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Objective: Epilepsy is a condition hallmarked by synchronized depolarizations of groups of neurons resulting in seizures. The underlying conditions can vary extensively ranging from structural pathologies to trauma. However, the electrophysiological and micro-anatomical correlates of seizures are yet [for full text, please go to the a.m. URL]

Objective: Investigations of precision medicine related approaches for human CNS disease mostly rely on animal models or cell culture systems including human induced pluripotent stem cell technology. However, it frequently remains elusive how well such data translate to the native human brain. Devising [for full text, please go to the a.m. URL]

Epilepsia : the journal of the International League Against Epilepsy (2021). doi:10.1111/epi.17066, Published by Wiley-Blackwell, Oxford [u.a.]

International audience; Background: Proteopathic brain lesions are a hallmark of many age-related neurodegenerative diseases including synucleinopathies and develop at least a decade before the onset of clinical symptoms. Thus, understanding of the initiation and propagation of such lesions is key for developing therapeutics to delay or halt disease progression. Methods: Alpha-synuclein (αS) inclusions were induced in long-term murine and human slice cultures by seeded aggregation. An αS seed-recognizing human antibody was tested for blocking seeding and/or spreading of the αS lesions. Release of neurofilament light chain (NfL) into the culture medium was assessed. Results: To study initial stages of α-synucleinopathies, we induced αS inclusions in murine hippocampal slice cultures by seeded aggregation. Induction of αS inclusions in neurons was apparent as early as 1week post-seeding, followed by the occurrence of microglial inclusions in vicinity of the neuronal lesions at 2-3 weeks. The amount of αS inclusions was dependent on the type of αS seed and on the culture's genetic background (wildtype vs A53T-αS genotype). Formation of αS inclusions could be monitored by neurofilament light chain protein release into the culture medium, a fluid biomarker of neurodegeneration commonly used in clinical settings. Local microinjection of αS seeds resulted in spreading of αS inclusions to neuronally connected hippocampal subregions, and seeding and spreading could be inhibited by an αS seed-recognizing human antibody. We then applied parameters of the murine cultures to surgical resection-derived adult human long-term neocortical slice cultures from 22 to 61-yearold donors. Similarly, in these human slice cultures, proof-of-principle induction of αS lesions was achieved at 1week post-seeding in combination with viral A53T-αS expressions. Conclusion: The successful translation of these brain cultures from mouse to human with the first reported induction of human αS lesions in a true adult human brain environment underlines the potential of this model to study proteopathic lesions in intact mouse and now even aged human brain environments.

Objective: Micro-Electrode Arrays (MEAs), novel culturing methods for human brain tissue, and advanced tools in data science enable us for the first time to analyze massive parallel recordings of spike trains in human cortical tissue. Measuring neuronal connectivity on a millimeter scale in real time[for full text, please go to the a.m. URL], 72. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgie

In the version of this article initially published, multiple errors appeared in the author and affiliations lists. The errors have been corrected in the PDF and HTML versions of this article.

Additional file 4: Supplementary Fig. 4. Time course of seeded αS aggregation in Thy1-h[A53T]αS tg mice. (A, B) Immunohistochemistry for pS129 (black) of DG from Thy1-h[A53T]αS tg mice injected at 3–4 months of age with Thy1-h[A53T]αS tg brain homogenate (A) or wt brain homogenate (B) at one day post-injection (dpi), 7 dpi or 30 dpi. For each group, three mice were used. Sections were counter stained using nuclear fast red. Note that the same brain homogenates were used for slice culture experiments. (A) First inclusions appeared around 7 dpi in all three mice and became more abundant by 30 dpi. (B) In contrast, no inclusions were found in wt brain homogenate-treated mice at any time point analysed. Scale bar represents 100 μm.

Frontiers in cellular neuroscience 15, 754530 (2021). doi:10.3389/fncel.2021.754530 special issue: "Cellular Neurophysiology / Editors: Enrico Cherubini, Arianna Maffei, Giorgio Aicardi, Joseph P. Albanesi", Published by Frontiers Research Foundation, Lausanne

Additional file 1: Supplementary Fig. 1. αS pff characterization. (A, B) Proteolytic profiles of monomeric (A) and fibrillar (B) αS (100 M in PBS) after proteinase K treatment (3.7 μg/μl) at 37 °C. Aliquots were removed from the reaction at the time indicated (in min), immediately denatured with Laemmli buffer at 90 °C for 5 min and analysed on 15% PAGE. The gels were stained with Coomassie blue. The molecular weight markers are shown on the left of each gel. The αS fibrils reveal the typical proteolytic pattern as reported previously [30, 31]. (C, D) Transmission electron micrographs of the αS fibrils before (C) and after fragmentation (D). The scale bar represents 200 nm.

