Isolation and culture of human neuromicrovascular endothelial cells for the study of angiogenesis in vitro

Neovascularization in the adult central nervous system occurs as a response to several pathophysiological conditions such as ischemia, wound repair, or neoplasia. Endothelial cells from different blood vessel types, different organs, and different species are heterogeneous; therefore, the appropriate cell type should be used to study specific aspects of vascular pathology. We have developed a method to isolate human cerebral microvascular endothelial cells (CMECs) from small, freshly obtained specimens of normal brain adherent to human arteriovenous malformations (AVMs). The isolation procedure involves enzymatic digestions and gradient centrifugations, yielding over 95% pure primary cultures. Alternative isolation methods using magnetic beads, panning, or cloning were not superior with regard to cell purity or yield. CMECs were identified by their immunoreactivity for vWF, CD34, EN4, binding of Ulex europeus lectin, and uptake of DiI-Ac-LDL. They displayed ultrastructural features characteristic of blood-brain barrier endothelial cells and expressed GLUT-1. CMECs were subcultured; however, prolonged culture led to reduced culture purity. Vascular endothelial growth factor, basic fibroblast growth factor and hepatocyte growth factor/scatter factor stimulated the directional motility of CMECs, with dose-response profiles similar to human umbilical vein endothelial cells (HUVECs). In contrast, to stimulate proliferation, lower concentrations of growth factors tended to be necessary for CMECs than for the large vessel endothelial cells. CMECs formed capillary tube-like structures in an in vitro angiogenesis assay using matrigel. This study expands the spectrum of available tissue sources for the isolation of human neuromicrovascular endothelial cells, which are essential for the in vitro study of blood-brain barrier function and cerebral angiogenesis.

Thromboxane synthase regulates the migratory phenotype of human glioma cells

The capacity of glial tumor cells to migrate and diffusely infiltrate normal brain compromises surgical eradication of the disease. Identification of genes associated with invasion may offer novel strategies for anti-invasive therapies. The gene for TXsyn, an enzyme of the arachidonic acid pathway, has been identified by differential mRNA display as being overexpressed in a glioma cell line selected for migration. In this study TXsyn mRNA expression was found in a large panel of glioma cell lines but not in a strain of human astrocytes. Immunohistochemistry demonstrated TXsyn in the parenchyma of glial tumors and in reactive astrocytes, whereas it could not be detected in quiescent astrocytes and oligodendroglia of normal brain. Glioma cell lines showed a wide range of thromboxane B2 formation, the relative expression of which correlated with migration rates of these cells. Migration was effectively blocked by specific inhibitors of TXsyn, such as furegrelate and dazmegrel. Other TXsyn inhibitors and cyclooxygenase inhibitors were less effective. Treatment with specific inhibitors also resulted in a decrease of intercellular adhesion in glioma cells. These data indicate that TXsyn plays a crucial role in the signal transduction of migration in glial tumors and may offer a novel strategy for anti-invasive therapies.

Tissue culture of human neurocytomas induces the expression of glial fibrilary acidic protein

Cell cultures were established from three human neurocytoma specimens (primary and recurrent). The phenotypic evolution was analyzed by immunocytology in different culture conditions in the presence and absence of serum including the addition of epidermal growth factor, rat caudate extract, retinoic acid, and N-acetyl cystein. The cells were grown on glass cover slides or an extracellular matrix (ECM) from bovine corneal endothelial cells. Immunostainings were performed after overnight incubation and were repeated after 5 and 10 days of culture. The cultures were compared to an oligoastrocytoma also arising at the foramen of Monro and an ependymoma of the frontal lateral ventricle, two tumors supposedly originating from the same tissue matrix as the neurocytoma. After overnight incubation, 90% of the neurocytoma cells were positive for A2B5 and synaptophysin. GFAP reactivity appeared in the periphery of cell processes in less than 1% of the cells. The staining patterns and morphology were nearly identical under the different culture conditions. After 5 days, almost all cells were strongly positive for GFAP, while the number of cells remaining positive for synaptophysin and A2B5 was unchanged from the earlier time point. Again, there were no fundamental differences between the incubation conditions. At this point, cultures maintained on ECM were compared to their counterparts on untreated glass cover slides with identical staining results, although many fewer cells had attached. An identical immuno-reactive pattern was found on day 10. In contrast to the neurocytoma cultures, there was an immediate strong GFAP signal in both the mixed glioma and the ependymoma. A2B5 was also positive, but synaptophysin was absent. Because the neurocytoma specimens were synaptophysin positive but GFAP negative by immunohistochemistry, it is concluded that neurocytomas may represent a human neuronoglial precursor tumor that switches its phenotype in culture to astroglial differentiation despite very diverse culture conditions.

Trk A, B, and C are commonly expressed in human astrocytes and astrocytic gliomas but not by human oligodendrocytes and oligodendroglioma

Neurotrophins regulate the proliferation and differentiation of neurons in the central nervous system via a family of specialized receptors, including TrkA, TrkB, and TrkC. As little is known about their expression or potential role in human glial tissues and glial tumors, we undertook an immunohistochemical analysis of human glia, glioma tissues and cell cultures of glial tumors to characterize the expression of Trk family members (full-length TrkA, TrkB, the truncated form of TrkB, and TrkC). In normal human brain Trk A, B, and C immunoreactivity was found in neurons and some weak staining was also seen astrocytes. No Trk expression was seen on oligodendrocytes. Strong reactivity was seen in reactive astrocytes in a glial scar. In a total of 34 glioma tissue specimens, which included 16 astrocytic tumors (4 low-grade astrocytomas and 12 glioblastomas multiforme) and 15 oligodendrogliomas (8 low-grade and 7 anaplastic) as well as 3 oligoastrocytomas (WHO grade II), TrkA, B, and C immunoreactivity was observed exclusively in specimens from astrocytic gliomas (16/16), but not in any of the oligodendrocytic gliomas (0/15). In the oligoastrocytomas, staining was restricted to the astrocytic component. In the astrocytoma and oligodendroglioma specimens, Trk A, B, and C immunoreactivity was also seen in the surrounding reactive astrocytes. Trk expression was independent of age, sex or histological grade of the investigated tumors. In six primary cell cultures, one derived from human astrocytes and five established from malignant astrocytomas, only TrkA immunoreactivity could be detected, while TrkB (both full-length and truncated isoforms) and TrkC were absent. The TrkA expression in primary cell cultures decreased with continuous cell passaging, and no Trk could be detected in established cell lines derived from glioblastoma. In conclusion, our data suggest that in human glial tissues Trk A, B, and C may be expressed in a lineage-restricted manner, thereby distinguishing between astrocytes and oligodendrocytes in a marker-like fashion. Trk expression, like GFAP expression appears to be increased in activated (reactive)/neoplastic astrocytes.

