AB014. The accurate classification of high-grade glioma, IDH-wildtype, is based on methylation profiling: a case report.

BACKGROUND: The 2021 World Health Organization (WHO) classification has significantly enhanced the molecular diagnostics of diffuse gliomas, emphasizing the role of molecular features alongside histology. However, accurate classification remains challenging, particularly for high-grade gliomas, IDH-wildtype. DNA methylation profiling provides an unbiased diagnostic approach, offering valuable insights into tumor classification. Here, we present a case of a high-grade glioma, initially diagnosed as glioblastoma, IDH-wildtype based on histological and genetic analysis, but later reclassified as a diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype (RTK2 subtype) through methylation profiling. CASE DESCRIPTION: A 7-year-old boy presenting with seizures was admitted to our hospital, where brain magnetic resonance imaging revealed a tumor in the right temporal lobe. Intraoperative histology indicated a high-grade glioma, prompting maximal resection. Diagnosis according to the 2021 WHO classification involved histological analysis, immunohistochemistry, testing for specific genetic alterations, and DNA methylation profiling. Histological and immunohistochemical assessment initially identified the tumor as a high-grade astrocytoma, IDH-wildtype. Specific genetic testing revealed IDH1-wildtype, IDH2-wildtype, and TERT promoter mutation, consistent with a diagnosis of glioblastoma, IDH-wildtype. However, methylation profiling yielded a classifier score of 0.99 for a diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype (RTK2 subtype). CONCLUSIONS: Our case illustrated that conventional histological and genetic analysis classification can be reclassified according to the DNA methylation analysis, demonstrating that methylation profiling is useful to accurately classify high-grade gliomas, particularly those of the IDH-wildtype subtype.

Single-cell atlas of the human brain vasculature across development, adulthood and disease.

A broad range of brain pathologies critically relies on the vasculature, and cerebrovascular disease is a leading cause of death worldwide. However, the cellular and molecular architecture of the human brain vasculature remains incompletely understood1. Here we performed single-cell RNA sequencing analysis of 606,380 freshly isolated endothelial cells, perivascular cells and other tissue-derived cells from 117 samples, from 68 human fetuses and adult patients to construct a molecular atlas of the developing fetal, adult control and diseased human brain vasculature. We identify extensive molecular heterogeneity of the vasculature of healthy fetal and adult human brains and across five vascular-dependent central nervous system (CNS) pathologies, including brain tumours and brain vascular malformations. We identify alteration of arteriovenous differentiation and reactivated fetal as well as conserved dysregulated genes and pathways in the diseased vasculature. Pathological endothelial cells display a loss of CNS-specific properties and reveal an upregulation of MHC class II molecules, indicating atypical features of CNS endothelial cells. Cell-cell interaction analyses predict substantial endothelial-to-perivascular cell ligand-receptor cross-talk, including immune-related and angiogenic pathways, thereby revealing a central role for the endothelium within brain neurovascular unit signalling networks. Our single-cell brain atlas provides insights into the molecular architecture and heterogeneity of the developing, adult/control and diseased human brain vasculature and serves as a powerful reference for future studies.

Inhibition of VEGF receptors induces pituitary apoplexy: An experimental study in mice.

