Functional Capacity of Neonatal Mammalian Myocardial Cells during Aging in Tissue Culture

Abstract

Human aging accompanied by a logarithmic increase in death rate from disease, especially from cardiovascular disorders and decreased efficiency in homeostatic mechanisms. Comfort (1) speculates that, is throughout life man had the same resistance to stress and disease as at age 20, one-half of us could expect to live to the age of 700. Heart diseases are the leading causes of death in people over the age of 55. Since the best way to prolong life in humans is to remove the pathologic causes of death, it would be the most effective course ofaction. The heart is responsive to a multiplicity of external influences impinging on it through the circulation and by the nervous system. Within the heart, self-regulation occurs by means of pacemaker tissue and the Purkinje fiber system (2). Because of these factors which complicate studies of the cellular changes of myocardial cells during aging, we have chosen to work with ventricular newborn rat heart cells in culture as an experimental model. The initial studies on this material were made by Harary and Farley (3) and later by Mark and Strasser (4). We find that the individual myocardial cells are self-contracting units which rapidly link up in vitro to form beating networks. In long-term primary cultures which are kept as long as 100 days, these networks aggregate during this period and produce “mini-hearts” and fibers which are visible to the eye. Cultured cells can be sucessfully stored at liquid nitrogen temperature and recultured several times. These and other results were presented at the meeting, partly in the form of two 16 mm movie films --- “Mitosis and Differentiated Properties of Mammalian Myocardial Cells in Culture”, and “Contractile Behavior of Myocardial Cells In Vitro”. For the purpose of documentation, still photomicrographs, which are based on the same biological material as that employe- in the films, are used in the manuscript.