Tumor-brain Interface Research Articles

Characterization of Immune Cell Infiltration Into Canine Intracranial Meningiomas

Meningiomas are the most common intracranial tumors in dogs. A variety of inflammatory cells have been shown to invade these tumors in people, but little is known about interactions between the immune system and naturally occurring brain tumors in dogs. The purpose of this study was to investigate the presence of a variety of immune cell subsets within canine intracranial meningiomas. Twenty-three formalin-fixed, paraffin-embedded tumor samples were evaluated using immunohistochemistry with antibodies specific for CD3, CD79a, CD18, CD11d (αD), CD45RA, forkhead box P3, and Toll-like receptors 4 and 9. Immune cell infiltration was evident in all samples, with a predominance of CD3(+) T cells. Large numbers of CD18(+) microglia and macrophages were noted surrounding and infiltrating the tumors, and a subset of these cells within the tumor appeared to be CD11d(+). Scattered macrophages at the tumor-brain interface were TLR4(+) and TLR9(+). Rare CD79a(+) B cells were noted in only a small subset of tumors. Lesser numbers of lymphocytes that were CD11d(+), CD45RA(+), or FoxP3(+) were noted in a number of the meningiomas. Although the function of these cells is not yet clear, work in other species suggests that evaluation of this immune cell infiltrate may provide important prognostic information and may be useful in the design of novel therapies.

Intraoperative confocal microscopy in the visualization of 5-aminolevulinic acid fluorescence in low-grade gliomas

Greater extent of resection (EOR) for patients with low-grade glioma (LGG) corresponds with improved clinical outcome, yet remains a central challenge to the neurosurgical oncologist. Although 5-aminolevulinic acid (5-ALA)-induced tumor fluorescence is a strategy that can improve EOR in gliomas, only glioblastomas routinely fluoresce following 5-ALA administration. Intraoperative confocal microscopy adapts conventional confocal technology to a handheld probe that provides real-time fluorescent imaging at up to 1000× magnification. The authors report a combined approach in which intraoperative confocal microscopy is used to visualize 5-ALA tumor fluorescence in LGGs during the course of microsurgical resection. Following 5-ALA administration, patients with newly diagnosed LGG underwent microsurgical resection. Intraoperative confocal microscopy was conducted at the following points: 1) initial encounter with the tumor; 2) the midpoint of tumor resection; and 3) the presumed brain-tumor interface. Histopathological analysis of these sites correlated tumor infiltration with intraoperative cellular tumor fluorescence. Ten consecutive patients with WHO Grades I and II gliomas underwent microsurgical resection with 5-ALA and intraoperative confocal microscopy. Macroscopic tumor fluorescence was not evident in any patient. However, in each case, intraoperative confocal microscopy identified tumor fluorescence at a cellular level, a finding that corresponded to tumor infiltration on matched histological analyses. Intraoperative confocal microscopy can visualize cellular 5-ALA-induced tumor fluorescence within LGGs and at the brain-tumor interface. To assess the clinical value of 5-ALA for high-grade gliomas in conjunction with neuronavigation, and for LGGs in combination with intraoperative confocal microscopy and neuronavigation, a Phase IIIa randomized placebo-controlled trial (BALANCE) is underway at the authors' institution.

Intraoperative Confocal Microscopy for Brain Tumors: A Feasibility Analysis in Humans

The ability to diagnose brain tumors intraoperatively and identify tumor margins during resection could maximize resection and minimize morbidity. Advances in optical imaging enabled production of a handheld intraoperative confocal microscope. To present a feasibility analysis of the intraoperative confocal microscope for brain tumor resection. Thirty-three patients with brain tumor treated at Barrow Neurological Institute were examined. All patients received an intravenous bolus of sodium fluorescein before confocal imaging with the Optiscan FIVE 1 system probe. Optical biopsies were obtained within each tumor and along the tumor-brain interfaces. Corresponding pathologic specimens were then excised and processed. These data was compared by a neuropathologist to identify the concordance for tumor histology, grade, and margins. Thirty-one of 33 lesions were tumors (93.9%) and 2 cases were identified as radiation necrosis (6.1%). Of the former, 25 (80.6%) were intra-axial and 6 (19.4%) were extra-axial. Intra-axial tumors were most commonly gliomas and metastases, while all extra-axial tumors were meningiomas. Among high-grade gliomas, vascular neoproliferation, as well as tumor margins, were identifiable using confocal imaging. Meningothelial and fibrous meningiomas were distinct on confocal microscopy--the latter featured spindle-shaped cells distinguishable from adjacent parenchyma. Other tumor histologies correlated well with standard neuropathology tissue preparations. Intraoperative confocal microscopy is a practicable technology for the resection of human brain tumors. Preliminary analysis demonstrates reliability for a variety of lesions in identifying tumor cells and the tumor-brain interface. Further refinement of this technology depends upon the approval of tumor-specific fluorescent contrast agents for human use.

