SUSTAINED INHIBITION OF INTIMAL THICKENING - IN-VITRO AND IN-VIVO EFFECTS OF POLYMERIC BETA-CYCLODEXTRIN SULFATE

Intimal thickening after vascular injury may be modulated in part by h eparin binding growth factors. We hypothesized that placement of a the rapeutic polymer in the periadventitial space capable of tightly bindi ng growth factors might alter the vascular response to injury, We firs t demonstrated that incubation of rat aortic smooth muscle cells with an insoluble, sulfated polymer of beta-cyclodextrin (P-CDS) was associ ated with a dose-dependent inhibition of proliferation induced by feta l calf serum, fibroblast growth factor-2 (FGF-2), platelet-derived gro wth factor BE, of epidermal growth factor, Preincubation studies of P- CDS with FGF-2 revealed a very rapid removal of mitogenic activity, Us ing radiolabeled FGF-2 (0.25 mu g/ml), we observed a very rapid associ ation rate (0.34+/-0.07 min(-1), n = 4) and a very slow dissociation r ate (3.3+/-0.2 x 10(-7) min(-1)) at 37 degrees C, suggesting a high af finity interaction, Using both Transwell and linear under-agarose assa ys, we demonstrated a significant inhibition of random migration (chem okinesis) by P-CDS, Unsulfated polymeric beta-cyclodextrin (P-CD) had little if any of these effects, suggesting that the high negative char ge density of P-CDS was important for the effects, Finally, rats under going carotid artery balloon injury were randomized to treatment with periadventitial P-CDS or no treatment, and were killed at 4 (n = 20), 14 (n = 59), and 88 d (n = 14), Morphometric analysis demonstrated sig nificant and sustained inhibition of intimal thickening in P-CDS-treat ed rats at 14 (P < 0.01) and 88 d (P < 0.05) using absolute intimal ar ea or intima/media area ratios, No inhibition was seen in a group of r ats treated with P-CD, In P-CDS - treated rats, bromodeoxyuridine labe ling studies revealed fewer labeled smooth muscle cells in the intima at 14 d (P = 0.01), while staining with Evans blue revealed enhanced l ate endothelial cell regrowth, Thus, periadventitially applied sulfate d beta-cyclodextrin polymer, which can tightly bind heparin binding gr owth factors, inhibits intimal thickening in vivo in a sustained fashi on without using an additional delivery system, These studies suggest that cellular processes mediated by heparin binding growth factors may be modulated by P-CDS.