Establishment of vessel-like structures in long-term three-dimensional tissue culture of myocardium: an electron microscopy study.

ABSTRACT

To assess whether long-term three-dimensional (3D) tissue culture of myocardium enables the in vitro establishment of vessel-like structures, myocardial tissue from newborn mice was incubated under conditions of 3D culture for at least 3 weeks, and studied by phase-contrast microscopy, conventional histology, immunohistochemistry, and electron microscopy. During 3 weeks of culture, a mean 24.35 +/- 3.74% of all aggregates contracted spontaneously. The contracting aggregates displayed a tissue-like architecture with small basal and apical zones, and a large central zone. The basal and apical zone consisted of immature mesenchymal cells. The underlying shell of the aggregate contained many cardiomyocytes. Vessel-like structures were found concentrated within the aggregates. Immunohistochemistry showed that up to 15% of the cells in the central zone of the aggregate were positive for the endothelial-specific BS-I lectin. Vessel-like structures were formed by cells, which often showed intracytoplasmatic lumena. Surrounding the neocapillaries, structures of a rudimentary basal membrane could be detected. A 3D culture of myocardial tissue permits the establishment of a rudimentary capillary network within the tissue aggregates, which presumably guarantees a sufficient tissue perfusion up to a maximum aggregate diameter of approximately 900 microm.