Stereotactic volumetric resection, intracavitary carmustine wafers, and radiation therapy for brain metastases: The Moffitt Cancer Center experience.

2077 Background: NCCN guidelines for brain metastases (BM) endorse surgery and whole brain radiation therapy (WBRT). Early clinical data suggest that addition of intracavitary carmustine wafers yields superior local control. Methods: A retrospective analysis of 49 consecutive BM patients undergoing MR-guided, gross total resection with chemowafers was compared to a similar cohort of 174 BM patients treated without wafers during a 6-year period at Moffitt Cancer Center. Results: Of the 49 patients, 4 had two sites of resection/wafer placement; 45 had a single surgical bed. The median age was 59 years; 49% had lung cancer, 24% melanoma, 26% were other histologies. Thirty-five patients had newly diagnosed BM; 14 were recurrent tumors. Fifteen patients were RPA class I, 27 class II, and 7 class III. The maximal resection bed diameter ranged from 1.0 to 7.2 cm (mean, 3.1). The median post-operative stay was one day. There were no infections. The KPS was stable or improved in 90% of the patients at 3 months, and 73% at 6 months (Table). The median survival for newly diagnosed patients was 9 months, and for those with recurrences, 6 months. For newly diagnosed metastases, treated with surgery + wafers + WBRT, only 1/35 (3%) patients had local recurrence. In 14 patients with recurrent metastases, there were no recurrences in those treated using surgery + wafer. By contrast, in tumor resected without wafers, local recurrence was 13% (17/130) and in those resected at recurrence, further recurrence occurred in 40% (6/15). The wafers were well-tolerated in tumors located within or near the primary motor cortex. Conclusions: Intracavitary carmustine wafers can be used in the treatment of upfront and recurrent brain metastases with excellent local control, minimal morbidity, and good neurological outcomes. Chemowafers can be useful near eloquent brain where the tumor-brain interface limits the surgical resection. KPS change from day of surgery Stable Improved (neurological) Declined (systemic) 3 months 59% 31% 10% 6 months 46% 27% 27%

Pathological characterization of the glioblastoma border as shown during surgery using 5-aminolevulinic acid-induced fluorescence

Thirty consecutive surgical patients with glioblastoma, were operated upon using fluorescence induced by 5-aminolevulinic acid as guidance. The fluorescent quality of the tissue was used to take biopsies from the tumor center, from the invasive area around it and from adjacent normal-looking tissue. These samples were analyzed with HE, Ki-67 and nestin. Nestin expression in tissue surrounding glioblastoma cases was compared to tissue surrounding vascular lesions, metastasis and hippocampal sclerosis. The rate of gross total resection assessed by volumetric MRI was 83%. Using HE examination as the gold standard, fluorescence identified solid tumor with 100% positive predictive value, invasive areas with 97%, and normal tissue with 67% negative predictive value. Ki67 stained some cells in 69% of the non-fluorescent samples around the tumor. There was always strong nestin expression around the tumor but it was similar to control cases in non-glioma lesions with subacute expansion. 5-aminolevulinic acid fluorescence guidance is very reliable and can help to study the tumor-brain interface. Nestin expression is strong and constant in the tissue around the tumor, but is mostly an acute glial reaction, not specific of the neoplasm. Nestin staining is not recommended as a tumor stem cell marker.

