Treg cell-derived osteopontin promotes microglia-mediated white matter repair after ischemic stroke

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Inhibition of platelet-derived growth factor promotes pericyte loss and angiogenesis in ischemic retinopathy

We investigated whether inhibition of platelet-derived growth factor (PDGF) receptor tyrosine kinase activity would affect pericyte viability, vascular endothelial growth factor (VEGF)/vascular endothelial growth factor receptor-2 (VEGFR-2) expression and angiogenesis in a model of retinopathy of prematurity (ROP). ROP was induced in Sprague Dawley rats by exposure to 80% oxygen from postnatal (P) days 0 to 11 (with 3 hours/day in room air), and then room air from P12-18 (angiogenesis period). Shams were neonatal rats in room air from P0-18. STI571, a potent inhibitor of PDGF receptor tyrosine kinase, was administered from P12-18 at 50 or 100 mg/kg/day intraperitoneal (i.p.). Electron microscopy revealed that pericytes in the inner retina of both sham and ROP rats appeared normal; however STI571 induced a selective pericyte and vascular smooth muscle degeneration. Immunolabeling for caspase-3 and alpha-smooth muscle cell actin in consecutive paraffin sections of retinas confirmed that these degenerating cells were apoptotic pericytes. In all groups, VEGF and VEGFR-2 gene expression was located in ganglion cells, the inner nuclear layer, and retinal pigment epithelium. ROP was associated with an increase in both VEGF and VEGFR-2 gene expression and blood vessel profiles in the inner retina compared to sham rats. STI571 at both doses increased VEGF and VEGFR-2 mRNA and exacerbated angiogenesis in ROP rats, and in sham rats at 100 mg/kg/day. In conclusion, PDGF is required for pericyte viability and the subsequent prevention of VEGF/VEGFR-2 overexpression and angiogenesis in ROP.     

SDF-1/CXCR4对缺血性卒中后神经发生的调节作用研究进展

脑缺血损伤后表达增高的基质细胞来源因子-1(SDF-1)和C-X-C趋化因子受体4(CXCR4)可以调控内源性神经干细胞增殖、分化和迁移。     

Soluble N-cadherin fragment promotes angiogenesis

Endothelial cells express two dependent intercellular adhesion molecules: vascular endothelial (VE)-cadherin, specific for endothelial cells, and N-cadherin, also present in neuronal, lens, skeletal and heart muscle cells, osteoblasts, pericytes and fibroblasts. While there exists a vast amount of evidence that VE-cadherin promotes angiogenesis, the role of N-cadherin still remains to be elucidated. We found that a soluble 90-kDa fragment N-cadherin promotes angiogenesis in the rabbit cornea assay and in the chorioallantoic assay when cleaved enzymatically from the extracellular domain of N-cadherin. Soluble N-cadherin stimulates migration of endothelial cells in the wound healing assay and stimulates phosphorylation of extracellular regulated kinase. In vitro experiments with PD173074 and knock-down of N-cadherin and fibroblast growth factor (FGF)-receptor, showed that the pro-angiogenic effect of soluble N-cadherin is N-cadherin- and FGF-receptor-dependent. Our results suggest that soluble N-cadherin stimulates migration of endothelial cells through the FGF-receptor.     

人胶质瘤干细胞趋化因子受体CXCR4活化促进血管生成的作用

目的从人恶性胶质瘤细胞系U87中分离、培养和鉴定胶质瘤干细胞,观测其CXCR4表达情况及其活化后促血管生成因子分泌的变化。方法通过流式细胞术检测U87细胞中CD133阳性细胞的比例。使用CD133免疫磁珠分离试剂盒通过磁性细胞分选系统分离胶质瘤干细胞。采用间接免疫荧光标记、激光共聚焦扫描显微术观测胶质瘤干细胞中神经巢蛋白（nestin）、胶质纤维酸性蛋白（GFAP）、趋化因子受体CXCR4的表达;以CXCR4配体刺激通过钙流试验检测受体功能,采用酶联免疫吸附试验（EIJSA）检测培养上清中血管内皮生长因子（VEGF）和白细胞介素-8（IL-8）的含量。建立裸鼠皮下移植瘤模型,观察胶质瘤干细胞成瘤情况及瘤体内VEGF表达情况。结果U87细胞系中CD133阳性细胞的比例为0．5％,这些细胞具有干细胞增殖和生长特性;它们表达CXCR4,用其相应配体激活后导致胞内钙流增加、分泌VEGF和IL-8增多。与CD133阴性细胞相比,CD133阳性细胞在体外分泌VEGF、IL-8多,在体内成瘤率高,形成的移植瘤生长迅速,表达更多VEGF。结论人恶性胶质细胞瘤细胞系U87中含有极少量胶质瘤干细胞,表达功能性CXCR4、分泌更多促血管生成因子,提示这些干细胞也直接参与胶质瘤血管生成。     

