Alexander Brawanski

CD133+ and CD133− Glioblastoma-Derived Cancer Stem Cells Show Differential Growth Characteristics and Molecular Profiles

Although glioblastomas show the same histologic phenotype, biological hallmarks such as growth and differentiation properties vary considerably between individual cases. To investigate whether different subtypes of glioblastomas might originate from different cells of origin, we cultured tumor cells from 22 glioblastomas under medium conditions favoring the growth of neural and cancer stem cells (CSC). Secondary glioblastoma (n = 7)-derived cells did not show any growth in the medium used, suggesting the absence of neural stem cell-like tumor cells. In contrast, 11/15 primary glioblastomas contained a significant CD133(+) subpopulation that displayed neurosphere-like, nonadherent growth and asymmetrical cell divisions yielding cells expressing markers characteristic for all three neural lineages. Four of 15 cell lines derived from primary glioblastomas grew adherently in vitro and were driven by CD133(-) tumor cells that fulfilled stem cell criteria. Both subtypes were similarly tumorigenic in nude mice in vivo. Clinically, CD133(-) glioblastomas were characterized by a lower proliferation index, whereas glial fibrillary acidic protein staining was similar. GeneArray analysis revealed 117 genes to be differentially expressed by these two subtypes. Together, our data provide first evidence that CD133(+) CSC maintain only a subset of primary glioblastomas. The remainder stems from previously unknown CD133(-) tumor cells with apparent stem cell-like properties but distinct molecular profiles and growth characteristics in vitro and in vivo.

Temozolomide Preferentially Depletes Cancer Stem Cells in Glioblastoma

The prognosis of patients suffering from glioblastoma (GBM) is dismal despite multimodal therapy. Although chemotherapy with temozolomide may contain tumor growth for some months, invariable tumor recurrence suggests that cancer stem cells (CSC) maintaining these tumors persist. We have therefore investigated the effect of temozolomide on CD133(+) and CD133(-) GBM CSC lines. Although differentiated tumor cells constituting the bulk of all tumor cells were resistant to the cytotoxic effects of the substance, temozolomide induced a dose- and time-dependent decline of the stem cell subpopulation. Incubation with sublethal concentrations of temozolomide for 2 days completely depleted clonogenic tumor cells in vitro and substantially reduced tumorigenicity in vivo. In O(6)-methylguanine-DNA-methyltransferase (MGMT)-expressing CSC lines, this effect occurred at 10-fold higher doses compared with MGMT-negative CSC lines. Thus, temozolomide concentrations that are reached in patients were only sufficient to completely eliminate CSC in vitro from MGMT-negative but not from MGMT-positive tumors. Accordingly, our data strongly suggest that optimized temozolomide-based chemotherapeutic protocols might substantially improve the elimination of GBM stem cells and consequently prolong the survival of patients.

Comparison of serial S-100 and NSE serum measurements after severe head injury

SummaryWe investigated the time course of neuron specific enolase (NSE) and S-100 protein after severe head injury in correlation to outcome. We included 30 patients (GCS<9), who had been admitted within 5 hours after injury, in a prospective study. Blood samples were taken on admission, 6, 12. and 24 hours and every 24 hours up to the fifth day after injury. The outcome was estimated on discharge using the Glasgow Outcome Scale. 70% reached a good outcome. All concentrations of NSE and 83% of the S-100 samples were elevated concerning the first probe (30.2 μg/l NSE mean and 2.6 μg/l S-100 mean). Patients with bad outcome had an NSE concentration of 38 μg/l (mean) compared with 26.9 μg/l (mean) in patients with good outcome. Patients with bad outcome had an S-100 concentration of 4.9 μg/l (mean) compared with 1.7 μg/l (mean) in patients with good outcome (p<0.05). The mean values of NSE and S-100 decreased during the first 5 days. Four patients with increasing intracranial pressure showed a quick increasing concentration of NSE, in two patients the S-100 level showed a slower rise. The NSE serum levels did not correlate with intracranial pressure values. Our results show that the first serum concentration of S-100 seems to be predictive for outcome after severe head injury.

