Glycosaminoglycan changes in human gliomas. A biochemical study

Evaluation of the Cytotoxicity of Cationic Polymers on Glioblastoma Cancer Stem Cells

Cationic polymers such as polyethylenimine (PEI) have found a pervasive place in laboratories across the world as gene delivery agents. However, their applications are not limited to this role, having found a place as delivery agents for drugs, in complexes known as polymer-drug conjugates (PDCs). Yet a potentially underexplored domain of research is in their inherent potential as anti-cancer therapeutic agents, which has been indicated by several studies. Even more interesting is the recent observation that certain polycations may present a significantly greater toxicity towards the clinically important cancer stem cell (CSC) niche than towards more differentiated bulk tumour cells. These cells, which possess the stem-like characteristics of self-renewal and differentiation, are highly implicated in cancer drug resistance, tumour recurrence and poor clinical prognosis. The search for compounds which may target and eliminate these cells is thus of great research interest. As such, the observation in our previous study on a PEI-based PDC which showed a considerably higher toxicity of PEI towards glioblastoma CSCs (GSCs) than on more differentiated glioma (U87) cells led us to investigate other cationic polymers for a similar effect. The evaluation of the toxicity of a range of different types of polycations, and an investigation into the potential source of GSC's sensitivity to such compounds is thus described.

Comparison of Dynamic Contrast-Enhancement Parameters between Gadobutrol and Gadoterate Meglumine in Posttreatment Glioma: A Prospective Intraindividual Study

BACKGROUND AND PURPOSE

Differences in molecular properties between one-molar and half-molar gadolinium-based contrast agents are thought to affect parameters obtained from dynamic contrast-enhanced imaging. The aim of our study was to investigate differences in dynamic contrast-enhanced parameters between one-molar nonionic gadobutrol and half-molar ionic gadoterate meglumine in patients with posttreatment glioma.

MATERIALS AND METHODS

This prospective study enrolled 32 patients who underwent 2 20-minute dynamic contrast-enhanced examinations, one with gadobutrol and one with gadoterate meglumine. The model-free parameter of area under the signal intensity curve from 30 to 1100 seconds and the Tofts model-based pharmacokinetic parameters were calculated and compared intraindividually using paired t tests. Patients were further divided into progression (n = 12) and stable (n = 20) groups, which were compared using Student t tests.

RESULTS

Gadobutrol and gadoterate meglumine did not show any significant differences in the area under the signal intensity curve or pharmacokinetic parameters of K ^trans, V_e, V_p, or K_ep (all P > .05). Gadobutrol showed a significantly higher mean wash-in rate (0.83 ± 0.64 versus 0.29 ± 0.63, P = .013) and a significantly lower mean washout rate (0.001 ± 0.0001 versus 0.002 ± 0.002, P = .02) than gadoterate meglumine. Trends toward higher area under the curve, K ^trans, V_e, V_p, wash-in, and washout rates and lower K_ep were observed in the progression group in comparison with the treatment-related-change group, regardless of the contrast agent used.

CONCLUSIONS

Model-free and pharmacokinetic parameters did not show any significant differences between the 2 gadolinium-based contrast agents, except for a higher wash-in rate with gadobutrol and a higher washout rate with gadoterate meglumine, supporting the interchangeable use of gadolinium-based contrast agents for dynamic contrast-enhanced imaging in patients with posttreatment glioma.

Involvement of Heparan Sulfate and Heparanase in Neural Development and Pathogenesis of Brain Tumors

Brain tumors are aggressive and devastating diseases. The most common type of brain tumor, glioblastoma (GBM), is incurable and has one of the worst five-year survival rates of all human cancers. GBMs are invasive and infiltrate healthy brain tissue, which is one main reason they remain fatal despite resection, since cells that have already migrated away lead to rapid regrowth of the tumor. Curative therapy for medulloblastoma (MB), the most common pediatric brain tumor, has improved, but the outcome is still poor for many patients, and treatment causes long-term complications. Recent advances in the classification of pediatric brain tumors reveal distinct subgroups, allowing more targeted therapy for the most aggressive forms, and sparing children with less malignant tumors the side-effects of massive treatment. Heparan sulfate proteoglycans (HSPGs), main components of the neurogenic niche, interact specifically with a large number of physiologically important molecules and vital roles for HS biosynthesis and degradation in neural stem cell differentiation have been presented. HSPGs are composed of a core protein with attached highly charged, sulfated disaccharide chains. The major enzyme that degrades HS is heparanase (HPSE), an important regulator of extracellular matrix (ECM) remodeling which has been suggested to promote the growth and invasion of other types of tumors. This is of clinical interest because GBM are highly invasive and children with metastatic MB at the time of diagnosis exhibit a worse outcome. Here we review the involvement of HS and HPSE in development of the nervous system and some of its most malignant brain tumors, glioblastoma and medulloblastoma.

