Establishment and characterization of a human leptomeningeal cell line

Characterization of primary human leptomeningeal cells in 2D culture

Maintaining the integrity of brain barriers is critical for a healthy central nervous system. While extensive research has focused on the blood-brain barrier (BBB) of the brain vasculature and blood-cerebrospinal fluid barrier (BCSFB) of the choroid plexus, the barriers formed by the meninges have not received as much attention. These membranes create a barrier between the brain and cerebrospinal fluid (CSF), as well as between CSF and blood. Recent studies have revealed that this barrier has been implicated in the development of neurological and immunological disorders. In order to gain a deeper comprehension of the functioning and significance of the meningeal barriers, sophisticated models of these barriers, need to be created. The aim of this paper is to investigate the characteristics of commercially available primary leptomeningeal cells (LMCs) that form the meningeal barriers, in a cultured environment, including their morphology, proteomics, and barrier properties, and to determine whether passaging of these cells affects their behaviour in comparison to their in vivo state. The results indicate that higher passage numbers significantly alter the morphology and protein localisation and expression of the LMCs. Furthermore, the primary cell culture co-stained for S100A6 and E-cadherin suggesting it is a co-culture of both pial and arachnoid cells. Additionally, cultured LMCs showed an increase in vimentin and cytokeratin expression and a lack of junctional proteins localisation on the cell membrane, which could suggest loss of epithelial properties due to culture, preventing barrier formation. This study shows that the LMCs may be a co-culture of pial and arachnoid cells, that the optimal LMC passage range is between passages two and five for experimentation and that the primary human LMCs form a weak barrier when in culture.

Micromechanical heterogeneity of the rat pia-arachnoid complex

To better understand the onset of damage occurring in the brain upon traumatic events, it is essential to analyze how external mechanical loads propagate through the skull and meninges and down to the brain cortex. However, despite their crucial role as structural dampers protecting the brain, the mechanical properties and dynamic behavior of the meningeal layers are still poorly understood. Here, we characterized the local mechanical heterogeneity of rat pia-arachnoid complex (PAC) at the microscale via atomic force microscopy (AFM) indentation experiments to understand how microstructural variations at the tissue level can differentially affect load propagation. By coupling AFM mechanical testing with fresh tissue immunofluorescent staining, we could directly observe the effect of specific anatomical features on the local mechanical properties of tissue. We observed a two-fold stiffening of vascularized tissue when compared to non-vascularized PAC (with instantaneous Young's modulus distribution means of 1.32  ±  0.03 kPa and 2.79  ±  0.08 kPa, respectively), and statistically significant differences between regions of low- and high-vimentin density, reflecting trabecular density (with means of 0.67  ±  0.05 kPa and 1.29  ±  0.06 kPa, respectively). No significant differences were observed between cortical and cerebellar PAC. Additionally, by performing force relaxation experiments at the AFM, we identified the characteristic time constant τ₁ of PAC tissue to be in the range of 2.7  ±  1.2 s to 3.1  ±  0.9 s for the different PAC regions analyzed. Taken together, the results presented point at the complex biomechanical nature of the meningeal tissue, and underscore the need to account for its heterogeneity when modeling its behavior into finite element simulations or other computational methods enabling the prediction of load propagation during injury events. STATEMENT OF SIGNIFICANCE: The meningeal layers are pivotal in shielding the brain during injury events, yet the mechanical properties of this complex biological interface are still under investigation. Here, we present the first anatomically-informed micromechanical characterization of mammalian pia-arachnoid complex (PAC). We developed a protocol for the isolation and fresh immunostaining of rat PAC and subjected the tissue to AFM indentation and relaxation experiments, while visualizing the local anatomy via fluorescence microscopy. We found statistically significant variations in regional PAC stiffness according to the degree of vascularization and trabecular cell density, besides identifying the tissue's characteristic relaxation constant. In essence, this study captures the relationship between anatomy and mechanical heterogeneity in a key component of the brain-skull interface for the first time.

