Urao Norifumi, Inomata Hyoe, Razvi Masooma, Kim Ha Won, Wary Kishore, McKinney Ronald, Fukai Tohru, Ushio-Fukai Masuko
Department of Pharmacology, Center for Lung and Vascular Biology, University of Illinois at Chicago, Chicago, IL 60612, USA.
Circ Res. 2008 Jul 18;103(2):212-20. doi: 10.1161/CIRCRESAHA.108.176230. Epub 2008 Jun 26.
Bone marrow (BM) is the major reservoir for endothelial progenitor cells (EPCs). Postnatal neovascularization depends on not only angiogenesis but also vasculogenesis, which is mediated through mobilization of EPCs from BM and their recruitment to the ischemic sites. Reactive oxygen species (ROS) derived from Nox2-based NADPH oxidase play an important role in postnatal neovascularization; however, their role in BM and EPC function is unknown. Here we show that hindlimb ischemia of mice significantly increases Nox2 expression and ROS production in BM-mononuclear cells (BMCs), which is associated with an increase in circulating EPC-like cells. Mice lacking Nox2 show reduction of ischemia-induced flow recovery, ROS levels in BMCs, as well as EPC mobilization from BM. Transplantation of wild-type (WT)-BM into Nox2-deficient mice rescues the defective neovascularization, whereas WT mice transplanted with Nox2-deficient BM show reduced flow recovery and capillary density compared to WT-BM transplanted control. Intravenous infusion of WT- and Nox2-deficient BMCs into WT mice reveals that neovascularization and homing capacity are impaired in Nox2-deficient BMCs in vivo. In vitro, Nox2-deficient c-kit+Lin- BM stem/progenitor cells show impaired chemotaxis and invasion as well as polarization of actins in response to stromal derived factor (SDF), which is associated with blunted SDF-1-mediated phosphorylation of Akt. In conclusion, Nox2-derived ROS in BM play a critical role in mobilization, homing, and angiogenic capacity of EPCs and BM stem/progenitor cells, thereby promoting revascularization of ischemic tissue. Thus, NADPH oxidase in BM and EPCs is potential therapeutic targets for promoting neovascularization in ischemic cardiovascular diseases.
骨髓（BM）是内皮祖细胞（EPCs）的主要储存库。出生后新血管形成不仅依赖于血管生成，还依赖于血管发生，这是通过将EPCs从骨髓中动员并募集到缺血部位来介导的。源自基于Nox2的NADPH氧化酶的活性氧（ROS）在出生后新血管形成中起重要作用；然而，它们在骨髓和EPC功能中的作用尚不清楚。在这里，我们表明小鼠后肢缺血显著增加了骨髓单个核细胞（BMCs）中Nox2的表达和ROS的产生，这与循环中EPC样细胞的增加有关。缺乏Nox2的小鼠显示缺血诱导的血流恢复减少、BMCs中的ROS水平降低以及EPCs从骨髓中的动员减少。将野生型（WT）骨髓移植到Nox2缺陷小鼠中可挽救有缺陷的新血管形成，而与移植WT骨髓的对照相比，移植Nox2缺陷骨髓的WT小鼠显示血流恢复和毛细血管密度降低。将WT和Nox2缺陷的BMCs静脉内注入WT小鼠表明，Nox2缺陷的BMCs在体内的新血管形成和归巢能力受损。在体外，缺乏Nox2的c-kit+Lin-骨髓干/祖细胞对基质衍生因子（SDF）的趋化性、侵袭以及肌动蛋白极化受损，这与SDF-1介导的Akt磷酸化减弱有关。总之，骨髓中源自Nox2的ROS在EPCs和骨髓干/祖细胞的动员、归巢和血管生成能力中起关键作用，从而促进缺血组织的血管再通。因此，骨髓和EPCs中的NADPH氧化酶是促进缺血性心血管疾病中新血管形成的潜在治疗靶点。