Radiological Predictive Factors for Regrowth of Residual Benign Meningiomas

The pre- and postoperative radiological predictive factors for the regrowth of residual benign meningiomas were investigated in 80 of 327 patients who underwent first surgery for intracranial meningioma, who met the following conditions: residual tumor observed on postoperative imaging, follow up for more than 5 years or until regrowth of the residual tumor, histological diagnosis of World Health Organization grade I, and no additional therapy performed within 1 month after surgery. These 80 patients were divided into those with no regrowth during the follow-up period (Group A, n = 54) and those with regrowth (Group B, n = 26), and the clinical characteristics and pre- and postoperative imaging findings were compared. Univariate analysis of factors influencing regrowth showed 6 factors were significant: tumor size ≥4 cm (p = 0.043), tumor volume ≥30 cm(3) (p = 0.026), presence of edema (p = 0.036), unclear brain-tumor interface (p < 0.001), presence of a pial-cortical blood supply (p = 0.031), and residual tumor volume ≥3.0 cm(3) (p < 0.001). Multivariate analysis showed only residual tumor volume ≥3.0 cm(3) was significant (p = 0.001). Generally, the significant imaging findings on univariate analysis suggest malignant meningioma. Similar findings may be observed even in grade I cases, and residual tumors may regrow in such cases. The possibility is particularly high if the residual tumor volume exceeds 3.0 cm(3), so early radiotherapy should be performed to prevent regrowth.

Metastasis Infiltration: An Investigation of the Postoperative Brain–Tumor Interface

This study aims to evaluate brain infiltration of metastatic tumor cells past the main tumor resection margin to assess the biological basis for the use of stereotactic radiosurgery treatment of the tumor resection cavity and visualized resection edge or clinical target volume. Resection margin tissue was obtained after gross total resection of a small group of metastatic lesions from a variety of primary sources. The tissue at the border of the tumor and brain tissue was carefully oriented and processed to evaluate the presence of tumor cells within brain tissue and their distance from the resection margin. Microscopic assessment of the radially oriented tissue samples showed no tumor cells infiltrating the surrounding brain tissue. Among the positive findings were reactive astrocytosis observed on the brain tissue immediately adjacent to the tumor resection bed margin. The lack of evidence of metastatic tumor cell infiltration into surrounding brain suggests the need to target only a narrow depth of the resection cavity margin to minimize normal tissue injury and prevent treatment size-dependent stereotactic radiosurgery complications.

The using of intra - operative ultrasound in gliomas(212 cases reports)

Objective To share the experience in using intra-operative ultrasound(IOUS)for brain gliomas removal. Method From July 2007 to August 2009,212 patients with brain gliomas were included in the study. Depending on the distance to the cortex,we divided the patiens into shallow location(＜ 2 cm)groups and deep location(≥2 cm)groups. The IOUS was used before,during and after tumors resection to localize the tumors, define their margins and assess the extent of resection at the end of surgery. The suspected signal region in the tumor-brain interface which were reported as tumor or normal tissue on IOUSwere submitted to histopathology. MRI review in 5 days after operation to assessment the tumor resection. Results Total resection in 192 cases and subtotal resection in 20 cases in MRI. There were 110cases in shallow group and 102 cases in deep group. The sensitivity and specificity of IOUS was 93.9% and 95.1% in shallow location group,and 95.7% and 36.4% in deep location group. Conclusions IOUS is a useful tool for determining the extent of resection and improve the operation resection rate, especially to the deep location tumors. IOUS should be routine use in the glioma operation. Key words: Ultrasonography; Glioma

Neural cell adhesion molecule isoform 140 declines with rise of WHO grade in human gliomas and serves as indicator for the invasion zone of multiform glioblastomas and brain metastases

Gliomas are highly invasive neuroepithelial tumors with a propensity of malignant transformation and very restricted treatment options. The neural cell adhesion molecule (NCAM) modulates cellular migration, proliferation, and synaptic plasticity by homophilic and heterophilic interactions. Hereby, we investigated its relevance as a glioma tissue marker for the biological aggressiveness of these tumors and compared these features with the carcinoma brain metastasis invasion zone. We analyzed 194 human brain samples. Human tumor-free brain specimens served as control for the white and gray matter. In addition to that, we used human glioblastomas from nude rats. All tissues were investigated immunohistochemically for the expression of the NCAM isoform 140. Additionally, the multiplanar MRI-CT fusion neuronavigation-guided serial stereotactic biopsy was performed and completed by histopathological workup. Human gliomas loose NCAM-140 with the rise of their WHO grade. Meningiomas are NCAM-140 negative. As the most striking feature, human brain metastases and the majority of human glioblastomas of our patients and of nude rats were totally NCAM-140 negative. This NCAM negativity led us to the conclusion of three different main glioblastoma invasion patterns. Surprisingly, the majority of brain metastasis samples that contained surrounding brain parenchyma demonstrated invasive tumor cell nests beyond the sharply demarcated metastasis border. We also found invasive metastatic cell nests outside the contrast enhancing tumor zone by means of the MRI-CT fusion neuronavigation-guided serial stereotactic biopsy. The expression of NCAM-140 inversely correlates with the WHO grade of human gliomas. The lost expression of NCAM-140 in human glioblastomas and in brain metastases enables the investigation of the brain-tumor interface and the definition of glioblastoma invasion patterns and shows that brain metastases are more invasive than ever thought.