Dissecting and rebuilding the glioblastoma microenvironment with engineered materials

Glioblastoma (GBM) is the most aggressive and common form of primary brain cancer. Several decades of research have provided great insight into GBM progression; however, the prognosis remains poor with a median patient survival time of ~ 15 months. The tumour microenvironment (TME) of GBM plays a crucial role in mediating tumour progression and thus is being explored as a therapeutic target. Progress in the development of treatments targeting the TME is currently limited by a lack of model systems that can accurately recreate the distinct extracellular matrix composition and anatomic features of the brain, such as the blood-brain barrier and axonal tracts. Biomaterials can be applied to develop synthetic models of the GBM TME to mimic physiological and pathophysiological features of the brain, including cellular and ECM composition, mechanical properties, and topography. In this Review, we summarize key features of the GBM microenvironment and discuss different strategies for the engineering of GBM TME models, including 2D and 3D models featuring chemical and mechanical gradients, interfaces and fluid flow. Finally, we highlight the potential of engineered TME models as platforms for mechanistic discovery and drug screening as well as preclinical testing and precision medicine.

Surfen-mediated blockade of extratumoral chondroitin sulfate glycosaminoglycans inhibits glioblastoma invasion

Invasive spread of glioblastoma (GBM) is linked to changes in chondroitin sulfate (CS) proteoglycan (CSPG)-associated sulfated glycosaminoglycans (GAGs) that are selectively up-regulated in the tumor microenvironment (TME). We hypothesized that inhibiting CS-GAG signaling in the TME would stem GBM invasion. Rat F98 GBM cells demonstrated enhanced preferential cell invasion into oversulfated 3-dimensional composite of CS-A and CS-E [4- and 4,6-sulfated CS-GAG (COMP)] matrices compared with monosulfated (4-sulfated) and unsulfated hyaluronic acid matrices in microfluidics-based choice assays, which is likely influenced by differential GAG receptor binding specificities. Both F98 and human patient-derived glioma stem cells (GSCs) demonstrated a high degree of colocalization of the GSC marker CD133 and CSPGs. The small molecule sulfated GAG antagonist bis-2-methyl-4-amino-quinolyl-6-carbamide (surfen) reduced invasion and focal adhesions in F98 cells encapsulated in COMP matrices and blocked CD133 and antichondroitin sulfate antibody (CS-56) detection of respective antigens in F98 cells and human GSCs. Surfen-treated F98 cells down-regulated CSPG-binding receptor transcripts and protein, as well as total and activated ERK and protein kinase B. Lastly, rats induced with frontal lobe tumors and treated with a single intratumoral dose of surfen demonstrated reduced tumor burden and spread compared with untreated controls. These results present a first demonstration of surfen as an inhibitor of sulfated GAG signaling to stem GBM invasion.-Logun, M. T., Wynens, K. E., Simchick, G., Zhao, W., Mao, L., Zhao, Q., Mukherjee, S., Brat, D. J., Karumbaiah, L. Surfen-mediated blockade of extratumoral chondroitin sulfate glycosaminoglycans inhibits glioblastoma invasion.

Toward 3D biomimetic models to understand the behavior of glioblastoma multiforme cells

Glioblastoma multiforme (GBM) tumors are one of the most deadly forms of human cancer and despite improved treatments, median survival time for the majority of patients is a dismal 12-15 months. A hallmark of these aggressive tumors is their unique ability to diffusively infiltrate normal brain tissue. To understand this behavior and successfully target the mechanisms underlying tumor progression, it is crucial to develop robust experimental ex vivo disease models. This review discusses current two-dimensional (2D) experimental models, as well as animal-based models used to examine GBM cell migration, including their advantages and disadvantages. Recent attempts to develop three-dimensional (3D) tissue engineering-inspired models and their utility in unraveling the role of microenvironment on tumor cell behaviors are also highlighted. Further, the use of 3D models to bridge the gap between 2D and animal models is explored. Finally, the broad utility of such models in the context of brain cancer research is examined.

