PHENOTYPIC CHARACTERIZATION OF HUMAN SMOOTH-MUSCLE CELLS DERIVED FROMATHEROSCLEROTIC TIBIAL AND PERONEAL ARTERIES

Purpose: The vascular smooth muscle cell plays a pivotal role in the d evelopment of atherosclerosis. The objectives of this study were to ch aracterize smooth muscle cells from the human atherosclerotic tibial a rtery to determine their phenotypic properties and to examine the cont ractile reactions of these cells to physiologic and pharmacologic stim uli. Methods: After below-knee amputations were performed, vascular sm ooth muscle cells were harvested and cultivated from tibioperoneal sou rce. Characterization was done with transmission electron microscopy a nd immunocytochemistry. The contractile properties were determined by observing the response to various stimuli. In addition, segments of ve ssels harvested were submitted to electron microscopy studies for comp arison with the cultured cells. Results: Immunofluorescent labeling wa s positive for ct-smooth muscle actin. Electron microscopy revealed th e presence of a thickened basal laminae and large intracellular lipid vacuoles. The earlier passages revealed cells with a large number of m icrofilaments characteristic of a contractile cell. As later passages were examined, there was a notable change in character with an increas ing amount of rough endoplasmic reticulum and Golgi complexes. The inc reased thickness of the basal lamina in the cultured cells resembled t hat found in vessel segments studied by electron microscopy. A rapid c ontraction response was seen when the cells were incubated with angiot ensin II, bradykinin, or endothelin. No response was seen with the add ition of isoproterenol, nitroglycerin, or nitroprusside, known smooth- muscle relaxants. Conclusion: This model demonstrates the apparent ina bility of these smooth muscle cells from atherosclerotic tibial arteri es to relax to pharmacologic and physiologic stimuli. In addition, as seen by transmission electron microscopy, these cells maintain their a therosclerotic phenotype after multiple passages.