INVITRO ANALYSIS OF EXTRACELLULAR-MATRIX PRODUCTION BY PORCINE GLOMERULAR MESANGIAL AND VASCULAR SMOOTH-MUSCLE CELLS

Proliferation potential and extracellular matrix production were compared in cultured porcine glomerular mesangial cells and arterial and venous smooth muscle cells. Mesangial and arterial smooth muscle cells proliferated more rapidly than venous smooth muscle cells. In immunofluorescence studies, mesangial and arterial smooth muscle cells stained strongly for collagen types I, III, and V; venous smooth muscle showed weaker staining for collagens III and V. Total collagen synthesis in cultured mesangial and arterial smooth muscle cells was lower than in venous smooth muscle cells. Electrophoretic analysis showed type I collagen predominated in all cell types, although levels were highest in mesangial and arterial smooth muscle cells. Collagen V (alpha-3) occurred only in venous smooth muscle cells. Mesangial and arterial smooth muscle cells showed cell-bound fibronectin and laminin, which also were secreted into the medium. Venous smooth muscle cells secreted fibronectin, but all laminin was cell bound. The findings suggest a strong similarity between mesangial and arterial smooth muscle cells.