Rapamycin Treatment Reduces Brain Pericyte Constriction in Ischemic Stroke

雷帕霉素治疗可减少缺血性卒中的脑周细胞收缩

The contraction and subsequent death of brain pericytes may play a role in microvascular no-reflow following the reopening of an occluded artery during ischemic stroke. Mammalian target of rapamycin (mTOR) inhibition has been shown to reduce motility/contractility of various cancer cell lines and reduce neuronal cell death in stroke. However, the effects of mTOR inhibition on brain pericyte contraction and death during ischemia have not yet been investigated. Cultured pericytes exposed to simulated ischemia for 12 h in vitro contracted after less than 1 h, which was about 7 h prior to cell death. Rapamycin significantly reduced the rate of pericyte contraction during ischemia; however, it did not have a significant effect on pericyte viability at any time point. Rapamycin appeared to reduce pericyte contraction through a mechanism that is independent of changes in intracellular calcium. Using a mouse model of middle cerebral artery occlusion, we showed that rapamycin significantly increased the diameter of capillaries underneath pericytes and increased the number of open capillaries 30 min following recanalisation. Our findings suggest that rapamycin may be a useful adjuvant therapeutic to reduce pericyte contraction and improve cerebral reperfusion post-stroke.

脑周细胞的收缩和随后的死亡可能在缺血性卒中期间闭塞的动脉重新开放后的微血管无复流中起作用。哺乳动物雷帕霉素靶蛋白 (mTOR) 抑制已显示降低各种癌细胞系的运动性/收缩性并减少卒中中的神经元细胞死亡。然而，尚未研究mTOR抑制对缺血期间脑周细胞收缩和死亡的影响。体外暴露于模拟缺血12小时的培养周细胞在不到1小时后收缩，这是细胞死亡前约7小时。雷帕霉素显著降低缺血期间周细胞收缩的速率; 然而，它在任何时间点对周细胞活力没有显著影响。雷帕霉素似乎通过独立于细胞内钙变化的机制来减少周细胞收缩。使用大脑中动脉闭塞的小鼠模型，我们发现雷帕霉素在再通后30分钟显着增加了周细胞下方毛细血管的直径，并增加了开放毛细血管的数量。我们的发现表明，雷帕霉素可能是减少周细胞收缩和改善卒中后脑再灌注的有用辅助治疗剂。

REF: Beard DJ, Brown LS, Morris GP, et al. Rapamycin Treatment Reduces Brain Pericyte Constriction in Ischemic Stroke. Transl Stroke Res. Published online September 27, 2024. doi:10.1007/s12975-024-01298-x PMID: 39331260

Blood–Brain Barrier Disruption and Imaging Assessment in Stroke

卒中的血脑屏障破坏和影像学评估

Disruption of the blood-brain barrier (BBB) is an important pathological hallmark of ischemic stroke. Blood-brain barrier disruption (BBBD) is a consequence of ischemia and may also exacerbate damage to brain parenchyma. Therefore, maintaining BBB integrity is critical for the central nervous system (CNS) homeostasis. This review offers a concise overview of BBB structure and function, along with the mechanisms underlying its impairment following a stroke. In addition, we review the recent imaging techniques employed to study blood-brain barrier permeability (BBBP) in the context of ischemic brain injury with the goal of providing imaging guidance for stroke diagnosis and treatment from the perspective of the BBBD. This knowledge is vital for developing strategies to safeguard the BBB during cerebral ischemia.

血脑屏障 (BBB) 的破坏是缺血性卒中的重要病理标志。血脑屏障破坏 (BBBD) 是缺血的结果，也可能加剧对脑实质的损害。因此，维持BBB完整性对于中枢神经系统 (CNS) 稳态至关重要。这篇综述简要概述了BBB的结构和功能，以及卒中后其损伤的机制。此外，我们回顾了用于研究缺血性脑损伤背景下血脑屏障通透性 (BBBP) 的最新成像技术，目的是从BBBD的角度为卒中诊断和治疗提供成像指导。这些知识对于开发在脑缺血期间保护BBB的策略至关重要。

REF: Liang Y, Jiang Y, Liu J, et al. Blood-Brain Barrier Disruption and Imaging Assessment in Stroke. Transl Stroke Res. Published online September 25, 2024. doi:10.1007/s12975-024-01300-6 PMID: 39322815

12/15-Lipooxygenase Inhibition Reduces Microvessel Constriction and Microthrombi After Subarachnoid Hemorrhage in Mice

