Biology subjects

Ottoboni, L.

Publications and source records attributed to Ottoboni, L..

6 recordsLinked to original sources

bioRxiv2025

Electrical stimulation elicits space- and parameter-dependent spiking responses in human cortical organoids

Electrical stimulation (ES) is used to treat neuropsychiatric disorders and investigate brain dynamics, yet its effects on human cortical microcircuits remain poorly understood. Cortical organoids provide a unique platform to investigate these mechanisms in isolation from subcortical and long-range cortical inputs. Here we illustrate how cortical organoids respond to ES, identifying the response profiles of isolated cortical circuits while detailing a roadmap of how ES parameters affect the organoid spiking activity. We employed a high-density multielectrode array to record neuronal activity from cortical organoids (n=417 units in N=7 organoids) during ES, systematically varying stimulation frequency, intensity, pulse width, and charge density. By analyzing single unit spiking activity, we found that ES elicits excitatory, inhibitory, and mixed responses in 39%, 12%, and 17% of the units, respectively. On average, this response lasted 100 ms and became stable within 26 trials. The magnitude of both excitatory and inhibitory responses was maximal near the stimulation site and decayed with distance. The response magnitude was inversely correlated with pulse intensity and duration, but not with stimulation frequency and charge density. These findings demonstrate that local cortical circuits are sufficient to initiate the early excitatory phase of the canonical ES response, whose magnitude depends on ES parameters, and can sustain the excitatory phase for over 100 ms. The reduced late inhibitory phase, together with the absence of late excitatory components observed 200 ms after ES in intact adult brains in-vivo, suggests that these phases may depend on neuronal maturation or inter-area connections. Our work thus establishes cortical organoids as a framework for studying the local contributions to ES-induced activity in a developmental model of the human cortex.

neuroscience↗

bioRxiv2025

Statistical Characterization of Cortical-Thalamic Dynamics Evoked by Cortical Stimulation in Mice

ObjectiveStatistical models are powerful tools for describing biological phenomena such as neuronal spiking activity. Although these models have been widely used to study spontaneous and stimulated neuronal activity, they have not yet been applied to analyze responses to electrical cortical stimulation. In this study, we present an innovative approach to characterize neuronal responses to electrical stimulation in the mouse cortex, providing detailed insights into cortical-thalamic dynamics. ApproachOur method applies Mixture Models to analyze the Peri-Stimulus Time Histogram of each neuron, predicting the probability of spiking at specific latencies following the onset of electrical stimuli. By applying this approach, we investigated neuronal responses to cortical stimulation recorded from the motor cortex, somatosensory cortex, and sensorimotor-related thalamic nuclei in the mouse brain. Main resultsThe characterization approach achieved high goodness of fit, and the model features were leveraged by applying machine learning methods for stimulus intensity decoding and classification of brain regions to which a neuron belongs given its response to the stimulus. The Random Forest model demonstrated the highest F1 scores, achieving 92.86% for stimulus intensity decoding and 84.35% for brain zone classification. SignificanceThis study presents a novel statistical framework for characterizing neuronal responses to electrical cortical stimulation, providing quantitative insights into cortical-thalamic dynamics. Our approach achieves high accuracy in stimulus decoding and brain region classification, providing valuable contributions for neuroscience research and neuro-technology applications.

neuroscience↗

bioRxiv2025

C9orf72 Repeat Expansion Induces Metabolic Dysfunction in Human iPSC- Derived Microglia and Modulates Glial-Neuronal Crosstalk

The C9orf72 hexanucleotide repeat expansion mutation is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia, but its cell type-specific effects on energy metabolism and immune pathways remain poorly understood. Using induced pluripotent stem cell (iPSC)-derived motor neurons, astrocytes and microglia from C9orf72 patients and their isogenic controls, we investigated metabolic changes at the single-cell level under basal and inflammatory conditions. Our results showed that microglia are particularly susceptible to metabolic disturbances. While C9orf72 motor neurons exhibited impaired mitochondrial respiration and reduced ATP production, C9orf72 microglia presented pronounced increases in glycolytic activity and oxidative stress, accompanied by the upregulation of the expression of key metabolic enzymes. These metabolic changes in microglia were exacerbated by inflammatory stimuli. To investigate how these changes affect the broader cellular environment, we developed a human iPSC-derived triculture system comprising motor neurons, astrocytes and microglia. This model revealed increased metabolic activity in all cell types and highlighted that microglia-driven metabolic reprogramming in astrocytes contributes to the vulnerability of motor neurons under inflammatory conditions. Our findings highlight the central role of microglia in driving metabolic dysregulation and intercellular crosstalk in ALS pathogenesis and suggest that targeting metabolic pathways in immune cells may provide new therapeutic avenues.

neuroscience↗

bioRxiv2024

Improved synthesis and application of an alkyne-functionalized isoprenoid analogue to study the prenylomes of motor neurons, astrocytes and their stem cell progenitors

