Ultrastructural Pathology of Oligodendroglial Cells in Traumatic and Hydrocephalic Human Brain Edema: A Review

Oligodendroglial cell changes in human traumatic brain injuries and hydrocephalus have been reviewed and compared with experimental brain edema. Resting unreactive oligodendrocytes, reactive oligodendrocytes, anoxic-ischemic oligodendrocytes, hyperthrophic phagocytic oligodendrocytes, and apoptotic oligodendrocytes are found. Anoxic-ischemic oligodendrocytes exhibit enlargement of endoplasmic reticulum, Golgi complex, and enlargement and disassembly of nuclear envelope. They appear in contact with degenerated myelinated axons. Hypertrophic phagocytic oligodendrocytes engulf degenerated myelinated axons exerting myelinolytic effects. A continuum oncotic and apoptotic cell death type leading to necrosis is observed. The vasogenic and cytotoxic components of brain edema are discussed in relation to oligodendroglial cell changes and reactivity.     

Lysosome abnormalities and lipofucsin content of nerve cells of oedematous human cerebral cortex

Lysosome alterations and lipofucsin content of nerve cells, capillary endothelial cells and pericytes were examined in the anoxic-ischaemic brain parenchyma of thirty two patients with congenital hydrocephalus, complicated brain traumatic injuries, brain tumours and vascular anomalies. Cortical biopsies of frontal, parietal and temporal cortex were processed for transmission electron microscopy. In oedematous non pyramidal and pyramidal nerve cells, lysosomes showed fragmentation of their limiting membranes and an associated dense granulation. Areas of cytoplasmic focal necrosis were observed surrounding the lysosomes. Lipofucsin granules were also observed in neonate and infant patients with congenital hydrocephalus, suggesting that lipofucsin formation is a life span process. Lysosomes coexisting with an increased amount of lipofucsin granules were observed in young and adult patients with brain trauma, tumours and vascular anomalies. Phagocytic astrocytes and activated oligodendroglial cells showed the overall spectrum of an altered endosomal/lysosomal system. Lipofucsin granules and multivesicular bodies also were distinguished in endothelial and pericyte cells. The role of released and activated lysosomal enzymes is discussed in relation with the cytoplasmatic focal necrosis of nerve cells and the genesis of moderate and severe oedema.     

The Extracellular Space in the Edematous Human Cerebral Cortex: An Electron Microscopic Study Using Cortical Biopsies

In a vascular anomaly showing moderate edema, the extracellular space appeared apparently normal, exhibiting a membrane to membrane space of about 20?nm in width. In congenital hydrocephalus, this space appeared notably enlarged and occupied by an electron transparent, nonproteinaceous interstitial edema fluid, due to abnormal accumulation of cerebrospinal fluid. In brain trauma, the distended extracellular space contained either electron-lucid nonproteinaceous or electron-dense proteinaceous edema fluid. Hemorrhagic foci, fibrinoid material, and non-nervous invading cells, such as macrophages and monocytes, were also found. In brain tumors, the widened extracellular space showed electron-dense proteinaceous edema fluid and bundles of fibrinoid material. The enlarged extracellular space found in congenital hydrocephalus, vascular anomalies, brain trauma, and tumors is closely related to the clinical symptoms exhibited by the patients under study.     

Nerve cell nuclear and nucleolar abnormalities in the human oedematous cerebral cortex. An electron microscopic study using cortical biopsies