Influence of chondroitin sulfate and hyaluronic acid on structure, mechanical properties, and glioma invasion of collagen I gels

To mimic the extracellular matrix surrounding high grade gliomas, composite matrices composed of either acid-solubilized (AS) or pepsin-treated (PT) collagen and the glycosaminoglycans chondroitin sulfate (CS) and hyaluronic acid (HA) are prepared and characterized. The structure and mechanical properties of collagen/CS and collagen/HA gels are studied via confocal reflectance microscopy (CRM) and rheology. CRM reveals that CS induces fibril bundling and increased mesh size in AS collagen but not PT collagen networks. The presence of CS also induces more substantial changes in the storage and loss moduli of AS gels than of PT gels, in accordance with expectation based on network structural parameters. The presence of HA significantly reduces mesh size in AS collagen but has a smaller effect on PT collagen networks. However, both AS and PT collagen network viscoelasticity is strongly affected by the presence of HA. The effects of CS and HA on glioma invasion is then studied in collagen/GAG matrices with network structure both similar to (PT collagen-based gels) and disparate from (AS collagen-based gels) those of the corresponding pure collagen matrices. It is shown that CS inhibits and HA has no significant effect on glioma invasion in 1.0 mg/ml collagen matrices over 3 days. The inhibitory effect of CS on glioma invasion is more apparent in AS than in PT collagen gels, suggesting invasive behavior in these environments is affected by both biochemical and network morphological changes induced by GAGs. This study is among the few efforts to differentiate structural, mechanical and biochemical effects of changes to matrix composition on cell motility in 3D.

Molecular neuro-oncology and the development of targeted therapeutic strategies for brain tumors. Part 3: brain tumor invasiveness

Brain tumors are a diverse group of malignancies that remain refractory to conventional treatment approaches. Molecular neuro-oncology has now begun to clarify the transformed phenotype of brain tumors and identify oncogenic pathways that might be amenable to targeted therapy. Cellular invasion of surrounding brain is one of the key features of brain tumor behavior and is currently under evaluation for potential therapeutic targets. Tumor invasion occurs in the context of the extracellular matrix (ECM) of the brain and involves the interaction between cell-surface adhesion molecules, such as integrins and proteins embedded within the ECM. The overexpression of integrins is often associated with invasive behavior and can be inhibited by targeted approaches such as antibodies, antisense constructs and cyclic peptides. Tumor cell-secreted matrix metalloproteinases and serine proteinases degrade ECM proteins and provide space for movement and infiltration. The expression of proteinases positively correlates with tumor grade and infiltrative capacity. Proteinase activity can be reduced by several methods, including antibodies and small-molecule inhibitors such as marimastat. Early clinical trials suggest that marimastat may have activity in combination with traditional chemotherapy regimens. Further development of targeted therapies designed to inhibit tumor infiltration, and evaluation of these new agents in clinical trials, will be needed to improve survival and quality of life for patients with brain tumors.

Effect of hydrophilic components of the extracellular matrix on quantifiable diffusion-weighted imaging of human gliomas: preliminary results of correlating apparent diffusion coefficient values and hyaluronan expression level

OBJECTIVE

The purpose of this study was to evaluate the relationship between apparent diffusion coefficient (ADC) measured by MR imaging and the level of immunohistochemical expression of hyaluronan or hyaluronic acid as one of the main hydrophilic components of the extracellular matrix in brain glial tumors.

MATERIALS AND METHODS

Nineteen patients with primary glial brain tumors were included in the study. Mean ADC values were calculated in all tumors and were normalized with the ADC values of the contralateral normal-appearing brain ratios. All tumors underwent surgical resection, and the histologic diagnosis was based on the analysis of the surgical specimen. Mean values of the labeling index of hyaluronan (LI-HA) were calculated to determine quantifiably the histochemical expression of hyaluronan in the tumor. The mean ADC values and the mean ADC ratios (ADC(ratio)) of the tumors were then correlated to the mean values of the LI-HA.

RESULTS

The mean ADC (93 x 10(-5) mm(2)/sec) and the mean ADC(ratio) (1.25) of the high-grade glial tumors were significantly lower than the mean ADC (123 x 10(-5) mm/sec) and the mean ADC(ratio) (1.64) of the low-grade glial tumors (p < 0.01). The mean LI-HA (72.8%) was also significantly lower in the high-grade gliomas than the mean LI-HA (93.4%) in the low-grade gliomas (p < 0.001). A positive correlation was found between mean ADC values and the mean LI-HA (tau = 0.35, p < 0.05) and also between the mean ADC(ratio) and the mean LI-HA (tau = 0.33, p < 0.05).