Comparison of clinical, radiologic, and serum marker as prognostic factors after severe head injury.

BACKGROUND S-1OOB, a protein of astroglial cells, is described as a marker for neuronal damage. Reliable outcome prediction from severe head injury is still unresolved. Clinical scores such as the Glasgow Coma Scale score (GCS) and diagnostic scores such as the Marshall Computed Tomographic Classification are well established and investigated, but there are still some concerns about these tools. The aim of this study was to investigate the predictive value of the initial serum level of S-100B compared with the predictive value of the GCS score and the Marshall Computed Tomographic Classification to outcome after severe head injury. METHODS Forty-four patients with severe head injury (GCS score < 9) were included. Blood samples were drawn within 1 to 6 hours of injury. After a period of 11 months, their outcome was correlated by using the Glasgow Outcome Scale. Patients with an S-100B serum level above 2 microg/L, a GCS score between 3 and 5, and a computed tomographic scan in the categories 4 to 6 are predicted to have an unfavorable outcome. The predictive values of these tools were calculated according to these definitions. RESULTS The protein S-100B had with 17% the lowest total misclassification rate. When compared with the GCS score and Marshall Computed Tomographic Classification the S-100B serum level calculated on admission had the highest positive predictive value (87%) and negative predictive value (77%). CONCLUSION The serum level of S-100B calculated within 1 to 6 hours of a severe head injury is a useful additional outcome predictor.

CD133 Expression and Cancer Stem Cells Predict Prognosis in High-grade Oligodendroglial Tumors

High‐grade oligodendroglial tumors, that is, anaplastic oligodendroglial tumors and glioblastomas with oligodendroglial component, differ significantly in terms of prognosis and response to chemotherapy. Differentiation might be difficult because the histological differences are vague and reliable markers are not established. We correlated the presence of putative cancer stem cells (CSC) in high‐grade oligodendroglial tumors (WHO grades III and IV) with clinical outcome. Tumors with favorable prognosis neither contained CSC nor did they show CD133 expression. Tumor cells resembled lineage‐restricted progenitor cells with limited proliferative capacity and differentiation profile. In contrast, CD133 expression and stem cell‐like tumor cells characterized tumors with poor prognosis. They showed neurosphere‐like growth, differentiated into cells of all neural lineages, and were tumorigenic in nude mice. In our series, CSC and expression of CD133 predicted the clinical course of disease better than the histological grading. To confirm these results, we retrospectively analyzed 36 high‐grade oligodendroglial tumors. Again, CD133 expression indicated shorter survival and predicted clinical outcome more reliable than the histological assessment.

S-100 serum levels after minor and major head injury.

BACKGROUND S-100, a protein of astroglial cells, is described as a marker for central nervous system damage. The aim of this study was to evaluate whether the marker could give information about the severity and possibility of functional recovery after minor and severe head injury. METHODS Thirty patients after severe head injury (Glasgow Coma Scale score < 9) and 11 patients after minor head injury (Glasgow Coma Scale score > 12) were included. In each case, blood samples were drawn within 6 hours after injury. Outcome was estimated at hospital discharge using the Glasgow Outcome Scale. RESULTS All patients who sustained minor head injury had reached a favorable outcome by the time they were discharged from the hospital. Their mean S-100 serum level was 0.35 microg/L. Patients who sustained severe head injury and were classified as having an unfavorable outcome (31%) showed a mean serum concentration of 4.9 microg/L, whereas patients classified as having a favorable outcome (69%) had a mean S-100 level of 1.2 microg/L. All groups differed significantly (p < 0.05). CONCLUSION S-100 appears to be a promising marker for the severity of head injury and neuronal damage.