Anti-vascular endothelial growth factor (VEGF) therapy has been developed for the treatment of a variety of cancers. Although this therapy may be a promising alternative treatment for refractory pituitary adenomas and pituitary carcinomas, the effects of anti-VEGF agents on the pituitary gland are not yet well understood. Here, we found that mice administered with OSI-930, an inhibitor of receptor tyrosine kinases including VEGF receptor 1 and 2, frequently exhibited hemorrhage in the pituitary gland. This is the first report that anti-VEGF therapy can cause pituitary apoplexy. C57BL/6 mice were daily injected intraperitoneally with 100 mg/kg body weight of OSI-930 for one to six days. Pituitary glands were immunohistochemically examined. Four of six mice treated for three days and all of five mice treated for six days exhibited hemorrhage in the pituitary gland. In all cases, the hemorrhage occurred just around Rathke's cleft. In OSI-930-administered mice, the vascular coverage and branching were reduced in the anterior lobe, and capillary networks were also decreased in the intermediate lobe in a treatment-day dependent manner. Few blood vessels around Rathke's cleft of the intermediate lobe express VE-cadherin and are covered with platelet-derived growth factor receptor-ß (PDGFR-ß)-positive cells, which suggests that capillaries around Rathke's cleft of the intermediate lobe were VE-cadherin-negative and not covered with pericytes. The reduction of capillary plexus around Rathke's cleft was observed at the site where hemorrhage occurred, suggesting a causal relationship with the pathogenesis of pituitary hemorrhage. Our study demonstrates that anti-VEGF agents have a risk of pituitary apoplexy. Pituitary apoplexy should be kept in mind as an adverse effect of anti-VEGF therapy.

Stromal cells of hemangioblastomas exhibit mesenchymal stem cell-derived vascular progenitor cell properties.

Hemangioblastoma is composed of neoplastic stromal cells and a prominent capillary network. To date, the identity of stromal cells remains unclear. Mesenchymal stem cells can give rise to committed vascular progenitor cells, and ephrin-B2/EphB4 and Notch signaling have crucial roles in these steps. The aim of our study was to elucidate that stromal cells of central nervous system hemangioblastomas have mesenchymal stem cell-derived vascular progenitor cell properties. Ten hemangioblastomas were investigated immunohistochemically. CD44, a mesenchymal stem cell marker, was detected in stromal cells of all cases, suggesting that stromal cells have mesenchymal stem cell-like properties. Neither CD31 nor α-SMA was expressed in stromal cells, suggesting that stromal cells have not acquired differentiated vascular cell properties. Both ephrin-B2 and EphB4, immature vascular cell markers, were detected in stromal cells of all cases. Jagged1, Notch1, and Hesr2/Hey2, which are known to be detected in both immature endothelial cells and mural cells, were expressed in stromal cells of all cases. Notch3, which is known to be detected in differentiating mural cells, was also expressed in all cases. These results suggest that stromal cells also have vascular progenitor cell properties. In conclusion, stromal cells of hemangioblastomas exhibit mesenchymal stem cell-derived vascular progenitor cell properties.

Role of Endothelial-to-Mesenchymal Transition in the Pathogenesis of Central Nervous System Hemangioblastomas.

OBJECTIVE: Hemangioblastomas (HBs) are benign vascular tumors of the central nervous system and histologically contain abundant microvessels. Therefore, they clinically exhibit vascular malformation-like characteristics. It has been described that endothelial-to-mesenchymal transition (EndMT) contributes to the pathogenesis of cerebral cavernous malformations. However, it remains unknown whether EndMT contributes to the pathogenesis of central nervous system HBs. The aim of our study was to investigate whether EndMT occurs in central nervous system HBs. METHODS: Ten central nervous system HBs were immunohistochemically investigated. RESULTS: Cluster of differentiation (CD) 31 (an endothelial marker) and EndMT markers, such as α-smooth muscle actin (a mesenchymal marker) and CD44 (a mesenchymal stem cell marker), were expressed in the endothelial layer of microvessels in all cases. These findings suggest that endothelial cells (ECs) of microvessels in central nervous system HBs have acquired mesenchymal and stem cell-like characteristics and undergone EndMT. In all cases, both ephrin-B2 and EphB4, which are not detected in adult normal brain vessels, were expressed in the endothelial layer of microvessels. These data suggest that ECs of microvessels in central nervous system HBs are immature or malformed cells and have both arterial and venous characteristics. CONCLUSIONS: To our knowledge, this is the first report showing the possibility that EndMT contributes to the pathogenesis of central nervous system HBs. It is likely that ECs of microvessels in central nervous system HBs are immature or malformed cells and have both arterial and venous characteristics. EndMT is expected to be a new therapeutic target in central nervous system HBs.