Protein prenylation is one example of a broad class of post-translational modifications where proteins are covalently linked to various hydrophobic moieties. To globally identify and monitor levels of all prenylated proteins in a cell simultaneously, our laboratory and others have developed chemical proteomic approaches that rely on the metabolic incorporation of isoprenoid analogues bearing bio-orthogonal functionality followed by enrichment and subsequent quantitative proteomic analysis. Here, several improvements in the synthesis of the alkyne-containing isoprenoid analogue C15AlkOPP are reported to improve synthetic efficiency. Next, metabolic labeling with C15AlkOPP was optimized to obtain useful levels of metabolic incorporation of the probe in several types of primary cells. Those conditions were then used to study the prenylomes of motor neurons (ES-MNs), astrocytes (ES-As), and their embryonic stem cell progenitors (ESCs), which allowed for the identification of 54 prenylated proteins from ESCs, 50 from ES-MNs and 84 from ES-As, representing all types of prenylation. Bioinformatic analysis revealed specific enriched pathways, including nervous system development, chemokine signaling, Rho GTPase signaling, and adhesion. Hierarchical clustering showed that most enriched pathways in all three cell types are related to GTPase activity and vesicular transport. In contrast, STRING analysis showed significant interactions in two populations that appear to be cell type dependent. The data provided herein demonstrates that robust incorporation of C15AlkOPP can be obtained in ES-MNs and related primary cells purified via magnetic-activated cell sorting allowing the identification and quantification of numerous prenylated proteins. These results suggest that metabolic labeling with C15AlkOPP should be an effective approach for investigating the role of prenylated proteins in primary cells in both normal cells and disease pathologies, including ALS. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=96 SRC="FIGDIR/small/583211v1_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@193cfe1org.highwire.dtl.DTLVardef@134edccorg.highwire.dtl.DTLVardef@1e81deforg.highwire.dtl.DTLVardef@56406_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2021

Heparin protects human neural progenitor cells from Zika Virus-induced cell death and preserves their differentiation into mature neural-glia cells

Zika virus (ZIKV) is an arbovirus member of the Flaviviridae family that causes severe congenital brain anomalies in infected fetuses. Human neural progenitor cells (hNPCs) are highly permissive to ZIKV infection, causing inhibition of cell proliferation concomitant with an induction of cell death. We previously demonstrated that pharmaceutical-grade heparin inhibited virus-induced cell death with minor effects on in vitro virus replication in ZIKV-infected hNPCs. Here we show that heparin prevented ZIKV-induced intracellular vacuoles, a signature characteristic of paraptosis, but also inhibited necrosis and apoptosis of hNPCs when grown as neurospheres (NS). Furthermore, heparin preserved the differentiation of both ZIKV-infected human-induced pluripotent stem cells (hiPSC) derived-NPCs and fetus-derived NPCs into neural-glial cells. Collectively, these results highlight the potential neuroprotective effect of heparin that could be re-purposed and exploited to drive the development of novel agents for preventing ZIKV damage.

microbiology↗

bioRxiv2020

Multiple sclerosis iPSC-derived oligodendroglia conserve their intrinsic properties to functionally interact with axons and glia in vivo

The remyelination failure in multiple sclerosis (MS) is associated with a migration/differentiation block of oligodendroglia. The reason for this block is highly debated. It could result from disease-related extrinsic regulators of the oligodendroglial biology or reflect MS oligodendrocyte intrinsic properties. To avoid confounding immune-mediated extrinsic effect, we used an immune-deficient, dysmyelinating mouse model, to compare side-by-side induced pluripotent stem-cell-derived O4+ oligodendroglia from MS and healthy donors following their engraftment in the developing CNS. We show that the MS-progeny survives, proliferates and differentiates into oligodendrocytes to the same extent as controls. Quantitative multi-parametric imaging indicates that MS and control oligodendrocytes generate equal amounts of myelin, with bona-fide nodes of Ranvier and promote equal restoration of their host slow conduction. Moreover, the MS-derived progeny expressed oligodendrocyte- and astrocyte-specific connexins and established functional connections with donor and host glial cells. Thus, MS pluripotent stem cell-derived progeny fully integrates into functional axo-glial and glial-glial components, reinforcing the view that the MS oligodendrocyte differentiation block is not due to intrinsic oligodendroglial deficits. These biological findings as well as the fully integrated human-murine chimeric model should facilitate the development of pharmacological or cell-based therapies to promote CNS remyelination. One Sentence SummaryMultiple Sclerosis oligodendroglia, regardless of major immune manipulators, are intrinsically capable of myelination and making functional axo-glia and glia-glia connections after engraftment in the murine CNS, reinforcing the view that the MS oligodendrocyte differentiation block is not due to major intrinsic oligodendroglial deficits but most likely to environmental conditions.

neuroscience↗