Primary Extracerebral Meningeal Glioblastoma: Clinical and Pathological Analysis

Primary meningeal gliomas are uncommon tumors in the subarachnoid space, their primary characteristic being the absence of any obvious connection to the brain parenchyma. Rarely, they are quite malignant and assume a bulky, well circumscribed appearance rendering the differential diagnosis from other CNS neoplasms difficult. A 53-year-old man presented with a history of persistent headaches and left sided weakness. Magnetic resonance imaging revealed a temporoparietal mass attached to the dura that strongly resembled a meningioma. At surgery, the outer layer of the dura mater was intact and there was a clear brain-tumor interface without obvious pial disruption. Histological examination showed a biphasic pattern consisting of benign connective tissue intermingled with bundles of what seemed to be a glioblastoma. The mass demonstrated strong positivity for GFAP and the MIB labeling index focally exceeded 20%. The tumor was identified as a primary meningeal glioblastoma. The patient was disease-free for 42 months, after which he developed a recurrence for which he was re-operated. This time, the pathological findings of the tumor were those of a typical glioblastoma multiforme. We discuss the origin of the initial neoplasm and also the differential diagnosis that needs to include meningioma, aggressive glioblastoma infiltrating the dura and a recently recognized bimorphic CNS tumor: the desmoplastic glioblastoma.

Anaplastic meningioma: Progression from atypical and chordoid morphotype with morphologic spectral variation at recurrence

The current WHO 2007 classification divides meningiomas into a 3-grade prognostic hierarchy. Recent literature evokes two pathways to disease progression in meningiomas akin to a comparable paradigm in gliomas, but without similar prognostic connotation: de novo anaplastic meningioma (better prognosis), and transformed meningioma (worse prognosis). We present two adult cases of transformed meningiomas that display a spectrum of morphologic progression. Case 1 at presentation showed a random admixture of meningothelial, atypical and anaplastic meningioma. The tumor recurred as anaplastic meningioma. Case 2 presented as a chordoid meningioma, but recurred as anaplastic meningioma mainly at the invasive front in transition with residual chordoid pattern. Of interest, portions of tumor also showed papillary configuration. In accordance with the dire prognosis for anaplastic meningioma, both patients succumbed to their disease within 2 months of recurrence. The present study highlights two main points: First, that proper recognition of focal high-grade areas in a heterogeneous low-grade meningioma (case 1) provides critical morphologic clues to spatial histologic progression and predicts aggressive biologic behavior, as evidenced by progression to frankly anaplastic meningioma at recurrence. Second, the presence of papillary in addition to anaplastic areas, in the recurrence of a previously diagnosed chordoid meningioma supports the ostensibly heightened transforming potential of grade II meningiomas, but also reflects on the morphologic heterogeneity of high-grade meningiomas, and their potentially diverse pathways of progression. We propose that grading of meningiomas as outlined by WHO is of more critical prognostic import than histologic sub-typing, and must include a thorough survey of the tumor-brain interface. Future molecular genetic correlates, akin to those characterized in gliomas, could help stratify prognostic subcategories to refine meningioma grading, and govern optimal therapeutic strategies.

Noninvasive imaging of the functional effects of anti-VEGF therapy on tumor cell extravasation and regional blood volume in an experimental brain metastasis model

