增龄对大鼠缺血后肢侧支血管生长的影响

Effect of aging on collateral vessel growth in rats with ischemic hind limbs

背景:以往动物实验发现,将血管生成细胞或生长因子注入实验动物可显著促进侧支血管的生长。然而,临床随机对照试验包括给予重症下肢缺血或心肌梗死患者血管生成细胞均显示没有改善缺血组织血流恢复。对比动物实验的显著效果和令人失望的临床试验结果可能反映出一个事实,即在多数实验室研究用的是年轻动物,而缺血性心血管疾病患者大多数都是老年人。目的:利用成年和老年大鼠股动脉结扎的后肢缺血模型探讨增龄对大鼠缺血后肢侧支血管生长的影响。方法:健康成年大鼠(6月龄)和老年大鼠(20月龄)各12只,均分为假手术组和结扎组。结扎组大鼠行股动脉结扎手术建立后肢缺血模型。大鼠术后存活1周,每组3只大鼠取后肢带侧支血管的肌肉做冰冻切片用于免疫荧光组织化学染色法检测内皮型一氧化氮合酶,Ki67和基质金属蛋白酶2的表达;另外每组3只使用明胶四氧化三铅进行血管造影再用X射线拍照观察侧支血管的生长情况。结果与结论:(1)与同月龄假手术组的大鼠相比,结扎组的大鼠后肢的侧支血管数量、Ki67阳性细胞数量、内皮型一氧化氮合酶和基质金属蛋白酶2的表达也显著增强(P<0.01);(2)与成年大鼠结扎组相比,老年大鼠结扎组后肢的侧支血管数量和Ki67阳性细胞数量少(P<0.01),内皮型一氧化氮合酶和基质金属蛋白酶2的表达显著减弱(P<0.05);(3)结果证实,增龄可导致大鼠缺血后肢侧支血管生长受损。

BACKGROUND:Animal experiments have found that injection of angiogenic cells or growth factors into experimental animals significantly promotes the growth of collateral vessels.However,a large number of clinical randomized controlled trials,including administration of angiogenic cells to patients with severe lower limb ischemia or myocardial infarction,have been ineffective to restore the blood flow in ischemic tissues.By comparing the remarkable effects of animal experiments and disappointing clinical trial results,it may reflect a fact that young animals are used in most laboratories,while most of the patients with ischemic diseases are elderly.OBJECTIVE:To explore the effect of aging on the growth of collateral vessels in ischemic hind limbs in adult and aged rat models of femoral artery ligation.METHODS:Twelve healthy adult rats(6-month-old)were divided into adult sham group and adult ligation group,and 12 aged rats(20-month-old)were divided into aged sham group and aged ligation group.Rats in the ligation groups underwent femoral artery ligation.The rats survived for 1 week after surgery.Three rats in each group were taken and the muscles with collateral vessels in the hind limbs were taken for frozen section for immunofluorescence histochemical detection of endothelial nitric oxide synthase,Ki67 and matrix metalloproteinase 2.Another three rats from each group were subjected to angiography using gelatin trioxide and X-ray for observing the growth of collateral vessels.RESULTS AND CONCLUSION:Compared with the sham groups,rats in the ligation groups had more collateral vessels in hind limbs,increased number of Ki67-positive cells and increased expression of endothelial nitric oxide synthase and matrix metalloproteinase 2(P<0.01).Compared with the adult ligation group,the number of collateral vessels was less(P<0.01),the number of Ki67 positive cells was reduced(P<0.01),and the expression of endothelial nitric oxide synthase and matrix metalloproteinase 2 was significantly decreased in the aged ligation group(P<0.01).Overall,aging impairs the growth of collateral vessels in ischemic hind limbs of rats.