Transient but not permanent benefit of neuronal progenitor cell therapy after traumatic brain injury: potential causes and translational consequences

Background:: Numerous studies have reported a beneficial impact of neural progenitor cell transplantation on functional outcome after traumatic brain injury (TBI) during short and medium follow-up periods. However, our knowledge regarding long-term functional effects is fragmentary while a direct comparison between local and systemic transplantation is missing so far. Objectives:: This study investigated the long-term (12 week) impact of human fetal neuronal progenitor cell (hNPC) transplantation 24 h after severe TBI in rats. Methods:: Cells were either transplanted stereotactically (1 × 105) into the putamen or systemically (5 × 105) via the tail vein. Control animals received intravenous transplantation of vehicle solution. Results: An overall functional benefit was observed after systemic, but not local hNPC transplantation by area under the curve analysis (p < 0.01). Surprisingly, this effect vanished during later stages after TBI with all groups exhibiting comparable functional outcomes 84 days after TBI. Investigation of cell-mediated inflammatory processes revealed increasing microglial activation and macrophage presence during these stages, which was statistically significant after systemic cell administration (p < 0.05). Intracerebral hNPC transplantation slightly diminished astrogliosis in perilesional areas (p < 0.01), but did not translate into a permanent functional benefit. No significant effects on angiogenesis were observed among the groups. Conclusion: Our results suggest the careful long-term assessment of cell therapies for TBI, as well as to identify potential long-term detrimental effects of such therapies before moving on to clinical trials. Moreover, immunosuppressive protocols, though widely used, should be rigorously assessed for their applicability in the respective setup

Cerebrovascular Insult as Presenting Symptom of Neurofibromatosis Type 2 in Children, Adolescents, and Young Adults

Background and Purpose: Neurofibromatosis Type 2 (NF2) is an autosomal-dominant tumor-prone disorder characterized by the manifestations of central nervous system lesions. However, the first clinical signs of disease are often non-tumorous. Cerebrovascular insults are known in NF2, however, not yet described as first symptom in young NF2 patients.Methods: Magnetic resonance image scans of 298 NF2 patients treated in our neurofibromatosis center in Tübingen from 2003 to 2017 were retrospectively evaluated focusing on presence of aneurysms and ischemic stroke. Clinical data were used to clarify whether or not ischemic stroke or aneurysm rupture were the first presentation of disease. Blood of the patients were subjected to genetic screening for constitutional NF2 mutations.Results: We identified 5 cases under age of 25 years with aneurysms or ischemic stroke. Among them three had ischemic strokes of the brain stem and one aneurysmal subarachnoid hemorrhage as the first symptom of the disease. Incidental finding of 2 intracranial aneurysm occurred in one patient. All aneurysms were clipped. Patients with ischemia suffered from dysarthria, gait disturbances, dizziness, and hemiparesis. Residual signs of hemiparesis and dysarthria persisted in one patient. All others fully recovered from the cerebrovascular insult. Bilateral vestibular schwannomas and intracranial meningiomas were found in all five patients.Conclusions: A cerebrovascular insult in the vertebrobasilar territory may occur as first symptom of disease in young NF2 patients. The brain stem seems to be especially prone to ischemic stroke. Multicenter studies on large NF2 cohorts are needed to determine the prevalence and pattern of cerebrovascular insults and disease in NF2 patients

Next generation of ventricular catheters for hydrocephalus based on parametric design

Background The flow pattern of the cerebrospinal fluid is probably the most important factor related to obstruction of ventricular catheters during the normal treatment of hydro cephalus. To better comprehend the flow pattern, we have carried out a parametric study via numerical models of ven tricular catheters. In previous studies, the flow was studied under steady and, recently, in pulsatile boundary conditions by means of computational fluid dynamics (CFD) in three dimensional catheter models. Objective This study aimed to bring in prototype models of catheter CFD flow solutions as well to introduce the theory behind parametric development of ventricular catheters. Methods A preceding study allowed deriving basic principles which lead to designs with improved flow patterns of ventric ular catheters. The parameters chosen were the number of drainage segments, the distances between them, the number and diameter of the holes on each segment, as well as their relative angular position. Results CFD results of previously unreleased models of ven tricular catheter flow solutions are presented in this study. Parametric development guided new designs with better flow distribution while lowering the shear stress of the catheters holes. High-resolution 3D printed catheter solutions of three models and basic benchmark testing are introduced as well. Conclusions The next generation of catheter with homoge neous flow patterns based on parametric designs may repre sent a step forward for the treatment of hydrocephalus, by possibly broadening their lifespan

Neurosurgical morbidity in pediatric supratentorial midline low‐grade glioma: results from the German LGG studies