Cerebral cortical biopsies of 17 patients with clinical diagnosis of congenital hydrocephalus, complicated brain trauma, cerebellar syndrome and vascular anomaly were examined with the transmission electron microscope to study the nuclear and nucleolar abnormalities induced by moderate and severe brain oedema, and the associated anoxic-ischemic conditions of brain tissue. In infant patients with congenital hydrocephalus and Arnold-Chiari malformation two different structural patterns of immature chromatin organization were found: the clear type characterized by a clear granular and fibrillar structure of euchromatin, scarce heterochromatin masses and few perichromatin granules, and a dense granular and fibrillar euchromatin with abundant and scattered heterochromatin masses, and increased number of perichromatin granules. The lobulated nuclei exhibited an irregularly dilated and fragmented perinuclear cistern, and areas of apparently intact nuclear pore complexes alternating with regions of nuclear pore complex disassembly. In moderate traumatic brain injuries some nucleoli exhibit apparent intact nucleolar substructures, and in severe brain oedema some nucleoli appeared shrunken and irregularly outlined with one or two fibrillar centers, and others were disintegrated. The nuclear and nucleolar morphological alterations are discussed in relation with oxidative stress, peroxidative damage, hemoglobin-induced cytotoxicity, calcium overload, glutamate excitotoxicity, and caspase activation.     

A new splice variant of the glutamate-aspartate transporter: cloning and immunolocalization of GLAST1c in rat, pig and human brains

GLAST (EAAT1) is an abundant glial glutamate transporter in the mammalian brain. It plays important roles in terminating excitatory transmission in grey matter, as well as pathophysiological roles, including protecting white matter from excitotoxic injury. In normal brain, alternative splicing of GLAST has been described: GLAST1a and GLAST1b arise from the splicing out of exons 3 and 9, respectively. This study describes the isolation of a novel cDNA clone from neonatal hypoxic pig brain, referred to as GLAST1c, where exons 5 and 6 are skipped. GLAST1c encodes a protein of 430 amino acids. RT-PCR analysis showed that GLAST1c mRNA was readily detectable in control and hypoxic pig cortex, as well as in various brain regions of rat (cortex, mid, hind and cerebellum), and human cortex, retina and optic nerve. We have raised antibodies that selectively recognize GLAST1c and demonstrate expression of this novel splice variant in astrocytes and oligodendrocytes in rat brain, pig brain and human brain, including grey and white matter. Similarly expression of GLAST1c was observed in primary astrocyte cultures and in cultured oligodendrocytes. In unstimulated astrocytes GLAST1c exhibited an intracellular peri-nuclear distribution similar to that observed when GFP-tagged GLAST1c was transfected into COS 7 cells. In astrocytes this protein rapidly redistributed to the surface upon stimulation of protein kinase with phorbol esters. We conclude that GLAST1c may represent an astrocyte and oligodendrocyte glutamate transporter, though this could not be formally validated by D-aspartate uptake studies, due to the low transfection efficiency of constructs into COS 7 cells.     

Inhibition of excitatory neurotransmission with kynurenate reduces brain edema in neonatal anoxia

Excitatory amino acid neurotransmitters have been implicated in fostering brain edema and neuronal death in ischemia. As both of these processes are involved in nervous system damage during neonatal anoxia, the effect of blockade of cell excitation with kynurenate upon brain water was studied following anoxic-ischemic brain injury in neonatal rats. Such treatment attenuated brain edema immediately after, and 24 h following anoxia-ischemia.     

小鼠脑缺血再灌流对铁及其调节蛋白在神经胶质细胞内分布的影响──免疫组织化学观察

应用免疫组织化学、荧光双标记和组织化学方法,对双侧颈总动脉反复短暂缺血造成再灌流损伤的小鼠部分脑区（额、颞叶大脑皮质、海马、胼胝体、丘脑和纹状体）中的铁、铁蛋白和转铁蛋白的分布变化进行了观察。结果显示：在正常状况下,铁蛋白和转铁蛋白阳性细胞以少突胶质细胞为主,部分星形胶质细胞也显示阳性反应,阳性细胞分布密度在胼胝体、丘脑和纹状体内较高,在皮质和海马处较低。铁阳性细胞也是少突胶质细胞,分布密度同铁蛋白阳性细胞。缺血再灌流损伤后,在上述脑区中铁蛋白和转铁蛋白阳性的少突胶质细胞密度下降;而星形胶质细胞及小胶质细胞除反应性增生外．部分仍含有铁蛋白或转铁蛋白,神经元呈弱阳性。铁的含量变化不大。提示少突胶质细胞在缺血、缺氧后,因铁代谢失调造成损伤,说明铁及其调节蛋白参与了缺血再灌流的病理过程。同时星形胶质细胞和小胶质细胞在铁代谢调节中可能起到一定的代偿作用。本文还对神经胶质细胞在缺血再灌流损伤与修复中的地位进行了讨论。     