Brain metastasis has become an increasing cause of morbidity and mortality in cancer patients as the treatment of systemic disease has improved. Brain metastases frequently are highly vascularized, a process driven primarily by VEGF. VEGF mediates numerous changes within the vasculature including endothelial cell retraction and increased permeability, vasodilation, and new vessel formation. Here we describe a xenograft brain metastasis model that mimics the critical steps of metastasis including tumor cell dissemination and vascular adhesion, tumor growth and tumor associated angiogenesis. Magnetic resonance (MR) imaging was used to evaluate two aspects of the functional response of brain metastasis to the anti-VEGF receptor therapeutic, AZD2171 (Cediranib, RECENTIN). MR tracking of individual cells demonstrated that cediranib did not impede tumor cell extravasation into the brain parenchyma despite evidence that anti-VEGF treatment decreases the permeability of the blood brain barrier. In a second assay, blood volume imaging using ultrasmall superparamagnetic iron oxide revealed that treatment of well-developed brain metastasis with cediranib for 7 days led to a heterogeneous response with respect to individual tumors. Overall, there was a significant average decrease in the tumor vascular bed volume. The majority of large tumors demonstrated substantially reduced central blood volumes relative to normal brain while retaining a rim of elevated blood volume at the tumor brain interface. Small tumors or occasional large tumors displayed a static response. Models and assays such as those described here will be important for designing mechanism-based approaches to the use of anti-angiogenesis therapies for the treatment of brain metastasis.

Small Solutions for Big Problems: The Application of Nanoparticles to Brain Tumor Diagnosis and Therapy

Nanoparticles have the potential for advancing the diagnosis, operative management and adjuvant therapy brain tumors in the future. Nanoparticle-based MR contrast agents have the potential to uncover portions of tumor, especially along the tumor-brain interface, that would have been unclear with traditional gadolinium-enhanced MRI. In addition, several nanoparticles, developed with the objective of allowing the surgeon to see tumor margins intraoperatively, may ultimately enable neurosurgeons to improve the extent of brain tumor resection. Moreover, the delivery of chemotherapy and non-traditional therapies to brain tumors will likely be greatly improved by nanoparticle based-drug delivery devices. As our knowledge of their pharmacology and long-term health effects expands, nanoparticles are likely to play a central role in the future management of the brain tumor patient.

The microglial/macrophagic response at the tumour–brain border of invasive meningiomas

Little is known about the immune response of the brain to invasive meningiomas. The present study was based upon the hypothesis that the microglial/macrophagic response towards brain-invasive meningiomas is dependent on the intactness of the pial-glial basement membrane. We immunostained sections from 40 brain-invasive meningiomas that were graded according to World Health Organization (WHO) 2007 criteria. Thirty-three tumours were histologically WHO grade II (18, 'otherwise benign', and 15, 'otherwise atypical'), and seven, grade III. Microglial/macrophagic cells were labelled with antibodies directed against major histocompatibility complex class II, CD68, CD14 and CD163. Anti-collagen IV was used to visualize basement membranes. Twenty-five per cent (10/40) meningiomas (1/18 WHO grade II 'otherwise benign', 3/15 grade II 'otherwise atypical' and 6/7 WHO grade III) contained microglial/macrophagic cells at the tumour-brain border. The presence of these cells correlated with the absence of the pial-glial basement membrane (BM) and with WHO grade III. The monocytic response was of two kinds: one consisted of a dense layer of mononuclear cells at the tumour-brain border in nine cases, the other of an elevated number of microglial cells expressing CD14 or CD163 (two cases). The immune response at the tumour-brain interface correlates with the absence of the pial-glial BM and with malignancy grade. It remains to be established whether the mononuclear cells at the tumour-brain border are native microglia or blood-derived macrophages.

Local versus diffuse recurrences of meningiomas: factors correlated to the extent of the recurrence

The aim of this study is to evaluate the factors correlated with the different patterns (local, peripheral and diffuse) of meningioma recurrence. 55 patients with benign (WHO I) meningiomas which recurred after seemingly complete removal were reviewed; 40 (Group I) had local or peripheral recurrences (< 3 cm from the initial dural attachment) and 15 (Group II) had distant and diffuse recurrences. Patient age and sex, tumor location, interval of recurrence, tumor shape, type of brain-tumor interface, histological subtype, mitotic index (MI) and progesterone receptor (PR) expression of the initial tumor, histological WHO Grade of the recurrent tumor and patient outcome were analyzed and correlated with the pattern of recurrence. Flat-shaped meningiomas with large dural attachment showed a significantly higher rate of diffuse recurrences than round tumors, whereas the brain-tumor interface and the tumor location were not relevant (excepting the lack of convexity meningiomas in the group of diffuse tumors). There were no significant differences of histology, MI and PR expression of the initial tumor and histological grade of the recurrent tumor between the two groups. The different patterns of meningioma recurrences (local, peripheral, diffuse) are not correlated with the tumor location and histology and do not represent a different biological tumor progression. We agree that most unexpected extensive recurrences result from a more extensive microscopic dural involvement.

