H. Maximilian Mehdorn

Expression of stem cell markers in human astrocytomas of different WHO grades

According to new hypotheses astrocytomas/gliomas either arise from or attract neural stem cells. Biological markers, particularly antigenic markers, have played a significant role for the characterization of these tumour stem cells (TSCc). Because these studies have been performed with single experimental samples mostly from gliomas, we investigated the expression of the stem cell markers CD133/Prominin, Nestin, Sox-2, Musashi-1, CXCR4, Flt-4/VEGFR-3 and CD105/Endoglin in 72 astrocytomas of different WHO-grades and compared it to normal adult human brain. Expression of their mRNA was quantified by quantitative RT-PCR, of their protein by counting immunopositive cells. In contrast to normal brain, tumour samples showed a high variability for the expression of all markers. However, their mean expression was significantly increased in astrocytomas, but this depended on the WHO grade only for CD133, Nestin, Sox-2 and Musashi-1. Confocal microscopy revealed that these markers mostly could be co-stained with glial fibrillary acidic protein, a marker for astoglial cells, but less frequently with the proliferation marker Ki-67/MIB-1. These markers sometimes, but not necessarily could be co-stained with each other in complex patterns. Our results show that most astrocytomas contain considerable portions of cells expressing stem cell markers. It appears that some of these cells originate from tumour genesis (supporting the stem cell hypothesis) while others are attracted by the tumours. Further functional markers are required to differentiate these TSC-types.

Cerebral autoregulation testing after aneurysmal subarachnoid hemorrhage: the phase relationship between arterial blood pressure and cerebral blood flow velocity.

ObjectiveImpairment of cerebral autoregulation (CA) appears to be an important cause for secondary ischemia after subarachnoid hemorrhage (SAH). It has been shown that graded CA impairment is predictive of outcome. Little is known about whether such impairment is present, what causes CA impairment, whether it precedes vasospasm, and whether it is predictive of outcome in patients with severe aneurysmal SAH. DesignProspective, controlled study. SettingNeurosurgical intensive care unit. PatientsTwelve patients after aneurysmal subarachnoid hemorrhage, 40 controls. InterventionsRecording of cerebral blood flow velocities and continuous measurement of arterial blood pressure at a controlled ventilatory frequency of six per minute to standardize the influence of intrathoracic pressure changes on blood pressure. Measurements and Main Results We calculated the phase shift angles (&Dgr;&phgr;°) between slow (0.1 Hz) arterial blood pressure and cerebral blood flow velocity waves measured by transcranial Doppler ultrasound in the middle cerebral artery during a) posthemorrhage days (PHD) 1–6 (early or prevasospasm phase), and b) during PHD 7–13 (late or vasospasm phase) using a 6/min ventilation protocol, and in 40 controls spontaneously ventilating at the same rate. &Dgr;&phgr; <30° indicated lost CA. Mean flow velocities >100 cm/sec were considered vasospasm. We combined early and late measurements to assess the CA relationship with low cerebral perfusion pressure (CPP) and/or vasospasm. We assessed the Glasgow Outcome Scale (GOS) score at discharge (1 = worst, 5 = best).The admission Hunt and Hess score was 3.6 ± 0.7. GOS scores were n = 3 (GOS 1), n = 2 (GOS 2), n = 5 (GOS 3), n = 1 (GOS 4), and n = 1 (GOS 5). In the early phase, &Dgr;&phgr; was 40.4 ± 19.8° (left), and 40.4 ± 19.2° (right). CPP was 69.4 ± 10.9, intracranial pressure (ICP) was 6.7 ± 2.8 mm Hg. In the late phase, &Dgr;&phgr; worsened in six patients and none improved: 32.1 ± 21° (left), and 26.9 ± 17.2° (right); CPP was 68.1 ± 12.1, ICP was 7.5 ± 3.7 mm Hg. CA was significantly impaired in both phases when compared with normal subjects (&Dgr;&phgr;: 65.7 ± 24.5°;p < .01 for early, p < .001 for late phase). In the early phase, seven of eight patients in whom autoregulation was intact had a GOS >2 at discharge and disturbed CA on at least one side was predictive of either vegetative condition at discharge or death (p < .01). In the late phase, &Dgr;&phgr; was no longer predictive of outcome. Spasm was present in 8 of 17 vessels (47%) in which CA was lost; no spasm was found in 25 of 28 vessels (89%) in which CA was intact (p < .01). A low CPP was present in 6 of 17 vessels (35%) in which CA was lost; a normal CPP was found in 21 of 27 vessels (78%) in which CA was intact (p > .05, NS). However, 14 of 17 vessels (82%) with lost CA showed spasm and/or low CPP while only 8 of 27 cases (30%) with intact CA had either spasm or low CPP (p < .001). ConclusionsCA can be assessed in a graded fashion in SAH patients. CA impairment precedes vasospasm; ongoing vasospasm worsens CA. CA assessment early after subarachnoid hemorrhage, within PHD 1–6, is predictive of outcome whereas late assessment is not. CA impairment is associated with cerebral vasospasm and low CPP.