PGRN阳性神经细胞在新生大鼠大脑皮层内的分布

目的:观察颗粒蛋白(progranulin,PGRN)阳性细胞在新生大鼠大脑皮层内的分布和PGRN在新生鼠大脑皮层神经元、星形胶质细胞和少突胶质细胞中的表达情况,探讨PGRN在新生鼠早期神经发育中的作用。方法:制备新生SD大鼠(1、7 d)脑组织切片,采用PGRN多克隆抗体进行免疫荧光组织化学染色法检测PGRN在新生鼠脑内的表达部位,免疫荧光组织化学双标法检测PGRN在新生鼠皮层内不同细胞中的定位。结果:新生鼠大脑皮质、侧脑室周围、胼胝体及海马中均表达PGRN。PGRN主要在新生鼠皮层内神经元中表达,而在星形胶质细胞和少突胶质细胞中几乎不表达。结论:新生鼠脑内表达PGRN,在大脑皮层内不同细胞表达模式有所不同,提示PGRN可能参与大鼠神经发育早期过程。     

Morphological changes of dendrites in the human edematous cerebral cortex. A transmission electron microscopic study

The structural pathology of dendritic processes has been examined in 38 patients with clinical diagnosis of brain trauma, brain tumours and congenital malformations. Cortical biopsies of frontal, parietal, temporal and occipital cortex were conventionally processed for transmission electron microscopy. Isolated ultrathin sections and montages of electron micrographs were used to trace the intracortical dendritic course. Swollen and beaded dendrites were observed in all cases examined, which exhibited fragmentation of limiting plasma membrane and cytoskeletal structures. The swollen dendrites showed vacuolization, dense residual bodies, enlarged rough and smooth endoplasmic reticulum, edematous clear and dark mitochondria, a decreased synaptic density of shaft synapses, edematous and dystrophic changes of spine apparatus and a partial loss of dendritic spines. A wide variety of dendritic spine shapes were observed: mushroom-type, stubby, gem-like filiform spine, and megaspine, considered as spine dysgenesis in the congenital malformations and spine pathology and spine plasticity in brain traumatic injuries and brain tumours. The multifactorial processes associated with brain edema and brain ischemia, such as calcium overload, activation of calcium-dependent proteolytic enzymes, protein aggregation, glutamate-induced neurotoxicity, release of lysosomal enzymes, deficit of ATP, stress oxidative and lipid peroxidation have been considered in relation with the pathological dendritic changes. Dendrotoxicity due to brain edema and brain ischemia seems to be the fundamental pathogenetic mechanism.     

The generation of cellular diversity in the cerebral cortex.

We have studied cell lineage in the rat cerebral cortex using retroviral vectors. With this technique, the virus is used to introduce a marker gene into dividing precursor cells such that their fate can be followed. We have studied cell lineage by using this method in the following ways. First, we have labelled germinal cells of the cerebral cortex in vivo during the period of neurogenesis. Second, we have grown cortical precursor cells in dissociated cell culture, and used the viral labelling technique to follow their development in vitro. Both types of study have shown that by the time neurogenesis is under way, the majority of precursor cells are restricted to the production of a single cell type: neurones, astrocytes, or oligodendrocytes. The only exception is a cell we call the N-O cell because it has the ability to generate both neurones and oligodendrocytes. These data suggest that the ventricular zone, the germinal layer of the embryonic cortex, is a mosaic of different precursor cells each with a different restricted potential. However, this restriction of potential of cortical precursor cells does not extend to their ability to contribute to more than one cortical lamina or cytoarchitectonic area. The precursors of both neurones and grey matter astrocytes contribute cells to multiple layers of the cortex. Moreover, in the hippocampal formation, neuronal precursors can contribute cells to more than one hippocampal field.     

