Inhibition of Cultured Bovine Aortic Smooth Muscle Cell Proliferation by Colominic Acid

Abstract

Colominic acid (CA) is an a2,8-linked polymer of sialic acid, originally isolated from capsular Escherichia coli K1. 2) have several biological activities including antiviral activities, [3][4][5] inhibition of the cytotoxic action of bee and snake venom, 6) inhibition of P-selectin-dependent macrophage infiltration in the glomeruli in experimental rat crescentic glomerulonephritis 7) and inhibition of fertilization of mouse gametes. 8)Atherosclerosis is the principal vascular lesion in the pathogenesis of myocardial and cerebral infarction, which is initiated by vascular endothelial cell damage followed by an intimal hyperplasia of vascular smooth muscle cells. 9) Although the pathogenesis of atherosclerosis is not simple, inhibition of arterial smooth muscle cell proliferation is one of the effective strategies to prevent atherosclerosis.We have investigated the effects of sodium spirulan (Na-SP), a sulfated polysaccharide isolated from the blue-green alga Spirulina platensis 10) on vascular endothelial and smooth muscle cell functions, and found that the polysaccharide potently inhibits the proliferation of vascular smooth muscle cells.11) In vascular endothelial cells, Na-SP elevates the fibrinolytic activity of vascular endothelial cells through inhibition of the secretion of plasminogen activator inhibitor type 1.12) In addition, Na-SP promotes the secretion of anticoagulant proteoglycans 13) such as perlecan and biglycan, 14) as well as exhibiting an antithrombin activity through activation of heparin cofactor II. 15,16) We hypothesized that CA or SCA may inhibits the proliferation of vascular smooth muscle cell proliferation, as does natural or semi-synthetic polysaccharides, including Na-SP, heparin, 17) pentosan polysulfate 18) and fucoidan.19) The present study was undertaken to examine this hypothesis using a culture system of bovine aortic smooth muscle cells. It was found that both CA and SCA moderately inhibit the proliferation of the cells without nonspecific cell damage. MATERIALS AND METHODS MaterialsVascular smooth muscle cells obtained from bovine aorta were a gift from Professor Yasuo Suda (Graduate School of Science and Engineering, Kagoshima University, Kagoshima, Japan). Dulbecco's modified Eagle's medium (DMEM) and fetal bovine serum were from Nissui Pharmaceutical (Tokyo, Japan) and MP Biomedicals (Irvine, CA, U.S.A.), respectively. Tissue culture plates and dishes were obtained from Iwaki (Chiba, Japan). H]thymidine (3.3 TBq/mmol) was from Parkin Elmer Life Sciences (Boston, MA, U.S.A.). Lactate dehydrogenase kit was from Wako Pure Chemical (Osaka, Japan). CA 20) (M r ca. 17000) and SCA 2) (M r ca. 22000) containing sulfur of 13.4% were isolated from capsular Escherichia coli K1 as sodium salt of an a2,8-linked homopolymer of N-acetylneuraminic acid with or without sulfation. Na-SP and Ca-SP were isolated and purified from the blue-green alga Spirulina platensis as described previously. 10,21,22) Heparin derived from porcine intestine (M r ca. 10000) was purchased from Sigma (St Louis...