Morishita R, Gibbons G H, Ellison K E, Lee W, Zhang L, Yu H, Kaneda Y, Ogihara T, Dzau V J
Division of Cardiovascular Medicine, Falk Cardiovascular Research Center, Stanford University School of Medicine, California 94305.
J Clin Invest. 1994 Sep;94(3):978-84. doi: 10.1172/JCI117464.
In vitro studies have demonstrated that angiotensin (Ang) II directly stimulates vascular smooth muscle cell (VSMC) growth. However, it is still unclear if Ang II exerts a direct effect on vascular hypertrophy in vivo independent of its effect on blood pressure. In vivo gene transfer provides the opportunity to assess the effects of increased activity of the vascular angiotensin system in the intact animal while avoiding an increase in circulating angiotensin or in blood pressure. Accordingly, we transfected the human angiotensin converting enzyme (ACE) vector into intact rat carotid arteries by the hemagglutinating virus of Japan-liposome method. 3 d after transfection, we detected increased ACE activity in the transfected artery. Immunohistochemistry localized immunoreactive ACE in the medial VSMC as well as in the intimal endothelial cells. The increase in vascular ACE activity was associated with a parallel increase in DNA synthesis as assessed by BrdU (bromo-deoxyuridine) index and vascular DNA content. This increase in DNA synthesis was abolished by the in vivo administration of an Ang II receptor-specific antagonist (DuP 753). Morphometry at 2 wk after transfection revealed an increase in the wall to lumen ratio of the ACE-transfected blood vessel as compared with control vector transfected vessels. This was accompanied by increases in protein and DNA contents without an increase in cell number. Local transfection of ACE vector did not result in systemic effects such as increased blood pressure, heart rate, or serum ACE activity. These morphological changes were abolished by the administration of the Ang II receptor antagonist. In this study, we used in vivo gene transfer to increase local expression of vascular angiotensin converting enzyme and provided proof that increased autocrine/paracrine angiotensin can directly cause vascular hypertrophy independent of systemic factors and hemodynamic effects. This approach has important potentials for defining the role of autocrine/paracrine substances in vascular biology and hypertension.
体外研究表明，血管紧张素（Ang）II可直接刺激血管平滑肌细胞（VSMC）生长。然而，Ang II在体内是否独立于其对血压的影响而对血管肥大产生直接作用仍不清楚。体内基因转移提供了一个机会，可以在完整动物中评估血管紧张素系统活性增加的影响，同时避免循环血管紧张素或血压升高。因此，我们通过日本血凝病毒-脂质体方法将人血管紧张素转换酶（ACE）载体转染到完整大鼠的颈动脉中。转染后3天，我们检测到转染动脉中ACE活性增加。免疫组织化学将免疫反应性ACE定位在内膜平滑肌细胞以及内膜内皮细胞中。通过BrdU（溴脱氧尿苷）指数和血管DNA含量评估，血管ACE活性的增加与DNA合成的平行增加相关。体内给予Ang II受体特异性拮抗剂（DuP 753）可消除这种DNA合成的增加。转染后2周的形态计量学显示，与对照载体转染的血管相比，ACE转染血管的壁腔比增加。这伴随着蛋白质和DNA含量的增加，但细胞数量没有增加。ACE载体的局部转染未导致诸如血压、心率或血清ACE活性增加等全身效应。这些形态学变化可通过给予Ang II受体拮抗剂而消除。在本研究中，我们利用体内基因转移增加血管紧张素转换酶的局部表达，并提供证据表明自分泌/旁分泌血管紧张素增加可直接导致血管肥大，而不受全身因素和血流动力学效应的影响。这种方法对于确定自分泌/旁分泌物质在血管生物学和高血压中的作用具有重要潜力。
