Antiproliferative capacity of synthetic dextrans on smooth muscle cell growth: the model of derivatized dextrans as heparin-like polymers

Abstract

Proliferation of vascular smooth muscle cells (SMC) is postulated to be a key step in the pathogenesis of atherosclerosis or restenosis after vascular interventions such as angioplasty. Natural glycosaminoglycans, such as heparin and heparan sulfate, are known for their ability to inhibit SMC proliferation in vivo and in vitro. The antiproliferative activity of synthetic derivatized dextrans exhibiting heparin-like anticoagulant and anticomplement capacities have been investigated with rat aorta smooth muscle cells in culture. We report here that some derivatized dextrans grafted with benzylamide sulfonate moieties are potent antiproliferative agents for rat smooth muscle cell (SMC) in vitro. These synthetic polymers inhibit the SMC proliferation as well as heparin. The SMC growth inhibition is dose dependent, reversible and non-toxic. Highly anionic carboxylic dextrans are not capable of inhibiting the SMC growth, excluding a simple charge effect mechanism. Using fluorescent (DTAF) probes, we demonstrated that the synthetic antiproliferative polymers and heparin are internalized into the SMC. No binding or internalization was observed with native dextran devoid of antiproliferative capacity. We conclude that a suitable distribution of functional groups on the dextran backbone can simulate heparin activity in terms of antiproliferative capacity on SMC growth.

Staining particulate organic matter with DTAF--a fluorescence dye for carbohydrates and protein:a new approach and application of a 2D image analysis system

“…The original use of DTAF was to fluorescently label certain polysaccharides, in particular dextrans, in order to follow their fate in animal or human tissue (e.g. Letourneur et al 1993) or to label proteins, a role in which the relative resistance of DTAF to hydrolysis was confirmed (Siegler et al 1989). Remarkably, binding with DTAF did not alter the reactivity and biological function of the protein molecule (Keith et al 1981).…”

Fluorescent and radiolabeling of polysaccharides: Binding and internalization experiments on vascular cells

“…For all growth experiments, SMCs were incubated for 5 days in 10% FBS medium containing polysaccharides as previously described. 10,24 The concentration that inhibited cell growth by 50% (IC 50 ) was determined from log dose-response curves.…”

“…Derivatized dextran (CMDBS) and fucan were able, as was heparin, to inhibit rat aortic SMC growth in culture, 10,24,25,32,33 whereas native dextran (Dx) and dextran substituted with carboxymethyl (CMD) were totally inactive even at high concentrations. 10,24 All antiproliferative polymers grafted by DTAF remained active on SMC proliferation (IC 50 ≈ 10 g/mL) (Table II).…”

“…[6][7][8] For this purpose, convenient and reliable methods for labeling different polysaccharidic structures are required. Several methods have already been published that include grafting of fluorescent tags 9,10 or radiolabeled elements-namely, 3 H, 35 S, 125 I, or 131 I. [11][12][13][14] Labeling with 125 I of fluoresceinated heparin was also described.…”

“…10,24,25 Fucan, another polysaccharide extracted from seaweed, was also shown to exhibit antiproliferative activity on SMCs. 25 However, the precise mechanisms of the antiproliferative effect are still not understood.…”