Type V collagen represses the attachment, spread, and growth of porcine vascular smooth muscle cells in vitro

Abstract

We attempted to clarify the effects of various purified extracellular components, including types I, III, IV, and V collagen and fibronectin on attachment, spread, growth, and DNA synthesis of porcine aortic smooth muscle cells (SMCs) in vitro. The number, area and shape index ( SI = 4π S L 2 ) of cells attached to different substrates were determined at various intervals of incubation. The cell number and [ 3H]thymidine incorporation into DNA were measured on the 1st and 6th days of culture. SMCs showed the largest number of attached cells on fibronectin, but the smallest number of attached cells on type V collagen. There was no evidence of effects of the serum in media on the attachment of SMCs to the substrates. The areas of attached SMCs were the largest on fibronectin and the smallest on type V collagen. The shape index of SMCs on fibronectin decreased relative to those on other substrates. On the 6th day in culture, the number and population doubling of SMCs on type V collagen were significantly fewer than those on other substrates. Both the incorporation rate of [ 3H]thymidine into DNA and the percentage of nuclei labeled with [ 3H]thymidine were significantly less in the SMCs on type V collagen on the 1st day than those on other substrates. SMCs on types I, III, and IV collagen showed intermediate levels of cell attachment, spread, and growth. These results suggest that attachment, spread, and growth of SMCs are affected mainly by solid phase purified extracellular components and are most strongly suppressed by type V collagen. When DNA synthesis of growth-arrested SMCs was reinitiated by the addition of serum, type V collagen most intensively inhibited the rate and amount of [ 3H]thymidine incorporation. Flow cytometric analysis demonstrated an increase in the proportion of cells in G 0 G 1 phase on type V collagen in comparison with that on other substrates. Thus, the antiproliferative effect of type V collagen may relate to inhibition of transition of SMCs from the G 0 G 1 into the S phase.