Biology subjects

Dirven, C.

Publications and source records attributed to Dirven, C..

4 recordsLinked to original sources

bioRxiv2024

Mobile Human Brain Imaging using Functional Ultrasound

Imagine being able to study the human brain in real-world scenarios while the subject displays natural behaviors such as locomotion, social interaction, or spatial navigation. The advent of ultrafast ultrasound imaging brings us closer to this goal with functional Ultrasound imaging (fUSi), a new mobile neuroimaging technique. Here, we present real-time fUSi monitoring of brain activity during walking in a subject with a clinically approved sonolucent skull implant. Our approach utilizes personalized 3D-printed fUSi-helmets for stability, optical tracking for cross-modal validation with fMRI, advanced signal processing to estimate hemodynamic responses and facial tracking of a lick licking paradigm. These combined efforts allowed us to show consistent fUSi signals over 20 months, even during high-motion activities like walking. These results demonstrate the feasibility of fUSi for monitoring brain activity in real-world contexts, marking an important milestone for fUSi-based insights in clinical and neuroscientific research.

neuroscience↗

bioRxiv2023

A minimum threshold for myelination of pyramidal cells in human and mouse neocortex

Neocortical pyramidal neurons are frequently myelinated. Diversity in the topography of axonal myelination in the cerebral cortex has been attributed to a combination of electrophysiological activity, axonal morphology, and neuronal-glial interactions. Previously, we showed that axonal segment length and calibre are critical determinants of fast-spiking interneuron myelination (Stedehouder, J. et al (2019). However, the factors that determine the myelination of individual axonal segments along neocortical pyramidal neurons remain largely unexplored. Here, we used structured illumination microscopy and cell type-specific manipulations to examine the extent to which axonal morphology determines the topography of axonal myelination in mouse neocortical pyramidal neurons. We found that, unlike what was determined for fast-spiking interneurons, the joint combination of axonal calibre and interbranch distance does not predict axonal myelination in pyramidal neurons, rather it provides a minimum threshold for myelination; pyramidal neurons with an axon calibre and interbranch distance lower than 0.24 {micro}m and 19 {micro}m, respectively, are almost never myelinated. Moreover, we further confirmed that these findings in mice also extend to human neocortical pyramidal cell myelination, suggesting that this mechanism is evolutionarily conserved. Taken together, our findings suggest that axonal morphology is highly deterministic of the topography and cell-type specificity of neocortical myelination.

neuroscience↗

bioRxiv2023

Dissecting the neurotropism and neurovirulence of MPXV using human stem cell-based models

Mpox is a zoonotic illness of international concern that can lead to severe disease including neurological sequelae. However, the neurotropism of monkeypox virus (MPXV) and the mechanisms regulating cell-intrinsic antiviral immunity within the central nervous system (CNS) remain poorly understood. Here, we investigated the neurotropism of MPXV using astrocytes, cortical neurons, and microglia derived from human pluripotent stem cells (hPSCs) and ex vivo human brain tissue to demonstrate that MPXV infects and replicates more efficiently in astrocytes and microglia compared to cortical neurons. Upon MPXV exposure, glial cells, in contrast to cortical neurons, inhibit type I IFN antiviral programs potentially conferring differential susceptibility to MPXV. Furthermore, we demonstrate that treatment using either IFN-beta or tecovirimat inhibits MPXV infection. Together, our results suggest that MPXV has a broad tropism within the CNS and that differential type I IFN signaling underpins cell type-specific susceptibility to MPXV infection.

microbiology↗

bioRxiv2021

Generation, characterization and drug sensitivities of twelve patient-derived IDH1 mutant glioma cell cultures

BackgroundMutations of the isocitrate dehydrogenase (IDH) gene occur in over 80% of low-grade gliomas and secondary glioblastomas. Despite considerable efforts, endogenous in vitro IDH-mutated glioma models remain scarce. Availability of these models is key for the development of new therapeutic interventions. MethodsCell cultures were established from fresh tumor material and expanded in serum-free culture media. D-2-Hydroxyglutarate levels were determined by mass-spectrometry. Genomic and transcriptomic profiling were carried out on the Illumina Novaseq platform, methylation profiling was performed with the Infinium MethylationEpic BeadChip array. Mitochondrial respiration was measured with the Seahorse XF24 Analyzer. Drug screens were performed with an NIH FDA-approved anti-cancer drug set and two IDH-mutant specific inhibitors. ResultsA set of twelve patient-derived IDHmt cell cultures was established. We confirmed high concordance in driver mutations, copy number and methylation profiles between the tumors and derived cultures. Homozygous deletion of CDKN2A/B was observed in all cultures. IDH-mutant cultures had lower mitochondrial reserve capacity. IDH-mutant specific inhibitors did not affect cell viability or global gene expression. Screening of 107 FDA-approved anti-cancer drugs identified nine compounds with potent activity against IDHmt gliomas, including three compounds with favorable pharmacokinetic characteristics for CNS penetration: teniposide, omacetaxine mepesuccinate, and marizomib. ConclusionsOur twelve IDH-mutant cell cultures show high similarity to the parental tissues and offer a unique tool to study the biology and drug sensitivities of high-grade IDHmt gliomas in vitro. Our drug screening studies reveal lack of sensitivity to IDHmt inhibitors, but sensitivity to a set of nine available anti-cancer agents. Key pointsO_LIIDHmt glioma cultures closely resemble their parental tumors C_LIO_LIMicroscopic monitoring of early passages and colony isolation increases IDH1mt culture success C_LIO_LIDrug screening identified nine candidate repurposed drugs for IDHmt glioma C_LI Importance of the studyIDH-mutations are highly prevalent in low grade and secondary high-grade gliomas. Despite this high frequency however, very few in vitro models have been reported for IDH-mutated gliomas. In this manuscript we describe and characterize in detail twelve primary cultures from IDH-mutant astrocytomas. We show that these cultures retain most of the genetic, epigenetic and metabolic features of their respective parental tumors. Because of these similarities, these independent model systems will not only help understand the molecular defects driven by the mutation, but are also vital to identify means to target these tumors. Screening of 107 FDA-approved anti-cancer agents on these cultures identified a set of highly effective agents that may offer candidates for either systemic or assisted delivery treatment of this tumor subtype.

cancer biology↗