Li Q, Bolli R, Qiu Y, Tang X L, Murphree S S, French B A
Molecular Cardiology Unit and the Experimental Research Laboratory of the Division of Cardiology, University of Louisville, KY, USA.
Circulation. 1998 Oct 6;98(14):1438-48. doi: 10.1161/01.cir.98.14.1438.
Administration of Cu/Zn superoxide dismutase (SOD) without catalase fails to alleviate myocardial stunning, but extracellular SOD (Ec-SOD) may be more effective because it binds to heparan sulfate proteoglycans on the cellular glycocalyx. We therefore used in vivo gene transfer to increase systemic levels of Ec-SOD and determined whether this gene therapy protects against myocardial stunning.
The cDNA for human Ec-SOD was cloned behind the cytomegalovirus (CMV) promoter and incorporated into a replication-deficient adenovirus (Ad5/CMV/Ec-SOD). Injection of this virus (2x10(8) pfu/kg IV) produced high levels of Ec-SOD in the liver, which could be redistributed to the heart and other organs by injection of heparin. Conscious rabbits underwent a sequence of six 4-minute coronary occlusion/4-minute reperfusion cycles for 3 consecutive days starting 3 days after intravenous injection of Ad5/CMV/Ec-SOD or Ad5/CMV/nls/LacZ (negative control). Both groups were given heparin (2000 U/kg IV) 2 hours before the first sequence of occlusions. The severity of myocardial stunning was measured as the total deficit of LV wall thickening after the last reperfusion. On day 1, the total deficit of wall thickening was markedly decreased in Ad5/CMV/Ec-SOD rabbits versus controls and similar to that seen on days 2 and 3 in controls.
The results demonstrate that in vivo gene transfer of the cDNA encoding Ec-SOD provides the heart with substantial protection against myocardial stunning without the need for concomitant administration of catalase. The present observations provide the basis for controlling gene therapy at the posttranslational level and for simultaneously protecting multiple organs from oxidant stress.
在没有过氧化氢酶的情况下给予铜/锌超氧化物歧化酶（SOD）并不能减轻心肌顿抑，但细胞外超氧化物歧化酶（Ec-SOD）可能更有效，因为它能与细胞糖萼上的硫酸乙酰肝素蛋白聚糖结合。因此，我们采用体内基因转移来提高Ec-SOD的全身水平，并确定这种基因治疗是否能预防心肌顿抑。
将人Ec-SOD的cDNA克隆到巨细胞病毒（CMV）启动子后，并整合到复制缺陷型腺病毒（Ad5/CMV/Ec-SOD）中。注射这种病毒（2×10⁸ pfu/kg静脉注射）可在肝脏中产生高水平的Ec-SOD，通过注射肝素可将其重新分布到心脏和其他器官。清醒家兔在静脉注射Ad5/CMV/Ec-SOD或Ad5/CMV/nls/LacZ（阴性对照）3天后开始，连续3天进行6次4分钟冠状动脉闭塞/4分钟再灌注循环。两组在第一次闭塞序列前2小时均给予肝素（2000 U/kg静脉注射）。心肌顿抑的严重程度通过最后一次再灌注后左室壁增厚的总缺损来衡量。在第1天，Ad5/CMV/Ec-SOD组家兔的壁增厚总缺损与对照组相比明显降低，且与对照组第2天和第3天的情况相似。
结果表明，编码Ec-SOD的cDNA的体内基因转移为心脏提供了对心肌顿抑的实质性保护，而无需同时给予过氧化氢酶。目前的观察结果为在翻译后水平控制基因治疗以及同时保护多个器官免受氧化应激提供了基础。
