Growth, structure and function of baboon aortic smooth muscle cells in culture

Procedures for the successful culture of aortic medial smooth muscle cells (SMC) from the baboon (Papio cynocephalus) have been described. Growth rates, plating efficiency, and doubling times were determined. SMC showed increasing growth with increasing concentrations of heat-inactivated homologous serum. Growth on glass was accelerated relative to plastic surfaces, a difference reflected in the more numerous and extensive attachment sites on glass and more extensive cellular spreading. Attachment sites on both glass and plastic were associated with short parallel arrays of thin filaments (50 Å). The fine structure of SMC grown on plastic or glass was examined at intervals from 7 to 74 days in culture. Cells exhibited many of the features traditionally associated with cultured SMC, including basement membrane material and extracellular matrix, predominantly thin cytoplasmic filaments (40-80 Å) with dense bodies, coated pits and vesicles, caveolae and pinocytotic vesicles, and both cell-cell and internalized gap junctions. Changes with increasing time in culture included an increased extracellular matrix, more numerous lipid inclusions, residual bodies, myelin forms, multivesicular bodies, and crystalline lysosomal inclusions. Membranous multivesicular blebs and extruded autophagosomes were also seen with increasing frequency. An increasing culture age was also associated with changes in organelles, including less prominent Golgi profiles, more free ribosomes, dilatation of the cisternae of the RER, and less prominent shorter profiles of mitochondria with increasing electron density. Cultured SMC exhibited both a continuous and a homogeneous ruthenium red-staining glycocalyx around their perimeter, and the ability to respond to the polycationic ligand, CF, with a redistribution of surface-associated anionic binding sites. Additionally, they have been shown to possess high-affinity LDL receptors (K_d = 1 × 10^-7 M) with binding showing half-maximal saturation at 20 μg/ml.