Expression Of Chondroitin Sulfate Proteoglycans Research Articles

Differential Expression of Proteoglycans in Tissue Remodeling and Lymphangiogenesis after Experimental Renal Transplantation in Rats

BackgroundChronic transplant dysfunction explains the majority of late renal allograft loss and is accompanied by extensive tissue remodeling leading to transplant vasculopathy, glomerulosclerosis and interstitial fibrosis. Matrix proteoglycans mediate cell-cell and cell-matrix interactions and play key roles in tissue remodeling. The aim of this study was to characterize differential heparan sulfate proteoglycan and chondroitin sulfate proteoglycan expression in transplant vasculopathy, glomerulosclerosis and interstitial fibrosis in renal allografts with chronic transplant dysfunction.MethodsRenal allografts were transplanted in the Dark Agouti-to-Wistar Furth rat strain combination. Dark Agouti-to-Dark Agouti isografts and non-transplanted Dark Agouti kidneys served as controls. Allograft and isograft recipients were sacrificed 66 and 81 days (mean) after transplantation, respectively. Heparan sulfate proteoglycan (collXVIII, perlecan and agrin) and chondroitin sulfate proteoglycan (versican) expression, as well as CD31 and LYVE-1 (vascular and lymphatic endothelium, respectively) expression were (semi-) quantitatively analyzed using immunofluorescence.FindingsArteries with transplant vasculopathy and sclerotic glomeruli in allografts displayed pronounced neo-expression of collXVIII and perlecan. In contrast, in interstitial fibrosis expression of the chondroitin sulfate proteoglycan versican dominated. In the cortical tubular basement membranes in both iso- and allografts, induction of collXVIII was detected. Allografts presented extensive lymphangiogenesis (p<0.01 compared to isografts and non-transplanted controls), which was associated with induced perlecan expression underneath the lymphatic endothelium (p<0.05 and p<0.01 compared to isografts and non-transplanted controls, respectively). Both the magnitude of lymphangiogenesis and perlecan expression correlated with severity of interstitial fibrosis and impaired graft function.InterpretationOur results reveal that changes in the extent of expression and the type of proteoglycans being expressed are tightly associated with tissue remodeling after renal transplantation. Therefore, proteoglycans might be potential targets for clinical intervention in renal chronic transplant dysfunction.

Extracellular Matrix-Glial Abnormalities in the Amygdala and Entorhinal Cortex of Subjects Diagnosed With Schizophrenia

Chondroitin sulfate proteoglycans (CSPGs), a main component of the brain extracellular matrix, regulate developmental and adult neural functions that are highly relevant to the pathogenesis of schizophrenia. Such functions, together with marked expression of CSPGs in astrocytes within the normal human amygdala and evidence of a disruption of astrocytic functions in this disease, point to involvement of CSPG-glial interactions in schizophrenia. Chondroitin sulfate proteoglycan-related abnormalities involve glial cells and extracellular matrix pericellular aggregates (perineuronal nets) in the amygdala and entorhinal cortex of subjects with schizophrenia. Postmortem case-control study. The Translational Neuroscience Laboratory at McLean Hospital, Harvard Medical School. Specimens were obtained from the Harvard Brain Tissue Resource Center at McLean Hospital. Two separate cohorts of healthy control (n = 15; n = 10) and schizophrenic (n = 11; n = 10) subjects and a cohort of subjects with bipolar disorder (n = 11). Quantitative, immunocytological, and histological postmortem investigations. Numerical densities of CSPG-positive glial cells and perineuronal nets, glial fibrillary acidic protein-positive astrocytes, and total numbers of parvalbumin-positive neurons in the deep amygdala nuclei and entorhinal cortex. In schizophrenia, massive increases in CSPG-positive glial cells were detected in the deep amygdala nuclei (419%-1162%) and entorhinal cortex (layer II; 480%-1560%). Perineuronal nets were reduced in the lateral nucleus of the amygdala and lateral entorhinal cortex (layer II). Numerical densities of glial fibrillary acidic protein-positive glial cells and total numbers of parvalbumin-positive neurons were unaltered. Changes in CSPG-positive elements were negligible in subjects with bipolar disorder. Marked changes in functionally relevant molecules in schizophrenia point to a pivotal role for extracellular matrix-glial interactions in the pathogenesis of this disease. Disruption of these interactions, unsuspected thus far, may represent a unifying factor contributing to disturbances of neuronal migration, synaptic connectivity, and GABAergic, glutamatergic, and dopaminergic neurotransmission in schizophrenia. The lack of CSPG abnormalities in bipolar disorder points to a distinctive aspect of the pathophysiology of schizophrenia in key medial temporal lobe regions.

