急性脑梗塞静脉溶栓因为治疗"时间窗"的限制，大部分病人就诊时已经超出"时间窗"范围，得不到有效的治疗。而动脉内机械性溶栓因不用纤溶酶原激活剂，避免了它所带来的副作用，是最有希望延长治疗的"时间窗"，临床上也取得了不错疗效。但动脉内机械性超"时间窗"溶栓术，仍不能避免血管再通后梗塞部位脑组织的再灌注损伤。缺血再灌注损伤主要是由于缺血区域产生大量的氧自由基引发的脂质过氧化反应。在已通畅的动脉内经微导管直接注入胞外超氧化物歧化酶(EC-SOD)基因转染的骨髓间充质干细胞(MSCs)至梗塞区，操作简单、易行。如果EC-SOD基因转染的MSCs能够在梗塞区存活并不断分泌SOD，不但能够减轻再灌注损伤，而且能促使受损脑组织的恢复，从而提高其治疗效果。本研究以毕格犬脑梗塞模型为研究对象，通过影像学、组织学、同步辐射等先进的实验手段来研究EC-SOD基因转染MSCs延长犬急性脑梗塞"时间窗"的作用机制。

Most patients diagnosed with acute ischemic stroke are admitted far behind the "time window" for effecive intravenous thrombolysis. Since intraarterial mechanical thrombolysis is spared from plasminogen activator and ensuing side effects, it contributes to extending "time window" and improving prognosis. However, cerebral reperfusion damage still seems to be inevitable in case of intraarterial mechanical thrombolysis beyond "time window". As reperfusion damage is generally acknowledged as the lipid peroxidation reaction due to overwhelming oxygen free radicals within ischemic region, it is feasible and practical for injected EC-SOD gene transfected MSCs to migrate to ischemic region and secret SOD continously thereby reducing reperfusion damage,accelerating cerebral recovery and improving prognosis. This study is dedicated to exploring the role of MSCs transfected with EC-SOD gene in extended "time window" for beagles with the help of imaging, histology and synchrotron radiation.