Glioma cell adhesion and migration on human brain sections

Within the brain, dissemination of glioma cells follows myelinated fiber tracts and extracellular matrix containing structures such as the basement membranes of blood vessels. These patterns represent the two major routes of invasion frequently observed in clinical disease. Previously, we have characterized the substrates for preferential glioma adhesion and migration on purified ECM protein. In this study sections of human brain from different anatomical regions were used as adhesive substrates and also characterized for the presence and distribution of matrix proteins. Adhesion of marker gene transfected glioma cell suspensions to different regions and anatomical structures of human brain was quantified using a computer assisted image analysis system. Monoclonal antibodies against different adhesion molecules were used to inhibit glioma cell attachment ot specific anatomical structures. In addition, glioma cell aggregates were allowed to adhere to brain sections and single cells were observed to migrate out of these aggregates. Scanning electron microscopy was used to morphologically study the preferred routes of glioma dissemination on brain sections. In brain sections different kinetics of cell adhesion to distinct structures were observed. Within 15 minutes cells adhered and spread on blood vessels and arachnoid tissue containing sections. Choroid plexus and the ventricular wall were also adhesive structures. Adhesion to cortex required 1 hour, while adhesion and spreading on myelinated fiber tracts was retarded and required several hours of incubation. The predominant matrix proteins in small vessels were found to be laminin, collagen type IV, and fibronectin. Choroid plexus and the ependyma showed a similar composition of matrix proteins. Arachnoid fibers contained different types of collagens, predominately type I and III, whereas the only matrix protein identified in the subependyma was fibronectin. Antibodies to the alpha 2, alpha 3, and beta 1 integrin subunits completely blocked adhesion to arachnoid tissue, anti-NCAM inhibited attachment to cortex. Adhesion to blood vessels in brain sections could only be inhibited to 50% by anti-integrin beta 1. Antibodies to the av containing integrin av beta 3 also blocked 50% of adhesion to vessels. Our findings indicate that adhesion of glioma cells to brain sections most rapidly takes place on ECM protein containing regions, especially blood vessels which may serve as guiding structures for glioma dissemination.

G protein beta subunit-null mutants are impaired in phagocytosis and chemotaxis due to inappropriate regulation of the actin cytoskeleton

Chemotaxis and phagocytosis are basically similar in cells of the immune system and in Dictyostelium amebae. Deletion of the unique G protein beta subunit in D. discoideum impaired phagocytosis but had little effect on fluid-phase endocytosis, cytokinesis, or random motility. Constitutive expression of wild-type beta subunit restored phagocytosis and normal development. Chemoattractants released by cells or bacteria trigger typical transient actin polymerization responses in wild-type cells. In beta subunit-null cells, and in a series of beta subunit point mutants, these responses were impaired to a degree that correlated with the defect in phagocytosis. Image analysis of green fluorescent protein-actin transfected cells showed that beta subunit- null cells were defective in reshaping the actin network into a phagocytic cup, and eventually a phagosome, in response to particle attachment. Our results indicate that signaling through heterotrimeric G proteins is required for regulating the actin cytoskeleton during phagocytic uptake, as previously shown for chemotaxis. Inhibitors of phospholipase C and intracellular Ca2+ mobilization inhibited phagocytosis, suggesting the possible involvement of these effectors in the process.

Microtubule-mediated centrosome motility and the positioning of cleavage furrows in multinucleate myosin II-null cells

To study centrosome motility and the interaction of microtubules with the cell cortex in mitotic, post-mitotic and interphase cells, (alpha)-tubulin was tagged in Dictyostelium discoideum with green fluorescent protein. Multinucleate cells formed by myosin II-null mutants proved to be especially suited for the analysis of the control of cleavage furrow formation by the microtubule system. After docking of the mitotic apparatus onto the cell cortex during anaphase, the cell surface is activated to form ruffles on top of the asters of microtubules that emanate from the centrosomes. Cleavage furrows are initiated at spaces between the asters independently of the positions of spindles. Once initiated, the furrows expand as deep folds without a continued connection to the microtubule system. Occurrence of unilateral furrows indicates that a closed contractile ring is dispensable for cytokinesis in Dictyostelium. The progression of cytokinesis in the multinucleate cells underlines the importance of proteins other than myosin II in specifying a cleavage furrow. The analysis of centrosome motility suggests a major role for a minus-end directed motor protein, probably cytoplasmic dynein, in applying traction forces on guiding microtubules that connect the centrosome with the cell cortex.

[Congestive myelopathy caused by spinal dural arteriovenous fistulas. Anamnesis, clinical aspects, diagnosis, therapy and prognosis]

Congestive myelopathy, formerly referred to as varicosis spinalis or Foix-Alajouanine syndrome, is caused by a spinal dural arteriovenous fistula (SDAVF). So far, the blood supply from the meningeal arteries draining through the fistula into the medullary venous system can only be verified by spinal angiography. Patients predominantly male and over the age of 60 are afflicted. Initially reversible functional disorders caused by the congestion of the spinal cord veins eventually become irreversible, the most common symptom being an increasingly paretic gait disorder, the signs of which generally begin symmetrically and progress from distal to proximal signs. Simultaneously, predominantly transverse sensory dysfunctions develop, as well as bladder and bowel dysfunctions, most often leading to incontinence. MRI typically shows a central medullary signal enhancement with slight swelling of the afflicted region, initially indicative of a reversible congestive edema and later of an irreversible infarction, and extended perimedullar vessels. Thus, if the clinical course and the characteristic MRI findings suggest the possibility of disease related to congestive myelopathy, spinal angiography becomes indispensable. Since ensuing the success of therapy and prognosis depends on rapid determination of the extent of the illness, a speedy diagnostic reaction is mandatory to institute the treatment necessary to prevent paraplegia.

Absence of polyomavirus JC in glial brain tumors and glioma-derived cell lines

The human neurotropic papovavirus JC, a close relative of simian virus 40, has been associated with the formation of brain tumors in humans because of its ability to induce such tumors in other primates under experimental conditions. Here we have analyzed 30 brain tumors classified as either oligodendroglioma or astrocytoma and 22 cell lines derived from human gliomas for the presence of JC viral sequences using polymerase chain reaction with two different sets of primers. None of the tumors or cell lines contained JC viral sequences. Similarly, we failed to detect expression of JC T antigen in any of 26 human glioma lines analyzed in this study. We conclude that JC virus is not a major cause of human brain tumors.