CONCLUSION

Hyaluronan as one of the main hydrophilic components of the extracellular matrix in gliomas likely contributes to differences in the ADC values between high- and low-grade glial tumors.

Implantation of C6 astrocytoma spheroid into collagen type I gels: invasive, proliferative, and enzymatic characterizations

A three-dimensional model has been developed in which C6 astrocytoma spheroids of defined sizes are embedded into collagen type I gels. The authors have monitored cell invasive behavior; obtained quantitative data on cell invasion, proliferation, and enzymatic activity; assessed cell-cell interactions by altering the spheroid size used; and studied cell-matrix interactions by modifying the matrix components. Their results show that C6 astrocytoma cells detach from the spheroid surface and invade the gel as single cells by means of a system that appears to be dependent on metalloprotease function. These invasive cells have a low proliferative index. Larger spheroids with central hypoxic microregions possess cells that invade the gel at faster rates; this could be correlated with the release of increased collagen type I degrading activity. Extracellular matrix proteins, such as laminin, fibronectin, and collagen type IV have no significant influence on invasive activity, whereas hyaluronic acid decreases and human central nervous system myelin increases invasion. New strategies directed at the treatment of malignant gliomas must take into account the subpopulation of malignant cells located long distances from the major tumor mass. The spheroid invasion model may provide specific insights into the behavior of these invasive cells.

Morphological and biochemical investigations of mitral valve endocardiosis in pigs

Pig endocardiosis is a pathological process affecting cardiac valves that is characterised by the accumulation of glycosaminoglycans (GAG) in the extracellular matrix. To investigate the involvement of GAG in the condition, the morphology of the mitral valves from 23 affected pigs and seven normal controls was studied and qualitative and quantitative biochemical analyses of GAG were made. Gross and histopathological lesions were characterised by valve enlargement, collagen disorganisation and myxoid degeneration. No differences between normal and diseased valves were detected by lectin histochemistry. Electron microscopy revealed myofibroblast differentiation of many fibroblasts. A statistically significant increase of total GAG and hyaluronan was detected in the mitral valves of the pigs with endocardiosis by spectrophotometric, electrophoretic and densitometric analysis of the extracted GAG. Although it is not known whether the change in hyaluronan is a primary event or a result of other changes in the extracellular matrix, its accumulation in association with myofibroblast differentiation suggests that it plays a pathogenetic role in pig endocardiosis.

Glioma invasion in the central nervous system

Invading glioma cells seem to follow distinct anatomic structures within the central nervous system. Tumor cell dissemination may occur along structures, such as the basement membranes of blood vessels or the glial limitans externa, that contain extracellular matrix (ECM) proteins. Frequently, invasive glioma cells are also found to migrate along myelinated fiber tracts of white matter. This behavior is most likely a consequence of using constitutive extracellular ligands expressed along the pathways of preferred dissemination. The extracellular space in anatomic structures, such as blood vessel basement membranes or between myelinated axons, is profoundly different, thus suggesting that glioma cells may be able to use a multiplicity of matrix ligands, possibly activating separate mechanisms for invasion. In addition, enzymatic modification of the extracellular space or deposition of ECM by the tumor cells may also create a more permissive environment for tumor spread into the adjacent brain. Tumor cell invasion is defined as translocation of neoplastic cells through host cellular and ECM barriers. This process has been studied in other cancers, in which a cascade of events has been described that involves receptor-mediated matrix adhesion, degradation of matrix by tumor-secreted metalloproteinases, and, subsequently, active cell locomotion into the newly created space. Although some of these mechanisms may play an important role in glioma invasion, there are some significant differences that are mainly the result of the profoundly different composition of the extracellular environment within the brain. This review focuses on the composition of central nervous system ECM and the recent evidence for the use by glioma cells of multiple invasion mechanisms in response to this unique environment.