Reduced metastasis-suppressor gene mRNA-expression in breast cancer brain metastases

Purpose Brain metastases are an increasingly common complication in breast cancer patients. The Metastasis Suppressor Genes (MSG) Nm23, KISS1, KAI1, BRMS1, and Mkk4 have been associated with the metastatic potential of breast cancer in vitro and in vivo.Methods The mRNA expression of Nm23, KISS1, KAI1, BRMS1, and Mkk4 in fresh frozen tissue samples of brain metastases from ductal invasive breast cancer specimens was examined in relation to primary tumors. In a first step, mRNA expression screening was carried out using a semi-quantitative RT-PCR approach, in a second step quantitative real-time RT-PCR was performed on selected specimens. By immunohistochemical staining, gene products were visualized on the protein level.Results Semi-quantitative RT-PCR revealed reduced mRNA expression of Nm23, KISS1, KAI1, BRMS, and Mkk4 in brain metastases. Results for KISS1, KAI1, BRMS, and Mkk4 were confirmed by real-time RT-PCR. In detail, mRNA expression reduction in breast cancer brain metastases was tenfold. Expression of MSG could be confirmed by immunohistochemical staining on protein level.Conclusions Our investigations revealed significantly reduced mRNA expression of metastases suppressor genes KISS1, KAI1, BRMS1, and Mkk4 in breast cancer brain metastasis. Particularly, in the case of KISS1 and Mkk4, an important role for future treatment of patients with breast cancer brain metastatic lesions can be assumed.

Matrix-degrading proteases ADAMTS4 and ADAMTS5 (disintegrins and metalloproteinases with thrombospondin motifs 4 and 5) are expressed in human glioblastomas

Brain tumors, in particular glioblastomas, have a high morbidity and mortality, mainly due to their invasive nature. A prerequisite for this invasiveness is cell migration based on increased expression of proteases digesting the extracellular matrix. Brevican, an important extracellular proteoglycan that is upregulated in glioblastomas, can be degraded by certain proteases. We demonstrate that in human glioblastomas secretory proteases like ADAMTS4 and ADAMTS5 (aggrecanases 1 and 2; ADAMTS = a disintegrin and metalloproteinase with thrombospondin motifs) are expressed on the mRNA and protein levels in considerable amounts. Real‐time RT‐PCR shows a higher levels of ADAMTS4 and 5 expressions in glioblastomas in situ, compared to cultured human glioblastoma cells. The upregulation of these proteases in vivo by cytokines may explain this difference. In vitro, transforming growth factor‐β induces ADAMTS4, but less ADAMTS5, and interleukin‐1β ADAMTS5, but not ADAMTS4. As demonstrated by immunohistochemistry and confocal microscopy in situ, ADAMTS5 expression is confined to proliferating glioblastoma cells of surgical tumor sections and with lower intensity to astroglial cells in normal brain sections, as opposed to brevican. In vitro, glioblastoma‐derived ADAMTS5 degrades recombinant human brevican to several smaller fragments. Our results show that ADAMTS4 and 5 are upregulated on proliferating glioblastoma cells and these proteases may contribute to their invasive potential.