12/15-脂氧合酶抑制减少小鼠蛛网膜下腔出血后微血管收缩和微血栓

Impaired cerebral circulation, induced by blood vessel constrictions and microthrombi, leads to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). 12/15-Lipooxygenase (12/15-LOX) overexpression has been implicated in worsening early brain injury outcomes following SAH. However, it is unknown if 12/15-LOX is important in delayed pathophysiological events after SAH. Since 12/15-LOX produces metabolites that induce inflammation and vasoconstriction, we hypothesized that 12/15-LOX leads to microvessel constriction and microthrombi formation after SAH, and thus, 12/15-LOX is an important target to prevent delayed cerebral ischemia. SAH was induced in C57BL/6 and 12/15-LOX-/- mice of both sexes by endovascular perforation. Expression of 12/15-LOX was assessed in brain tissue slices and in vitro. C57BL/6 mice were administered either ML351 (12/15-LOX inhibitor) or vehicle. Mice were evaluated for daily neuroscore and euthanized on day 5 to assess cerebral 12/15-LOX expression, vessel constrictions, platelet activation, microthrombi, neurodegeneration, infarction, cortical perfusion, and development of delayed deficits. Finally, the effect of 12/15-LOX inhibition on platelet activation was assessed in SAH patient samples using a platelet spreading assay. In SAH mice, 12/15-LOX was upregulated in brain vascular cells, and there was an increase in 12-S-HETE. Inhibition of 12/15-LOX improved brain perfusion on days 4-5 and attenuated delayed pathophysiological events, including microvessel constrictions, microthrombi, neuronal degeneration, and infarction. Additionally, 12/15-LOX inhibition reduced platelet activation in human and mouse blood samples. Cerebrovascular 12/15-LOX overexpression plays a major role in brain dysfunction after SAH by triggering microvessel constrictions and microthrombi formation, which reduces brain perfusion. Inhibiting 12/15-LOX may be a therapeutic target to improve outcomes after SAH.

由血管收缩和微血栓引起的脑循环受损导致蛛网膜下腔出血 (SAH) 后迟发性脑缺血。12/15-脂加氧酶 (12/15-LOX) 过表达与SAH后早期脑损伤结果恶化有关。然而，尚不清楚12/15-LOX在SAH后延迟的病理生理事件中是否重要。由于12/15-LOX产生诱导炎症和血管收缩的代谢物，因此我们假设12/15-LOX导致SAH后微血管收缩和微血栓形成，因此，12/15-LOX是预防迟发性脑缺血的重要靶标。通过血管内穿孔在两种性别的C57BL/6和12/15-LOX-/-小鼠中诱导SAH。在脑组织切片和体外评估12/15-LOX的表达。向C57BL/6小鼠施用ML351 (12/15-LOX抑制剂) 或媒介物。评估小鼠的每日神经核心并在第5天实施安乐死以评估脑12/15-LOX表达、血管收缩、血小板活化、微血栓、神经变性、梗塞、皮质灌注和延迟性缺陷的发展。最后，使用血小板铺展测定在SAH患者样品中评估12/15-LOX抑制对血小板活化的影响。在SAH小鼠中，12/15-LOX在脑血管细胞中上调，并且12-s-hete增加。12/15-LOX的抑制改善了第4-5天的脑灌注，并减弱了延迟的病理生理事件，包括微血管收缩，微血栓，神经元变性和梗塞。此外，12/15-LOX抑制降低了人和小鼠血样中的血小板活化。脑血管12/15-LOX过表达通过触发微血管收缩和微血栓形成，从而减少脑灌注，在SAH后脑功能障碍中起主要作用。抑制12/15-LOX可能是改善SAH后结果的治疗靶标。

REF: Dienel A, Hong SH, Zeineddine HA, et al. 12/15-Lipooxygenase Inhibition Reduces Microvessel Constriction and Microthrombi After Subarachnoid Hemorrhage in Mice. Transl Stroke Res. Published online September 19, 2024. doi:10.1007/s12975-024-01295-0 PMID: 39294532

Alterations in the Glymphatic System and Association with Brain Structure and Cognitive Function in Moyamoya Disease