大鼠星形胶质细胞在高血糖脑缺血再灌注损伤中的变化

目的:探讨星形胶质细胞在高血糖脑缺血再灌注损伤中的变化规律。方法:采用链脲佐菌素(STZ)诱导Ⅰ型糖尿病高血糖大鼠模型,通过双侧颈总动脉夹闭联合股动脉放血法建立全脑缺血再灌注模型,应用组织学、免疫荧光、组织化学及Western Blot方法,对比观察糖尿病高血糖脑缺血再灌注组(简称糖尿病组)与正常血糖脑缺血再灌注组(简称正常血糖组)在脑缺血15 min、再灌注1 h和6 h大脑额叶皮质区神经元、星形胶质细胞组织学变化及GFAP的表达。结果:正常血糖组再灌注1 h脑组织出现轻度水肿;再灌注6 h脑水肿加重,出现神经元固缩;再灌注1 h,糖尿病组病变与正常血糖组基本相同,再灌注6 h脑水肿加重,固缩神经元进一步增加。再灌注1 h和6 h,糖尿病组Nissl体平均光密度值明显低于正常血糖组(P<0.05)。脑组织GFAP免疫荧光检查可见,再灌注6 h正常血糖组GFAP免疫阳性细胞明显增加。糖尿病组再灌注1 h和6 h,出现GFAP阳性星形胶质细胞数目增加(P<0.05),胞体显著增大,突起增长、增粗。Western Blot结果可见,糖尿病组GFAP的表达明显高于正常血糖组。结论:糖尿病高血糖脑缺血再灌注能够加重神经元损伤,星形胶质细胞出现更明显的数量增加和GFAP表达。     

大鼠淋巴滞留性脑水肿的病理学研究

目的：探讨淋巴滞留性脑水肿的发病过程及病理特点。方法：采用阻断大鼠脑淋巴引流的方法,建立淋巴滞留性脑水肿模型,观察其行为变化,并从术后不同时间取脑标本,进行肉眼观察、HE染色及TUNEL染色光镜观察、透射及扫描电镜观察。结果：自术后第2天动物出现明显行为改变;脑膜及脑组织肿胀、充血、小血管壁外膜及Virchow-Robin间隙增宽,内含大量水肿液,毛细血管基底膜肥厚,神经元固缩、凋亡及肿胀、坏死、胶质细胞增生,硬脑膜表面凹凸不平,水肿明显。上述变化以术后5天最显著。结论：脑淋巴引流阻断后,可以导致淋巴滞留性脑水肿,其发病机制与3种传统类型的脑水肿不同,属于另一独立类型的脑水肿。     

干细胞在脑性瘫痪治疗中的应用

背景：干细胞在适当条件下可以分化为神经元细胞、星形胶质细胞与少突胶质细胞,可能从根本上改善脑性瘫痪患儿神经元缺失及神经胶质细胞变性,进而改善患儿脑功能障碍,从理论上达到根治目的。 目的：回顾性分析不同来源干细胞经不同途径治疗脑性瘫痪患儿的疗效。 方法：由第一作者检索1992/2011 PubMed数据及万方数据库有关脑性瘫痪的治疗及不同来源干细胞在治疗脑性瘫痪等方面的文献。 结果与结论：神经干细胞在动物神经功能损伤中的修复作用已有很多国内外报道,但目前其在人体的临床应用仍处于临床试验阶段。虽然胚胎、骨髓血、胎儿脐带血、脐带来源的干细胞已在部分医院应用到脑性瘫痪患儿中,并取得了初步的疗效,其具体评定标准及长期疗效仍有待进一步随访、观察。     

Transplantation of glial cell progenitors from brains of normal rats and mice into brains of neonatal carbonic anhydrase II-deficient mutant mice