Scatter factor promotes motility of human glioma and neuromicrovascular endothelial cells

Malignant gliomas are characterized by rapid growth, infiltration of normal brain tissue, and high levels of tumor-associated angiogenesis. The genetic and local environmental tissue factors responsible for the malignant progression from low to high grade gliomas and the highly malignant behavior of glioblastomas are not well understood. In a study of 77 human brain tissue extracts, high grade (III-IV) tumors had significantly greater scatter factor (SF) content than did low grade tumors or non-neoplastic tissue. To investigate the potential significance of SF accumulation in gliomas, we measured the effects of SF on DNA synthesis and motility of cultured human glioma cell lines. SF stimulated DNA synthesis in 7/10 glioma cell lines and in 3/3 neuromicrovascular endothelial cell (NMVEC) lines, consistent with our previous report that SF stimulated cell proliferation of a few human glioma cell lines. SF markedly stimulated the chemotactic migration of 10/10 glioma cell lines as well as 3/3 NMVEC lines. In addition, SF stimulated the 2-dimensional migration of glioma cells on culture surfaces coated with specific extracellular matrix molecules (collagen i.v., laminin, and fibronection). As expected based on these biologic responses to SF, 10/10 glioma lines and 4/4 NMVEC lines expressed mRNA for c-met, the SF receptor. To assess the possible in vivo significance of these migration assays, we compared the chemotactic response of a glioma cell line to human brain cyst fluids and tumor extracts that contained high or low SF concentrations. Fluids and extracts with high SF content tended to induce higher levels of chemotactic migration than did fluids and extracts with low SF content. Addition of anti-SF monoclonal antibody (MAb) inhibited migration induced by fluids and extracts with high SF content by about 30-50%.

Expression and synthesis of insulin-like growth factor-binding proteins in human glioma cell lines

We previously demonstrated the presence of insulin-like growth factors (IGFs) and IGF-receptors in human glioma cell lines derived from primary glioblastomas. The biological action of IGFs is modulated by specific IGF-binding proteins (IGFBP)-1 to -7. By means of polymerase chain reaction (PCR), we detected mRNA transcripts for IGFBP-1 in 42%, IGFBP-2 in 65%, IGFBP-3 in 97%, IGFBP-4 in 3%, IGFBP-5 in 74%, IGFBP-6 in 94% and IGFBP-7 in 87% of the glioma cell lines. The specificity of the PCR reaction was verified by direct sequencing of the PCR product. In addition, the content of the most prevalent IGFBP-3 was measured in conditioned medium from glioma cells by specific radioimmunoassay with levels ranging from < 1 to 620 ng/ml. Moreover, the presence of membrane-bound IGFBPs (44, 50 and 60 kDa) as well as IGF-II receptors was demonstrated by using 125I-labelled IGF-II as a ligand. In conclusion, IGFBPs may modulate the IGF-mediated effects in these cell lines.

Heregulins and the ErbB-2/3/4 receptors in gliomas

The activation of autocrine loops involving proto-oncogene related receptor tyrosine kinases has led to the analysis of a large number of growth factor systems in human glioma specimens and cell lines. The ErbB-2 system, also called HER-2 or neu, is analogous to the epidermal growth factor receptor system (EGF-R, ErbB-1). Neuregulins consist of a large family of proteins arising from alternative mRNA splicing of a single gene located at 8p22-p11. Activation of ErbB-2 by neuregulins occurs in heterodimeric complexes with ErbB-3 and ErbB-4. A panel of human glioma cell lines, which had previously been analyzed for ErbB-2 expression, was examined for ErbB-3 and ErbB-4 expression. Coordinate expression of ErbB-2, -3 or -4 was not observed in these cell lines. Despite the presence of a complete system capable of signaling in about half the cell lines, no constitutive activation of ErbB-2, -3 or -4 was observed, and autophosphorylation of ErbB-2 in response to heregulin was observed only in one cell line from the panel, NCE-G84. Moreover, the addition of recombinant heregulin or antibodies capable of disrupting ErbB-2/ErbB-3 complexes had no effect on cell proliferation. We conclude that the role of neuregulins and its receptors in the control of glioma cell proliferation may be limited or may be context dependent on in situ conditions which are lost in vitro. Alternatively, neuregulins may be involved in cell differentiation or survival in the central nervous system. Data supporting these conclusions are described in more detail herein.

The road less travelled: c-kit and stem cell factor

Autocrine stimulation of growth factor receptors by autonomously produced ligands regulates different aspects of cellular transformation and progression. In several tumors, including gliomas, multiple autocrine systems are activated and may exert different functions in the malignant transformation process. The c-kit proto-oncogene is widely expressed in human gliomas, and it may be activated by its co-expressed ligand, stem cell factor (SCF). Studies in glioma cell lines as well as different tumor types suggest the possibility of intracellular interactions of c-kit with SCF. Although c-kit and SCF may not play a primary and causal role in the initiation and progression of glial tumors they may still be contributing factors in glioma biology. It can be hypothesized that the parallel activation of several autocrine systems including some of which have found less attention in gliomas, such as c-kit/SCF, could compromise the efficacy of therapies targeting different autocrine loops. A better understanding of the multiplicity and mechanisms of autocrine stimulation has implications for the development of new therapies interfering with autocrine tumor cell growth.

Somatostatin and somatostatin receptors in the diagnosis and treatment of gliomas

