Histotypic Angiogenesis in vitro: Light Microscopic, Ultrastructural, and Radioautographic Studies

• Published in: In Vitro 1982-06, Vol.18 (6), p.538-549
• Main Authors: Nicosia, Roberto F., Tchao, Ruy, Leighton, Joseph
• Format: Article
• Language: English
• Subjects: Angiogenesis; Animals; Aorta; Aorta - anatomy & histology; Aorta - metabolism; Autoradiography; Capillaries; Cell growth; Cultured cells; DNA - biosynthesis; Endothelial cells; Endothelium; Luminous intensity; Male; Microscopy, Electron; Models, Biological; Neovascularization, Pathologic; Organ Culture Techniques; Rats; Rats, Inbred F344; Ruthenium; Sprouting
• ISSN: 0073-5655; 1475-2689
• DOI: 10.1007/bf02810077

A model for the study of angiogenesis in vitro is described. Rat aortas, cultured in a tridimensional matrix of clotted chick plasma, gave rise to luxuriant outgrowth of vascular channels. We studied this process with light microscopic, radioautographic, and ultrastructural techniques. On the 2nd d of culture, endothelial cells sprouted from the intima of the aorta and its collateral branches into the surrounding clot, forming solid cellular cords. A complex vascular network was established within the 1st wk by spindly, poorly differentiated endothelial cells. At this stage cells were migrating, branching, and proliferating in a longitudinal fashion (labeling index: 67.4% ± 7.7). Lumens, when present, appeared as slitlike spaces enclosed with junctional complexes. By the end of the 2nd wk the migratory activity decreased and proliferation occurred mostly in a cross-sectional plane, with formation of large patent lumens (labeling index: 48% ± 3.1). Vascular channels were lined by prominent endothelial cells rich in rough endoplasmic reticulum, polysomes, mitochondria, Golgi apparatuses, and coated vesicles. Cells were enveloped with a ruthenium red positive layer, particularly abundant on the luminal surface and in the inter-endothelial space. A discontinuous basal lamina was present along the abluminal side. At 28 d the labeling index was reduced to 2.25% ± 0.9. The still viable endothelium exhibited numerous microfilaments and microtubules, decreased cytoplasmic organelles, and increased pinocytotic activity. This experimental model, histophysiologic gradient culture, provides us with a new tool for the study of vascular morphogenesis, angiogenesis dependent growth of tumors, and neoplastic intravasation.