In vitro engineering of heart muscle: artificial myocardial tissue.

INTRODUCTION Myocardial infarction followed by heart failure represents one of the major causes of morbidity and mortality, particularly in industrialized countries. Engineering and subsequent transplantation of contractile artificial myocardial tissue and, consequently, the replacement of ischemic and infarcted areas of the heart provides a potential therapeutic alternative to whole organ transplantation. METHODS Artificial myocardial tissue samples were engineered by seeding neonatal rat cardiomyocytes with a commercially available 3-dimensional collagen matrix. The cellular engraftment within the artificial myocardial tissues was examined microscopically. Force development was analyzed in spontaneously beating artificial myocardial tissues, after stretching, and after pharmacologic stimulation. Moreover, electrocardiograms were recorded. RESULTS Artificial myocardial tissues showed continuous, rhythmic, and synchronized contractions for up to 13 weeks. Embedded cardiomyocytes were distributed equally within the 3-dimensional matrix. Application of Ca(2+) and epinephrine, as well as electrical stimulation or stretching, resulted in enhanced force development. Electrocardiographic recording was possible on spontaneously beating artificial myocardial tissue samples and revealed physiologic patterns. CONCLUSIONS Using a clinically well-established collagen matrix, contractile myocardial tissue can be engineered in vitro successfully. Mechanical and biologic properties of artificial myocardial tissue resemble native cardiac tissue. Use of artificial myocardial tissues might be a promising approach to reconstitute degenerated or failing cardiac tissue in many disease states and therefore provide a reasonable alternative to whole organ transplantation.