Somatostatin analogues are in clinical use for the diagnosis and treatment of several oncological indications, namely pituitary adenomas and endocrine gastrointestinal tumors. In addition for a variety of malignancies their potential value is being studied. It has been speculated that somatostatin plays a role in the homeostasis of gliomas, and that gliomas could be susceptible to antiproliferative effects of somatostatin analogues. These assumptions were tested in 20 human cell lines derived from malignant gliomas and 4 glioblastoma tissue specimens, which were analyzed for their expression of the five known somatostatin receptor genes (SSTR1-5) and for the receptor function. Using semiquantitative PCR techniques, SSTR2 transcripts were found in all 20 cell lines and 4 glioblastomas, SSTR1 transcripts were detected in 9 cell lines and 4 glioblastomas, and SSTR3 transcripts were noted in 7 cell lines and 1 glioblastoma. SSTR4 and SSTR5 transcripts were only rarely detected. Gene expression profiles in glioblastoma tissue specimens resembled those of the cell lines in quality as well as quantity, with average transcript levels being highest for the SSTR2, followed by SSTR1 and SSTR3. However, when compared to GH3 anterior pituitary tumor cells, the relative amounts of PCR amplified DNA fragments were found to be at least 120 fold lower in glioblastoma cell lines and tumor specimens. Binding studies indicated that glioblastoma derived cells contained only minute amounts of SSTRs. No inhibition of proliferation was observed when 10 selected cell lines were incubated with somatostatin-14 (SST-14) or octreotide (SMS 201-995) at concentrations ranging from 10(-9) M to 10(-6) M, however, the proliferation of two cell lines was weakly stimulated after 6 days of incubation with 10(-6) M octreotide. The activity of adenylate cyclase, stimulated by forskolin, was inhibited by maximally 25% at 10(-6) M SST-14 or octreotide in one of 5 selected glioblastoma cell lines. Somatostatin peptides do not seem to exert anti-proliferative effects on glioblastoma cells and therefore appear to be of no obvious value for glioblastoma therapy. Most likely the amount of cell surface SSTRs is not sufficient to mediate antiproliferative effects. Since it has been described that SSTRs are detectable on most differentiated gliomas as well as astrocytes, it may be speculated that SSTRs may be relevant only in the context of well differentiated cellular programs but lose their significance with progressive dedifferentiation.

[Differential therapy of cerebral angiomas]

Patients with cerebral arteriovenous malformations (cAVMs) are usually young at the time of diagnosis with a mean age of 32 years. These patients are in a crucial phase of their lives, starting a family and establishing a professional position. Facing a relative annual risk of 2 to 3% for a severe hemorrhage which cumulates to a 50% risk of hemorrhage over the next four decades of their lives, these patients have to make the decision about possible treatment of their cAVM. Advice can only be given to the patients on an individual basis because there are almost no two identical lesions. Nevertheless, based on a grading system and within established treatment regimens, risk estimations are possible and particularly with close neuroradiological/neurosurgical cooperation these risks can be defined and minimized. In this context we report a series of 184 patients with cAVMs which were taken care of at the Departments of Neurosurgery and Neuroradiology at the University of Hamburg between February 1988 and July 1996 and who were treated according to a standardized joint protocol with interventional and microsurgical options.

[Asymptomatic cerebral aneurysms--surgical and endovascular therapy options]

Aneurysmal subarachnoid hemorrhage carries a risk of 50% mortality. Therefore it is recommended to also treat asymptomatic, previously unruptured aneurysms. Deciding whether to treat or to observe depends on the consideration of risk of hemorrhage and the surgical risk. Such decision could be facilitated if predisposing factors affecting the outcome were known. 15 Patients with 19 unruptured aneurysms managed in a period when both, surgical and endovascular treatment options were available, were selected from a group of 47 asymptomatic patients documented since 1984. The patients were either operated (n = 9) or were treated by endovascular occlusion with GDC coils (n = 6). In most cases, a long history of headaches eventually lead to a CT-scan or MRI in which a suspicious abnormality was found. Upon subsequent angiography, 8 middle cerebral, 6 carotid, 3 basilar and 1 pericallosal, and ophthalmic artery aneurysm(s), respectively, were found. The aneurysms varied from 4 to 30 mm in diameter. The patients were followed between 9 months and 2.5 years. Treatment results in this small series were independent from size, location, age or sex of the patient. The initial, mostly unrelated symptoms persisted after treatment in most cases. The morbidity according to GOS in this small series (3 out of 19 patients deteriorated) is not representative of the complete series where morbidity and mortality was 5.4% and 1.2% respectively). In agreement with the literature reviewed herein, we recommend surgical treatment of previously unruptured aneurysms, especially when the patients are below 60 years of age. In patients with posterior circulation aneurysms, endovascular coil occlusion is a valid alternative, especially in older patients with concurrent medical problems.

Microfilament dynamics during cell movement and chemotaxis monitored using a GFP-actin fusion protein

BACKGROUND

The microfilament system in the cortex of highly motile cells, such as neutrophils and cells of the eukaryotic microorganism Dictyostelium discoideum, is subject to rapid re-organization, both spontaneously and in response to external signals. In particular, actin polymerization induced by a gradient of chemoattractant leads to local accumulation of filamentous actin and protrusion of a 'leading edge' of the cell in the direction of the gradient. In order to study the dynamics of actin in these processes, actin was tagged at its amino terminus with green fluorescent protein (GFP) and observed with fluorescence microscopy in living cells of D. discoideum.

RESULTS

Purified GFP-actin was capable of copolymerizing with actin. In the transfected cells of D. discoideum studied, GFP-actin made up 10-20% of the total actin. Microfilaments containing GFP-actin were capable of generating force with myosin in an in vitro assay. Observations of single living cells using fluorescence microscopy showed that the fusion protein was enriched in cell projections, including filopodia and leading edges, and that the fusion protein reflected the dynamics of the microfilament system in cells that were freely moving, being chemotactically stimulated, or aggregated. When confocal sections of fixed cells containing GFP-actin were labeled with fluorescent phalloidin, which binds only to filamentous actin, there was a correlation between the areas of GFP-actin and phalloidin fluorescence, but there were distinct sites in which GFP-actin was more prominent.

CONCLUSIONS

Double labeling with GFP-actin and other probes provides an indication of the various states of actin in motile cells. A major portion of the actin assemblies visualized using GFP-actin are networks or bundles of filamentous actin. Other clusters of GFP-actin might represent stores of monomeric actin in the form of complexes with actin-sequestering proteins.

Migration of human glioma cells in response to tumour cyst fluids

Glial tumours often show high degrees of local invasion that lead to local recurrence of the disease. Extracellular matrix components as well as soluble factors may play a critical role in this poorly understood process. Cyst fluid from human brain tumours may accumulate such autocrine produced factors and may represent a source were those factors may be easily obtained and studied. We have studied the effect of cyst fluids harvested from 17 glial tumours, 3 meningiomas, and three metastases on the motility of established human glioma cell lines. Both cyst fluids of high grade and low grade gliomas contained varying degrees of motility enhancing activity. No such activity was identified in cyst fluids obtained from meningiomas. The relation of mitogenic and motogenic activity in three selected cyst fluids was analysed using a quantitative monolayer migration assay. Quantitative analysis of cyst fluid effects on both proliferation and migration indicate that tumour cyst fluids contain factors that strongly stimulate cell migration and that maximum stimulation of migration did not occur at concentrations optimal for cell proliferation. Our findings indicate that glial tumours in fact produce and secrete soluble factors that may contribute to their dissemination in brain tissue.