Contribution of Endothelial-to-Mesenchymal Transition to the Pathogenesis of Human Cerebral and Orbital Cavernous Malformations.

BACKGROUND: The analysis of gene-targeted mouse mutants has demonstrated that endothelial-to-mesenchymal transition (EndMT) is crucial to the onset and progression of cerebral cavernous malformations (CMs). It has also been shown that Notch and ephrin/Eph signaling are involved in EndMT. However, their roles in the pathogenesis of human intracranial CMs remain unclear. OBJECTIVE: To elucidate the contribution of EndMT, the Notch pathway, and ephrin-B2/EphB4 signaling to the pathogenesis of human intracranial CMs. METHODS: Eight human intracranial CMs (5 cerebral and 3 orbital CMs) were immunohistochemically investigated. RESULTS: CD31 (an endothelial marker) and EndMT markers, such as α-smooth muscle actin (a mesenchymal marker) and CD44 (a mesenchymal stem cell marker), were expressed in the endothelial layer of vascular sinusoids in all cases, suggesting that endothelial cells (ECs) have acquired mesenchymal and stem-cell-like characteristics and undergone EndMT in all cerebral and orbital CMs. EndMT was observed in about 70% and 35% of ECs in cerebral and orbital CMs, respectively. In all cases, Notch3 was expressed in the endothelial layer, indicating that ECs of vascular sinusoids have acquired mesenchymal features. In all cases, both ephrin-B2 and EphB4 were detected in the endothelial layer, suggesting that ECs of vascular sinusoids are immature or malformed cells and have both arterial and venous characteristics. CONCLUSION: EndMT plays a critical role in the pathogenesis of human cerebral and orbital CMs. Modulating EndMT is expected to be a new therapeutic strategy for cerebral and orbital CMs.

Torcular dural arteriovenous fistula treated via stent placement and angioplasty in the affected straight and transverse sinuses: case report.

The successful obliteration of torcular dural arteriovenous fistula (DAVF) with a diffuse shunt in the affected sinus may require complex treatment strategies. Therapeutic goals include the preservation of normal venous drainage and complete obliteration of shunt flow. The authors report the case of a torcular DAVF. The treatment of this type of AVF may require a combined approach with transarterial and transvenous embolization, open surgery, or radiosurgery and is associated with many problems. Stent placement and angioplasty in the affected sinus result in compression of the fistulous dural wall of the sinus and decrease shunt flow. In cases in which there is a diffuse shunt in the affected sinus and no evident shunt point, such as in AVFs involving venous pouches and parasinuses, sealing the fistula orifice with self-expandable stents and angioplasty (balloon inflation) is considered the best treatment option to preserve normal cerebral venous sinus drainage and obliterate shunt flow. In such cases, the authors recommend using one or more self-expandable and closed-cell stents and using angioplasty to avoid endoleakage into the gap between the stent graft and the vessel wall.

Utility of intraoperative fetal heart rate monitoring for cerebral arteriovenous malformation surgery during pregnancy.

We report two methods of intraoperative fetal heart rate (FHR) monitoring in cases of cerebral arteriovenous malformation surgery during pregnancy. In one case in her third trimester, cardiotocography was used. In another case in her second trimester, ultrasound sonography was used, with a transesophageal echo probe attached to her lower abdomen. Especially, the transesophageal echo probe was useful because of the advantages of being flexible and easy to attach to the mother's lower abdomen comparing with the usual doppler ultrasound probe. In both cases, the surgery was successfully performed and FHR was monitored safely and stably. The use of intraoperative FHR monitoring provides information about the influence of induced maternal hypotension and unexpected bleeding on fetus during surgery. These monitoring techniques would be especially emphasized in cerebrovascular surgery for the safe management of both mother and fetus.