Chondroitin sulfate proteoglycan staining in astrocyte-Schwann cell co-cultures

Transplantation of Schwann cells (SCs) in the central nervous system (CNS) for remyelination in pathological situations has been considered a promising approach. However, numerous studies have indicated that astrocytes have a restrictive effect on SC migration within the CNS. We have previously established an in vitro model which demonstrates the restrictive effect of astrocytes on SCs (Ghirnikar and Eng, Glia 4:367-377, 1994). Using this culture model, in the present study, we have characterized the molecular basis underlying astrocyte-SC interaction and demonstrated chondroitin sulfate proteoglycan (CSP) staining in the co-cultures. Following 1-2 weeks of incubation, CSP staining was specifically associated with SCs co-cultured with astrocytes. Staining with antibodies specific for the different chondroitin sulfate isomers revealed the presence of both, chondroitin-4- and 6-sulfates in SCs. In contrast, SCs when cultured alone, or in the presence of astrocytes conditioned medium did not show CSP staining. These data suggest that CSP staining is associated with SCs following co-culture with astrocytes and mediated by cell to cell contact. We hypothesize that the CSP, alone or in combination with other molecules expressed by astrocytes and/or SCs, may be involved in the restrictive effects of astrocytes on SCs. Identification of molecules involved in the unfavorable interaction between astrocytes and SCs will have an important bearing on efforts to remyelinate demyelinated axons by SC transplantation within the damaged CNS.

A protective action of chondroitin sulfate proteoglycans against neuronal cell death induced by glutamate

The role of chondroitin sulfate proteoglycans (CSPGs) on excitotoxic cell death and long-term survival of neurons were investigated in primary cultured neurons of the rat cortex. Soluble CSPGs were prepared from 10-day-old and adult rat brains by the ion-exchange chromatography on DEAE-Sephacel. CSPGs were added to the culture medium on culture day 4, and glutamate neurotoxicity was examined on culture day 7 by both microscopic cell count and measurement of lactate dehydrogenase activity in culture media. The effect on long-term survival was evaluated by counting viable neurons until culture day 28. CSPGs and core proteins, but not glycosaminoglycan chains (GAGs), protected cultured neurons from excitotoxic cell death induced by 24 h exposure to 1 mM glutamate, but CSPGs did not promote the long-term survival of neurons. The neuroprotective effect of CSPGs and core proteins was dose-dependent with ED50 about 10 microM hexuronate and 2 micrograms/ml protein respectively. This effect was not considered to be due to adsorption of glutamate by CSPGs because [3H]glutamate was not adsorbed by CSPGs added to the culture medium. Based on these findings, we suggested that CSPGs may exert their neuroprotective action through molecular interactions with the binding sites on neuronal membrane, neurotrophic factors, or other extracellular matrix molecules and may be involved in the pathogenesis of neuronal cell death in acute pathological conditions and chronic degenerative diseases of the brain.

Interferon effect on glycosaminoglycans in mouse glioma in vitro

The effect of mouse interferon alpha/beta (MuIFN alpha/beta) on the production of glycosaminoglycans (GAGs) by mouse glioma G-26 in vitro was evaluated. Two GAG species secreted extracellularly by the mouse glioma G-26 were isolated using cellulose acetate electrophoresis. They were identified as hyaluronic acid (HA) and chondroitin sulfate (CS) following enzymatic digestion with enzymes: hyaluronidase and chondroitinase ABC. Further characterization of CS by enzymatic digestion with specific chondroitinases for chondroitin 4-sulfate (CSA) and chondroitin 6-sulfate (CSC), revealed that the isolated CS was neither CSA nor CSC. Therefore, it may be either chondroitin sulfate B (CSB) (dermatan sulfate) or one of the 'chondroitin sulfate isomers' (D-H). The three day incubation of glioma G-26 cells with 8 x 10-8 x 10(4) U/ml of MuIFN alpha/beta resulted in a dose dependent inhibition of cell proliferation measured by 3H-thymidine incorporation and the MTT assay. The significant decrease of the CS (p < 0.008) but not the HA level, (measured densitometrically), was observed following 72 hours (hrs) incubation of G-26 cells with 8 x 10(3) U/ml of MuIFN alpha/beta (IFN treated cells: 0.03 +/- 0.007 integrated optical density (IOD); control cells: 0.07 +/- 0.01 IOD). The decreased CS production may be the underlying cause of IFN mediated inhibition of glioma cell proliferation.

Adhesion molecules and malignant gliomas: implications for tumorigenesis

Adhesion molecules, a family of cell-surface molecules, are likely to be of central importance in mediating cell-extracellular matrix and specific cell-cell interactions within both neoplastic and inflammatory sites. The recently discovered expression of adhesion molecules on glioma cells, tumor-infiltrating lymphocytes, and endothelial cells within the tumor offers insight into the molecular basis of the interactions both between the glioma cell and surrounding heterologous cell types within the tumor environment, and between the tumor cell and the extracellular matrix. Such interactions suggest that these molecules may play roles in the homing of immune cells to these tumors and in regulating the extent of local tumor invasion. The ability to modulate adhesion molecule expression on either immune cells or their respective ligands on gliomas provides an approach to modify cell-cell interactions that may be used to increase tumor kill by the immune system. A similar approach in the modulation of adhesion molecules involved in tumor cell adhesion to the extracellular matrix or endothelial cells may be a method to limit local invasion in these lesions.

