Vascular smooth muscle cells cultured on elastin membranes

Smooth muscle cells from thoracic aortas of 12-week-old rats were cultured on elastin membranes for up to 21 days. The cell cultures were examined using light microscopy, trasmission and scanning electron microscopy. The contractile phenotype characteristic for resident arterial wall muscle cell changed to the synthetic phenotype. In the synthetic state, the muscle cells contain few filaments, but a substantial amount of orgenelles are involved with synthesis. The cells grown on elastin substrates showed a multilayered pattern with the formation of nodules. Cell degeneration was present from dayeight and increased with time. At the end of the experiment, the center of the multilayered areas showed degenerative changes with numerous foam cells of smooth muscle origin, areas of necrosis and a considerable amount of calcium deposit. Our experimental model would be valuable in the investigation of the pathological changes associated with smooth muscle cell proliferation in vessels

Cell to stroma contacts in the tunica media of the hypertensive rat thoracic aorta

The variation in mechanical stress to which the aortic wall is subjected requires that forces be transmited between its components by means of relatively strong but compliant attachments. We have used transmission electron microscopy in order to study the cell to stroma contacts (smooth muscle cell-elastic fiber contact) in the tunica media of normotensive and hypertensive aortas of Sprague-Dawley rats. Hypertension was produced with a silver clip positioned around the left renal artery and the vessels were fexed by intravital perfusion at normal and elevated pressure. In ultrathin sections, the density of cell to stroma contacts per 100 µm cell perimeter and per 100 cell profiles were determined using an image analysis computer. In the hypertensive group the density of cell to stroma contacts fell considerably when compared with the control group. This research provides insights into the conditions under which high blood pressure may produce medial injuries and, perhaps, be a factor in the precipitation of dissections