Structure and Junctional Complexes of Endothelial, Epithelial and Glial Brain Barriers

The homeostasis of the central nervous system (CNS) is ensured by the endothelial, epithelial, mesothelial and glial brain barriers, which strictly control the passage of molecules, solutes and immune cells. While the endothelial blood-brain barrier (BBB) and the epithelial blood-cerebrospinal fluid barrier (BCSFB) have been extensively investigated, less is known about the epithelial and mesothelial arachnoid barrier and the glia limitans. Here, we summarize current knowledge of the cellular composition of the brain barriers with a specific focus on describing the molecular constituents of their junctional complexes. We propose that the brain barriers maintain CNS immune privilege by dividing the CNS into compartments that differ with regard to their role in immune surveillance of the CNS. We close by providing a brief overview on experimental tools allowing for reliable in vivo visualization of the brain barriers and their junctional complexes and thus the respective CNS compartments.

Spatiotemporal resolution of spinal meningeal and parenchymal inflammation during experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) induced by active immunization of C57BL/6 mice with peptide from myelin oligodendrocyte protein (MOG_35-55), is a neuroinflammatory, demyelinating disease widely recognized as an animal model of multiple sclerosis (MS). Typically, EAE presents with an ascending course of paralysis, and inflammation that is predominantly localized to the spinal cord. Recent studies have further indicated that inflammation - in both MS and EAE - might initiate within the meninges and propagate from there to the underlying parenchyma. However, the patterns of inflammation within the respective meningeal and parenchymal compartments along the length of the spinal cord, and the progression with which these patterns develop during EAE, have yet to be detailed. Such analysis could hold key to identifying factors critical for spreading, as well as constraining, inflammation along the neuraxis. To address this issue, high-resolution 3-dimensional (3D) confocal microscopy was performed to visualize, in detail, the sequence of leukocyte infiltration at distinct regions of the spinal cord. High quality virtual slide scanning for imaging the entire spinal cord using epifluorescence was further conducted to highlight the directionality and relative degree of inflammation. Meningeal inflammation was found to precede parenchymal inflammation at all levels of the spinal cord, but did not develop equally or simultaneously throughout the subarachnoid space (SAS) of the meninges. Instead, meningeal inflammation was initially most obvious in the caudal SAS, from which it progressed to the immediate underlying parenchyma, paralleling the first signs of clinical disease in the tail and hind limbs. Meningeal inflammation could then be seen to extend in the caudal-to-rostral direction, followed by a similar, but delayed, trajectory of parenchymal inflammation. To additionally determine whether the course of ascending paralysis and leukocyte infiltration during EAE is reflected in differences in inflammatory gene expression by meningeal and parenchymal microvessels along the spinal cord, laser capture microdissection (LCM) coupled with gene expression profiling was performed. Expression profiles varied between these respective vessel populations at both the cervical and caudal levels of the spinal cord during disease progression, and within each vessel population at different levels of the cord at a given time during disease. These results reinforce a significant role for the meninges in the development and propagation of central nervous system inflammation associated with MS and EAE.

Drug transporters on arachnoid barrier cells contribute to the blood-cerebrospinal fluid barrier

The subarachnoid space, where cerebrospinal fluid (CSF) flows over the brain and spinal cord, is lined on one side by arachnoid barrier (AB) cells that form part of the blood-CSF barrier. However, despite the fact that drugs are administered into the CSF and CSF drug concentrations are used as a surrogate for brain drug concentration following systemic drug administration, the tight-junctioned AB cells have never been examined for whether they express drug transporters that would influence CSF and central nervous system drug disposition. Hence, we characterized drug transporter expression and function in AB cells. Immunohistochemical analysis showed P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in mouse AB cells but not other meningeal tissue. The Gene Expression Nervous System Atlas (GENSAT) database and the Allen Mouse Brain Atlas confirmed these observations. Microarray analysis of mouse and human arachnoidal tissue revealed expression of many drug transporters and some drug-metabolizing enzymes. Immortalized mouse AB cells express functional P-gp on the apical (dura-facing) membrane and BCRP on both apical and basal (CSF-facing) membranes. Thus, like blood-brain barrier cells and choroid plexus cells, AB cells highly express drug transport proteins and likely contribute to the blood-CSF drug permeation barrier.