CX3CR1 promotes recruitment of human glioma-infiltrating microglia/macrophages (GIMs)

The transmembrane chemokine CX3CL1 and its receptor CX3CR1 are thought to be involved in the trafficking of immune cells during an immune response and in the pathology of various human diseases including cancer. However, little is known about the expression and function of CX3CR1 in human glioma-infiltrating microglia/macrophages (GIMs), representing the major cellular stroma component of highly malignant gliomas. Here, we show that CX3CR1 is overexpressed at both the mRNA and protein level in solid human astrocytomas of different malignancy grades and in glioblastomas. CX3CR1 was localized in ionized calcium-binding adapter molecule 1 (Iba1) and CD11b/c positive GIMs in situ as shown by fluorescence microscopy. In accordance with this, freshly isolated human GIM-enriched fractions separated by CD11b MACS technology displayed high Iba1 and CX3CR1 mRNA expression levels in vitro. Moreover, cultured human GIMs responded to CX3CL1-triggered activation of CX3CR1 with adhesion and migration in vitro. Besides an increase in motility, CX3CL1 also enhanced expression of matrix metalloproteases 2, 9, and 14 in GIM fractions in vitro. These data indicate that the CX3CL1/CX3CR1 system has a crucial tumor-promoting role in human glioblastomas via its impact on glioma-infiltrating immune subsets.

Glioblastoma: Clinical characteristics, prognostic factors and survival in 492 patients

OBJECTIVE Glioblastoma is the most common and most malignant primary brain tumor in adults. The only overall accepted independent prognostic factors are patient age and performance. We present a large single institution patient series examined for prognostic factors using uni- and multivariate survival analysis. METHODS 492 patients were included who underwent craniotomy for newly diagnosed glioblastoma WHO grade IV between 1990 and 2007 at our department. The association to patient survival was estimated using log-rank test for univariate analysis and cox regression method for multivariate analysis. RESULTS Median patient age was 62 years (mean: 60.4 years, range: 22-93 years), the male: female ratio was 1.26:1. Primary genesis was found in 91.0% of cases. A multifocal tumor was present in 110 cases (22.4%). The median pre- and post-operative Karnofsky Performance Score was 70. Total tumor resection was performed in 288 cases (58.5%), subtotal removal in 134 cases (27.2%). The following parameters were significantly associated with survival in univariate analysis: age, performance, primary genesis, multifocal tumor, neurological deficit, neuropsychological findings, seizures, incidental finding, total or subtotal resection, radiotherapy, chemotherapy, combined radio-/chemotherapy with temozolomide, re-craniotomy, second tumor in patient history. The following parameters were significantly associated with survival in multivariate analysis: age, performance, multifocal tumor, total or subtotal resection, radiotherapy, chemotherapy, combined radio-/chemotherapy with temozolomide. CONCLUSION In addition to patient age and performance, we identified multiple lesions and resection status as independent prognostic factors. Radiotherapy, chemotherapy and combined radio-/chemotherapy with temozolomide were significantly associated with prolonged survival.

Surgical treatment for brain metastases: prognostic factors and survival in 177 patients

Brain metastases are an increasingly frequent complication of cancer. Advances in diagnosis and treatment have led to wider indications for surgery. We present a single-institution series of 177 patients and discuss our results with regard to the literature. Special focus is on patients with advanced age, multiple brain metastases, extracranial metastases, and brain metastasis recurrence. All patients underwent craniotomy for the resection of solid tumor brain metastases between 1994 and 2001 in our department. Perioperative morbidity and mortality as well as survival were evaluated. The median patient age was 59 years (range 32–86 years). In 177 patients, 348 brain metastases were detected, of which 68.0% were supratentorial and 32.0% were infratentorial. According to univariate analysis, the following parameters were significantly associated with prolonged patient survival: (1) age <70 years, (2) one to three intracranial metastases, (3) favorable postoperative performance, (4) resection of all intracranial lesions, and (5) recraniotomy for brain metastasis recurrence. In contrast, the presence of extracranial metastases, metachronous diagnosis, and solitary brain metastases had no influence on survival. As expected, younger age and limited number of brain metastases (up to three) are favorable prognostic factors. Remarkably, the presence of extracranial metastases had no influence on patient survival.