Reducing Intracortical Inhibition in the Adult Visual Cortex Promotes Ocular Dominance Plasticity

Experience-dependent plasticity in the cortex is often higher during short critical periods in postnatal development. The mechanisms limiting adult cortical plasticity are still unclear. Maturation of intracortical GABAergic inhibition is suggested to be crucial for the closure of the critical period for ocular dominance (OD) plasticity in the visual cortex. We find that reduction of GABAergic transmission in the adult rat visual cortex partially reactivates OD plasticity in response to monocular deprivation (MD). This is accompanied by an enhancement of activity-dependent potentiation of synaptic efficacy but not of activity-dependent depression. We also found a decrease in the expression of chondroitin sulfate proteoglycans in the visual cortex of MD animals with reduced inhibition, after the reactivation of OD plasticity. Thus, intracortical inhibition is a crucial limiting factor for the induction of experience-dependent plasticity in the adult visual cortex.

Distribution of extracellular matrix macromolecules in the brainstem of rodents

Event Abstract Back to Event Distribution of extracellular matrix macromolecules in the brainstem of rodents Adám Deák1*, Ali J. Nikkhah1, Botond Gaál1, Katalin Szakszon2, Tímea Bácskai3 and Klára Matesz1 1 University of Debrecen, Institute of Anatomy, Histology and Embryology, Hungary 2 University of Debrecen, Department of Pediatrics, Hungary 3 University of Debrecen, Hungary The intercellular space of brain is filled with macromolecules of extracellular matrix (ECM). Recent studies hypothesized that ECM has important role in responses of cells to the changes of environment. In our previous study we have demonstrated that the expression of chondroitinsulfate proteoglycans (CSPG), key molecule of ECM, is changing in vestibular nuclei following the injury of vestibular nerve. We intend to investigate whether the expression of CSPG shows similar modification in the brainstem areas that are connected with the vestibular nuclei. In the present study, we have made a detailed ECM-mapping of CSPG in order to compare the changes of expression pattern. Experiments were performed on adult mice and rats. On anesthetized animals the brainstem was removed and immersed into Sainte-Marie’s fixative. The paraffin embedded specimens were cut in transverse and sagittal plane and biotinylated Wisteria floribunda agglutintin (WFA) was applied to detect the CSPG. The WFA reaction showed an area–dependent distribution in the gray and white matter of brainstem. In the gray matter, the WFA positivity displayed a homogenous or fine granular appearance in the neuropil. The perikarya and dendrites were surrounded with a narrow area representing the perineuronal net (PN). In the mesencephalon, the WFA reaction was intensive in the eye moving motor nuclei, red nucleus and substantia nigra. In the rhombencephalon, each somatomotor cranial nerve nucleus displayed moderate or strong reaction. The PN was intensively stained in the magnocellular nucleus of reticular formation, trapezoid body and the inferior olive. The white matter showed a very intensive reaction in the cerebellar peduncle. The heterogeneous distribution of CSPG in the neural network of brainstem underlying the gaze and posture control may indicate their different involvement in the restoration of vestibular function following the nerve injury. This work was supported by OTKA K 67641 and MTA-TKI 242. Conference: IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010. Presentation Type: Poster Presentation Topic: Sensory and motor systems Citation: Deák A, Nikkhah AJ, Gaál B, Szakszon K, Bácskai T and Matesz K (2010). Distribution of extracellular matrix macromolecules in the brainstem of rodents. Front. Neurosci. Conference Abstract: IBRO International Workshop 2010. doi: 10.3389/conf.fnins.2010.10.00156 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 30 Apr 2010; Published Online: 30 Apr 2010. * Correspondence: Adám Deák, University of Debrecen, Institute of Anatomy, Histology and Embryology, Debrecen, Hungary, adam@chondron.anat.dote.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Adám Deák Ali J Nikkhah Botond Gaál Katalin Szakszon Tímea Bácskai Klára Matesz Google Adám Deák Ali J Nikkhah Botond Gaál Katalin Szakszon Tímea Bácskai Klára Matesz Google Scholar Adám Deák Ali J Nikkhah Botond Gaál Katalin Szakszon Tímea Bácskai Klára Matesz PubMed Adám Deák Ali J Nikkhah Botond Gaál Katalin Szakszon Tímea Bácskai Klára Matesz Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Metallothionein induces a regenerative reactive astrocyte phenotype via JAK/STAT and RhoA signalling pathways

