脑缺血后半乳糖凝集素-1对微血管的保护作用及机制研究

Stroke is the second commonest cause of death, thus comes to be a serious health problem worldwide. Despite a wealth of insight into the pathogenesis of stroke, current therapies for this devastating disease are far from optimal. Since the 2002 Report of the Stroke Progress Review Group, more attention has been paid to the concept of neurovascular unit (NVU)..NVU is composed of neurons, glial cells (astrocytes, microglia, oligodendrocytes), vascular cells (endothelial cells, smooth muscle cells, and pericytes), and extracellular matrix. Multifaceted events in the NVU emerges new concepts for stroke treatment..Cerebral microvasuclar changes are considered the initiation of NVU injury after ischemia/ reperfusion damage. Especially, situated at the interface between the circulating blood and brain parenchyma, endothelial cells structurally and functionally interact with basal lamina, astrocytic end-foot processes, and pericytes to form the blood-brain barrier (BBB), all of which are essential for maintaining circulatory homeostasis and neural function via facilitating neurovascular coupling, modulating vessel tone, and regulating the barrier functions of the BBB..Galectin-1 (Gal-1) was reported to be the essential factor for tumor vascularization; our past researches showed that Gal-1 was expressed by ischemic neuron and activated astrocyte, can depress astrogliosis, neuroinlammation and neuronal apoptosis, and promote the functional recovery of ischemic rats. All documents above demonstrate that Gal-1 is potential to be the a therapeutic target after CNS injury, through influencing NVU..Because no previous reports showed the effect of Gal-1 on microvascular injury and protection, we hypothesize that: Gal-1 may take an important role in regulating capillary vessel associated structural and functional damages, thus is potential to be a protective target for NVU. .We prepare to: mimic chronic cerebral ischemia by bilateral common carotid artery occlusion, and induce acute brain ischemia with intraluminal middle cerebral artery occlusion/ reperfusion, by the help of Gal-1 knockout mouse, Meanwhile, primary culture of endothelial cell will performed for in vitro experiments. Gal-1 will be given to treat animal models and cultured cells, in order to observe its effects on structural and functional recovery of capillary vessel and NVU after ischemia. During the experiments, electron, confocal microscopes, laser speckle blood flow imaging, immunofluorescent staining, western blot, microdialysis, Transwell migration test, ELISA, and other techniques will be enrolled to discover the changes of endothelial cells, BBB, inflammation, leukocyte exudation, neurovascular dysfunction and cell signal molecules..Clearing all above points will illustrate the influence and mechanism of gal-1 on capillary vessel and NVU after brain ischemia. Multifactorial beneficial outcomes brought by Gal-1 is hoped to help the recovery after brain ischemia..

“神经血管单元”概念的提出，为脑梗死治疗靶点的发现指明了新的方向。缺血导致的微血管损伤，是“神经血管单元”损伤的起点和中心环节。肿瘤研究中发现，半乳糖凝集素-1（Gal-1）是血管发生的关键性因子。申请人发现，Gal-1促进大鼠的神经功能恢复，可能成为脑梗死的治疗靶点。然而，Gal-1在脑梗死后对微血管的作用尚不可知。本课题假设Gal-1减轻脑缺血导致的微血管损伤及级联的神经血管功能失调，从而保护神经血管单元。我们拟在Gal-1敲除或干预的基础上，通过动物和细胞实验，结合电镜、双光子显微镜、激光散斑血流成像、免疫荧光染色、微透析及成分分析技术、流式细胞术、Transwell迁移检测和ELISA等，研究Gal-1对缺血损伤的微血管内皮细胞、血脑屏障、血管性炎症、微血流和血管再生的作用及相关发生机制。明确以上内容，有利于Gal-1这一新的脑梗死治疗靶点的开发，以期使患者受益。

脑卒中是危害人类健康的重大疾病之一。前期研究表明，Galectin-1在大鼠脑卒中模型中能够起到神经保护作用，其作用的产生，主要来自于星形胶质细胞。本课题与之前的侧重点有所不同，拟从微血管内皮细胞相关的角度，研究Galectin-1在脑卒中后的作用及其机制。主要的研究发现：通过对Bend.3细胞进行Galectin-1的敲除和过表达研究，你Galectin-1通过调节微血管内皮细胞的黏附分子和紧密连接蛋白的表达，从而调节了血脑屏障的功能；通过Galectin-1基因敲除小鼠和干预模型，说明Galectin-1通过内皮细胞加剧了早期的血脑屏障的破坏；通过星形胶质细胞和微血管内皮细胞的共培养，已经基因敲除小鼠和干预小鼠的研究，表明星形胶质细胞来源的Galectin-1促进了脑卒中后的微血管的再生。通过星形胶质细胞和小胶质细胞的相互作用研究，发现星形胶质细胞表达的Galectin-1对于小胶质细胞存在调控作用，减轻了小胶质细胞介导的炎症改变。以上研究结果，从微血管内皮细胞和神经血管单元角度，进一步阐明了Galectin-1在脑缺血后的作用及其机制，从而为Galectin-1作为一种新型治疗手段提供了理论依据。