The effects of zoledronic acid on neointimal hyperplasia: a rabbit carotid anastomosis model

Objective: The aim of the present study was to investigate the effect of zoledronic acid (ZA), as a matrix metalloproteinase inhibitor, on neointimal hyperplasia in rabbit carotid anastomosis model. Methods: New Zealand male rabbits were divided into two groups as placebo and treatment groups in this experimental study. After anesthesia, the right carotid artery of each rabbit was end-to-end anastomosed with an 8/0 polypropylene suture. Left carotid artery was kept as control without any operation. Placebo group (n=6) received phosphate buffered saline (PBS) (0.5mL/kg/day/s.c.) for 28 days postoperatively, whereas ZA group (n=6) received ZA (100μg/kg/day/s.c.) for the same period. After sacrification, the anastomosed and control arteries were isolated. Morphometric and immunohistochemical examinations were performed. Statistical analyses of morphometric and immunohistochemical data were performed using two-way ANOVA and Chi-square test respectively. Results: In PBS group, vascular injury in the anastomosed artery significantly increased the intimal area (anastomosed: 112.51±61.18 μm2*1000 vs. control: 22.62±4.26 μm2*1000, p 0.01) and intima/media index (anastomosed: 0.347±0.29 vs. control: 0.075±0.01, p 0.05) compared to control artery. ZA significantly reduced the intimal area (39.29±18.21 μm2*1000, p 0.01) and intima/media index (0.112±0.07, p 0.05) compared to PBS group. Additionally, α-smooth muscle actin immunopositivity was found significantly decreased in anastomosed arteries from ZA group (ZA: 2.33±0.52 vs. PBS: 3.50±0.5, p 0.05). Moreover, intensive gelatinase (MMP-2 and MMP-9) immunoreactivities were clearly seen in anastomosed arteries compared to control arteries from PBS group. ZA apparently decreased immunopositivities for gelatinases in anastomosed arteries. Conclusion: ZA might be a promising agent for prevention of neointimal hyperplasia, which is the most significant cause of graft failures in late postoperative period.