Arachnoid cell involvement in the mechanism of coagulation-initiated inflammation in the subarachnoid space after subarachnoid hemorrhage

OBJECTIVE

To assess if arachnoid cells have the capability to present antigen and activate T-lymphocytes after stimulation by bloody cerebrospinal fluid (CSF), and to illuminate the mechanism of coagulation-initiated inflammation in the subarachnoid space after subarachnoid hemorrhage (SAH).

METHODS

Arachnoid cells were cultured, characterized, and examined by immunofluorescence for the basal expression of human leukocyte antigen-DR (HLA-DR). Expression of HLA-DR, after co-culturing arachnoid cells in vitro with bloody CSF, was investigated by immunofluorescence and flow cytometry (FCM). The variation of arachnoid cells' ultrastructure was observed by transmission electron microscope (TEM). Arachnoid cells were co-cultured with peripheral blood mononuclear cells (PBMCs). The content of soluble interleukin-2 receptor (sIL-2r) in culture medium was detected by enzyme-linked immunosorbent assay (ELISA).

RESULTS

(1) Arachnoid cells were successfully cultured for many passages. The immunofluorescent staining was positive for HLA-DR in over 95% of the human arachnoid cells. The punctate HLA-DR was distributed in cytoplasm and not in the karyon. (2) After co-culturing arachnoid cells in vitro with bloody CSF, numerous particles with strong fluorescence appeared in the cytoplasm on Day 6. On Day 8, the quantity of particles and fluorescent intensity were maximal. FCM showed that the percentage of HLA-DR expressing cells was (2.5+/-0.4)% at the first 5 d, increasing to (60.8+/-3.6)% on Day 7. (3) After co-culturing arachnoid cells in vitro with bloody CSF, many lysosome and secondary lysosome particles were present in the cytoplasm. Hyperplasia of rough endoplasmic reticulum and enlarged cysts were observed, with numerous phagocytizing vesicles also observed at the edge of the arachnoid cells. (4) Arachnoid cells stimulated by bloody CSF were co-cultured in vitro with PBMCs. The content of sIL-2r in the culture medium, having been maintained at around 1.30 ng/ml during the first 3 d, had increased by Day 4. The content of sIL-2r peaked 7.53 ng/ml on Day 7 and then reduced gradually.

CONCLUSIONS

(1) Basic HLA-DR expression is present in arachnoid cells. (2) After stimulation by bloody CSF, arachnoid cells have the potential to serve as antigen presenting cells (APCs) and the ability to activate T-lymphocytes, indicating that arachnoid cells are involved in the mechanism of coagulation-initiated inflammation in the subarachnoid space after SAH.

Characterization of cytoskeletal and junctional proteins expressed by cells cultured from human arachnoid granulation tissue

BACKGROUND

The arachnoid granulations (AGs) are projections of the arachnoid membrane into the dural venous sinuses. They function, along with the extracranial lymphatics, to circulate the cerebrospinal fluid (CSF) to the systemic venous circulation. Disruption of normal CSF dynamics may result in increased intracranial pressures causing many problems including headaches and visual loss, as in idiopathic intracranial hypertension and hydrocephalus. To study the role of AGs in CSF egress, we have grown cells from human AG tissue in vitro and have characterized their expression of those cytoskeletal and junctional proteins that may function in the regulation of CSF outflow.

METHODS

Human AG tissue was obtained at autopsy, and explanted to cell culture dishes coated with fibronectin. Typically, cells migrated from the explanted tissue after 7-10 days in vitro. Second or third passage cells were seeded onto fibronectin-coated coverslips at confluent densities and grown to confluency for 7-10 days. Arachnoidal cells were tested using immunocytochemical methods for the expression of several common cytoskeletal and junctional proteins. Second and third passage cultures were also labeled with the common endothelial markers CD-31 or VE-cadherin (CD144) and their expression was quantified using flow cytometry analysis.

