The tumour microenvironment, treatment resistance and recurrence in glioblastoma.

The adaptability of glioblastoma (GBM) cells, encouraged by complex interactions with the tumour microenvironment (TME), currently renders GBM an incurable cancer. Despite intensive research, with many clinical trials, GBM patients rely on standard treatments including surgery followed by radiation and chemotherapy, which have been observed to induce a more aggressive phenotype in recurrent tumours. This failure to improve treatments is undoubtedly a result of insufficient models which fail to incorporate components of the human brain TME. Research has increasingly uncovered mechanisms of tumour-TME interactions that correlate to worsened patient prognoses, including tumour-associated astrocyte mitochondrial transfer, neuronal circuit remodelling and immunosuppression. This tumour hijacked TME is highly implicated in driving therapy resistance, with further alterations within the TME and tumour resulting from therapy exposure inducing increased tumour growth and invasion. Recent developments improving organoid models, including aspects of the TME, are paving an exciting future for the research and drug development for GBM, with the hopes of improving patient survival growing closer. This review focuses on GBMs interactions with the TME and their effect on tumour pathology and treatment efficiency, with a look at challenges GBM models face in sufficiently recapitulating this complex and highly adaptive cancer.

Endoscopic neuroendoscopy using a novel ventricular access port.

BACKGROUND: Hydrocephalus remains an important aspect of neurosurgical care and in select circumstances, the endoscopic third ventriculostomy (ETV) continues to remain an important treatment. In our initial experience of ETV using the commercially available plastic ventricular ports we found them both restrictive and expensive. Following this experience, we developed a stainless steel ventricular access port (VAP). We present our novel method of access involving this non-disposable ventricular port. METHOD: We have developed a series of custom-made, 316-grade stainless steel VAPs designed specifically for our ventricular endoscopes. Following a standard Burr-hole, cannulation of the lateral ventricle is performed inserting this port and removing the trocar allowing free access using a standard ventriculoscope without the requirement for disposable plastic ports. Since 2008 our unit has used a standard method of ventricular access using this device. We present our long-term experience of cases of endoscopic ventriculoscopy and ventriculostomy using this method of ventricular access. RESULTS: From December 2008 to January 2016, 56 patients underwent an endoscopic third ventriculostomy using the stainless steel ventricular port. Two 2 patients (3.6%) had a recorded complication in the form of minor self-limiting intraventricular haemorrhage. No cases of infection or mortality were noted in this patient series. CONCLUSION: We demonstrate our long-term experience with a non-disposable VAP for ventricular access. This method remains safe with results that are comparable to published series. We suggest this method may be a less expensive and safe alternative to standard disposable methods of ventricular access.

Image-guided transthoracic transpedicular microdiscectomy for a giant thoracic disc herniation: patient series.

BACKGROUND: This case series reports on five consecutive patients who underwent image-guided transpedicular transthoracic microdiscectomy. The authors retrospectively reviewed five patients who had undergone Stealth image-guided transpedicular transthoracic microdiscectomy between 2015 and 2021. OBSERVATIONS: Image guidance with O-arm verified critical anatomical landmarks in the setting of large central calcified and/or soft tissue disc prolapse. This allowed limited rib head resection, pedicle removal, and corpectomy to give adequate access and not require interbody fusion. The authors performed a partial posterior corpectomy anterior to the affected disc prolapse and microsurgical delivery of the affected disc anteriorly into the corpectomy cave away from the thecal sac. Electronic and radiographic records were analyzed at their initial presentation and at follow-up. The median patient age was 51 years (range, 44-56 years), with 80% of the patients being males. Four of five patients had significant improvement of their presenting clinical symptoms. One patient had a complicated postoperative recovery with a pneumothorax and subsequent bilateral pneumonia requiring intensive care. Another patient developed delayed postoperative worsening of paraparesis. LESSONS: The use of Stealth image guidance with O-arm for transthoracic microdiscectomy for complex calcified thoracic disc herniation is an effective operative technical adjunct to verify anatomical landmarks and limit the microsurgical procedure.

Treatment of glioblastoma with re-purposed renin-angiotensin system modulators: Results of a phase I clinical trial.

