Culture and characterization of fetal human atrial and ventricular cardiac muscle cells.

Atrial and ventricular cardiac muscle cells isolated from 14- to 18-wk old fetal human hearts were grown in culture and characterized. Once established in culture the flattened cells contracted spontaneously and possessed differentiated ultrastructural characteristics including organized sarcomeres, intercalated discs, and transverse tubules with couplings. Atrial granules were present in the cultured atrial cells. Some cultured ventricular myocytes also contained electron-dense granules associated with Golgi cisternae, which were similar in size and appearance to atrial granules. The cultured ventricular myocytes divided and expressed the genes for thymidine kinase, histone H4, myosin heavy chain, muscle-specific creatine kinase, atrial natriuretic factor, and insulin-like growth factor II. These results establish that differentiated fetal human heart muscle cells can be cultured in sufficient quantities for biochemical, molecular, and morphological analyses.