Predicting the Probability of Meningioma Recurrence in the Preoperative and Early Postoperative Period: A Multivariate Analysis in the Midterm Follow-Up

We reviewed the clinical, radiological, surgical, and histopathological features of patients with meningiomas to identify factors that can predict tumor recurrence after "microscopic total removal," to improve preoperative surgical planning, and to help determine the need for close radiological observation at shorter intervals or the need for radiotherapy as an adjuvant treatment in the early postoperative period. Clinical data, magnetic resonance imaging studies, angiographic data, operative reports, and histopathological findings were examined retrospectively in 137 patients with a meningioma treated microsurgically and with no evidence of residual tumor on postoperative MR images. Based on univariate analysis, tumor size, a mushroom shape, proximity to major sinuses, edema, osteolysis, cortical penetration, signal intensity on T2-weighted MRIs, pial-cortical arterial supply, presence of a brain-tumor interface in surgery, Simpson's criteria, and histopathological classification were significant predictors for recurrence. However, age, gender, location of tumor, dural tail, calcification, signal intensity on T1-weighted images, and histopathologic subtypes in the benign group were not significant predictors. By Cox regression analysis the most important variables related to the time to recurrence were mushroom shape, osteolysis, dural tail, and proximity to major sinuses. Aggressive surgical therapy with wider dural removal should be considered in the presence of the preoperative predictors of a recurrence. Close radiological observation at shorter intervals or radiotherapy should be considered as adjuvant therapy in high-risk patients based on surgical findings predicting recurrence related to the brain-tumor interface, Simpson's criteria, and histopathological findings in the early postoperative period.

The astrocytic response towards invasive meningiomas

meningiomas disrupt the pial-glial basement membrane. This membrane is closely attached to the subpial glial endfeet forming the glia limitans. The fate of subpial astrocytes during the course of brain invasion by meningiomas is not known. In the present study we immunolabelled sections of 35 brain-invasive meningiomas (14 meningothelial meningiomas WHO grade I, 11 atypical WHO grade II and 10 anaplastic WHO grade III) using anti-collagen IV to label basement membrane material, and antibodies against astrocytic markers CD44, SPARC (secreted protein, acidic and rich in cysteine) and glial fibrillary acidic protein (GFAP). Astrocytes were present at the tumour-brain interface of 14/14 WHO grade I meningiomas, 9/11 WHO grade II tumours and 9/10 WHO grade III tumours. The presence of astrocytes was associated with an intact basement membrane in 11/14 WHO grade I meningiomas (P < 0.01), 6/9 WHO grade II tumours, and 6/9 WHO grade III tumours. However, tumour embedded in deep brain parenchyma lacked both an astrocytic reaction and basement membrane material. In conclusion, astrocytes eventually disappear from the tumour-brain interface during the course of meningioma infiltration. This observation might indicate that the survival of subpial astrocytes is dependent on an intact pial-glial basement membrane.

Multiphoton Excitation of Autofluorescence for Microscopy of Glioma Tissue

Intraoperative detection of residual tumor tissue in glioma surgery remains an important challenge because the extent of tumor removal is related to the prognosis of the disease. Multiphoton excited fluorescence tomography of living tissues provides high-resolution structural and photochemical imaging at a subcellular level. In this conceptual study, we have used multiphoton microscopy and fluorescence lifetime imaging (4D microscopy) to image cultured glioma cell lines, solid tumor, and invasive tumor cells in an experimental mouse glioma model and human glioma biopsy specimens. A laser imaging system containing a mode-locked 80 MHz titanium:sapphire laser with a tuning range of 710 to 920 nm, a scan unit, and a time correlated single photon counting board was used to generate autofluorescence intensity images and fluorescence lifetime images of cultured cell lines, experimental intracranial gliomas in mouse brain, and biopsies of human gliomas. Multiphoton microscopy of native tumor bearing brain provided structural images of the normal brain anatomy at a subcellular resolution. Solid tumor, the tumor-brain interface, and single invasive tumor cells could be visualized. Fluorescence lifetime imaging demonstrated significantly different decay of the fluorescent signal in tumor versus normal brain, allowing a clear definition of the tumor-brain interface based on this parameter. Distinct fluorescence lifetimes of endogenous fluorophores were found in different cellular compartments in cultured glioma cells. The analysis of the relationship between the laser excitation wavelength and the lifetime of excitable fluorophores demonstrated distinct profiles for cells of different histotypes. Multiphoton excited fluorescence of endogenous fluorophores allows structural imaging of tumor and central nervous system histo-architecture at a subcellular level. The analysis of the decay of the fluorescent signal within specific excitation volumes by fluorescent lifetime imaging discriminates glioma cells and normal brain, and the excitation/lifetime profiles may further allow differentiation of cellular histotypes. This technology provides a noninvasive optical tissue analysis that may potentially be applied to an intraoperative analysis of resection plains in tumor surgery.