RESULTS

Confluent cultures of arachnoidal cells expressed the intermediate filament protein vimentin. Cytokeratin intermediate filaments were expressed variably in a subpopulation of cells. The cultures also expressed the junctional proteins connexin43, desmoplakin 1 and 2, E-cadherin, and zonula occludens-1. Flow cytometry analysis indicated that second and third passage cultures failed to express the endothelial cell markers CD31 or VE-cadherin in significant quantities, thereby showing that these cultures did not consist of endothelial cells from the venous sinus wall.

CONCLUSION

To our knowledge, this is the first report of the in vitro culture of arachnoidal cells grown from human AG tissue. We demonstrated that these cells in vitro continue to express some of the cytoskeletal and junctional proteins characterized previously in human AG tissue, such as proteins involved in the formation of gap junctions, desmosomes, epithelial specific adherens junctions, as well as tight junctions. These junctional proteins in particular may be important in allowing these arachnoidal cells to regulate CSF outflow.

In vitro culture of various typed meningiomas and characterization of a human malignant meningioma cell line (HKBMM)

We placed on culture the 13 cases of meningiomas, succeeded in making a primary culture of 10 cases and maintained 5 cases in vitro over considerable period of time (over three month), and one cell line derived from a malignant meningioma were established. In the early period of the primary culture, meningioma cells were spindle- or round-shaped cells. In the case of psammomatous type, the cultured cells were characterized as forming psammoma bodies. A cell line designated "HKBMM" was established from a human malignant meningioma occurred from frontal lobe. This line grew well without interruption for 5 years and was subcultivated over 120 times. The cells were spindle and fibrous in shape, and neoplastic and pleomorphic features, and multilayering without contact inhibition. The cells proliferated rapidly, and the population doubling time was about 29 hours. The chromosome number showed a wide distribution of aneuploidy. The mode was in the diploid range. The culture cells were easily transplanted into the subcutis of nude mice and produced the tumor resembling the original tumor.

Molecular pathogenesis of meningiomas

Meningiomas are common central nervous system tumors that originate from the meningeal coverings of the brain and the spinal cord. Most meningiomas are slowly growing benign tumors that histologically correspond to World Health Organization (WHO) grade I. However, certain rare histological variants (clear cell, chordoid, papillary, and rhabdoid), as well as atypical (WHO grade II) and anaplastic (WHO grade III) meningiomas show a more aggressive biological behavior and are clinically associated with a high risk of local recurrence and a less favorable prognosis. This review summarizes the most important features of meningioma pathology and provides an up-to-date overview about the molecular mechanisms involved in meningioma initiation and progression. Current data indicate that meningioma initiation is closely linked to the inactivation of one or more members of the highly conserved protein 4.1 superfamily, including the neurofibromatosis type 2 gene product merlin/schwannomin, protein 4.IB (DAL-1) and protein 4.1R. The genetic alterations in atypical meningiomas are complex and involve losses on 1p, 6q, 10, 14q and 18q, as well as gains on multiple chromosomes. The relevant genes are still unknown. Anaplastic meningiomas show even more complex genetic alterations, including frequent alteration of the CDKN2A, p14ARF, and CDKN2B tumor suppressor genes at 9p21, as well as gene amplification on 17q23. A better understanding of the molecular mechanisms involved in meningioma pathogenesis may not only lead to the identification of novel diagnostic and prognostic marker but will also facilitate the development of new pathogenesis-based therapeutic strategies.