Adenovirus-mediated p53 gene transfer suppresses growth of human glioblastoma cells in vitro and in vivo

Alterations in the p53 tumor-suppressor gene occur in 35-60% of human glioblastomas, and re-introduction of p53 can suppress neoplastic growth. To evaluate the potential for p53 gene therapy of glioblastoma, we have analyzed the response of human glioblastoma cell lines in vitro and in vivo to experimental therapy with replication-deficient recombinant adenoviruses encoding wild-type p53 (rAd-p53). Western blot analyses showed high-level expression of p53 protein after treatment with rAd-p53, and transgene expression was dependent on promoter strength. A p53-specific dose-dependent inhibition of in vitro cellular proliferation was observed in 5 of 6 cell lines, and growth inhibition corresponded to adenovirus-mediated gene transfer and expression. p53-specific cell death was quantitated by release of the lactate dehydrogenase enzyme. Fragmentation of DNA into nucleosomal oligomers and the occurrence of a hypodiploid cell population detected by flow cytometry provided evidence for apoptosis. Studies in nude mice demonstrated that ex vivo infection with rAd-p53 suppressed the tumorigenic potential of human glioblastoma cells. Furthermore, direct injection of rAd-p53 into established s.c. xenografts inhibited tumor growth. Our observations suggest that re-introduction of wild-type p53 may have potential clinical utility for gene therapy of glioblastoma.

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.

Migration of human glioma cells on myelin

Histoanatomically invading astrocytoma cells appear to migrate along distinct structures within the brain. Astrocytoma invasion may occur along extracellular matrix (ECM) protein-containing structures, such as blood vessels, but most frequently occurs along tracts of myelinated fibers. This behavior most likely is a consequence of the use of constitutive extracellular ligands expressed along the pathways of preferred dissemination. Enzymatic modification of the extracellular space or deposition of ECM by the tumor cells may also create a more permissive environment. Established human glioma cell lines and two preparations of primary cells isolated from glioblastoma biopsies were studied with the use of cell adhesion and monolayer migration assays to investigate whether crude human central nervous system myelin extracts present specific cell adhesion ligands that promote glioma attachment and cell migration. Two cell lines showed high levels of adhesion and migration on central nervous system myelin similar to levels of migration on the ECM protein merosin, which has previously been shown to be a highly permissive substrate for cultured astrocytoma cells. Two other cell lines showed lower but specific migratory response; one cell line did not attach or specifically migrate on crude myelin extracts. For both glioblastoma primary cell preparations, myelin and merosin were the most permissive substrates for attachment and migration. Other ECM proteins (collagen type IV, fibronectin, and vitronectin) were moderate or nonpermissive substrates. Our findings indicated that astrocytoma cells may be able to use oligodendrocyte membrane-associated ligands as well as ECM proteins of the basement membranes for invasion of normal brain.

Cell culture of human brain tumors on extracellular matrices : methodology and biological applications

Cell culture is one of the major tools of cell biologists. It has also become an integral part of the daily routine of most oncology laboratories for the purpose of karyotyping, chemoresistance testing, or basic research. It provides investigators with an opportunity to investigate many cellular parameters and interactions in an in vitro system in which the experimental conditions can be controlled and repeated With many tissues, either human or animal, the problems of cell culture are cell attachment and initial survival. Particularly the primary cultures derived from tumor specimens are a problem in many laboratories. Apart from modifications in the composition of tissue-culture plastic materials, other approaches have been used to get around this problem, such as coating of tissue-culture dishes with attachment enhancers, such as polyamino acids (1), fibronectin (2), laminin (3), and collagen (4) Since it was known that endothelial cells are capable of producing a basement membrane even in vitro, bovine cornea1 endothelial basement membrane was explored by Gospodarowicz et al. for its role in regeneration and nonregeneration of cornea1 endothelium in different species This bovine cornea1 extracellular matrix (bECM) was found useful in the cell culture of a wide range of different cells (5, 6), and bECM as well as other ECMs were employed in the cell biology of tumor cells derived from mammary carcinomas (7), urological tumors (8), and different kinds of pituitary adenomas (9, 10), as well as CNS tumors (11), which is the topic of this chapter.

Central neurocytoma: clinical, immunohistologic, and biologic findings of a human neuroglial progenitor tumor

BACKGROUND

Central neurocytomas are rare brain tumors recognized by their typical radiologic and histologic features. In general, a good prognosis is achieved by total removal. The histogenesis is still under debate, but a neuronal origin is widely assumed.

METHODS

This study presents the clinical and immunohistologic findings of five patients and the results of cell culture experiments of two patients with central neurocytoma treated surgically between 1983 and 1993.

RESULTS

The patient age at diagnosis ranged from 21 to 30 years (mean, 25 years). The male-to-female ration was 1:4. Raised intracranial pressure due to hydrocephalus was the main cause of the clinical manifestations. Total resection was achieved in two cases. Four patients received radiotherapy. One patient suffered a recurrence 1 year after surgery, requiring a second resection and radiotherapy. Follow-up studies took place between 1 and 10.5 years (mean, 7.1 years). To date, all patients are free of their tumors. Two patients suffered from permanent memory disturbances after surgery. Immunohistochemistry confirmed the neuronal nature of the tumors. Cell-culture studies, which have been carried out for the first time, demonstrated concomitant expression of neuronal (synaptophysin) and glial (GFAP) markers.

CONCLUSION

Total removal is the therapy of choice. In tumor recurrence or limited surgery (e.g. due to severe affliction of the fornical structures), radiotherapy has shown to be efficacious. The cell-culture experiments give new insight on the histogenesis of central neurocytoma, indicating that the tumor arises from an undifferentiated precursor cell with the capacity of bipotential neuroglial differentiation.

pDcsA vectors for strictly regulated protein synthesis during early development of Dictyostelium discoideum

Two expression vectors have been constructed to express proteins exclusively in developing cells of Dictyostellium discoideum. In these Escherichia coli/D. discoideum shuttle vectors, proteins are synthesized under control of the promoter of the contact site A (csA) gene, which is efficiently suppressed during growth and becomes strongly activated during early development of D. discoideum. The pDcsA vectors appear to be valuable tools for the production of proteins that are not compatible with growth of D. discoideum cells.

