Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
PLoS One. 2012;7(7):e41065. doi: 10.1371/journal.pone.0041065. Epub 2012 Jul 25.
Bisphosphonates are a class of pharmacologic compounds that are commonly used to treat postmenopausal osteoporosis and malignant osteolytic processes. Studies have shown that bone marrow-derived endothelial progenitor cells (EPCs) play a significant role in postnatal neovascularization. Whether the nitrogen-containing bisphosphonate zoledronate inhibits ischemia-induced neovascularization by modulating EPC functions remains unclear.
METHODOLOGY/PRINCIPAL FINDINGS: Unilateral hindlimb ischemia was surgically induced in wild-type mice after 2 weeks of treatment with vehicle or zoledronate (low-dose: 30 μg/kg; high-dose: 100 μg/kg). Doppler perfusion imaging demonstrated that the ischemic limb/normal side blood perfusion ratio was significantly lower in wild-type mice treated with low-dose zoledronate and in mice treated with high-dose zoledronate than in controls 4 weeks after ischemic surgery (control vs. low-dose vs. high-dose: 87±7% vs. *61±18% vs. **49±17%, *p<0.01, **p<0.005 compared to control). Capillary densities were also significantly lower in mice treated with low-dose zoledronate and in mice treated with high-dose zoledronate than in control mice. Flow cytometry analysis showed impaired mobilization of EPC-like cells (Sca-1(+)/Flk-1(+)) after surgical induction of ischemia in mice treated with zoledronate but normal levels of mobilization in mice treated with vehicle. In addition, ischemic tissue from mice that received zoledronate treatment exhibited significantly lower levels of the active form of MMP-9, lower levels of VEGF, and lower levels of phosphorylated eNOS and phosphorylated Akt than ischemic tissue from mice that received vehicle. Results of the in vitro studies showed that incubation with zoledronate inhibited the viability, migration, and tube-forming capacities of EPC.
CONCLUSIONS/SIGNIFICANCE: Zoledronate inhibited ischemia-induced neovascularization by impairing EPC mobilization and angiogenic functions. These findings suggest that administration of zoledronate should be withheld in patients with ischemic events such as acute limb ischemia.
双膦酸盐是一类药理学化合物，常用于治疗绝经后骨质疏松症和恶性溶骨性过程。研究表明，骨髓来源的内皮祖细胞（EPCs）在出生后新生血管化中发挥重要作用。氮双膦酸盐唑来膦酸是否通过调节 EPC 功能来抑制缺血诱导的新生血管化尚不清楚。
方法/主要发现：在给予载体或唑来膦酸（低剂量：30μg/kg；高剂量：100μg/kg）治疗 2 周后，通过手术诱导野生型小鼠单侧后肢缺血。多普勒灌注成像显示，缺血后肢/正常侧血流灌注比值在低剂量唑来膦酸治疗的野生型小鼠和高剂量唑来膦酸治疗的小鼠中显著低于对照组（对照组 vs. 低剂量 vs. 高剂量：87±7% vs. *61±18% vs. **49±17%，*p<0.01，**p<0.005 与对照组相比）。低剂量唑来膦酸治疗的小鼠和高剂量唑来膦酸治疗的小鼠的毛细血管密度也明显低于对照组。流式细胞术分析显示，在接受唑来膦酸治疗的小鼠中，EPC 样细胞（Sca-1(+)/Flk-1(+))在手术诱导缺血后动员受损，但在接受载体治疗的小鼠中动员正常。此外，接受唑来膦酸治疗的小鼠缺血组织中 MMP-9 的活性形式、VEGF 水平以及磷酸化 eNOS 和磷酸化 Akt 水平均明显低于接受载体治疗的小鼠缺血组织。体外研究结果表明，唑来膦酸孵育抑制 EPC 的活力、迁移和管状形成能力。
结论/意义：唑来膦酸通过损害 EPC 的动员和血管生成功能来抑制缺血诱导的新生血管化。这些发现表明，在患有急性肢体缺血等缺血性事件的患者中应避免使用唑来膦酸。