烟雾病的淋巴系统改变及其与脑结构和认知功能的关系

The glymphatic system is crucial for clearing metabolic waste from the brain, maintaining neural health and cognitive function. This study explores the glymphatic system's role in Moyamoya disease (MMD), characterized by progressive cerebral artery stenosis and brain structural lesions. We assessed 33 MMD patients and 21 healthy controls using diffusion tensor imaging along the perivascular space (DTI-ALPS) and global cortical gray matter-cerebrospinal fluid (CSF) coupling indices (gBOLD-CSF), which are indirect measurements of the glymphatic system. Cerebral perfusion in patients was evaluated via computed tomography perfusion imaging. We also measured the peak width of skeletonized mean diffusivity (PSMD), white matter hyperintensity (WMH) burden, and cognitive function. MMD patients exhibited lower ALPS and gBOLD-CSF coupling indices compared to controls (P < 0.01), indicating disrupted glymphatic function. Significant cognitive impairment was also observed in MMD patients (P < 0.01). ALPS indices varied with cerebral perfusion stages, being higher in earlier ischemic stages (P < 0.05). Analysis of brain structure showed increased CSF volume, PSMD index, and higher WMH burden in MMD patients (P < 0.01). The ALPS index positively correlated with white matter volume and cognitive scores, and negatively correlated with CSF volume, PSMD, and WMH burden (P < 0.05). Mediation analysis revealed the number of periventricular WMH significantly mediated the relationship between glymphatic dysfunction and cognitive impairment. In summary, MMD patients exhibit significant glymphatic system impairments, associated with brain structural changes and cognitive deficits.

淋巴系统对于清除大脑中的代谢废物，维持神经健康和认知功能至关重要。这项研究探讨了淋巴系统在烟雾病 (MMD) 中的作用，其特征是进行性脑动脉狭窄和脑结构性病变。我们使用沿血管周围空间的扩散张量成像 (dti-alps) 和全局皮质灰质-脑脊液 (CSF) 耦合指数 (gbold-csf) 评估了33名MMD患者和21名健康对照，这是淋巴系统的间接测量。通过计算机断层扫描灌注成像评估患者的脑灌注。我们还测量了骨架化平均扩散率 (PSMD)，白质高强度 (WMH) 负担和认知功能的峰值宽度。与对照组相比，MMD患者的ALPS和gbold-csf偶联指数较低 (P <0.01)，表明淋巴功能受到破坏。在MMD患者中也观察到显著的认知损害 (P <0.01)。ALPS指数随脑灌注阶段而变化，在早期缺血阶段更高 (P <0.05)。脑结构分析显示MMD患者CSF体积增加，PSMD指数增加，WMH负荷增加 (P <0.01)。ALPS指数与脑白质体积、认知评分呈正相关，与CSF体积、PSMD、WMH负荷呈负相关 (P <0.05)。中介分析显示，脑室周围WMH的数量显着介导了淋巴功能障碍与认知功能障碍之间的关系。总之，MMD患者表现出显著的类淋巴系统损伤，与脑结构改变和认知缺陷相关。

REF: Zhu H, Zhu C, Liu T, et al. Alterations in the Glymphatic System and Association with Brain Structure and Cognitive Function in Moyamoya Disease. Transl Stroke Res. Published online September 9, 2024. doi:10.1007/s12975-024-01296-z PMID: 39245689

Extracellular Vesicles Obtained from Hypoxic Mesenchymal Stromal Cells Induce Neurological Recovery, Anti-inflammation, and Brain Remodeling After Distal Middle Cerebral Artery Occlusion in Rats

低氧间充质基质细胞获得的细胞外囊泡诱导大鼠大脑中动脉远端闭塞后的神经功能恢复，抗炎和脑重塑

Small extracellular vesicles (sEVs) obtained from mesenchymal stromal cells (MSCs) have shown considerable promise as restorative stroke treatment. In a head-to-head comparison in mice exposed to transient proximal middle cerebral artery occlusion (MCAO), sEVs obtained from MSCs cultured under hypoxic conditions particularly potently enhanced long-term brain tissue survival, microvascular integrity, and angiogenesis. These observations suggest that hypoxic preconditioning might represent the strategy of choice for harvesting MSC-sEVs for clinical stroke trials. To test the efficacy of hypoxic MSCs in a second stroke model in an additional species, we now exposed 6-8-month-old Sprague-Dawley rats to permanent distal MCAO and intravenously administered vehicle, platelet sEVs, or sEVs obtained from hypoxic MSCs (1% O2; 2 × 106 or 2 × 107 cell equivalents/kg) at 24 h, 3, 7, and 14 days post-MCAO. Over 28 days, motor-coordination recovery was evaluated by rotating pole and cylinder tests. Ischemic injury, brain inflammatory responses, and peri-infarct angiogenesis were assessed by infarct volumetry and immunohistochemistry. sEVs obtained from hypoxic MSCs did not influence infarct volume in this permanent MCAO model, but promoted motor-coordination recovery over 28 days at both sEV doses. Ischemic injury was associated with brain ED1+ macrophage infiltrates and Iba1+ microglia accumulation in the peri-infarct cortex of vehicle-treated rats. Hypoxic MSC-sEVs reduced brain macrophage infiltrates and microglia accumulation in the peri-infarct cortex. In vehicle-treated rats, CD31+/BrdU+ proliferating endothelial cells were found in the peri-infarct cortex. Hypoxic MSC-sEVs increased the number of CD31+/BrdU+ proliferating endothelial cells. Our results provide evidence that hypoxic MSC-derived sEVs potently enhance neurological recovery, reduce neuroinflammation. and increase angiogenesis in rat permanent distal MCAO.