Following central nervous system injury, astrocytes rapidly respond by undergoing a stereotypical pattern of molecular and morphological alterations termed “reactive” astrogliosis. We have reported previously that metallothioneins (MTs) are rapidly expressed by reactive astrocytes and that their secretion and subsequent interaction with injured neurons leads to improved neuroregeneration. We now demonstrate that exogenous MT induces a reactive morphology and elevated GFAP expression in cultured astrocytes. Furthermore, these astrogliotic hallmarks were mediated via JAK/STAT and RhoA signalling pathways. However, rather than being inhibitory, MT induced a form of astrogliosis that was permissive to neurite outgrowth and which was associated with decreased chondroitin sulphate proteoglycan (CSPG) expression. The results suggest that MT has an important role in mediating permissive astrocytic responses to traumatic brain injury.

Influence of aging on chondroitin sulfate proteoglycan expression and neural stem/progenitor cells in rat brain and improving effects of a herbal medicine, yokukansan

There is evidence of structural and functional deterioration in the brain, including the prefrontal cortex (PFC) and hippocampus, during the normal aging process in animals and humans. Extracellular matrix-associated glycoproteins, such as chondroitin sulfate proteoglycans (CSPGs), are involved in not only maintaining the structures and functions of adult neurons, but also regulating the proliferation, migration, and neurite outgrowth of neural stem cells in the brain. On the other hand, a herbal medicine, yokukansan (YKS), is used in a variety of clinical situations for treating symptoms associated with age-related neurodegenerative disorders such as Alzheimer's disease, but its pharmacological properties have not been fully understood. The present study was designed to clarify the influence of aging and the improving effects of YKS on the expression of aggrecan, a major molecule of CSPGs, and on the proliferation and migration of neural stem/progenitor cells identified by bromodeoxyuridine (BrdU) incorporation in the PFC and hippocampus including the dentate gyrus. Aged rats (24 months old) showed a significant increase in aggrecan expression throughout the PFC and in the hippocampus particularly in the CA3 subfield, but not the dentate gyrus compared to young rats (5 months old), evaluated by the immunohistochemical method. YKS treatment decreased the age-related increase in aggrecan expression as well as normal expression in young rats. Aged rats also showed a decreased number of BrdU-labeled cells in the PFC and hippocampus, and these decreases were improved by YKS treatment, which also increased the numbers in young rats. These results suggest that aging influences the microenvironment for adult and immature neurons in the brain, which may affect the proliferation and migration of neural stem/progenitor cells, and YKS has pharmacological potency for these age-related events. These findings help to understand the physiology and pathology of the aged brain and provide an anti-aging strategy for the brain.