Additional file 5: Supplementary Fig. 5. Treatment with highly concentrated αS pff is neurotoxic to Thy1-h[A53T]αS tg HSCs. (A) Immunostaining of pS129-positive aggregates in 50 μm-horizontal sections from Thy1-h[A53T]αS tg HSCs treated with 350 μM αS pff at 1, 2 and 5 weeks post-seeding. Scale bar = 500 μm. (B) Measurement of culture thickness (in μm at the time of fixation) in untreated, 350 μM αS pff-treated and 35 μM αS pff-treated tg HSCs. Mean ± SEM; n(untr., 1 week) = 6, n(untr., 3 weeks) = 18, n(untr., 5 weeks) = 19, n(35 μM pff, 1 week) = 15, n(35 μM pff, 2 weeks) = 10, n(35 μM pff, 3 weeks) = 31, n(35 μM pff, 4 weeks) = 9, n(35 μM pff, 5 weeks) = 18, n(350 μM pff, 1–4 weeks) = 6 each, n(350 μM pff, 5 weeks) = 35 HSCs per group. Note that culture thickness was routinely measured and results come from many different experiments, which accounts for the differences among the n/group. (C) Violin graphs displaying thickness of tg HSCs across different treatments at 5 weeks post-treatment. n(tg, untr.) = 19, n(tg, tg brain hom.) = 24, n(tg, 35 μM pff) = 18, n(tg, 350 μM pff) = 35. Kruskal-Wallis test (H = 45.82; p

Additional file 2: Supplementary Fig. 2 Induction of αS aggregation is dependent on endogenous αS expression. Immunofluorescence staining for pS129 showed inclusions in Thy1-h[A53T]αS tg HSCs seeded with Thy1-h[A53T]αS tg brain homogenate. In contrast, there was no induction of αS aggregation in Snca−/− HSCs after seeding using the same brain homogenate as seed. Analysis was done 5 weeks after treatment. See Fig. 1 for methodological detail. The experiment was done twice with 3 cultures each. Scale bar = 500 μm.

Human cerebrospinal fluid (hCSF) has proven advantageous over conventional medium for culturing both rodent and human brain tissue. In addition, increased activity and synchrony, closer to the dynamic states exclusively recorded in vivo, were reported in rodent slices and cell cultures switching from artificial cerebrospinal fluid (aCSF) to hCSF. This indicates that hCSF possesses properties that are not matched by the aCSF, which is generally used for most electrophysiological recordings. To evaluate the possible significance of using hCSF as an electrophysiological recording medium, also for human brain tissue, we compared the network and single-cell firing properties of human brain slice cultures during perfusion with hCSF and aCSF. For measuring the overall activity from a majority of neurons within neocortical and hippocampal human slices, we used a microelectrode array (MEA) recording technique with 252 electrodes covering an area of 3.2 × 3.2 mm2. A second CMOS-based MEA with 4225 sensors on a 2 × 2 mm2 area was used for detailed mapping of action potential waveforms and cell identification. We found that hCSF increased the number of active electrodes and neurons and the firing rate of the neurons in the slices and induced an increase in the numbers of single channel and population bursts. Interestingly, not only an increase in the overall activity in the slices was observed, but a reconfiguration of the network could also be detected with specific activation and inactivation of subpopulations of neuronal ensembles. In conclusion, hCSF is an important component to consider for future human brain slice studies, especially for experiments designed to mimic parts of physiology and disease observed in vivo.

Objective: Investigation of pathophysiological mechanisms of human disease affecting the CNS, such as epilepsy or neurodegenerative disorders, mostly relies on studies based on human tissue obtained post mortem or by biopsy/surgery and on studies using animal models, cell culture or heterologous[for full text, please go to the a.m. URL], 70. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Skandinavischen Gesellschaft für Neurochirurgie

ObjectiveLoss of function of the astrocyte‐specific protein MLC1 leads to the childhood‐onset leukodystrophy “megalencephalic leukoencephalopathy with subcortical cysts” (MLC). Studies on isolated cells show a role for MLC1 in astrocyte volume regulation and suggest that disturbed brain ion and water homeostasis is central to the disease. Excitability of neuronal networks is particularly sensitive to ion and water homeostasis. In line with this, reports of seizures and epilepsy in MLC patients exist. However, systematic assessment and mechanistic understanding of seizures in MLC are lacking.MethodsWe analyzed an MLC patient inventory to study occurrence of seizures in MLC. We used two distinct genetic mouse models of MLC to further study epileptiform activity and seizure threshold through wireless extracellular field potential recordings. Whole‐cell patch‐clamp recordings and K+‐sensitive electrode recordings in mouse brain slices were used to explore the underlying mechanisms of epilepsy in MLC.ResultsAn early onset of seizures is common in MLC. Similarly, in MLC mice, we uncovered spontaneous epileptiform brain activity and a lowered threshold for induced seizures. At the cellular level, we found that although passive and active properties of individual pyramidal neurons are unchanged, extracellular K+ dynamics and neuronal network activity are abnormal in MLC mice.InterpretationDisturbed astrocyte regulation of ion and water homeostasis in MLC causes hyperexcitability of neuronal networks and seizures. These findings suggest a role for defective astrocyte volume regulation in epilepsy. Ann Neurol 2018;83:636–649