成年小鼠缺血性脑卒中后病理及行为功能的变化

文题释义：大脑中动脉末端闭塞模型：该模型最先由TAMURA等在大鼠上开发出来,即开颅手术找到大脑中动脉皮质分支并对其进行结扎或电凝,可以引起稳定的局灶性皮质梗死,在很好模拟人类卒中病理状态的同时死亡率较低。但这种手术方式对手术人员的技术以及设备有较高要求,并且需要后期评估才能确定造模成功与否。缺血性脑卒中：脑卒中分缺血性和出血性脑卒中,缺血性卒中是由于脑的供血动脉狭窄或闭塞,造成脑组织缺血、缺氧性坏死,是中国致死和致残的主要原因。背景：大鼠大脑中动脉末端闭塞模型可以引起稳定的局灶性皮质梗死,在很好模拟人类卒中病理状态的同时死亡率较低,但对手术人员的技术以及设备有较高要求,并且需要后期评估才能确定造模成功与否。目的：建立有效稳定简便的缺血性小鼠脑卒中模型;揭示小鼠脑卒中后梗死区及周围区域的病理变化;探索小鼠脑卒中后的行为学改变。方法：对小鼠末端大脑中动脉进行永久电凝结扎,24 h后用TTC染色明确该模型梗死范围并统计该模型的成功概率;对小鼠大脑中动脉末端闭塞模型后不同时间点(1,3,7,10,14 d)的脑组织切片进行苏木精-伊红染色,观察缺血坏死区的体积在不同时间点的改变;进行胶质纤维酸性蛋白、Iba-1免疫组织化学染色,检测模型小鼠脑损伤后胶质反应及炎症反应变化;最后应用网格足部错误试验和圆柱体试验评价小鼠卒中后感觉运动功能的缺失情况。结果与结论：①大脑中动脉末端闭塞模型导致局灶性皮质梗死且该新模型死亡率仅9%,成功率达87%;②梗死区域主要位于M1/S1/S2区,梗死范围在闭塞10 d时趋于稳定;③脑卒中后3 d时炎症反应达到高峰,14 d时损伤区周围形成稳定星形胶质瘢痕;④局灶性皮质梗死后小鼠对侧肢体出现明显的感觉及运动的缺失;⑤结果表明,卒中后实验小鼠立即出现感觉及运动功能缺失,且持续至卒中后12周;实验建立的大脑中动脉末端闭塞模型稳定、可靠,梗死范围明确,适合缺血性脑卒中的研究。ORCID: 0000-0002-5489-3807(梁彦峰)中国组织工程研究杂志出版内容重点：组织构建;骨细胞;软骨细胞;细胞培养;成纤维细胞;血管内皮细胞;骨质疏松;组织工程     

A clinical trial of estrogen-replacement therapy after ischemic stroke.

BACKGROUND: Observational studies have suggested that estrogen-replacement therapy may reduce a woman's risk of stroke and death. METHODS: We conducted a randomized, double-blind, placebo-controlled trial of estrogen therapy (1 mg of estradiol-17beta per day) in 664 postmenopausal women (mean age, 71 years) who had recently had an ischemic stroke or transient ischemic attack. Women were recruited from 21 hospitals in the United States and were followed for the occurrence of stroke or death. RESULTS: During a mean follow-up period of 2.8 years, there were 99 strokes or deaths among the women in the estradiol group, and 93 among those in the placebo group (relative risk in the estradiol group, 1.1; 95 percent confidence interval, 0.8 to 1.4). Estrogen therapy did not reduce the risk of death alone (relative risk, 1.2; 95 percent confidence interval, 0.8 to 1.8) or the risk of nonfatal stroke (relative risk, 1.0; 95 percent confidence interval, 0.7 to 1.4). The women who were randomly assigned to receive estrogen therapy had a higher risk of fatal stroke (relative risk, 2.9; 95 percent confidence interval, 0.9 to 9.0), and their nonfatal strokes were associated with slightly worse neurologic and functional deficits. CONCLUSIONS: Estradiol does not reduce mortality orthe recurrence of stroke in postmenopausal women with cerebrovascular disease. This therapy should not be prescribed for the secondary prevention of cerebrovascular disease.     