Magnetic Resonance Imaging Diffusion Tensor Tractography: Evaluation of Anatomic Accuracy of Different Fiber Tracking Software Packages

BACKGROUND Diffusion tensor imaging (DTI)-based tractography has become an integral part of preoperative diagnostic imaging in many neurosurgical centers, and other nonsurgical specialties depend increasingly on DTI tractography as a diagnostic tool. The aim of this study was to analyze the anatomic accuracy of visualized white matter fiber pathways using different, readily available DTI tractography software programs. METHODS Magnetic resonance imaging scans of the head of 20 healthy volunteers were acquired using a Siemens Symphony TIM 1.5T scanner and a 12-channel head array coil. The standard settings of the scans in this study were 12 diffusion directions and 5-mm slices. The fornices were chosen as an anatomic structure for the comparative fiber tracking. Identical data sets were loaded into nine different fiber tracking packages that used different algorithms. The nine software packages and algorithms used were NeuroQLab (modified tensor deflection [TEND] algorithm), Sörensen DTI task card (modified streamline tracking technique algorithm), Siemens DTI module (modified fourth-order Runge-Kutta algorithm), six different software packages from Trackvis (interpolated streamline algorithm, modified FACT algorithm, second-order Runge-Kutta algorithm, Q-ball [FACT algorithm], tensorline algorithm, Q-ball [second-order Runge-Kutta algorithm]), DTI Query (modified streamline tracking technique algorithm), Medinria (modified TEND algorithm), Brainvoyager (modified TEND algorithm), DTI Studio modified FACT algorithm, and the BrainLab DTI module based on the modified Runge-Kutta algorithm. Three examiners (a neuroradiologist, a magnetic resonance imaging physicist, and a neurosurgeon) served as examiners. They were double-blinded with respect to the test subject and the fiber tracking software used in the presented images. Each examiner evaluated 301 images. The examiners were instructed to evaluate screenshots from the different programs based on two main criteria: (i) anatomic accuracy of the course of the displayed fibers and (ii) number of fibers displayed outside the anatomic boundaries. RESULTS The mean overall grade for anatomic accuracy was 2.2 (range, 1.1-3.6) with a standard deviation (SD) of 0.9. The mean overall grade for incorrectly displayed fibers was 2.5 (range, 1.6-3.5) with a SD of 0.6. The mean grade of the overall program ranking was 2.3 with a SD of 0.6. The overall mean grade of the program ranked number one (NeuroQLab) was 1.7 (range, 1.5-2.8). The mean overall grade of the program ranked last (BrainLab iPlan Cranial 2.6 DTI Module) was 3.3 (range, 1.7-4). The difference between the mean grades of these two programs was statistically highly significant (P < 0.0001). There was no statistically significant difference between the programs ranked 1-3: NeuroQLab, Sörensen DTI Task Card, and Siemens DTI module. CONCLUSIONS The results of this study show that there is a statistically significant difference in the anatomic accuracy of the tested DTI fiber tracking programs. Although incorrectly displayed fibers could lead to wrong conclusions in the neurosciences field, which relies heavily on this noninvasive imaging technique, incorrectly displayed fibers in neurosurgery could lead to surgical decisions potentially harmful for the patient if used without intraoperative cortical stimulation. DTI fiber tracking presents a valuable noninvasive preoperative imaging tool, which requires further validation after important standardization of the acquisition and processing techniques currently available.

Comparison of Near-Infrared Spectroscopy and Tissue Po2 Time Series in Patients After Severe Head Injury and Aneurysmal Subarachnoid Hemorrhage

Monitoring of local oxygen pressure in brain white matter (tipo2) and of local hemoglobin oxygen saturation (rSo2) with near-infrared spectroscopy (NIRS) are increasingly employed techniques in neurosurgical intensive care units. Using frequency-based mathematical methods, the authors sought to ascertain whether both techniques contained similar information. Twelve patients treated in the intensive care unit were included (subarachnoid hemorrhage, n = 3; traumatic brain injury, n = 9). A tipo2 probe and an NIRS sensor were positioned over the frontal lobe with the most pathologic changes on initial computed tomography scan. The authors calculated coherence of tipo2 and rSo2, its overall density distribution, its distribution per data set, and its time evolution. The authors identified a band of significantly correlated frequencies (from 0 to 1.3 × 103 Hz) in more than 90% of the data sets for coherence and overall density distribution. Time evolution showed slow but marked changes of significant coherence. By means of spectral analysis the authors show that tipo2 and rSo2 signals contain similar information, albeit using completely different registration methodologies.

