Laboratory of Veterinary Molecular Pathology and Therapeutics, Division of Animal Life Science, Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
Cardiovasc Res. 2011 Nov 1;92(2):209-17. doi: 10.1093/cvr/cvr203. Epub 2011 Jul 19.
Intermittent claudication (IC) is one of the serious symptoms of peripheral arterial disease (PAD) and is characterized by pain in the legs or buttocks that worsens with exercise and subsides with rest. The concept of 'therapeutic angiogenesis' for PAD has been widely proposed; however, the methodology, including cell transplantation, is still unclear. In this study, we examined the clinical efficacy of silencing the int6 gene, which encodes a protein that stabilizes hypoxia-inducible factor (HIF)-2α, on angiogenesis in PAD.
An animal model for IC was established in Sprague-Dawley rats by external iliac artery ligation and evaluated by quantitative analysis of gait disturbance. Next, we explored the therapeutic effects of int6 siRNA injected into the adductor magnus muscle on IC. Recovery of hindlimb function occurred in the early stages after int6 siRNA injection. The number of blood vessels showed an obvious increase in the int6 siRNA-treated muscles. Angiography revealed the recovery of peripheral circulation at the affected sites. Early up-regulation of HIF-2α and other angiogenic factors, including basic fibroblast growth factor and hepatocyte growth factor, was also apparent in the int6 siRNA-treated sites. We also confirmed the up-regulation of HIF-2α and its translocation to the nucleus in the int6 siRNA-injected muscle.
A single injection of int6 siRNA promoted angiogenesis via up-regulation of HIF-2α-related angiogenic factors in the muscles of the affected hindlimb and reduced gait disturbance. The int6 gene may be a novel therapeutic target for the treatment of IC in patients with PAD.
间歇性跛行（IC）是外周动脉疾病（PAD）的严重症状之一，其特征是腿部或臀部疼痛，在运动时加重，休息时缓解。PAD 的“治疗性血管生成”概念已被广泛提出；然而，包括细胞移植在内的方法仍不清楚。在这项研究中，我们研究了沉默编码稳定缺氧诱导因子（HIF）-2α的蛋白的 int6 基因对 PAD 血管生成的临床疗效。
通过结扎大鼠外髂动脉建立了 IC 的动物模型，并通过步态障碍的定量分析进行评估。接下来，我们探索了 int6 siRNA 注射到内收大肌对 IC 的治疗效果。注射 int6 siRNA 后早期，后肢功能恢复。在 int6 siRNA 处理的肌肉中，血管数量明显增加。血管造影显示受影响部位的外周循环恢复。在 int6 siRNA 处理的部位，HIF-2α和其他血管生成因子（包括碱性成纤维细胞生长因子和肝细胞生长因子）也明显上调。我们还证实了 HIF-2α及其向核内转位在 int6 siRNA 注射肌肉中的上调。
单次注射 int6 siRNA 通过上调受影响后肢肌肉中与 HIF-2α相关的血管生成因子促进血管生成，并减少步态障碍。int6 基因可能是治疗 PAD 患者 IC 的新治疗靶点。