Carbonic anhydrase II (CAII) is expressed in oligodendrocytes, astrocytes and myelin in brains of rats and normal mice, but not in the brains of CAII-deficient mutant mice. We have transplanted mixed glial-cell suspensions from normal mouse brains, and oligodendrocyte-enriched precursor cells cultured from normal rat brains, respectively, into the brains of neonatal CAII-deficient mutant mice. Some CAII-positive astrocytes and oligodendrocytes developed in the brains of the host CAII-deficient mice at 8, 14 and 18 days posttransplant (DPT). In transplants of either mixed glial cells or oligodendrocyte precursors, CAII-positive oligodendrocytes were less plentiful than CAII-positive astrocytes and appeared to be less healthy. CAII-positive astrocytes developed by 8 DPT, and there were some oligodendrocytes in cerebral cortex at 14 DPT and in brainstem by 18 DPT. The data suggested that if glial-cell progenitors were to be injected into demyelinated lesions, any oligodendrocytes descended from the donor would be accompanied by astrocytes also descended from donor cells.     

Brain cellular localization of endothelin receptors A and B in a rodent model of diffuse traumatic brain injury

Endothelin-1 exerts potent vasoconstrictor and vasodilatory effects through its actions on its receptors A (ETrA) and B (ETrB), respectively. While ETrA and B have classically been thought to be expressed on vascular cell types, more recent evidcence suggests that, particularly following brain injury, their expression may be seen in other, non-vascular cell types. To date no studies have comprehensively studied the cellular location of endothlelin receptors following traumatic brain injury (TBI). Therefore, this study investigates the cellular localization of ETrA and B in normal and traumatized brains using an impact acceleration device. Adult male Sprague–Dawley rats were subjected to TBI by weight drop (450 g) from either 1.5, a distance known to elicit mild TBI in the absence of changed in cerebral blood flow (CBF) or 2 m, a distance shown to cause a significant reduction in CBF. One set of impacted brains were processed for Western determination of ETrA and B expression. Another set were processed for immunofluorescence (IF). For IF, ETrA and ETrB antibodies were combined with cell markers for neurons, astrocytes, microglia, oligodendrocytes, smooth muscle cells and endothelial cells of blood vessels. While ETrA and B was upregulated after more moderate to severe injury (2 m) overall receptor expression was unchanged in response to mild trauma (1.5 m). Double labeling IF confirmed prominent ETrA and ETrB labeling in NeuN labeled pyramidal neurons and interneurons in sensorymotor cortex (smCx) and hippocampus (hipp) post TBI. ETrA rather than ETrB was preferentially co-localized in vascular smooth muscle cells. After injury, a subpopulation of astrocytes in white matter co-localized ETrA but not ETrB. Localization of either receptor in endothelial cells was sparse. No prominent IF was detected in microglia and oligodendrocytes. Taken together with previous findings in other pathological states that show an apparent shift in the localization of ETrA and B, the observed receptor shifts in this work may underlie the ET-1- mediated pathotrajectory of TBI including hypoperfusion.     

Lipoprotein receptor-related protein-1 mediates amyloid-beta-mediated cell death of cerebrovascular cells

Inefficient clearance of A beta, caused by impaired blood-brain barrier crossing into the circulation, seems to be a major cause of A beta accumulation in the brain of late-onset Alzheimer's disease patients and hereditary cerebral hemorrhage with amyloidosis Dutch type. We observed association of receptor for advanced glycation end products, CD36, and low-density lipoprotein receptor (LDLR) with cerebral amyloid angiopathy in both Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis Dutch type brains and increased low-density lipoprotein receptor-related protein-1 (LRP-1) expression by perivascular cells in cerebral amyloid angiopathy. We investigated if these A beta receptors are involved in A beta internalization and in A beta-mediated cell death of human cerebrovascular cells and astrocytes. Expression of both the LRP-1 and LDLR by human brain pericytes and leptomeningeal smooth muscle cells, but not by astrocytes, increased on incubation with A beta. Receptor-associated protein specifically inhibited A beta-mediated up-regulation of LRP-1, but not of LDLR, and receptor-associated protein also decreased A beta internalization and A beta-mediated cell death. We conclude that especially LRP-1 and, to a minor extent, LDLR are involved in A beta internalization by and A beta-mediated cell death of cerebral perivascular cells. Although perivascular cells may adapt their A beta internalization capacity to the levels of A beta present, saturated LRP-1/LDLR-mediated uptake of A beta results in degeneration of perivascular cells.     