Glioblastoma is the most common and most aggressive primary brain cancer in adults. Standard treatment of glioblastoma consisting of maximal safe resection, adjuvant radiotherapy and chemotherapy with temozolomide, results in an overall median survival of 14.6 months. The aggressive nature of glioblastoma has been attributed to the presence of glioblastoma stem cells which express components of the renin-angiotensin system (RAS). This phase I clinical trial investigated the tolerability and efficacy of a treatment targeting the RAS and its converging pathways in patients with glioblastoma. Patients who had relapsed following standard treatment of glioblastoma who met the trial criteria were commenced on dose-escalated oral RAS modulators (propranolol, aliskiren, cilazapril, celecoxib, curcumin with piperine, aspirin, and metformin). Of the 17 patients who were enrolled, ten completed full dose-escalation of the treatment. The overall median survival was 19.9 (95% CI:14.1-25.7) months. Serial FET-PET/CTs showed a reduction in both tumor volume and uptake in one patient, an increase in tumor uptake in nine patients with decreased (n = 1), unchanged (n = 1) and increased (n = 7) tumor volume, in the ten patients who had completed full dose-escalation of the treatment. Two patients experienced mild side effects and all patients had preservation of quality of life and performance status during the treatment. There is a trend towards increased survival by 5.3 months although it was not statistically significant. These encouraging results warrant further clinical trials on this potential novel, well-tolerated and cost-effective therapeutic option for patients with glioblastoma.

The Renin-Angiotensin System in the Tumor Microenvironment of Glioblastoma.

Glioblastoma (GB) is an aggressive primary brain tumor. Despite intensive research over the past 50 years, little advance has been made to improve the poor outcome, with an overall median survival of 14.6 months following standard treatment. Local recurrence is inevitable due to the quiescent cancer stem cells (CSCs) in GB that co-express stemness-associated markers and components of the renin-angiotensin system (RAS). The dynamic and heterogeneous tumor microenvironment (TME) plays a fundamental role in tumor development, progression, invasiveness, and therapy resistance. There is increasing evidence showing the critical role of the RAS in the TME influencing CSCs via its upstream and downstream pathways. Drugs that alter the hallmarks of cancer by modulating the RAS present a potential new therapeutic alternative or adjunct to conventional treatment of GB. Cerebral and GB organoids may offer a cost-effective method for evaluating the efficacy of RAS-modulating drugs on GB. We review the nexus between the GB TME, CSC niche, and the RAS, and propose re-purposed RAS-modulating drugs as a potential therapeutic alternative or adjunct to current standard therapy for GB.

The renin-angiotensin system in central nervous system tumors and degenerative diseases.

Despite their differences, central nervous system (CNS) tumors and degenerative diseases share important molecular mechanisms underlying their pathologies, due to their common anatomy. Here we review the role of the renin-angiotensin system (RAS) in CNS tumors and degenerative diseases, to highlight common molecular features and examine the potential merits in repurposing drugs that inhibit the RAS, its bypass loops, and converging signaling pathways. The RAS consists of key components, including angiotensinogen, (pro)renin receptor (PRR), angiotensin-converting enzyme 1 (ACE1), angiotensin-converting enzyme 2 (ACE2), angiotensin I (ATI), angiotensin II (ATII), ATII receptor 1 (AT1R), ATII receptor 2 (AT2R) and the Mas receptor (MasR). The RAS is integral to systemic and cellular pathways that regulate blood pressure and body fluid equilibrium and cellular homeostasis. The main effector of the RAS is ATII which exerts its effect by binding to AT1R and AT2R through two competitive arms: an ACE1/ATII/AT1R axis, which is involved in regulating oxidative stress and neuroinflammation pathways, and an ATII/AT2R and/or ATII/ACE2/Ang(1-7)/MasR axis that potentiates neuroprotection pathways. Alterations of these axes are associated with cellular dysfunction linked to CNS diseases. The generation of ATII is also influenced by proteases that constitute bypass loops of the RAS. These bypass loops include cathepsins B, D and G and chymase and aminopeptidases. The RAS is also influenced by converging pathways such as the Wnt/ß-catenin pathway which sits upstream of the RAS via PRR, a key component of the RAS. We also discuss the co-expression of components of the RAS and markers of pluripotency, such as OCT4 and SOX2, in Parkinson's disease and glioblastoma, and their potential influences on transduction pathways involving the Wnt/ß-catenin, MAPK/ERK, PI3K/AKT and vacuolar (H+) adenosine triphosphatase (V-ATPase) signaling cascades. Further research investigating modulation of the ACE1/ATII/AT1R and ACE2/Ang(1-7)/MasR axes with RAS inhibitors may lead to novel treatment of CNS tumors and degenerative diseases. The aim of this review article is to discuss and highlight experimental and epidemiological evidence for the role of the RAS, its bypass loops and convergent signaling pathways in the pathogenesis of CNS tumors and degenerative diseases, to direct research that may lead to the development of novel therapy.