Immunohistochemical staining patterns of canine meningiomas and correlation with published immunophenotypes

This study examined immunohistochemical staining patterns for several meningioma variants involving either the brain or spinal cord of dogs. Formalin-fixed, paraffin-embedded tissue from 15 tumors was obtained. The selected tumor group included seven meningothelial, three transitional, two malignant (anaplastic), one myxoid, one papillary, and one osteomatous meningiomas. Tumors were evaluated for reactivity to the following six immunohistochemical markers: vimentin, pancytokeratin, glial fibrillary acidic protein (GFAP), S100, neuron-specific enolase (NSE), and synaptophysin. Vimentin expression was detected in all meningiomas, and 14 of 15 tumors demonstrated intense vimentin staining in more than 50% of the neoplastic cells. Pancytokeratin expression was present in 11 of 15 neoplasms; however, positive staining frequently was focal and often involved a small percentage of the neoplastic cells. GFAP expression was detected in a single, anaplastic meningioma. Although expression of NSE and S100 was detected in 12 of 25 meningiomas, the intensity of the staining and the percentage of positive neoplastic cells was highly variable. Synaptophysin was uniformly negative. These results will help to establish immunohistochemical profiles for meningiomas that will improve our ability to correctly differentiate these neoplasms of meningeal origin from central nervous system tumors originating from other sites.

Characterization of rat meningeal cultures on materials of differing surface chemistry

To better understand the interactions of cells derived from meningeal tissues with the surfaces of devices used for the treatment of central nervous system disorders, the behavior of primary postnatal day 1 rat meningeal cultures was evaluated on biomaterials of differing surface chemistry. Meningeal cultures in serum containing media were analyzed for attachment, spread cell area, proliferation, the production of extracellular matrix (ECM), and neuronal outgrowth. In general, both cell attachment as well as cell spread area decreased with increasing substrate hydrophobicity, whereas cell division as indicated by BrdU incorporation and time to confluence, was lower on the most hydrophobic materials. We suggest that such differences immediately after cell seeding were most likely mediated by differences in surface adsorption of proteins. In longer-term experiments, most of the materials were colonized by meningeal cultures irrespective of surface chemistry, and all cultures were equally inhibitory to neuronal outgrowth suggesting that over time, cells can modify the substrate perhaps by secretion of extracellular matrix molecule proteins. Our data suggests that cell type-specific differences in response to different biomaterials may play an important role in determining the ultimate nature and composition of the CNS at the host-biomaterial interface.

Alterations of INK4a(p16-p14ARF)/INK4b(p15) expression and telomerase activation in meningioma progression

Dysregulation of cell cycle progression and telomerase activation have been implicated in malignant tumor progression as well as in the evasion of senescence and immortalization. We have investigated expression of the cell cycle control and tumor suppressor genes INK4a(p16-p14ARF), INK4b(p15-p10) and RB, and their relation to telomerase activation during malignant meningioma progression. 7/26 (27%) benign, 3/12 (25%) atypical but 4/7 (57%) anaplastic tumors lacked both, p16 and p15 protein expression. 14/39 (36%) benign and atypical but 5/7 (71%) anaplastic meningiomas contained no p14ARF mRNA. 2/46 (4%) tumors failed to express pRB. We observed frequent differential loss of expression of the alternatively spliced INK4a tumor suppressors p16 and p14ARF. Exclusive expression of the alternative INK4b transcript p10 possibly at the expense of p15 and therefore resulting in loss of p15 tumor suppressor activity was noted in two meningiomas. We have previously described telomerase activity or expression of the telomerase catalytic subunit hTERT in this meningioma series. Telomerase activation was detected in 10/27 (37%) benign, but 18/19 (95%) non-benign meningiomas. We observed no significant overall correlation between loss of INK4a/INK4b expression and telomerase activation. In conclusion, our results suggest a greater role for losses of INK4a/INK4b gene products in meningioma formation and malignant progression than previously thought. Inactivation of p16/p15- and pl4ARF-dependent pathways possibly in conjunction with telomerase activation might be critical steps for a meningioma cell towards escape from senescence, that is, immortalization.