Continuous artery‐selective spin labeling (CASSL)

A new technique for selective spin labeling of individual arteries is presented. It is based on continuous arterial spin labeling (CASL) with an amplitude‐modulated control experiment. Precessionary motion of the labeling gradient about the axis of the artery, combined with an appropriate frequency modulation of the labeling RF pulse, restricts the adiabatic inversion to the desired artery. In phantom studies, it was found that the level of selectivity could be controlled by the sequence parameters, and that the achievable labeling efficiency was at a level of ∼80% compared to a regular, nonselective CASL experiment. In a volunteer study we acquired high‐quality images of the perfusion territories of the internal carotid artery (ICA), the basilar artery (BA), the middle cerebral artery (MCA), and both anterior cerebral arteries (ACAs). The results show the methods flexibility for different geometries and flow velocities. Potential applications include perfusion territory imaging of smaller cerebral arteries, and selective angiography techniques. Magn Reson Med 53:1006–1012, 2005.

Skull metastases: clinical features, differential diagnosis, and review of the literature.

BACKGROUND Most metastatic skull lesions are asymptomatic, although they can cause severe disability due to compression of dural sinuses and cranial nerves. The authors present current cases of calvarial and skull base metastases. Clinical features are compared to those of primary skull tumors and tumor-like lesions. METHODS We retrospectively reviewed the charts and radiographic images of 38 patients who underwent surgery for a skull lesion at our department between 1991 and 2001. The literature on skull metastases was reviewed. RESULTS In 12 cases, histologic examination revealed skull metastases. Eleven patients were known to suffer from cancer at the time of presentation. However, in 5 cases metastatic lesions were the first evidence of disseminated disease. Radical resection was possible in 9 cases. Removal and reconstruction of the infiltrated dura mater was necessary in 5 patients, whereas reconstruction of the bone was required in 8 patients. In comparison to 18 cases with primary skull tumors, patients with skull metastases presented less frequently with a neurologic deficit (3/12 vs. 9/18), reported a shorter history of symptoms (median 2 months vs. 24 months), and were older (median 70 years vs. 51 years). CONCLUSION Patients presenting with skull metastases are often in an advanced stage of disease, although surgery can relieve symptoms quickly and effectively with low morbidity. In particular, patients with signs of dura infiltration and related neurologic deficit should be offered neurosurgical therapy.

Localized BCNU chemotherapy and the multimodal management of malignant glioma

ABSTRACT Background: Gliomas account for 42% of all primary CNS neoplasms and 77% of all malignant primary CNS neoplasms. Unfortunately the high-grade variant of gliomas, glioblastoma multiforme (GBM), is difficult to treat and generally considered incurable. Survival rates are generally poor, and neurological morbidity in the setting of disease progression is high. Fortunately, significant progress has been achieved in the past decade in our understanding of the molecular biology of this aggressive tumour histology and, as a consequence, there is renewed clinical trial activity in this area focused on improving quality of life, treatment-related morbidity and outcomes. Methods: A review of literature from June 2005 to June 2008 was conducted on multimodal treatment of malignant glioma (MG) patients, using specific search criteria in Medline, EMBASE, and BIOSIS. Abstracts from relevant US and European medical (cancer) meetings were also evaluated. Results: The established therapies for MG include surgery, radiotherapy (RT), and local or systemic chemotherapy. However, over the last 10 years only two chemotherapeutic agents have received regulatory approval for treatment of MG: polifeprosan 20 with carmustine (BCNU implant) and temozolomide (TMZ), an imidazotetrazine derivative of dacarbazine. More recent advances in the treatment of brain tumours have been in the development of multimodal approaches. Specific interest in the combination of BCNU implant and TMZ has arisen due to the demonstrable depletion by TMZ of the DNA repair enzyme responsible for resistance to a nitrosourea such as BCNU. Further interest in this combination stems from the observation that there is a difference in the time to peak effect for each agent. Additional emerging data suggest that multimodal therapy with maximal resection and BCNU implants, followed by adjuvant therapy with radiation and TMZ, is effective and well-tolerated in patients with initial high-grade, resectable MG. Conclusions: The increasing body of efficacy data suggests that this combination of BCNU implants and TMZ within a multimodal treatment strategy including surgery and RT may provide an enhanced benefit compared with the use of either of these agents alone in select patients with high-grade glioma.