ADAMTS13调控缺血性脑卒中后血管新生和功能重塑的作用和机制

Although the angiogenic response may be functionally important for brain repair after ischemic stroke, therapeutic options for promoting angiogenesis remain limited. The von Willebrand factor (VWF)–cleaving protease ADAMTS13 was shown to play a pivotal role after acute stroke. Recently, we have reported that recombinant ADAMTS13 (r-ADAMTS13) reduced tPA-related cerebral hemorrhage after acute ischemic stroke. Furthermore, we demonstrated that r-ADAMTS13 attenuated brain injury after intracerebral hemorrhage. However, the role of ADAMTS13 in angiogenesis after stroke is unknown. Our preliminary data show that Adamts13-/- mice had significant reduction in neovascularization and proliferation of endothelial cells at 14 days after ischemic stroke. These were accompanied by decreased brain capillary perfusion and increased vascular permeability. In this project, we will further assess the effects and mechanism of ADAMTS13 on formation, maturation, remodeling and function of the newly formed capillary after ischemic stroke. We will employ mouse stroke model, using Adamts13-/- and Adamts13-/- vwf/- mice, r-ADAMTS13, multi-photon microscopy, molecular biological and behavior analysis approaches to determine whether VWF and its ligands in endothelial cells as well as pVEGFR-2/Tie2 are involved in the effects of ADAMTS13 on neovascularization and vascular remodeling following ischemic stroke. We will also determine the effects of r-ADAMTS13 on angiogenesis, neurogenesis and functional recovery after ischemic stroke. These proposed studies may provide novel insights into improving post-stroke vascular remodeling and brain repair.

血管新生是缺血性脑卒中后损伤修复的重要机制，但是缺乏有效的调控手段。我们前期研究证明，重组ADAMTS13可降低急性脑缺血后溶栓引起的脑出血，并减轻脑水肿。我们近期在预实验中发现，Adamts13-/-小鼠在脑缺血后血管新生和内皮细胞增殖方面存在明显缺陷，并且其血管灌注能力下降，血管渗漏加重。综合国内外最新研究进展，本项目拟以ADAMTS13在脑缺血后新生血管形成、成熟和功能重塑中的作用为主线，运用基因敲除、重组蛋白、多光子显微镜活体动物脑血管成像、分子生物学以及行为学检测等手段，阐明ADAMTS13通过VWF及其内皮细胞配体和pVEGFR-2/Tie2途径，调控脑缺血后血管新生和功能重塑的关键环节和作用机制，发现和鉴定新的重要调控分子，并从转化应用的角度，探索重组ADAMTS13促进脑缺血后血管新生-神经再生-损伤修复的新策略，为缺血性脑卒中后神经功能障碍的治疗提供新的视点和理论基础。

血管新生对脑卒中后损伤的修复具有重要的作用。我们研究发现敲除VWF裂解酶ADAMTS13基因后，小鼠在缺血性脑卒中后14天时血管周细胞以及平滑肌细胞覆盖率明显减少，紧密连接蛋白和基膜蛋白损失明显增加，血脑屏障的破坏更加严重，血管内大分子物质的血管外渗漏更多，并伴随脑内毛细血管和灌注血管减少。VWF基因敲除以及VWF抑制抗体均可逆转ADAMTS13基因敲除引起的血脑屏障破坏和血管周细胞减少，并增加血管新生和修复。我们进一步研究发现ADAMTS13基因敲除减少脑微血管中angiopoietin-2和galectin-3表达，而VWF基因敲除增加脑微血管中angiopoietin-2和galectin-3表达。病毒过表达Ang-2或给与galectin-3重组蛋白都可逆转ADAMTS13基因敲除所引起的血管面积、灌注血管长度和周细胞覆盖率减少及血脑屏障破坏。然而，VEGFR-2拮抗剂SU1498可抵消Ang-2过表达或galectin-3重组蛋白对ADAMTS13基因敲除所引起的血管新生减少和血脑屏障破坏作用。进一步，我们发现重组ADAMTS13可增加小鼠脑内血管新生、成熟和稳定，并显著改善小鼠的感觉和运动功能。以上研究结果证明ADAMTS13是调控缺血性脑卒中后血管新生、成熟和功能重塑的重要分子。