The cardiovascular unit as a dynamic player in disease and regeneration.

Cell-mediated cardiac regeneration remains a challenge as a therapeutic option in heart failure, but modest success using experimental models suggests that a better understanding of normal histogenesis will be needed to make progress towards cardiac regeneration. Recent studies of the heart show that the interstitium informs organogenesis and responsiveness to pathological stimuli through continuous bidirectional cross-talk between cardiomyocytes and non-cardiac cells. Here, we introduce the concept of the "cardiovascular unit" (CVU) as a building block of the heart, which includes cardiomyocytes and adjacent capillaries and fibroblasts. We discuss how the CVU might be used as a tool for re-interpreting degenerative changes of the myocardium during aging and hypertrophy, and might represent the hallmark for successful cell therapy strategies in cardiac regeneration.