Transgenic inhibition of astroglial NF‐κB leads to increased axonal sparing and sprouting following spinal cord injury

We previously showed that Nuclear Factor kappaB (NF-kappaB) inactivation in astrocytes leads to improved functional recovery following spinal cord injury (SCI). This correlated with reduced expression of pro-inflammatory mediators and chondroitin sulfate proteoglycans, and increased white matter preservation. Hence we hypothesized that inactivation of astrocytic NF-kappaB would create a more permissive environment for axonal sprouting and regeneration. We induced both contusive and complete transection SCI in GFAP-Inhibitor of kappaB-dominant negative (GFAP-IkappaBalpha-dn) and wild-type (WT) mice and performed retrograde [fluorogold (FG)] and anterograde [biotinylated dextran amine (BDA)] tracing 8 weeks after injury. Following contusive SCI, more FG-labeled cells were found in motor cortex, reticular formation, and raphe nuclei of transgenic mice. Spared and sprouting BDA-positive corticospinal axons were found caudal to the lesion in GFAP-IkappaBalpha-dn mice. Higher numbers of FG-labeled neurons were detected immediately rostral to the lesion in GFAP-IkappaBalpha-dn mice, accompanied by increased expression of synaptic and axonal growth-associated molecules. After transection, however, no FG-labeled neurons or BDA-filled axons were found rostral and caudal to the lesion, respectively, in either genotype. These data demonstrated that inhibiting astroglial NF-kappaB resulted in a growth-supporting terrain promoting sparing and sprouting, rather than regeneration, of supraspinal and propriospinal circuitries essential for locomotion, hence contributing to the improved functional recovery observed after SCI in GFAP-IkappaBalpha-dn mice.

Effects of cornel iridoid glycoside on CNS microenvironment related to neurogenesis in AD-like rat model induced by fimbria-fornix transaction

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive decline of cognitive abilities and by neuropathological features, including diffuse loss of neurons in the hippocampus and neocortex. The local microenvironment in regions of ongoing neurogenesis in the adult mammalian brain regulates the self-renewal, activation and differentiation of stem cells. Cornel iridoid glycoside (CIG) is a main component extracted from a traditional Chinese herb Cornus officinalis. Our previous study found that CIG promoted neurogenesis and angiogenesis in the brain and improved neurological function after focal cerebral ischemia in rats. The aim of the present study is to investigate the effects of CIG on CNS microenvironment related to neurogenesis in AD-like rat model. AD-like rat model was induced by fimbria-fornix transaction (FFT), which injures the cholinergic nerve fiber projection from basal forebrain to hippocampus and cerebral cortex. Neurobehavioral deficits were determined by Morris water maze and step-through tests. Pathological change was evaluated with Nissl's staining. The expression of neurotrophic factors, growth-associated protein (GAP-43), NogoA, chondroitin sulfate proteoglycan (CSPG), synaptophysin (SYP) and apoptosis-regulating factors was detected by western blot and immunohistochemistry. Intragastrical administration of CIG to FFT model rats for 28 days significantly improved the learning-memory ability; increased the number of neurons, elevated the expression of nerve growth factor (NGF) and its receptor TrkA, brain-derived neurotrophic factor (BDNF), GAP-43 and SYP; inhibited the expression of NogoA and CSPG which impede nerve growth; increased apoptosis-inhibiting factor Bcl-2 and decreased apoptosis-promoting factors Bax and cytochrome C in the hippocampus and cerebral cortex of model rats. CIG effectively increased the beneficial factors and decreased the harmful factors in CNS microenvironment related to neurogenesis in AD-like rat model induced by fimbria-fornix transaction, suggesting that CIG may help to promote neurogenesis and have the potential to treat AD and other neurodegenerative diseases. Key words: cornel iridoid glycoside; Cornus officinalis; Alzheimer's disease; CNS microenvironment; neurogenesis; fimbria-fornix transaction

Traumatic brain injury results in disparate regions of chondroitin sulfate proteoglycan expression that are temporally limited