从间充质基质细胞 (msc) 获得的小细胞外囊泡 (sev) 已显示出作为恢复性卒中治疗的巨大前景。在暴露于短暂性近端大脑中动脉闭塞 (MCAO) 的小鼠的头对头比较中，从在缺氧条件下培养的msc获得的sev特别有效地增强了长期脑组织存活，微血管完整性和血管生成。这些观察结果表明，低氧预处理可能代表了收集msc-sev用于临床卒中试验的选择策略。为了在另外一个物种的第二个卒中模型中测试低氧MSCs的功效，我们现在将6-8个月大的sprague-dawley大鼠暴露于永久性远端MCAO和静脉内施用的载体，血小板sev或从低氧MSCs获得的sev (1% O2；2 × 106或2 × 107细胞当量/kg)，MCAO后3、7和14天。在28天内，通过旋转杆和圆柱体测试评估了运动协调恢复。通过梗塞体积法和免疫组织化学评估缺血性损伤，脑部炎症反应和梗塞周围血管生成。在这种永久性MCAO模型中，从低氧msc获得的sEV不会影响梗塞体积，但在两种sEV剂量下均能在28天内促进运动协调恢复。缺血性损伤与脑ED1 + 巨噬细胞浸润和Iba1 + 小胶质细胞在媒介物处理的大鼠的梗死周围皮质中的积累有关。缺氧msc-sevs减少了梗死周围皮质中脑巨噬细胞的浸润和小胶质细胞的积累。在媒介物处理的大鼠中，在梗死周围皮质中发现CD31 +/BrdU + 增殖内皮细胞。缺氧的msc-sevs增加了CD31/BrdU增殖内皮细胞的数量。我们的结果提供了证据，表明缺氧的MSC衍生的sEVs有效地增强了神经恢复，减少了神经炎症。并增加大鼠永久性远端MCAO的血管生成。

REF: Abuzan M, Surugiu R, Wang C, et al. Extracellular Vesicles Obtained from Hypoxic Mesenchymal Stromal Cells Induce Neurological Recovery, Anti-inflammation, and Brain Remodeling After Distal Middle Cerebral Artery Occlusion in Rats. Transl Stroke Res. Published online September 7, 2024. doi:10.1007/s12975-024-01266-5 PMID: 39243323

Perihematomal Neurovascular Protection: Blocking HSP90 Reduces Blood Infiltration Associated with Inflammatory Effects Following Intracerebral Hemorrhage in Rates

血肿周围神经血管保护: 阻断HSP90可减少脑出血后与炎症作用相关的血液浸润

The active hemorrhage surrounding the hematoma is caused by the infiltration of blood into the cerebral parenchyma through the ruptured vessel, including the compromised blood-brain barrier (BBB). This process is thought to be mainly driven by inflammation and serves as a significant pathological characteristic that contributes to the neurological deterioration observed in individuals with intracerebral hemorrhage (ICH). Heat shock protein 90 (HSP90) exhibits abnormally high expression levels in various diseases and is closely associated with the onset of inflammation. Here, we found that blocking HSP90 effectively alleviates the inflammatory damage to BBB and subsequent bleeding around the hematoma. We have observed increased HSP90 levels in the serum of patients with ICH and the perihematoma region in ICH rats. Treatment with anti-HSP90 drugs (Geldanamycin and radicicol) effectively reduced HSP90 levels, resulting in enhanced neurological outcomes, decreased hematoma volume, and prevented peripheral immune cells from adhering to the BBB and infiltrating the brain parenchyma surrounding the hematoma in ICH rats. Mechanistically, anti-HSP90 therapy alleviated BBB injury caused by ICH-induced inflammation by suppressing TLR4 signaling. The study highlights the potential of anti-HSP90 therapy in mitigating BBB disruption and hemorrhage surrounding the hematoma, providing new insights into the management of ICH by targeting HSP90.