Surgical resection is a mainstay of treatment for pediatric low-grade glioma (LGG) within all current therapy algorithms, yet associated morbidity is scarcely reported. As supratentorial midline (SML) interventions are particularly challenging, we investigated the frequency of neurosurgical complications/new impairments aiming to identify their risk factors. Records were retrospectively analyzed from 318 patients with SML-LGG from successive German multicenter LGG studies, undergoing surgery between May 1998 and June 2020. Exactly 537 operations (230 resections, 167 biopsies, 140 nontumor procedures) were performed in 318 patients (54% male, median age: 7.6 years at diagnosis, 9.5 years at operation, 11% NF1, 42.5% optic pathway glioma). Surgical mortality rate was 0.93%. Applying the Drake classification, postoperative surgical morbidity was observed following 254/537 (47.3%) and medical morbidity following 97/537 (18.1%) patients with a 40.1% 30-day persistence rate for newly developed neurological deficits (65/162). Neuroendocrine impairment affected 53/318 patients (16.7%), visual deterioration 34/318 (10.7%). Postsurgical morbidity was associated with patient age <3 years at operation, tumor volume ≥80 cm3, presence of hydrocephalus, complete resection, surgery in centers with less than median reported tumor-related procedures and during the earlier study period between 1998 and 2006, while the neurosurgical approach, tumor location, NF1 status or previous nonsurgical treatment were not. Neurosurgery-associated morbidity was frequent in pediatric patients with SML-LGG undergoing surgery in the German LGG-studies. We identified patient- and institution-associated factors that may increase the risk for complications. We advocate that local multidisciplinary teams consider the planned extent of resection and surgical skills

Natural and cryptic peptides dominate the immunopeptidome of atypical teratoid rhabdoid tumors

BACKGROUND: Atypical teratoid/rhabdoid tumors (AT/RT) are highly aggressive CNS tumors of infancy and early childhood. Hallmark is the surprisingly simple genome with inactivating mutations or deletions in the SMARCB1 gene as the oncogenic driver. Nevertheless, AT/RTs are infiltrated by immune cells and even clonally expanded T cells. However, it is unclear which epitopes T cells might recognize on AT/RT cells. METHODS: Here, we report a comprehensive mass spectrometry (MS)-based analysis of naturally presented human leukocyte antigen (HLA) class I and class II ligands on 23 AT/RTs. MS data were validated by matching with a human proteome dataset and exclusion of peptides that are part of the human benignome. Cryptic peptide ligands were identified using Peptide-PRISM. RESULTS: Comparative HLA ligandome analysis of the HLA ligandome revealed 55 class I and 139 class II tumor-exclusive peptides. No peptide originated from the SMARCB1 region. In addition, 61 HLA class I tumor-exclusive peptide sequences derived from non-canonically translated proteins. Combination of peptides from natural and cryptic class I and class II origin gave optimal representation of tumor cell compartments. Substantial overlap existed with the cryptic immunopeptidome of glioblastomas, but no concordance was found with extracranial tumors. More than 80% of AT/RT exclusive peptides were able to successfully prime CD8(+) T cells, whereas naturally occurring memory responses in AT/RT patients could only be detected for class II epitopes. Interestingly, >50% of AT/RT exclusive class II ligands were also recognized by T cells from glioblastoma patients but not from healthy donors. CONCLUSIONS: These findings highlight that AT/RTs, potentially paradigmatic for other pediatric tumors with a low mutational load, present a variety of highly immunogenic HLA class I and class II peptides from canonical as well as non-canonical protein sources. Inclusion of such cryptic peptides into therapeutic vaccines would enable an optimized mapping of the tumor cell surface, thereby reducing the likelihood of immune evasion

ETMR-05: Single-cell transcriptomics of ETMR reveals developmental cellular programs and tumor-pericyte communications in the microenvironment [Abstract]

BACKGROUND: Embryonal tumors with multilayered rosettes (ETMR) are pediatric brain tumors bearing a grim prognosis, despite intensive multimodal therapeutic approaches. Insights into cellular heterogeneity and cellular communication of tumor cells with cells of the tumor microenvironment (TME), by applying single-cell (sc) techniques, potentially identify mechanisms of therapy resistance and target-directed treatment approaches. MATERIAL AND METHODS: To explore ETMR cell diversity, we used single-cell RNA sequencing (scRNA-seq) in human (n=2) and murine ETMR (transgenic mode; n=4) samples, spatial transcriptomics, 2D and 3D cultures (including co-cultures with TME cells), multiplex immunohistochemistry and drug screens. RESULTS: ETMR microenvironment is composed of tumor and non-tumor cell types. The ETMR malignant compartment harbour cells representing distinct transcriptional metaprograms, (NSC-like, NProg-like and Neuroblast-like), mirroring embryonic neurogenic cell states and fuelled by neurogenic pathways (WNT, SHH, Hippo). The ETMR TME is composed of oligodendrocyte and neuronal progenitor cells, neuroblasts, microglia, and pericytes. Tumor-specific ligand-receptor interaction analysis showed enrichment of intercellular communication between NProg-like ETMR cells and pericytes (PC). Functional network analyses reveal ETMR-PC interactions related to stem-cell signalling and extracellular matrix (ECM) organization, involving factors of the WNT, BMP, and CxCl12 networks. Results from ETMR-PC co-culture and spatial transcriptomics pointed to a pivotal role of pericytes in keeping ETMR in a germinal neurogenic state, enriched in stem-cell signalling. Drug screening considering cellular heterogeneity and cellular communication suggested novel therapeutic approaches. CONCLUSION: ETMR demonstrated diversity in the microenvironment, with enrichment of cell-cell communications with pericytes, supporting stem-cell signalling and interfering in the organization of the tumor extracellular matrix. Targeting ETMR-PC interactions might bring new opportunities for target-directed therapy