Axonal injury is a major hallmark of traumatic brain injury (TBI), and it seems likely that therapies directed toward enhancing axon repair could potentially improve functional outcomes. One potential target is chondroitin sulfate proteoglycans (CSPGs), which are major axon growth inhibitory molecules that are generally, but not always, up-regulated after central nervous system injury. The current study was designed to determine temporal changes in cerebral cortical mRNA or protein expression levels of CSPGs and to determine their regional localization and cellular association by using immunohistochemistry in a controlled cortical impact model of TBI. The results showed significant increases in versican mRNA at 4 and 14 days after TBI but no change in neurocan, aggrecan, or phosphacan. Semiquantitative Western blot (WB) analysis of cortical CSPG protein expression revealed a significant ipsilateral decrease of all CSPGs at 1 day after TBI. Lower CSPG protein levels were sustained until at least 14 days, after which the levels began to normalize. Immunohistochemistry data confirm previous reports of regional increases in CSPG proteins after CNS injury, seen primarily within the developing glial scar after TBI, but also corroborate the WB data by revealing wide areas of pericontusional tissue that are deficient in both extracellular and perineuronal net-associated CSPGs. Given the evidence that CSPGs are largely inhibitory to axonal growth, we interpret these data to indicate a potential for regional spontaneous plasticity after TBI. If this were the case, the gradual normalization of CSPG proteins over time postinjury would suggest that this may be temporally as well as regionally limited.

Olfactory stem cells can be induced to express chondrogenic phenotype in a rat intervertebral disc injury model

Background In humans, lower back pain is one of the most common causes of morbidity. Many studies implicate degeneration of intervertebral discs as the cause. In the normal intervertebral disc, the nucleus pulposus exerts a hydrostatic pressure against the constraining annulus fibrosus, which allows the disc to maintain flexibility between adjacent vertebrae, while absorbing necessary compressive forces. The nucleus pulposus performs this role because of its hydrophilic gel-like structure. The extracellular matrix of the nucleus pulposus is up to 80% hydrated, as a result of large amounts of the aggregating proteoglycan, chondroitin sulfate proteoglycan (CSPG). This proteoglycan is enmeshed in a randomly orientated network of fine collagen Type II (CT2) fibers. Study design and purpose A useful adult tissue-derived stem cell is that from the olfactory mucosa, the organ of smell. These cells, accessible in humans from nasal biopsies, are multipotent and are able to make many cell types from all germ layers. They are easily grown in vitro and can be expanded to large numbers and stored frozen. These qualities indicate the potential for autologous transplantation for disc repair. In this article, using a rat model, we explore the hypothesis that olfactory stem cells can differentiate into a nucleus pulposus chondrocyte phenotype in vitro, as well as in vivo after transplantation into the injured intervertebral disc. Patient sample Female rats (14 weeks) were anesthetized with xylazine/ketamine. The abdominal wall was shaved and injected with local anesthetic (lidocaine) before incision. The ventral part of the lumbar spine, including two intervertebral discs, was exposed. Disc degeneration was then induced in the two exposed discs by needle aspiration of the nucleus pulposus. The prominent spina iliaca posterior superior was used as an anatomical landmark for identification of the first disc. Two weeks later, one injured intervertebral disc was exposed in a second, similar, surgery and 20,000 olfactory neurosphere-derived cells were transplanted with a 25-G needle. Outcome measures In vitro induction of nucleus pulposus chondrocyte phenotype is measured by the percentage of cells expressing CT2 and CSPG. In vivo, a successful outcome is evidence of engraftment of donor-derived cells and their expression of CT2 and CSPG. Methods In this article, we tested two hypotheses: the first that progenitor cells within olfactory neurospheres could be induced to express markers distinctive of the nucleus pulposus when placed in vitro in a coculture experiment. The second hypothesis tested the same induction in genetically labeled transplanted cells within damaged vertebral discs in vivo. The two markers measured are those held by current literature to engender the necessary cushioning characteristics of nucleus pulposus, CT2 and CSPG. Results Our experiments demonstrated virtually 100% induction of these two markers in vitro. Also, this induction was achieved in donor-derived cells after delivery to the nucleus pulposus region of animals whose discs had previously been lesioned 2 weeks before transplant. Conclusions These results provide a rationale for moving toward more extensive larger animal studies for assessment of regeneration before human trials where relief of symptoms can be more easily assessed.