Bone-related Genes Expressed in Advanced Malignancies Induce Invasion and Metastasis in a Genetically Defined Human Cancer Model

We employed a genetically defined human cancer model to investigate the contributions of two genes up-regulated in several cancers to phenotypic changes associated with late stages of tumorigenesis. Specifically, tumor cells expressing two structurally unrelated bone-related genes, osteonectin and osteoactivin, acquired a highly invasive phenotype when implanted intracranially in immunocompromised mice. Mimicking a subset of gliomas, tumor cells invaded brain along blood vessels and developed altered vasculature at the brain-tumor interface, suggesting that production of those two proteins by tumor cells may create a complex relationship between invading tumor and vasculature co-opted during tumor invasion. Interestingly, the same tumor cells formed massive spontaneous metastases when implanted subcutaneously. This dramatic alteration in tumor phenotype indicates that cellular microenvironment plays an important role in defining the specific effects of those gene products in tumor behavior. In vitro examination of tumor cells expressing either osteonectin or osteoactivin revealed that there was no impact on cellular growth or death but increased invasiveness and expression of MMP-9 and MMP-3. Specific pharmacologic inhibitors of MMP-2/9 and MMP-3 blocked the increased in vitro invasion associated with osteoactivin expression, but only MMP-3 inhibition altered the invasive in vitro phenotype mediated by osteonectin. Results from this genetically defined model system are supported by similar findings obtained from several established tumor cell lines derived originally from human patients. In sum, these results reveal that the expression of a single bone-related gene can dramatically alter or modify tumor cell behavior and may confer differential growth characteristics in different microenvironments. Genetically defined human cancer models offer useful tools in functional genomics to define the roles of specific genes in late stages of carcinogenesis.

Evaluation of the Tumor-brain Interface of Intracranial Meningiomas on MR Imaging including FLAIR Images

The usefulness of fluid-attenuated inversion recovery (FLAIR) imaging for the evaluation of brain diseases has been reported. The purpose of this study was to evaluate the brain-meningioma interface with MRI including FLAIR imaging. This study involved 48 patients with 50 intracranial meningiomas. We retrospectively evaluated the brain-meningioma interface by various imaging method including FLAIR. If a thin layer with a signal intensity different from that of the tumor and brain was observed in the areas of the tumor-brain interface in T(1)-weighted IR (T(1)WIR) and T(2)-weighted turbo SE (T(2)WTSE) images, we defined this structure as the rim. The presence or absence of the rim and the signal intensity were evaluated, and the length and the signal intensity of the rim observed with FLAIR and contrast-enhanced T(1)WIR (CE-T(1)WIR) images were evaluated. In 35 of the 50 lesions (70.0%), the rim was observed in the tumor-brain interface as a layer of low signal intensity in T(1)WIR images and high signal intensity in T(2)WTSE images. In 13 lesions (26.0%), no rim was detected. Flow voids were observed at the tumor-brain interface in 20 of the 50 lesions (40.0%). No rim showed a low signal intensity of the tumor-brain interface in both T(1)WIR and T(2)WTSE images. The rim exhibited an iso-to-high signal intensity compared to the tumor parenchyma in FLAIR images and an enhanced signal intensity in CE-T(1)WIR images. In contrast to T(1)WIR images, the rim in FLAIR images tended to be identified across the entire circumference. The rim at the brain-meningioma interface revealed as low signal intensity in T(1)WIR images and high signal intensity in T(2)WTSE images, which was conventionally considered to be the CSF cleft, was often revealed in FLAIR images as high signal intensity compared to the tumor parenchyma, and an enhanced signal intensity in CE-T(1)WIR images. Therefore, the presence of CSF in such rims is unlikely, and the rims might reflect the capsule structure of the tumor surface.