Neurofibromin colocalizes with mitochondria in cultured cells

Mutations in neurofibromatosis type 1 target the gene coding for neurofibromin. While neurofibromin is able to accelerate the rate of GTP hydrolysis by cellular Ras proteins, its biological function is not well understood. To gain information regarding its function, the intracellular localization of neurofibromin was analyzed in cultured cell lines using polyclonal antisera raised against four neurofibromin-specific peptides, three from the carboxyl terminus and one from the amino terminus. In methanol-fixed cells distinct rod-like structures distributed throughout the cytoplasm were recognized by the antisera. Similar structures were seen with each antiserum, including affinity-purified antibodies, and in each of the cultured cell lines tested. Similar structures were seen in paraformaldehyde-fixed cells. Double staining experiments showed that these structures colocalize with mitochondria, but not with actin, beta-tubulin, or endoplasmic reticulum. When actin or tubulin structures within the cell were disrupted by separate antimitotic drugs, these stained structures retained their shape. Neurofibromin association with mitochondria was confirmed biochemically when highly purified mitochondrial fractions from bovine heart tissue were shown in Western analysis to contain neurofibromin. This association might be helpful in predicting identification of some of the cellular proteins with which neurofibromin interacts.

Expression patterns of the p53 tumor suppressor gene and the mdm2 proto-oncogene in human meningiomas

Meningiomas represent a common class of tumors of the central nervous system. However, the molecular events underlying their formation are poorly understood. Because altered expression of the p53 tumor suppressor gene and the mdm2 proto-oncogene have been demonstrated in a wide variety of tumors, we carried out studies to assess the possible involvement of these two genes in meningioma tumorigenesis. We used Western blot analysis to examine the level of expression of the mdm2 and p53 proteins in a series of sixteen primary meningiomas and four meningioma cell lines. The data obtained from these studies suggest that elevated expression of the p53 or mdm2 protein products does not represent a common event in the development of human meningiomas.

Reduced expression of schwannomin/merlin in human sporadic meningiomas

OBJECTIVE

The neurofibromatosis type 2 gene is frequently mutated in sporadic meningiomas. The protein product of the neurofibromatosis type 2 gene is called schwannomin or merlin. Its expression in leptomeningeal cells from which meningiomas are derived and the characteristics of mutated forms in meningiomas, to our knowledge, have not been previously studied.

METHODS

Immunoblotting and immunoprecipitation experiments with two specific antibodies were used to determine the size and subcellular distribution of schwannomin/merlin in rabbit and human brain tissue and established human leptomeningeal LTAg2B cells. Immunoblotting was used to determine the expression level of schwannomin/merlin in 14 human sporadic meningiomas.

RESULTS

Both antibodies detect a protein of approximately 66 kDa, which is predominantly expressed in the Triton X-100-insoluble fraction of the brain and LTAg2B cells. The levels of schwannomin/merlin were severely reduced in eight tumors (57%) when compared with the expression levels in the human brain, LTAg2B cells, and the remaining six meningiomas. All six tumors with the normal schwannomin/merlin expression were of meningotheliomatous type. In contrast, all other histological types and one meningotheliomatous tumor with psammoma bodies were deficient in the 66-kDa schwannomin/merlin. Although nonsense mutations leading to premature stop codons are common in the neurofibromatosis type 2 gene in meningiomas, we found no evidence of truncated schwannomin/merlin forms in the tumors analyzed.

CONCLUSION

The absence of complete schwannomin/merlin in almost 60% of primary sporadic meningiomas seems to be an important factor in meningioma tumorigenesis. The development of meningotheliomatous meningiomas is probably linked to alterations in other oncogenes or tumor suppressor genes.