VEGF expression in human brain tissue after acute ischemic stroke

Ischemic stroke is the third most common cause of death in humans, requiring further studies to elucidate its pathophysiological background. One potential mechanism to increase oxygen delivery to the affected tissue is induction of angiogenesis. The most potent proangiogenic factor is VEGF. For this reason, our study investigated immunohistochemically VEGF reactivity in different cellular brain compartments from 15 ischemic stroke patients, as well as from 2 age control cases. By enzymatic immunohistochemistry, we investigate VEGF expression in different brain cell compartments and then we quantified its signal intensity by assessing integrated optical densities (IOD). To establish the exact cellular brain topography of VEGF immunoreactivity we performed double fluorescent immunohistochemistry series (VEGF÷NeuN, GFAP, CD68, CD105). In control samples, VEGF reactivity was observed especially in neurons from the Brodmann cortical layers IV to VI and in protoplasmic astrocytes from the deeper layers of gray matter and in endothelial cells from normal blood vessels because of systemic hypoxia generated after death. In acute ischemic stroke samples, this reactivity was noticed in all brain cellular compartments but with different intensities. The most reactive compartment was the neurons, the intensity of VEGF reaction decreasing with the lesional age from the core infarct toward intact adjacent brain cortex. With a lower intensity, VEGF reaction was noticed in astrocytes compartments, especially in gemistocytic astrocytes adjacent to the liquefaction zone. We also noticed a weak reaction in activated non-phagocytic microglia from the periphery of liquefaction zones, and high VEGF-CD105 colocalization values at the level of microvessels that surround the infarcted brain area. In conclusion, this reactivity could suggest that VEGF might exhibit neuronal and glial protective effects and also a neoangiogenic property in acute ischemic stroke, facts that may have significant therapeutically impact on these patients.     

Age,subjective stress,and depression after ischemic stroke

The incidence of stroke among younger adults in the United States is increasing. Few studies have investigated the prevalence of depressive symptoms after stroke among different age groups or the extent to which subjective stress at the time of stroke interacts with age to contribute to post-stroke depression. The present study examined whether there exists an age gradient in survivors’ level of depressive symptoms and explored the extent to which financial, family, and health-related stress may also impact on depression. Bivariate analyses (N = 322) indicated significant differences in depression and stress by age group, as well as differences in age and stress by 3-month depression status. Linear regression analyses indicated that survivors between the ages of 25–54 and 55–64 years old had, on average, significantly higher depressive symptom scores. Those with financial, family, and health-related stress at the time of stroke, irrespective of age, also had significantly higher scores.     

Vimentin-immunopositive cells in the rat telencephalon after experimental ischemic stroke

The aim of the present work was to perform immunocytochemical studies of cells synthesizing the intermediate filament protein vimentin in the telencephalon of intact rats and rats subjected to unilateral permanent occlusion of the middle cerebral artery, which models ischemic stroke. In the intact rat brain, vimentin-containing cells were seen in the brain barriers. At 14 days from occlusion of the middle cerebral artery, there were numerous vimentin-immunopositive cells in the perifocal damage zone, and these accounted for a significant proportion of the cells in the regenerating nervous tissue at the boundary with undamaged tissue. The subependymal proliferative zone contained a significant number of vimentin-negative small cells, located between the long processes of vimentin-immunopositive cells running towards the lesioned zone. These data provide evidence of the predominant location of vimentin-immunopositive brain cells (in both intact and lesioned animals) in the zones forming barrier structures. __________ Translated from Morfologiya, Vol. 132, No. 5, pp. 23–27, September–October, 2007.