Metaxa Eleni, Meng Hui, Kaluvala Shashikanth R, Szymanski Michael P, Paluch Rocco A, Kolega John
Toshiba Stroke Research Center, State Univ. of New York at Buffalo, Buffalo, NY 14214, USA.
Am J Physiol Heart Circ Physiol. 2008 Aug;295(2):H736-42. doi: 10.1152/ajpheart.01156.2007. Epub 2008 Jun 13.
Little is understood about endothelial cell (EC) responses to high flow, which mediate adaptive outward remodeling as well as cerebral aneurysm development. Opposite EC behaviors have been reported in vivo including cell loss during aneurysm initiation and cell proliferation during adaptive outward remodeling. This study aims at elucidating the EC growth response to elevated wall shear stress (WSS) and determining if nitric oxide (NO) is involved. A confluent EC monolayer was subjected to steady-state, laminar flow with WSS ranging from 15 to 100 dyn/cm(2) for 24 and 48 h. Cells oriented to the direction of the flow with a time course that varied with WSS. At 48 h, all cells were aligned with the flow. EC proliferation was examined using bromodeoxyuridine (BrdU) incorporation. The percentage of proliferating ECs rose linearly from 15 to 50 dyn/cm(2) to more than sixfold at 50-100 dyn/cm(2) compared with the accepted physiological baseline of 15-20 dyn/cm(2). In addition, terminal deoxynucleotidyl transferase dUTP-mediated nick-end labeling (TUNEL) staining revealed that apoptosis decreased with increasing WSS. These results demonstrate that high WSS stimulates EC proliferation and suppresses apoptosis. Furthermore, immunostaining revealed increased endothelial nitric oxide synthase (eNOS) production with increasing WSS. NOS inhibition with N(omega)-nitro-l-arginine methyl ester (l-NAME) drastically reduced the WSS-stimulated proliferation, indicating a critical role of NO production in the stimulation of EC proliferation by high WSS.
关于内皮细胞（EC）对高流量的反应了解甚少，而这种反应介导了适应性向外重塑以及脑动脉瘤的发展。体内已报道了相反的内皮细胞行为，包括动脉瘤起始过程中的细胞丢失和适应性向外重塑过程中的细胞增殖。本研究旨在阐明内皮细胞对升高的壁面剪切应力（WSS）的生长反应，并确定一氧化氮（NO）是否参与其中。将汇合的内皮细胞单层暴露于稳态层流中，WSS范围为15至100达因/平方厘米，持续24小时和48小时。细胞随着时间进程向流动方向定向，该时间进程随WSS而变化。在48小时时，所有细胞均与流动方向对齐。使用溴脱氧尿苷（BrdU）掺入法检测内皮细胞增殖。与公认的15 - 20达因/平方厘米的生理基线相比，增殖内皮细胞的百分比从15至50达因/平方厘米呈线性上升，在50 - 100达因/平方厘米时增加到六倍以上。此外，末端脱氧核苷酸转移酶dUTP介导的缺口末端标记（TUNEL）染色显示，细胞凋亡随着WSS的增加而减少。这些结果表明，高WSS刺激内皮细胞增殖并抑制细胞凋亡。此外，免疫染色显示随着WSS增加，内皮型一氧化氮合酶（eNOS）产生增加。用N（ω）-硝基-L-精氨酸甲酯（L-NAME）抑制一氧化氮合酶可显著降低WSS刺激的增殖，表明NO产生在高WSS刺激内皮细胞增殖中起关键作用。