Activity-dependent changes in expression of chondroitin sulfate proteoglycan

This chapter focuses on the changes in the expression of the axon growth-inhibitory chondroitin sulphate proteoglycans (CSPGs). CSPGs represent a varied class of complex extracellular matrix macromolecules. They share a general molecular structure comprising a central core protein with a number of covalently attached carbohydrate chains known as “glycosaminoglycans” (GAG). The experimental data indicates that the expression of a number of different CSPGs is increased following central nervous system (CNS) injury. The hyalectans neurocan—versican and brevican—plus NG2 and phosphacan are upregulated following injury and all have been shown to exhibit inhibitory effects on neurite outgrowth in vitro.

Matrix Metalloproteinase-9 Facilitates Glial Scar Formation in the Injured Spinal Cord

In the injured spinal cord, a glial scar forms and becomes a major obstacle to axonal regeneration. Formation of the glial scar involves migration of astrocytes toward the lesion. Matrix metalloproteinases (MMPs), including MMP-9 and MMP-2, govern cell migration through their ability to degrade constituents of the extracellular matrix. Although MMP-9 is expressed in reactive astrocytes, its involvement in astrocyte migration and formation of a glial scar is unknown. Here we found that spinal cord injured, wild-type mice expressing MMPs developed a more severe glial scar and enhanced expression of chondroitin sulfate proteoglycans, indicative of a more inhibitory environment for axonal regeneration/plasticity, than MMP-9 null mice. To determine whether MMP-9 mediates astrocyte migration, we conducted a scratch wound assay using astrocytes cultured from MMP-9 null, MMP-2 null, and wild-type mice. Gelatin zymography confirmed the expression of MMP-9 and MMP-2 in wild-type cultures. MMP-9 null astrocytes and wild-type astrocytes, treated with an MMP-9 inhibitor, exhibited impaired migration relative to untreated wild-type controls. MMP-9 null astrocytes showed abnormalities in the actin cytoskeletal organization and function but no detectable untoward effects on proliferation, cellular viability, or adhesion. Interestingly, MMP-2 null astrocytes showed increased migration, which could be attenuated in the presence of an MMP-9 inhibitor. Collectively, our studies provide explicit evidence that MMP-9 is integral to the formation of an inhibitory glial scar and cytoskeleton-mediated astrocyte migration. MMP-9 may thus be a promising therapeutic target to reduce glial scarring during wound healing after spinal cord injury.

Expression and tissue localization of β-catenin, α-actinin and chondroitin sulfate proteoglycan 6 is modulated during rat and human left ventricular hypertrophy

Left ventricular hypertrophy (LVH) correlates with chronic renal failure and is one of the most important causes of cardiac mortality. The understanding of the molecular complexity of the disease will help to find biomarkers that open new perspectives about early diagnosis and therapy. This work describes the identification of mediators during pathogenesis relevant for structural remodeling processes of cardiac tissue in uremic LVH. An established rat model of chronic renal failure allowed whole-genome transcriptome analyses as well as the investigation of differential expressed proteins in uremic LVH. The localization of potential biomarkers encoded by candidate genes was done by immunohistochemical analyses of cardiac tissue of the animal model as well as cardiac sections of LVH diseased patients. In addition, the induction of human cardiac fibroblasts (HCF) and human umbilical vein endothelial cells (HUVEC) with the LVH mediator angiotensin II enabled us to investigate uremic LVH progression in vitro. These results point to alterations of myocardial intercellular and cell–matrix contacts in hypertrophic cardiac tissue. Obviously, structural changes of the extracellular matrix are significantly modulated by β-catenin associated signaling pathways. Interestingly, intracellular translocation of β-catenin, α-actinin and chondroitin sulfate proteoglycan 6 (CSPG6/SMC3) was observed in the animal model and in LVH patients. Our results show that the parallel investigation of rat and human cardiac tissue as well as human cellular models in vitro represents a promising strategy to identify reliable biomarkers of LVH.