The epidermal growth factor receptor in glioblastoma: genomic amplification, protein expression, and patient survival data in a therapeutic trial

Human glioblastomas were evaluated for overexpression of the epidermal growth factor receptor (EGFR) in a therapeutic trial with the anti-EGFR antibody EMD 55900. A total of 55 cases were examined by immunohistochemistry using 4 different monoclonal antibodies on frozen or on paraffin sections: EGFR-1 (Amersham), E 62 (Merck), E 30 (Merck), and EMD 55900 (MAB 425, Merck). Definition for inclusion in clinical trials of EMD 55900 was an immunohistochemical overexpression of grade 4+ or 3+ in a scale of 4 grades of staining quality. The use of the 4 different antibodies gave essentially equal results. In 21 cases, the immunohistochemical results were supplemented by molecular genetic analysis of EGFR amplification on the corresponding locus of chromosome 7, using frozen tissue from the same blocks after screening for vital tumor areas. Since no other material was available, the differential polymerase chain reaction technique was applied. Interferon-gamma (IFN-gamma) served as a reference gene. In a preliminary experimental series with cases of known EGFR amplification, a densitometric EGFR/IFN-gamma ratio higher than 3 was determined as indicator for amplification of the EGFR gene. With this experimental approach we were able to identify an amplified EGFR gene in 13 specimens including 2 from recurrent glioblastomas in the same patients. All of these showed an increased immunoreactivity for EGFR protein. The degree of EGFR amplification (EGFR/IFN-gamma ratio as measured by DNA densitometry) showed a positive correlation with the grade of immunohistochemical protein expression, both in regard to the fraction of positive cells and to the overall staining intensity.(ABSTRACT TRUNCATED AT 250 WORDS)

Human neurocytoma cells in culture show characteristics of astroglial differentiation

Cultured human neurocytoma cells from two neurosurgical patients were analysed for their immunocytochemical staining patterns and growth characteristics. In both cases, the cells stained positive for glial acidic fibrillary protein (GFAP) within one day of tissue culture in medium, with and without fetal calf serum, whereas the histological tumor specimens were negative. Both cases contained cells concomitantly expressing GFAP and synaptophysin (SNP) in the primary cultures. Epidermal growth factor (EGF) was mitogenic for the cultured cells but not platelet derived growth factor alpha (PDGF AA) or nerve growth factor (NGF). It is concluded that the human neurocytomas may represent neoplasms of a pluripotent neuroglial cell which can provide an interesting model to study the determinants for human glial/neuronal differentiation in vitro.

Expression of retinoblastoma gene in human intracranial neoplasms

The retinoblastoma gene (RB) is a tumour suppressor gene, of which mutations are associated with carcinogenesis in a broad spectrum of human malignacies. To evaluate its putative role in tumorigenesis in intracranial tumours, we investigated cell lines derived from human gliomas and 91 fresh surgical specimens derived from a broad spectrum of intracranial tumours. We found 7 out of 24 cell lines with markedly reduced levels of the retinoblastoma gene protein (pRB) by Western blot and its mRNA by Northern blot analysis. Such a decrease of RB expression appeared not to be clonal, as none of these lines showed subpopulations with nuclear staining in immunocytochemistry. Loss or decreased expression of pRB, however, could only be detected in a small proportion of the glioma tissues. None of the informative lines or the 21 glioma specimens presented any mutation by Southern blot. Furthermore only in 2 out of 28 pituitary adenomas pRB was undetectable, which is interesting, as heterozygous RB-knockout mice are known to develop pituitary tumours. We conclude that alterations of the RB gene seem to be relevant in only a small subset of gliomas. Our findings also suggest, that not only loss, but also ineffectively low levels of pRB, which are not necessarily caused by mutations might play a role in the pathophysiology of tumours.

Treatment of cerebral arteriovenous malformations by neuroradiological intervention and surgical resection

We present the results of a series of 105 patients with cerebral arteriovenous malformations (AVMs) who were treated by a combined protocol including endovascular occlusive measures and open surgical resection. 25 patients were treated only by surgical intervention, 72 patients underwent preoperative endovascular embolization and 8 patients were treated only by embolization, seven of which were only treated for palliation. After superselective angiography the vascular territories suitable for endovascular or microsurgical approach were defined, and in most cases these territories were complementary to each other. In 56 cases, only one embolization was necessary and due to an advantageous co-localization of the departments the whole combined endovascular/neurosurgical procedure was done in one anesthesia. If several endovascular sessions were necessary (16 patients), the resection was mostly carried out immediately after the last neuroradiological session in the same anesthesia with total time of such combined procedure now averaging about 7 hours. According to the proposed grading system by Spetzler we treated 25 grade 1, 24 grade 2, 40 grade 3, 11 grade 4, and 5 grade 5 lesions. The overall success rate defined as complete resection without additional permanent neurological deficit was 89.6% (87 out of 97 surgical cases). The benefits of such combined approach to cerebral AVMs become apparent in shortened and safer surgical procedures as well as in a low complication rate.

Karyotype analyses of 20 human glioma cell lines

Human malignant gliomas are frequently associated with loss of gonosomes and chromosomes 13, 17, and 22. Their progression from anaplastic glioma to glioblastoma is marked by additional loss of chromosome 10. In addition, structural and numerical aberrations of chromosome 7 are frequently found. We report on the karyotypes of a series of 20 human gliomas of which 11 were analysed as established cell lines; 9 cases were investigated in early culture, 5 of which later also became established lines. In addition to the frequently reported overrepresentation of chromosome 7, four cell lines with polysomy for chromosome 22 were seen. A high incidence of structural chromosomal aberrations was present in early cultures as well as in cell lines after various in vitro passages. We found that the general characteristics of karyotypic aberrations found in early cultures or direct preparations of dispersed tumour material were reflected in the pattern of aberrations present in cell lines at much later time points. Thus it appears as if no systematic changes can be attributed to long-term cultures. Suspicious losses of chromosomes 14, 18, and 19 or gain of chromosome 22 indicate that individual cases may have originated due to other mechanisms than the ones already hypothesized, i.e., different suppressor genes or amplification of genes other than the EGF-R-gene. None of the established cell lines had a genomic rearrangement of c-erbB 1, c-erbB 2 or of the p 53 gene.

