Kallikrein基因转导对脑缺血再灌注后局部血流灌注恢复的作用

摘要

目的 探讨Kallikrein基因对脑缺血再灌注后梗死灶周围血管增生与局部脑血流灌注恢复的作用.方法 建立大鼠脑缺血再灌注模型,术后将90只大鼠按照随机数字表法分为3组.每组30只,分别是空白对照组、注射生理盐水、注射pAdCMV-人组织激肽释放酶(HTK)组.各组大鼠又分为治疗后12 h、24 h及72 h组,每组各10只.治疗前后行大鼠神经功能缺损评分.TTC染色方法测定脑梗死面积的变化,用免疫组化检测外源性HTK的表达以及局部血管内皮生长因子(VEGF)的表达,并通过14C-iodoantipyrine微示踪技术检测局部脑血流灌注(rCBF)情况.结果 与其他两组相比,pAdCMV-HTK组大鼠脑梗死面积在治疗后24h已有明显减小,72h后这种变化更明显,差异有统计学意义(P<0.05);在治疗后24 h,pAdCMV-HTK组大鼠神经功能缺损评分明显低于生理盐水组及空白对照组,治疗后72h差异更明显,差异有统计学意义(P<0.05).vEGF阳性细胞主要分布于脑梗死灶周边皮质与部分白质;pAdCMV-HTK组VEGF表达在治疗后12h、24h、72h均明显高于生理盐水组及空白对照组,差异有统计学意义(P<0.05).各组缺血再灌注后脑梗死灶周围白质与皮质rCBF均较对侧稍减少:pAdCMV-HTK组治疗后12h,梗死灶周围白质与皮质rCBF较空白对照组与生理盐水组有增高.但不明显,差异无统计学意义(P>0.05),而在治疗24h、72 h后rCBF则明显增高,差异有统计学意义(P<0.05).结论 在脑缺血再灌注后,Kallikrein基因转导可增加梗死灶周围脑组织的血管增生,改善rCBF,减小梗死面积,从而达到保护缺血神经细胞功能的作用.%Objective To investigate the effects ofkallikrein gene transfer on microvascularproliferation around the cerebral infarct and on the recovery of regional cerebral blood flow (rCBF)following ischemia/reperfusion injury in rats. Methods The rats with cerebral ischemia/reperfusioninjury induced by middle cerebral artery occlusion (MCAO) were randomly assigned into blank controlgroup, saline group, and pAdCMV-HTK treatment group and received corresponding injections into thetissues around the infarct area. Each group was divided into 3 subgroups (n=10) for observation at 12, 24and 72 h after the treatment. The neurological deficits of the rats before and after the treatment wereevaluated using neurological severity scores (NSS), and the expressions of exogenous human tissuekallikrein (HTK) and vascular endothelial growth factor (VEGF) in the brain tissues were detectedimmunohistochemically. TIC staining was performed to measure the changes in the infarct size.14C-iodoantipyrine tracing technique was used to define the rCBF in the rats. Results Compared tothe blank control group, the cerebral infarct size was significantly reduced in pAdCMV-HTK group 24 hafter the treatment, and was further reduced at 72 h (P<0.05). At 24 h after the treatment, the NSS inpAdCMV-HTK group was significantly lower than that in the blank euntrol and saline groups (P<0.05),and was further reduced at 72 h (P<0.01). After MCAO, the VEGF-positive cells were found mostly inthe cortex and the white matter around the infarct area. The expression of VEGF in pAdCMV-HTK groupwas markedly higher than that in the other two groups at 12, 24, and 72 h after the treatment (P<0.05). Inall the 3 groups, the rCBF around the infarct was slightly decreased as compared to that in thecontralateral hemisphere, pAdCMV-HTK slightly increased the rCBF 12 h after the injection (P>0.05),and significant increase in the rCBF occurred 24 h and 72 h after the injection (P<0.05). ConclusionKallikrein gene transfer following cerebral ischemia/reperfusion injury promotes vascular proliferationaround the infarct and increases the rCBF to reduce the infarct volume and attenuate neurological deficitsin rats.