血肿周围的活动性出血是由血液通过破裂的血管渗透到脑实质中引起的，包括受损的血脑屏障 (BBB)。该过程被认为主要由炎症驱动，并且是导致在脑内出血 (ICH) 个体中观察到的神经系统恶化的重要病理特征。热休克蛋白90 (HSP90) 在各种疾病中表现出异常高的表达水平，并且与炎症的发作密切相关。在这里，我们发现阻断HSP90有效地减轻了BBB的炎症损伤和随后的血肿周围出血。我们观察到ICH患者血清和ICH大鼠血肿周围区域的HSP90水平升高。用anti-HSP90药物 (格尔德霉素和radicicol) 治疗可有效降低HSP90水平，从而增强神经系统预后，减少血肿体积，并防止外周免疫细胞粘附于BBB并浸润ICH大鼠血肿周围的脑实质。从机制上讲，anti-HSP90疗法通过抑制TLR4信号传导来减轻由ICH诱导的炎症引起的BBB损伤。该研究强调了anti-HSP90疗法在减轻BBB破坏和血肿周围出血方面的潜力，为通过靶向hsp90治疗ICH提供了新的见解。

REF: Hu D, Yan C, Xie H, et al. Perihematomal Neurovascular Protection: Blocking HSP90 Reduces Blood Infiltration Associated with Inflammatory Effects Following Intracerebral Hemorrhage in Rates. Transl Stroke Res. Published online September 4, 2024. doi:10.1007/s12975-024-01289-y PMID: 39230786

Integrated Strategies for Targeting Arteriogenesis and Angiogenesis After Stroke

卒中后靶向动脉生成和血管生成的综合策略

The interdependence between arteriogenesis and angiogenesis is crucial for enhancing perfusion by synchronously improving leptomeningeal collaterals (LMCs) and microvascular networks after stroke. However, current approaches often focus on promoting arteriogenesis and angiogenesis separately, neglecting the potential synergistic benefits of targeting both processes simultaneously. Therefore, it is imperative to consider both arteriogenesis and angiogenesis as integral and complementary strategies for post-stroke revascularization. To gain a deeper understanding of their relationships after stroke and to facilitate the development of targeted revascularization strategies, we compared them based on their timescale, space, and pathophysiology. The temporal differences in the occurrence of arteriogenesis and angiogenesis allow them to restore blood flow at different stages after stroke. The spatial differences in the effects of arteriogenesis and angiogenesis enable them to specifically target the ischemic penumbra and core infarct region. Additionally, the endothelial cell, as the primary effector cell in their pathophysiological processes, is promising target for enhancing both. Therefore, we provide an overview of key signals that regulate endothelium-mediated arteriogenesis and angiogenesis. Finally, we summarize current therapeutic strategies that involve these signals to promote both processes after stroke, with the aim of inspiring future therapeutic advances in revascularization.

动脉生成与血管生成之间的相互依赖性对于通过同步改善卒中后的软脑膜侧支 (lmc) 和微血管网络来增强灌注至关重要。然而，目前的方法通常专注于分别促进动脉生成和血管生成，而忽略了同时靶向两个过程的潜在协同益处。因此，必须将动脉生成和血管生成都视为卒中后血运重建的整体和补充策略。为了更深入地了解它们在卒中后的关系并促进靶向血运重建策略的发展，我们根据它们的时间尺度，空间和病理生理学对它们进行了比较。动脉生成和血管生成发生的时间差异使它们能够在卒中后的不同阶段恢复血流。动脉生成和血管生成作用的空间差异使它们能够特异性靶向缺血半暗带和核心梗塞区域。此外，内皮细胞作为其病理生理过程中的主要效应细胞，是增强两者的有希望的目标。因此，我们概述了调节内皮介导的动脉生成和血管生成的关键信号。最后，我们总结了目前涉及这些信号以促进卒中后这两个过程的治疗策略，目的是激发未来血运重建的治疗进展。

REF: Wang J, Xiong T, Wu Q, Qin X. Integrated Strategies for Targeting Arteriogenesis and Angiogenesis After Stroke. Transl Stroke Res. Published online September 3, 2024. doi:10.1007/s12975-024-01291-4 PMID: 39225878