Reduced expression of neurofibromin in human meningiomas

Meningiomas are common, mostly benign, tumours arising from leptomeningeal cells of the meninges, which frequently contain mutations in the neurofibromatosis type 2 (NF2) gene. In this study, we analysed a protein product of the neurofibromatosis type 1 (NF1) gene, neurofibromin, in human established leptomeningeal cells LTAg2B, in 17 sporadic meningiomas and in a meningioma from a patient affected by NF2. The expression level of neurofibromin was determined by immunoblotting and immunoprecipitation with anti-neurofibromin antibodies. The functional status of neurofibromin was analysed through its ability to stimulate the intrinsic GTPase activity of p21 ras. In the cytosolic extracts of four sporadic meningiomas and in the NF2-related meningioma, the expression level and the GTPase stimulatory activity of neurofibromin were drastically reduced compared with the level present in the human brain, human established leptomeningeal cells LTAg2B and the remaining 13 meningiomas. Our results suggest that neurofibromin is expressed in leptomeningeal cells LTAg2B and in most meningiomas, i.e. tumours derived from these cells. The reduced expression and GTPase stimulatory activity of neurofibromin was found in about 23% of meningiomas and in the single NF2-related meningioma analysed. These results suggest that decreased levels of neurofibromin in these tumours may contribute to their tumorigenesis.

Androgen receptor expression in meningiomas

The predominance of meningiomas in females, the accelerated growth of these tumors during the luteal phase of the menstrual cycle and during pregnancy, and the association between meningiomas and breast cancer have led to a number of studies examining the potential role of steroids in the growth of meningiomas. The possibility that androgens play a role in meningioma proliferation has been suggested by a small number of investigators. The aim of this study was to examine the expression of androgen receptor messenger ribonucleic acid (mRNA) and correlate it using immunochemistry with the nuclear localization of androgen receptor in a large number of meningiomas. Thirty-nine meningiomas were examined by Northern blot analysis for the presence of measurable amounts of androgen receptor mRNA and eight of these were analyzed by immunohistochemistry for receptor protein. Sixty-seven percent of the meningiomas expressed androgen receptor mRNA. There was a marked predominance of women among the patients whose tumors expressed androgen receptor; 69% were women and 31% were men. The immunohistochemical data correlated with Northern blot analysis of mRNA. The staining was predominantly nuclear, suggesting that the androgen receptor resides in a location that can activate gene expression.

Subarachnoid haemorrhage induced proliferation of leptomeningeal cells and deposition of extracellular matrices in the arachnoid granulations and subarachnoid space. Immunhistochemical study

Subarachnoid haemorrhage (SAH) often leads to subarachnoid fibrosis and resultant normal pressure hydrocephalus; however, how subarachnoid fibrosis occurs is unknown. We examined the changes within arachnoid granulations (AGs) and the subarachnoid space (SAS) chronologically at the parasagittal region obtained from patients with SAH at autopsy and made comparison with controls by immunostaining for cytokeratin, specific marker for leptomeningeal cells and by the elastica Masson-Goldner methods. Within a week some AGs were torn, and many inflammatory cells filled the AGs and SAS. Cytokeratin positive cells were scarce. During the next two weeks cytokeratin positive cells increased. After three weeks, AGs and SAS were filled by dense deposits of extracellular matrices surrounded by multiple layers of leptomeningeal cells.

RNA expression of complement regulatory proteins in human brain tumors

The expression of complement regulatory proteins (CRP) on the surface of neoplastic cells has been proposed as a mechanism by which these cells evade immune surveillance. We have examined the RNA expression of the genes that encode 5 kinds of CRP in various human brain tumors to determine whether CRP expression might play a role in the malignant progression of these tumors. The benign and atypical meningiomas, and the astrocytomas showed high expression of SP-40,40, low expression of CD59, and barely detectable expression of CD46, CD55 and S-protein. The benign and atypical menigiomas showed significantly greater expression of SP-40,40 at the RNA level when compared to malignant meningiomas. This study describes the mRNA expression of meningiomas, astrocytomas, tumor cell lines and normal human tissues.

Primary culture of human leptomeningeal cells in serum-free medium

Human leptomeningeal (LM) cells were grown in serum-free medium supplemented with insulin, transferrin and bovine serum albumin. The cultured cells maintained the polygonal morphology characteristic of leptomeningeal cells. Electronmicroscopic and immunofluorescence examinations revealed interdigitation of cell membranes, invagination of cytoplasm into the nucleus, specialized intercellular junctions and the presence of cytokeratin. These characteristics are consistent with previous reports characterizing LM cells. This serum-free culture system may facilitate the in vitro study of the leptomeninges.