Occipital expansion without osteotomies in Apert syndrome.

INTRODUCTION: Cranial expansion has been the mainstay of initial management of children with Apert syndrome. Surgical timing is a balance between the risk of relapse if performed too early and the possibility of raised intracranial pressure and ossification defects if performed later. Primary occipital expansion has been proposed as a method to delay the timing of frontal surgery. We have applied the principal of spring expansion of patent sutures to expand the posterior cranial fossa without a cranial osteotomy. PATIENTS AND METHODS: All new Apert syndrome patients seen during the 3-year period December 2004-December 2007 underwent initial occipital expansion without osteotomy using spring expansion of the patent lambdoid suture. RESULTS: Four new Apert syndrome patients underwent posterior spring expansion of the patent lambdoid suture. Good occipital expansion was achieved in all cases. Standard frontal advancement was performed 5-18 months later. No relapse after frontal advancement has been seen after mean follow-up of 41 months. CONCLUSIONS: Spring expansion of the patent lambdoid suture is an alternative technique to expand the posterior cranial fossa. Compared to current techniques it has very low morbidity. Occipital expansion is thought to treat several of the mechanisms responsible for raised intracranial pressure in Apert syndrome. When performed at 6 months of age it has enabled us to delay the time at which we would normally perform frontal advancement surgery until a time when the surgical result is likely to be more stable.

An unusual case of post-nasal "clicking" after pituitary surgery.

We report a case of a 64-year-old female who represented two months after pituitary surgery with the novel complication of intermittent disabling post-nasal pulsatile "clicking". Imaging and endoscopic examination showed a residual sella cleft with the tumour capsule and diaphragma cupping against the anterior sella bony defect with each pulsation, causing the clicking. The clicking resolved following second redo surgical endoscopic repair to jail a fat graft within the residual cleft with a central barricade of conchal cartilage graft and onlay standard repair.

Embryonic stem cell-like subpopulations are present within Schwannoma.

BACKGROUND: There is accumulating evidence of the presence of embryonic stem cell (ESC)-like cells in benign tumors. AIM: This study aimed to identify ESC-like cells in Schwannoma using the induced-pluripotent stem cell (iPSC) markers OCT4, SOX2, NANOG, KLF4 and c-MYC. METHODS: Immunohistochemical (IHC) staining (n = 20) and RT-qPCR (n = 6) were performed on Schwannoma tissue samples (STS) to investigate protein and mRNA expression of these iPSC markers, respectively. Immunofluorescence (IF) staining was performed to investigate co-localization of the iPSC markers with CD34, α-SMA and CD133. RESULTS: IHC staining and RT-qPCR demonstrated protein and mRNA expression of all five iPSC markers, respectively. IF staining showed expression of SOX2, KLF4 and c-MYC on the tumor cells and the endothelium of the tumor microvessels which also expressed OCT4, while NANOG was exclusively expressed on the endothelium of the tumor microvessels. The OCT4+/CD34+ endothelium expressed CD133. CONCLUSION: We have identified a putative OCT4+/SOX2+/NANOG+/KLF4+/c-MYC+/CD133+ ESC-like subpopulation on the endothelium of tumor microvessels and an OCT4-/SOX2+/NANOG-/KLF4+/c-MYC+/CD133+ ESC-like subpopulation, within Schwannoma.

Correction of nonsynostotic scaphocephaly without cranial osteotomy: spring expansion of the sagittal suture.

