Isolation, Culture, and Live-Cell Imaging of Primary Rat Cardiomyocytes.

The heart is a complex organ consisting of a variety of different cardiomyocytes (ventricular vs. atrial, left vs. right ventricular, working vs. nodal) as well as other cell types, including endothelial cells and vascular smooth muscle cells. Pericytes, neurons, and immune cells are less abundant, yet still important. Whereas cardiomyocytes account for around 75% of the heart volume, 50-70% of the cells in the heart are non-myocytes. This complexity of the heart underlines the difficulties in interpreting data obtained in vivo. In the field of cardiac regeneration, it remains unclear whether it is possible to induce a significant number of cardiomyocytes to proliferate and whether the often-observed improvement in cardiac function after experimental therapies is due to the induction of cardiomyocyte proliferation. Therefore, the reductionist approach inherent to cultures of isolated cells continues to be of great importance, even though it is important to study heart disease in vivo due to interactions of the different cell types. Cultured cardiomyocytes allow for easy manipulation of cell behavior (e.g., cell division) and its analysis (e.g., live-cell imaging). In addition, isolated cells in culture are a valuable tool for pharmacological and toxicological studies. This chapter offers a practical guide to isolate and culture primary neonatal and adult rat cardiomyocytes and a detailed protocol for live-cell imaging of embryonic and neonatal cardiomyocytes.