Cranio-cervical decompression for Chiari I malformation. A retrospective evaluation of functional outcome with particular attention to the motor deficits

We report a series of 26 patients affected by a Chiari I malformation treated at our department between 1987 and 1993. All patients underwent pre- and postoperative evaluation by magnetic resonance imaging (MRI). Sequential perioperative motor evoked potential (MEP) recordings were performed in 8 patients. The preoperative symptoms can be divided into four subgroups: cephalgias (84.6%), cranial nerve deficits (69.2%), motor deficits (76.9%), sensory deficits (73%). Twenty-five out of 26 patients underwent craniovertebral decompression, 1 a transoral anterior decompression. One patient died 2 months after surgery because of progressive pulmonary failure. We registered following postoperative complications transient hypoglossal palsy (1 case), vertigo (2 cases), meningitis (1 case), minor CSF leaks (3 cases). Cephalgias subsided in 17 and improved in 4 out of 22 patients. Cranial nerve deficits improved in 8 and were stabilized in 7 out of 18 patients. A limited recovery of trigeminal function was possibly due to nuclear lesions. Five patients whose vestibular disturbances were not relieved by surgery were put on a course of carbazepine. Vertigo resolved in one case and in two others improved. While hypesthesia improved after decompression, the other sensory deficits were stabilized in 5% of the patients. Spasticity improved in 12 out of 18 patients, but weakness only in 7 out of 17 patients. Motor disturbances were always detected by MEP-recording. MEP-characteristics were not specific, resembling those of patients with other intra-, extramedullary myelopathies. Functional recovery was not matched by an improvement of the MEP parameters. MEP may be used as tool for surveillance of patients whose clinical findings are not progressive and are not at first surgical candidates.

Treatment of nongerminomatous germ-cell tumors of the pineal region

Germ-cell tumors can be subdivided into germinoma, embryonal carcinoma, choriocarcinoma, endodermal sinus tumor (yolk-sac tumor), and teratoma. They are also distinguished by their production of secreted markers such as alpha-fetoprotein produced in endodermal sinus tumors and embryonal carcinoma or beta-human chorionic gonadotropin, produced by choriocarcinoma and embryonal carcinoma. Germinoma and teratoma produce none of the markers. Because it has been proposed that teratomas may differentiate from multipotent stem cells contained in embryonal carcinoma and are thus lineage related, the presence of markers indicates the presence of a nongerminomatous germ-cell tumor. Nongerminomatous germ-cell tumors are an invariably fatal subgroup within the pediatric pineal region germ-cell tumors. There is no effective, established therapeutic regimen. We report the treatment regimen for three children diagnosed with this highly aggressive tumor entity. The children were first given a course of chemotherapy with bleomycin, etoposide, and cisplatin. This resulted in the normalization of markers and the shrinkage of tumors. These were then removed by the infratentorial supracerebellar approach. Removal was followed by a second course of chemotherapy with vinblastine, ifosfamide, and cisplatin; after which the children underwent radiotherapy. All three children are well and without evidence of residual or recurrent disease 20, 30, and 32 months after surgery, respectively. We propose this therapy regimen for children in whom the markers are positive.

p53 protein accumulation and gene mutations in human glioma cell lines

Mutations in, and aberrant expression of, the p53 tumor suppressor gene were assessed in 17 cell lines derived from human malignant brain tumors (glioblastoma multiforme). Exons 5 through 8 were screened by single strand conformational polymorphism analysis (SSCP), followed by direct DNA sequencing. Mutations were found in 6 of 17 glioma cell lines, i.e., at a frequency similar to that found in primary malignant gliomas. Loss of the wild type allele was observed in 4 of the mutated cell lines. Two cell lines had the same mutation (CGG-->TGG; Arg-->Trp) in codon 248. Five of 6 mutations were transitions, 4 of which occurred at CpG dinucleotides. In one cell line a 10-bp deletion at the intron 4/exon 5 junction was found. Five of 6 glioma cell lines contained a mutation identical to that in the respective primary tumor despite prolonged in vitro culture (140-221 passages). Thus, the acquisition of p53 mutations during culture appears to be infrequent. Two cell lines derived from heterozygous tumors maintained the wild type p53 allele during long term culture. p53 protein levels were assessed by immunofluorescence cytochemistry and immunoprecipitation followed by Western blot analysis and revealed elevated levels of the p53 protein, although to a variable extent, in all cell lines with p53 mutations. A marked p53 protein accumulation was also observed in two cell lines lacking p53 mutations in exons 5 through 8, indicating that a prolonged half life of the gene product is not solely dependent on an aberrant coding sequence. The remaining cell lines had either low levels or no detectable p53 protein; one of the latter contained a gross rearrangement of the p53 gene. Our results suggest that with respect to p53 gene status, glioma cell lines usually resemble the original tumors and may, therefore, be suitable for studying the biological changes associated with p53 mutations in glial tumors.

A joint protocol for the neurosurgical and neuroradiologic treatment of cerebral arteriovenous malformations: indications, technique, and results in 76 cases

We report on a group of 76 patients who had been treated during a period in which preoperative embolization using interventional neuroradiologic technique was standard procedure. During this time, 20 consecutive patients were operated on without embolization, eight patients were treated with embolization only, and 48 patients were operated on after embolization. In 35 cases surgery immediately followed the last embolization procedure. All arteriovenous malformations (AVMs) were classified and the outcome analyzed according to Spetzler [J Neurosurg 1986; 65: 476-83]. Those lesions treated with a combination of embolization and surgery had higher Spetzler grading than those that had been operated without previous embolization. The overall recovery rate was 82.9%. In 7.9% of the cases the AVMs were not totally extirpated. The overall complication rate was 9.2%. It is concluded that preoperative embolization facilitates surgery and reduces the risk of severe morbidity and mortality, especially in high-grade lesions. In addition to the clinical results, the application and usefulness of Ethibloc as an embolizing agent is reported.

Loss in expression of the retinoblastoma gene product in human gliomas is associated with advanced disease

The retinoblastoma susceptibility gene (RB), the prototype of the class of tumor suppressor genes, is inactivated in a number of human malignancies. We investigated a possible role of RB in human brain tumors. Immunoprecipitation revealed frequent loss of RB protein expression in glioma cell lines (8/24), which was accompanied by lack of RB encoded transcripts. Among seventeen primary brain tumors studied by Western blotting, loss of Rb protein expression was observed in WHO grade 3 and 4 gliomas (3/10). However, none of the low grade gliomas and the other primary brain tumors investigated lacked RB protein expression. These data suggest a role for RB in glial malignancy, and loss of Rb expression appears to be associated with glial tumor progression.