BACKGROUND: Scaphocephaly is usually due to sagittal synostosis. Scaphocephaly may also be seen in the presence of a nonsynostosed sagittal suture. In this situation traditional surgery is controversial due to the altered risk-benefit profile. This paper reports the first known series of patients with nonsynostotic scaphocephaly treated using spring assisted expansion of the sagittal suture. METHODS: All patients referred to our craniofacial program over the period February 2005-February 2008 were retrospectively reviewed. Eleven patients were seen with nonsynostotic scaphocephaly. Seven patients underwent spring expansion of the sagittal suture without osteotomy. RESULTS: Four female and three male patients had spring expansion of a patent sagittal suture. Four patients were born prematurely. Two patients had Beckwith-Weidemann syndrome. The ages ranged from 6 to 26 months (mean 12 months). The average preoperative cranial index was 66 (range 63-67). This improved to 76 at the time of spring removal (range 73-78). Springs were kept in situ for an average of 7.25 months. The mean blood loss was 7 ml and the mean operative time 36 min. CONCLUSION: Spring cranioplasty for sagittal synostosis is ideally performed before 6 months of age however in nonsynostotic scaphocephaly older children can be considered due to the absence of frontal bossing. Significant aesthetic improvement was achieved in all cases and normalization of the cranial index was achieved in 86% of cases with minimal morbidity and no significant complications. This technique is an alternative for nonsynostotic cases that were previously either untreated or undergone major remodelling surgery.

Anterior cervicothoracic approach to an upper thoracic spinal endodermal cyst.

Endodermal cysts are rare forms of benign tumors that comprise about 0.01% of all central nervous system (CNS) tumors. They are found in cranial and/or spinal locations. The posterior approach to the spinal cord is generally the approach of choice for safe resection of those lesions. We report on a thoracic endodermal cyst that was surgically resected using an anterior approach to the spinal cord.

Surgical management of craniofacial and skull base rhabdomyosarcomas.

INTRODUCTION: Craniofacial and skull base rhabdomyosarcomas (RMSs) are rare. Surgeons are involved both in the resection and the reconstruction of these tumors and in the management of late sequelae of earlier treatment. These tumors are highly heterogeneous, and the initial presentation may be insidious. We wished to determine how diagnostic difficulties could be overcome and how management outcomes could be optimized. MATERIALS AND METHODS: All cases of RMS in patients who presented to our craniofacial program between 2004 and 2008 were retrospectively reviewed. RESULTS: Eight consecutive patients with RMS were treated. Six patients are Maori. Four patients had surgical resections of their primary tumors including 3 with curative intent. One had a recurrent tumor, and 3 had functional reconstruction after an earlier treatment. Inaccuracies in histologic diagnosis occurred in 2 patients. Two patients developed postoperative cerebrospinal fluid leakage. Two patients had leptomeningeal involvement and died within 10 months. All patients treated with curative intent achieved complete macroscopic margins. Two remained disease-free at 10 and 22 months. DISCUSSION: Treatment must be in the context of a multidisciplinary team with the appropriate craniofacial, neurosurgical, and reconstructive skills. Expedient and accurate histologic diagnoses by experienced pathologists are critical in optimizing the outcomes. Oncologists must be well resourced to administer chemoradiation in a timely manner. Leptomeningeal invasion is a dire prognostic feature. Cerebrospinal fluid leak after resection must be identified early and repaired. Late consequences of early childhood craniofacial cancer treatment may be ameliorated by tailored reconstructions. The predominance of Maori in our series has not been reported previously.

Expression of Components of the Renin-Angiotensin System by the Putative Stem Cell Population Within WHO Grade I Meningioma.

Aim: We have recently demonstrated a putative stem cell population within WHO grade I meningioma (MG) that expressed embryonic stem cell (ESC) markers OCT4, NANOG, SOX2, KLF4 and c-MYC, localized to the endothelial and pericyte layers of the microvessels. There is increasing recognition that the renin-angiotensin system (RAS) plays a critical role in stem cell biology and tumorigenesis. This study investigated the expression of components of the RAS: pro-renin receptor (PRR), angiotensin converting enzyme (ACE), angiotensin II receptor 1 (ATIIR1), and angiotensin II receptor 2 (ATIIR2) on the putative stem cell population on the microvessels of WHO grade I MG. Methods: 3,3-Diaminobenzidine (DAB) immunohistochemical (IHC) staining was performed on WHO grade I MG tissue samples from 11 patients for PRR, ACE, ATIIR1, and ATIIR2. Two of the MG samples subjected to DAB IHC staining underwent immunofluorescence (IF) IHC staining to investigate co-expression of each of these components of the RAS in using combinations of CD34 and ESC marker SOX2 or OCT4. NanoString mRNA expression analysis and Western blotting (WB), were performed on six snap-frozen MG tissue samples to confirm mRNA and protein expression of these proteins, respectively. Results: DAB IHC staining demonstrated expression of PRR, ACE, ATIIR1, and ATIIR2 within all 11 MG tissue samples. WB and NanoString mRNA analyses, confirmed protein and mRNA expression of these proteins, respectively. IF IHC staining showed PRR, ATIIR1 and ATIIR2 were localized to the OCT4+ and SOX2+ endothelium and the pericyte layer of MG while ACE was localized to the OCT4+ endothelium of the microvesels. Conclusion: The novel finding of the expression of PRR, ACE, ATIIR1, and ATIIR2 on the putative stem cell population on the microvessels of WHO grade I MG, suggests that these stem cells may be a potential therapeutic target by manipulation of the RAS.