Quality of life after decompressive craniectomy in patients suffering from supratentorial brain ischemia

SummaryBackground. Decompressive craniectomy in patients suffering from severe ischemic stroke in the middle cerebral artery territory (MCA) decreases mortality to near 30%. Additionally functional outcome in patients after early craniectomy seems to be better than in patients without surgery. The aim of this study was to investigate the quality of life of patients who were treated with a decompressive craniectomy for severe ischemic stroke. Methods. We retrospectively investigated the patient records of 48 patients (26 men, mean age 48 years) suffering from ischemic strokes who underwent craniectomy since 1993. We registrated the preoperative neurological status, the diagnostic data as well as the operative procedure. The outcome was assessed using the Barthel Index, the Glasgow outcome score and a questionnaire to assess the quality of life according to Blau consisting of eleven items at follow-up. Findings. The mortality rate was 26%, age correlated to mortality (44.5 versus 60.3 years GOS 1, mean, p<0.0006). Craniectomy without dura patch correlated to mortality (58% versus 14% GOS 1 with dura patch, p<0.005). The quality of life index was 6 points mean. The quality of life index did neither differ significantly between patients with left or right sided lesions nor in patients with and without aphasia. 83% of the surviving patients and/or dependents would agree to surgery in the future. Conclusion. Despite the fact that some patients remain in a poor neurological condition, quality of life after decompressive surgery for ischemic stroke seems to be acceptable to the patients.

Monitoring of Cerebral Oxygen Metabolism in the Jugular Bulb: Reliability of Unilateral Measurements in Severe Head Injury

To investigate the reliability of unilateral jugular venous monitoring and to determine the appropriate side, we performed bilateral jugular venous monitoring in 22 head-injured patients. Fiberoptic catheters were placed in both jugular bulbs. Arterial and bilateral jugular venous blood samples were obtained simultaneously for in vitro determination of jugular venous oxygen saturation (SJO2), arterial minus jugular venous lactate content difference (AJDL), and modified lactate-oxygen index (mLOI). Ischemia was assumed if one of the following pathologic values occurred at least unilaterally: SJO2 <54%, AJDL <−0.37 mmol/L, mLOI >0.08. The sensitivity of calculated unilateral monitoring in detecting ischemia was evaluated by comparing the incidence detected unilaterally with that disclosed bilaterally. The mean and maximum bilateral SJO2 differences varied between 1.4% and 21.0%, and 8.1% and 44.3%, respectively. The bias and limits of agreement (mean differences ± 2 SD) between paired samples were 0.4% ± 12.8%. There was no significant variation in bilateral SJO2 differences with time. Decreasing cerebral perfusion pressure (r = −0.559, P < 0.001) and arterial Pco2 (r = −0.342, P < 0.001) were associated with increasing bilateral SJO2 differences. Regarding AJDL, the maximum bilateral differences varied between 0.04 mmol/L and 1.52 mmol/L. The bias and limits of agreement were −0.01 ± 0.18 mmol/L. At best, 87% of ischemic events were disclosed by monitoring on the side of predominant lesion or, in diffuse injuries, on the side of the larger jugular foramen (computed tomographic [CT] approach). We conclude that in severe head injury, even calculated unilateral jugular venous monitoring has an unpredictable risk for misleading or missing data. Therefore, the reliability of unilateral jugular venous monitoring appears suspicious. For diagnosing ischemia the CT approach is recommended.