Glioblastoma (GBM) is the most aggressive primary brain tumor. Its cellular composition is very heterogeneous, with cells exhibiting stem-cell characteristics (GSCs) that co-determine therapy resistance and tumor recurrence. Bone Morphogenetic Protein (BMP)-4 promotes astroglial and suppresses oligodendrocyte differentiation in GSCs, processes associated with superior patient prognosis. We characterized variability in cell viability of patient-derived GBM cultures in response to BMP4 and, based on single-cell transcriptome profiling, propose predictive positive and early-response markers for sensitivity to BMP4. Cell viability was assessed in 17 BMP4-treated patient-derived GBM cultures. In two cultures, one highly-sensitive to BMP4 (high therapeutic efficacy) and one with low-sensitivity, response to treatment with BMP4 was characterized. We applied single-cell RNA-sequencing, analyzed the relative abundance of cell clusters, searched for and identified the aforementioned two marker types, and validated these results in all 17 cultures. High variation in cell viability was observed after treatment with BMP4. In three cultures with highest sensitivity for BMP4, a substantial new cell subpopulation formed. These cells displayed decreased cell proliferation and increased apoptosis. Neuronal differentiation was reduced most in cultures with little sensitivity for BMP4. OLIG1/2 levels were found predictive for high sensitivity to BMP4. Activation of ribosomal translation (RPL27A, RPS27) was up-regulated within one day in cultures that were very sensitive to BMP4. The changes in composition of patient-derived GBM cultures obtained after treatment with BMP4 correlate with treatment efficacy. OLIG1/2 expression can predict this efficacy, and upregulation of RPL27A and RPS27 are useful early-response markers.

This systematic review and meta-analysis aims to provide an overview of the indications, selection criteria, and outcomes of intracranial direct bypass surgery. Embase, Ovid Medline, the Web of Science Core Collection, Google Scholar, and Cochrane Central Register of Controlled Trials were searched from inception to February 11, 2025, for original studies reporting indications for bypass surgery including human subjects. Patency, procedure-related neurological complications, postoperative poor clinical outcome, and mortality rates were analyzed using a random-effects model. Pooled prevalence rates and 95% confidence intervals (CIs) were presented. The search yielded 7449 articles of which 5478 remained after removing duplicates. After initial screening, 251 articles remained to be assessed for eligibility based on full-text sifting. Ultimately, 142 articles were included. One hundred six studies reported "steno-occlusive disease" as an indication. Postoperative poor clinical outcome occurred in 9% of the patients (95% CI 5.1-13.0; I² = 78%), and the mortality rate was 3.5% (95% CI 1.6-5.5; I² = 82%). Forty-one studies reported "Moyamoya vasculopathy" as an indication. Postoperative poor clinical outcome occurred in 5.5% of the patients (95% CI 0.6-10.4; I² = 78%), and the mortality rate was 0.6% (95% CI 0.0-1.7; I² = 0%). Seven studies reported "urgent bypass" as an indication, 7 studies "ruptured aneurysm treatment," and 29 studies "complex unruptured aneurysm treatment." Despite a decline in indications, intracranial bypass surgery remains a highly relevant option for the treatment of diseases such as Moyamoya vasculopathy, as a salvage option in steno-occlusive disease with hemodynamic compromise, and treatment of aneurysms not amenable to microsurgical or endovascular repair.

The application and interpretation of P values have caused debate for several decades, and this debate has become particularly relevant in the past few years. The P value represents the probability of seeing results as extreme or more extreme than those observed in a data analysis, were the null hypothesis and other underlying assumptions to be true. While P values are useful in pointing out where an effect may be present, they have often been misused in an attempt to oversell "statistically significant" findings. As P values rely on the spread and number of measurements, a smaller P value does not necessarily imply a larger effect size, which is better assessed via an effect estimate and confidence interval interpreted in the context of the study. The clinical relevance of a computed P value is context dependent. We investigated the current use of P values in a small sample of recent neurosurgical literature. Only a minority of manuscripts that reported statistical significance described confounder adjustment, or effect sizes. A common, incorrect assumption often observed was that statistical significance equals clinical relevance. To enable correct interpretation of clinical significance, it is crucial that authors describe the clinical implications of their findings.

To discover new treatment options for high-grade glioma (HGG), robust in vitro models are essential, but reliably establishing patient-derived cell cultures remains challenging. We established glioma stem-like cell (GSC) cultures from 114 consecutive HGG specimens via traditional surgical resection and/or ultrasonic aspiration, using completely dissociated single cell (single cell-derived, SCD) and partially dissociated 3D-derived (3DD) tissue fragments. Higher success rates in culture establishment were obtained from ultrasonic aspirates and 3DD surgical samples. Combining these approaches yielded a 96% success rate. Copy number profiling showed overall genetic similarities between cultures and parental tissue. Single-cell sequencing revealed greater transcriptomic heterogeneity in ultrasonic aspiration-derived cultures. Our protocol enabled the screening of 20 anti-cancer agents within a clinically relevant timeframe for 16 out of 18 HGG samples. This refined protocol serves as a robust tool for establishing HGG cell cultures that retain the molecular characteristics of the tumors and support applications in precision medicine.

One of the main causes of poor prognoses in patient with glioblastoma (GBM) is drug resistance to current standard treatment, which includes chemoradiation and adjuvant temozolomide (TMZ). In addition, the concept of cancer stem cells provides new insights into therapy resistance and management also in GBM and glioblastoma stem cell-like cells (GSCs), which might contribute to therapy resistance. Bone morphogenetic protein-4 (BMP4) stimulates astroglial differentiation of GSCs and thereby reduces their self-renewal capacity. Exposure of GSCs to BMP4 may also sensitize these cells to TMZ. A recent phase I trial has shown that local delivery of BMP4 is safe, but a large variation in survival is seen in these treated patients and in features of their cultured tumors. We wanted to combine TMZ and BMP4 (TMZ + BMP4) therapy and assess the inter-tumoral variability in response to TMZ + BMP4 in patient-derived GBM cultures. A phase II trial could then benefit a larger group of patients than those treated with BMP4 only. We first show that simultaneous treatment with TMZ + BMP4 is more effective than sequential treatment. Second, when applying our optimized treatment protocol, 70% of a total of 20 GBM cultures displayed TMZ + BMP4 synergy. This combination induces cellular apoptosis and does not inhibit cell proliferation. Comparative bulk RNA-sequencing indicates that treatment with TMZ + BMP4 eventually results in decreased MAPK signaling, in line with previous evidence that increased MAPK signaling is associated with resistance to TMZ. Based on these results, we advocate further clinical trial research to test patient benefit and validate pathophysiological hypothesis.