Therapeutic Targeting of Cancer Stem Cells via Modulation of the Renin-Angiotensin System.

Cancer stem cells (CSCs) are proposed to be the cells that initiate tumorigenesis and maintain tumor development due to their self-renewal and multipotency properties. CSCs have been identified in many cancer types and are thought to be responsible for treatment resistance, metastasis, and recurrence. As such, targeting CSCs specifically should result in durable cancer treatment. One potential option for targeting CSCs is by manipulation of the renin-angiotensin system (RAS) and pathways that converge on the RAS with numerous inexpensive medications currently in common clinical use. In addition to its crucial role in cardiovascular and body fluid homeostasis, the RAS is vital for stem cell maintenance and differentiation and plays a role in tumorigenesis and cancer prevention, suggesting that these roles may converge and result in modulation of CSC function by the RAS. In support of this, components of the RAS have been shown to be expressed in many cancer types and have been more recently localized to the CSCs in some tumors. Given these roles of the RAS in tumor development, clinical trials using RAS inhibitors either singly or in combination with other therapies are underway in different cancer types. This review outlines the roles of the RAS, with respect to CSCs, and suggests that the presence of components of the RAS in CSCs could offer an avenue for therapeutic targeting using RAS modulators. Due to the nature of the RAS and its crosstalk with numerous other signaling pathways, a systems approach using traditional RAS inhibitors in combination with inhibitors of bypass loops of the RAS and other signaling pathways that converge on the RAS may offer a novel therapeutic approach to cancer treatment.

Endoscopic transnasal repair of two cases of spontaneous cerebrospinal fluid fistula in the foramen rotundum.

We report two female patients aged 16 and 33 who presented with spontaneous cerebrospinal fluid (CSF) rhinorrhoea. Beta-2 transferrin was positive in both cases. Initial high-resolution CT showed fluid in the maxillary sinus but no obvious bony defect. MR imaging revealed maxillary sinus cysts with high signal on T2 sequences. Endoscopic transnasal surgery with intrathecal fluorescein was undertaken and in both cases a leak was identified from foramen rotundum and repaired. Both patients are symptom free at 6 months. These cases highlight the rare occurrence of spontaneous CSF leak from the foramen rotundum, and how they can be effectively repaired using the endoscopic transnasal approach.

Circulating tumor stem cells and glioblastoma: A review.

Glioblastoma (GB) is the most aggressive primary brain tumor in adults. The aggressive nature of GB has been attributed to the presence of cancer stem cells (CSCs) which drive tumorigenesis and are thought to be the root cause of the disease. Circulating tumor stem cells (CTSCs), which can be derived from CSCs, have been identified in numerous types of cancer including GB, have been proposed to contribute to local and distant recurrence. There are many technical difficulties in studying CTSCs, therefore there is a significant gap in the literature pertaining to how they arise and function, and how the understanding of the biology of CTSCs could elucidate the underlying cause of local recurrence and metastasis. An initial epithelial-to-mesenchymal transition (EMT) followed by mesenchymal-to-epithelial transition involving these primitive cells appear to be the critical processes underpinning metastasis. This review focuses on the association between CSCs undergoing EMT to become CTSCs, and how this could arise from the CSC subpopulation in GB, and contribute to the understanding of the pathogenesis and treatment.

Tumour stem cells in schwannoma: A review.