Expression of chondroitin sulfate proteoglycans in barrel field of mouse and rat somatosensory cortex

Chondroitin sulfate proteoglycans (CSPGs) consist of chondroitin sulfate (CS) glycosaminoglycans (GAGs) and core protein and regulate the migration, axonal outgrowth, and synaptogenesis in mammalian brains. In the present study, we investigated the localization of CSPGs, the effects of sensory deprivation on the density of perineuronal nets (PNNs), and the effects of chondroitinase ABC (Chase) on the formation of barrel structures in the posterior medial barrel subfield (PMBSF). In developing mouse and rat brains, the immunoreactivity of chondroitin-6-sulfate containing proteoglycan (CS-6-PG), phosphacan, and neurocan was stronger at barrel septa as compared with barrel hollows and surrounding cortex, while the labeling of Wisteria floribunda agglutinin (WFA) was observed at barrel hollows. In adult brains, CS-6-PG-immunoreactive and WFA-labeled PNNs were observed mainly at barrel hollows of mouse, but they were seen chiefly at barrel septa of rats. Sensory deprivation of facial vibrissae reduced the number of WFA-labeled PNNs at barrel hollows but not at barrel septa. Intracerebral injection of Chase did not affect the formation of barrel structures in the PMBSF. These data indicate species-dependent heterogeneity of CSPG expression and activity-dependent formation of PNNs in the PMBSF, but CS GAGs have no crucial function in constructing the barrel structures during early postnatal development.

A morphological and electrophysiological study on the postnatal development of oligodendrocyte precursor cells in the rat brain

A widespread population of cells in CNS is identified by specific expression of the NG2 chondroitin sulphate proteoglycan and named as oligodendrocyte precursor cell (OPC). OPCs may possess stem cell-like characteristics, including multipotentiality in vitro and in vivo. It was proposed that OPCs in the CNS parenchyma comprise a unique population of glia, distinct from oligodendrocytes and astrocytes. This study confirmed that NG2 immunoreactive OPCs were continuously distributed in cerebral cortex and hippocampus during different postnatal developmental stages. These cells rapidly increased in number over the postnatal 7 days and migrate extensively to populate with abundant processes both in developing cortex and hippocampus. The morphology of OPCs exhibited extremely complex changes with the distribution of long distance primary process gradually increased from neonatal to adult CNS. Immunohistochemical studies showed that OPCs exhibited the morphological properties that can be distinguished from astrocytes. The electrophysiological properties showed that OPCs expressed a small amount of inward Na + currents which was distinguished from Na + currents in neurons owing to their lower Na-to-K conductance ratio and higher command voltage step depolarized maximum Na + current amplitude. These observations suggest that OPCs can be identified as the third type of macroglia because of their distribution in the CNS, the morphological development in process diversity and the electrophysiological difference from astrocyte.

The influence of sub-micron inhibitory clusters on growth cone substratum attachments and CD44 expression

Proteoglycan expression patterns in the central nervous system guide neuronal pathfinding during development, but also disrupt regeneration after injuries. To deepen our understanding of the molecular level effects of proteoglycan spatial arrangements on neuronal pathfinding, we designed micropatterning stamps for the precise placement of near single molecule chondroitin sulfate proteoglycan (CSPG) clusters into regularly spaced arrays. Actin ultrastructural analysis in dorsal root ganglion neurons grown on laminin-coated substrata patterned with aggrecan cluster arrays revealed filopodial and lamellapodial edge contact avoidance of individual clusters, while growth cone lamellapodia and central domains were able to span multiple clusters over a range of cluster densities. Total internal reflection fluorescence microscopy interrogation of growth cone substratum morphology further revealed persistence of integrin mediated substratum adhesion and local out-of-plane membrane bending over clusters on the height scale of aggrecan glycosaminoglycan side chains. Direct imaging of cell adhesion molecule CD44 expression in growth cones revealed an aggrecan dose dependent upregulation in CD44 molecules. Evidence of CD44 clustering coinciding with underlying aggrecan molecules implies CSPG–CD44 interactions. The results reveal the limited local repulsive effect of CSPGs on neuronal structures and provide evidence that CD44 upregulation in neurons is affected by local CSPG expression.