中枢神经大麻素受体分布的细胞类型研究

目的研究不同脑区大麻素CB1、CB2受体分布的细胞类型,探索大麻素受体在中枢神经系统中的可能作用。方法运用免疫荧光单标、双标的方法研究2种大麻素受体在成年大鼠不同脑区、不同类型细胞中的表达分布情况。结果成年大鼠不同脑区的神经元中有CB1、CB2受体的表达,海马、大脑皮层、脑干以及小脑的浦肯野细胞层的神经元有较高表达,且2种大麻素受体的表达差异较小,基底神经节区有中等表达,而胼胝体区未发现有神经元表达。少突胶质细胞及星型胶质细胞中发现CB1、CB2受体的表达。结论大麻素受体CB1、CB2在中枢神经系统多种类型的细胞中均有分布,可能通过多种途径参与神经系统功能调节。     

Some mechanisms of brain edema studied in a kainic acid model

Kainic acid (KA) is a potent neuroexcitatory drug widely used in the experimental study of seizure activity. Subcutaneous injection of KA into rats (10 mg/kg in saline 10 mg/ml; pH 7.0) induced longlasting status epilepticus followed by damage of CNS tissue in the entorhinal/pyriform cortex and in the hippocampus. The studies covered by this report demonstrated the formation of cytotoxic brain edema characterized by massive swelling of perineuronal and perivascular astroglia with microcirculation disturbance after KA injection, resulting in parenchymal necrosis of the affected region; furthermore perivenous hemorrhages and necroses corresponding to herniation lesions of the brain appear. Tracer studies with Na-fluorescein, Evans blue, albumin, and horseradish peroxidase revealed only a mild increase in the permeability of cerebral vessels, topographically unrelated to areas of brain edema. Treatment of brain edema with dexamethasone did not influence the incidence and severity of edematous brain damage. Treatment with mannitol, however, completely prevented the lesion in 54% of animals injected with KA. The present results indicate that brain edema plays an important role in the pathogenesis of epileptic brain damage following systemic KA intoxication. It is suggested that in this model brain edema develops due to massive ionic imbalance caused by KA induced persistent neuronal excitation. In addition the model demonstrates the possible pathogenetic role of selective astrocytic swelling in the production of local hippocampal ischemia followed by herniation and its sequels. Such pathology originating from astrocytes probably may occur also in closed brain injury.     

Congenital arteriovenous malformation associated with progressive hydrocephalus in a newborn.

Intracranial arteriovenous malformation is rarely presented in newborns or infants. We describe an unusual case of congenital arteriovenous malformation of the brain with multiple sequestered grape-like venous sacs presented with congenital hydrocephalus. This 4-month-old girl born with a large head, presented with progressive hydrocephalus over a period of 4 months. The brain CT showed multiloculated cysts with a high-density mural nodule and thin cerebral mantle. The right lateral ventricle was collapsed by the cystic lesion, and the contralateral ventricle was markedly dilated, which was thought to be due to aqueductal obstruction by the conglomerated nidus of the arteriovenous malformation. Surgical removal of both hemispheric masses, including the overlying thin mantle. The lesion was pathologically confirmed as the arteriovenous malformation which was composed of markedly dilated veins and multiple sequestered aneurysmal sacs. The overlying cerebral tissue was dysplastic and partly infarcted. This case shows that intracerebral arteriovenous malformation is indeed a congenital anomaly and suggests that intrauterine vascular compromise can result in focal or wide maldevelopment of the brain.