Schwannoma is a peripheral nerve tumour, accounting for 5% of benign soft tissue tumours, with vestibular schwannoma comprising 6% of all intracranial tumours. The tumour stem cell concept is rapidly gaining traction underscoring the understanding of tumourigenesis. It proposes a small subpopulation of primitive cells as the origin of the tumour and these cells account for treatment resistance, local recurrence and distant metastasis in malignant tumours. This review outlines the stem cell markers used to identify and characterise stem cells and progenitor cells in tumours and examines current evidence of the presence of tumour stem cells in schwannoma.

Expression of Cathepsins B, D, and G in WHO Grade I Meningioma.

Aim: We have recently demonstrated the presence of putative tumor stem cells (TSCs) in World Health Organization (WHO) grade I meningioma (MG) localized to the microvessels, which expresses components of the renin-angiotensin system (RAS). The RAS is known to be dysregulated and promotes tumorigenesis in many cancer types, including glioblastoma. Cathepsins B, D, and G are isoenzymes that catalyze the production of angiotensin peptides, hence providing bypass loops for the RAS. This study investigated the expression of cathepsins B, D, and G in WHO grade I MG in relation to the putative TSC population we have previously demonstrated. Methods: 3,3-Diaminobenzidine (DAB) immunohistochemical (IHC) staining with antibodies for cathepsins B, D, and G was performed on WHO grade I MG tissue samples from 10 patients. Three of the MG samples subjected to DAB IHC staining underwent immunofluorescence (IF) IHC staining to investigate co-expression of each of these cathepsins using combinations of smooth muscle actin (SMA) and embryonic stem cell marker OCT4. NanoString mRNA expression (n = 6) and Western blotting (WB; n = 5) analyses, and enzyme activity assays (EAAs; n = 3), were performed on snap-frozen WHO grade I MG tissue samples to confirm transcriptional activation, protein expression, and functional activity of these proteins, respectively. Results: DAB IHC staining demonstrated expression of cathepsins B, D, and G in all 10 MG samples. NanoString mRNA expression and WB analyses showed transcriptional activation and protein expression of all three cathepsins, although cathepsin G was expressed at low levels. EAAs demonstrated that cathepsin B and cathepsin D were functionally active. IF IHC staining illustrated localization of cathepsin B and cathepsin D to the endothelium and SMA+ pericyte layer of the microvessels, while cathepsin G was localized to cells scattered within the interstitium, away from the microvessels. Conclusion: Cathepsin B and cathepsin D, and to a lesser extent cathepsin G, are expressed in WHO grade I MG. Cathepsin B and cathepsin D are enzymatically active and are localized to the putative TSC population on the microvessels, whereas cathepsin G was localized to cells scattered within the interstitium, These results suggest the presence of bypass loops for the RAS, within WHO grade I MG.

Therapeutic Targeting of Cancer Stem Cells in Human Glioblastoma by Manipulating the Renin-Angiotensin System.

Patients with glioblastoma (GB), a highly aggressive brain tumor, have a median survival of 14.6 months following neurosurgical resection and adjuvant chemoradiotherapy. Quiescent GB cancer stem cells (CSCs) invariably cause local recurrence. These GB CSCs can be identified by embryonic stem cell markers, express components of the renin-angiotensin system (RAS) and are associated with circulating CSCs. Despite the presence of circulating CSCs, GB patients rarely develop distant metastasis outside the central nervous system. This paper reviews the current literature on GB growth inhibition in relation to CSCs, circulating CSCs, the RAS and the novel therapeutic approach by repurposing drugs that target the RAS to improve overall symptom-free survival and maintain quality of life.

Expression of cancer stem cell markers in metastatic melanoma to the brain.

We have recently characterized cancer stem cell (CSC) subpopulations in different types of cancer. This study aimed to identify and characterize CSCs within metastatic melanoma (MM) to the brain. 3, 3-diaminobenzidine (DAB) immunohistochemical (IHC) staining of ten samples of MM to the brain demonstrated the expression of the embryonic stem cell (ESC) markers OCT4, NANOG, SALL4, SOX2 and pSTAT3. Protein expression of all five ESC markers except SALL4 were confirmed by Western blotting on five samples and transcriptional activation of all five markers was demonstrated using NanoString mRNA analysis on four samples. Immunofluorescence IHC staining suggested the presence of CSCs that stained for OCT4, SALL4, SOX2 or NANOG. Some of these cells also stained for Melan-A. Also, a pSTAT3+/CD34+ primitive subpopulation was detected on the endothelium of microvessels. These CSCs may be a novel therapeutic target for MM to the brain.