlled in vitro assays that allow for the comparative and quantitative studies of cardiomyocyte and donor cell interactions on several functional levels. Cellular therapies are emerging rapidly as one of the more promising methodologies to repair injured myocardium.