Neurotrophin gene expression by cell lines derived from human gliomas

The expression of neurotrophin (NGF, BDNF, and NT-3) mRNAs in 24 cell lines derived from human malignant gliomas was studied by Northern analysis. Widespread expression of neurotrophin genes was found with BDNF being the most abundantly expressed. Nearly all cell lines expressed BDNF, and about two-thirds of the cell lines expressed NGF and NT-3. Half of the cell lines analyzed expressed all three neurotrophins. Secretion of NGF into the medium of several cell lines could be detected by ELISA and a PC12 neurite outgrowth assay. Immuno- and bioactive NGF was isolated from conditioned medium of one cell line. No evidence of expression of the neurotrophin receptors trk and trkB by Northern analysis was found. Receptor crosslinking with radiolabeled cognate ligands failed to detect functional receptors in all but one cell line. In this cell line a receptor complex for BDNF was found that corresponded to truncated trkB receptors that lack the signal transducing tyrosine kinase domain. Neurotrophins did not stimulate mitosis of the glioma cultures. The findings suggest that production of neurotrophins by glioma cells is a general phenomenon, although neurotrophins made by gliomas lacking their receptors may not play an autocrine but rather a paracrine role.

Treatment of tumours of the pineal region and posterior part of the third ventricle

The evaluation of tumours located in the posterior part of the third ventricle or pineal region is achieved best by magnet resonance imaging (MRI). It shows the exact localization and extent, the involvement of neighbouring structures like thalamus or quadrigeminal plate and the displacement of the large veins, the internal cerebral veins, the vein of Galen and the veins of Rosenthal. If only CT is available, angiography should be performed prior to operation to identify the course of the veins. In children with a pineal region tumour the "tumour markers" AFP and beta-HCG should be determined before operation. We approach the rare tumours entirely located within the posterior part of the third ventricle by the posterior interhemispheric transcallosal route with the patient in prone position with the head elevated. The same approach is used for pineal region tumours extending above the internal cerebral veins. Tumours arising from the posterior thalamus extending into the thalamus and ventricle as well, are better approached by the posterior transcortical transventricular route since the lateral view is rather limited by the midline approach. The most frequent tumours in the pineal region are approached if they are located below the internal veins by the infratentorial, supracerebellar route in the sitting position. A total of 60 cases are evaluated. If AFP and/or beta-HCG are positive a highly malignant nongerminomatous germ-cell tumour must be suspected. We recommend initial chemotherapy with a combination of Vinblastine, Ifosfamide and Cis-platin without biopsy to avoid tumour seeding. After the "markers" are normalized operative removal of the residual tumour and radiotherapy should be carried out. In a series of 13 children operated on for pineal region tumours a rigid neuropsychological and endocrine evaluation was performed with encouraging results. During the last 10 years we have performed 49 open operations and 11 stereotactic biopsies. 40% of the patients were children under the age of 18. 40% of the tumours in childhood and 60% in adults were benign. In childhood 24% were germinomas and 20% non-germinomatous germ cell tumours.

Receptors for platelet derived growth factor in human glioma cell lines and influence of suramin on cell proliferation

A panel of 11 established human glioma cell lines was used to evaluate PDGF receptor binding using radioiodinated biosynthetic PDGF-AA and PDGF-AB as primary ligands. It was found that PDGF-receptor-binding was qualitatively heterogeneous. The affinities for PDGF-AA as well as PDGF-AB binding were within a close range of 0.13-0.33 nM and 0.16-1.1 nM, respectively. The number of binding sites per cell ranged between 56.000 and 250.000 for PDGF-AA and 72.000 to 300.000 for PDGF-AB. Two lines had only background levels of PDGF-AA binding. PDGF-AB binding was the dominant binding component in all but one cell line. In seven cell lines there were two binding components upon saturation analysis consisting of a high affinity component and a non-saturable low affinity component. PDGF and PDGF-receptors are suspected to be part of an autocrine loop in gliomas. Therefore, the effect of suramin on cell proliferation in serumfree cultures was tested in the same cell lines using doses of 25,200 or 500 micrograms/ml. It was found that the response to suramin was variable and that two cell lines still reached 2.8 fold and 4.5 fold their initial cell density even in the presence of 500 micrograms/ml whereas all other cells were completely arrested. Analyzing the response to 200 micrograms/ml it became evident, that the PDGF binding characteristics are of no reliable predictive value in respect to the efficacy of suramin.

Primary spinal malignant schwannoma: clinical, histological and cytogenetic findings

Of the 19 patients who presented between 1980 and 1990 to the Department of Neurosurgery, University of Hamburg, F. R. G. with malignant schwannoma, 5 patients suffered from primary malignant spinal schwannoma (mean age 44 years, only one patient with von Recklinghausen's disease). Here we report the clinical, histological, and cytogenetic features of the five cases with primary malignant spinal schwannoma and discuss the prognostic aspects of this rare tumor.

Antigenic staining patterns of human glioma cultures: primary cultures, long-term cultures and cell lines

The immunocytochemical staining patterns of cultured glioma cells were investigated. Fifty nine individual cases were stained at different in vitro ages for glial fibrillary acidic protein, fibronectin, galactocerebroside, HNK-1/Leu 7, A2B5, vimentin, factor VIII and A4. Histologically, the cases were composed of eight low-grade astrocytomas, 11 high-grade astrocytomas, four low-grade oligodendrogliomas, seven high-grade oligodendrogliomas and 29 glioblastomas. The 45 cases were analysed within the first 3 weeks of culture, many of them as primary cultures. In 11 cases stainings were performed repeatedly at intervals of up to 6 months. Glial fibrillary acidic protein staining was positive in most of the early cultures of astrocytomas (low and high grade) and glioblastomas; expression in more than 50% of the cells was found in 1 of 5 low-grade astrocytomas, 5 of 11 high-grade astrocytomas and 14 of 29 glioblastomas. Two of the high-grade astrocytomas were stained once more after 6 weeks in culture and were found to be only 1% positive for glial fibrillary acidic protein but strongly positive for fibronectin. The same was true for five of the glioblastoma cases. Two of these cases remained glial fibrillary acid protein positive and developed into stable permanent cell lines. Only one case started with 1% of glial fibrillary acidic protein positive cells and later developed into a 99% glial fibrillary acidic protein positive cell line. Neither HNK-1/Leu 7 expression nor A2B5 staining appeared to have a relationship to the glial fibrillary acidic protein staining. It was observed that glial fibrillary acidic protein and HNK-1/Leu 7 were both 100% in some cases but that later one of the two antigens disappeared but not the other. The amount of glial fibrillary acidic protein staining does not allow the prediction of A2B5 staining. The study shows that initiation of primary cultures on an extracellular matrix yields more glial fibrillary acidic protein positive cells in primary cultures than have been found in other studies. It is concluded that only a rigid standardization of culture conditions will ensure the validity of comparisons of in vitro data obtained in primary cultures.