Differential expression of the CD44 molecule in human brain tumours

Expression of the CD44 molecule was examined in a variety of human brain tumours, brain metastases and normal brain. Immunohistological staining with several CD44 antibodies demonstrated differential expression of the CD44 molecule among different brain tumour types. CD44 was strongly expressed in high-grade gliomas and weakly expressed in meningiomas, medulloblastomas and normal brain. Northern blot analysis revealed the presence of 3 major CD44 mRNAs of 1.6, 2.2, and 5.0 kb in glioblastomas and a mRNA of 5.6 kb in meningiomas. CD44 expression was also detected by flow cytometric analysis on cultured cells derived from a variety of human brain tumours including glioblastomas and meningiomas.

Chondroitin sulfate proteoglycan surrounds a subset of human and rat CNS neurons

Chondroitin sulfate proteoglycan (CS-PG) bearing glycosaminoglycan (GAG) chains containing unsulfate (COS) and 6-sulfate (C6S) disaccharides was immunolocalized in rat and human CNS by using monoclonal antibodies (MAb) specific for the two disaccharides. The immunostaining with both MAb was restricted to the periphery of a neuronal subset in rat and human CNS. Double immunofluorescence showed codistribution of the antigens around the same neuronal population. The staining with anti-COS MAb was stronger than with anti-C6S MAb, suggesting that the proteoglycan (PG) contains mainly COS disaccharides. In different rat cortical areas, 40-60/mm2 positive interneurons were found, the visual cortex showing the highest value. In human cortex, positivity was also observed around the soma of some pyramidal cells. In the rat, positive neurons were also localized in deep cerebellar nuclei, reticular nucleus of the thalamus, and other structures of the midbrain and hindbrain. CA3 region of hippocampus and the external layer of pyriform cortex were characterized by positivity of the neuropil. Immunoelectronmicroscopy showed the antigens in the extracellular space around the neuronal soma, the synaptic elements and the cell processes of the neuropil. The neuronal surface of the soma and of the proximal dendrites were positive, but the pre- and postsynaptic membranes and clefts were negative.

Chondroitin 4-sulfate proteoglycan forms an extracellular network in human and rat central nervous system

Chondroitin 4-sulfate proteoglycan (C4S-PG) was localized both in rat and human central nervous system (CNS) by monoclonal and polyclonal antisera recognizing the 4-sulfate disaccharide (C4S). In the rat the whole CNS was studied in serial coronal sections. A positive extracellular meshwork was observed both in white and grey matters. In the white matter (WM) C4S-PG formed a network around myelinated axons, sparing myelin sheaths and axoplasms. The neuropil of the grey matter (GM) showed a positive meshwork constituted by delicate intermingling filaments. The cytoplasms of neuronal, glial and endothelial cells were negative. Stronger straining than in the neuropil was observed around the soma and the proximal part of the cell processes of some neurons located in the cortex, in the deep cerebellar nuclei and in some other CNS nuclei. A similar pattern was also observed in human CNS, the only difference being a smaller amount of cortical neurons surrounded by a rim of C4S-PG. This study shows that a PG bearing C4S disaccharide is located extracellularly in the rodent and human CNS and that C4S disaccharides can be present in different types of CNS proteoglycans (PGs).

Immunohistochemical study of chondroitin sulfate in human gliomas

A polyclonal rabbit antiserum was utilized to localize chondroitin sulfate in human gliomas. Tissue sections were digested with chondroitinase ABC to create the antigenic determinant on the chondroitin sulfate proteoglycan molecule. Normal CNS tissue showed a positive immunohistochemical staining both in white and gray matter, sparing the cytoplasm of glial and neuronal cells. Differentiated astrocytomas presented the same pattern as the normal CNS. Anaplastic astrocytomas and glioblastomas showed progressive reduction of parenchymal positivity as anaplasia increased. These data suggest that chondroitin sulfate is a character expressed by differentiated CNS cells and that it is lost with dedifferentiation. Vascular structures presented positive material in the adventitia in all the oncotypes. A discontinuous positivity was observed in the basal membrane zone of the vessels.