Statins decrease chondroitin sulfate proteoglycan expression and acute astrocyte activation in central nervous system injury

Statins elicit numerous favorable effects on central nervous system (CNS) injury, including inhibition of the rhoA/ROCK pathway. In the present study, we show that statins decrease acute astrocyte activation in CNS injury, and decrease chondroitin sulfate proteoglycan (CSPG) levels in astrocyte cultures as well as CNS injury. CSPG levels decreased by up to 45% in simvastatin-treated astrocyte cultures compared to control cultures. In simvastatin-treated animals, CSPG levels declined by 60% 8 days after brain stab injury, and by 62–64% 4 weeks after spinal cord injury (SCI). Glial fibrillary acid protein (GFAP) levels decreased in brain stab at 8 days after surgery/intervention, suggesting that statins produce a decrease in astrocyte activation. Attenuation of astrocyte activation may contribute to the decline in CSPG levels. However, there are likely other contributing factors, since GFAP levels were not a contributing factor in the decline of CSPG levels in astrocyte cultures. Robust locomotor improvements were not observed with any treatment. The numerous beneficial effects of statins on CNS injury render them an attractive candidate in the treatment of CNS injury.

Methylprednisolone inhibits the expression of glial fibrillary acidic protein and chondroitin sulfate proteoglycans in reactivated astrocytes

Reactive gliosis caused by post-traumatic injury often results in marked expression of chondroitin sulfate proteoglycan (CSPG), which inhibits neurite outgrowth and regeneration. Methylprednisolone (MP), a synthetic glucocorticoid, has been shown to have neuroprotective and anti-inflammatory effects for the treatment of acute spinal cord injury (SCI). However, the effect of MP on CSPG expression in reactive glial cells remains unclear. In our study, we induced astrocyte reactivation using alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) and cyclothiazide to mimic the excitotoxic stimuli of SCI. The expression of glial fibrillary acidic protein (GFAP), a marker of astrocyte reactivation, and CSPG neurocan and phosphacan were significantly elevated by AMPA treatment. The conditioned media from AMPA-treated astrocytes strongly inhibited neurite outgrowth of rat dorsal root ganglion neurons, and this effect was reversed by pretreatment with MP. Furthermore, MP downregulated GFAP and CSPG expression in adult rats with SCI. Additionally, both the glucocorticoid receptor (GR) antagonist RU486 and GR siRNA reversed the inhibitory effects of MP on GFAP and neurocan expression. Taken together, these results suggest that MP may improve neuronal repair and promote neurite outgrowth after excitotoxic insult via GR-mediated downregulation of astrocyte reactivation and inhibition of CSPG expression.

Schwann cell precursors transplanted into the injured spinal cord multiply, integrate and are permissive for axon growth

There is a strong current interest in the use of cell transplantation for the treatment of spinal cord injuries. We report here the novel and potentially useful properties of an early cell in the Schwann cell lineage, the Schwann cell precursor (SCP). The experiments reveal a striking difference between these cells and Schwann cells when transplanted into the CNS. Unlike Schwann cells, SCPs thrive in the CNS where they initially proliferate rapidly but then fall out of division, thus effectively filling up the large cystic cavities formed following crush injury, while avoiding tumor formation. By 8 weeks, SCPs had started to express S100beta protein, a marker that differentiates Schwann cells from SCPs and had formed an apparently stable, vascularized cell mass, which created a continuous cellular bridge across the cystic cavities. The formation of the surrounding glial scar was reduced by local spread of the transplanted cells into the surrounding CNS tissue, where the cells integrated intimately with astrocytes and attenuated the physical barrier they normally form. SCP transplantation also altered and reduced the expression of chondroitin sulfate proteoglycans around the injury site. Caudal to the SCP transplants there was a large increase in the number of axons, compared with that seen in nontransplanted control tissue, showing that the implants effectively support axonal growth or sprouting. SCPs have advantageous attributes for CNS repair, despite the fact that sticky tape removal and ladder crossing tests at 8 weeks did not reveal significant functional improvements when compared with control animals.

Cutaneous Cancer Stem Cells: β-Catenin Strikes Again

Cancer stem cells (CSCs) are a subpopulation of tumor cells that retain properties of tissue-specific stem cells, including the ability to self-renew. In a recent article in Nature, Malanchi et al. (2008) identified a population of CD34(+) cells in epidermal tumors that require beta-catenin signaling to maintain a CSC phenotype.