Modularity and neuronal heterogeneity: Two properties that influence in vitro neuropharmacological experiments

IntroductionThe goal of this work is to prove the relevance of the experimental model (in vitro neuronal networks in this study) when drug-delivery testing is performed. MethodsWe used dissociated cortical and hippocampal neurons coupled to Micro-Electrode Arrays (MEAs) arranged in different configurations characterized by modularity (i.e., the presence of interconnected sub-networks) and heterogeneity (i.e., the co-existence of neurons coming from brain districts). We delivered increasing concentrations of bicuculline (BIC), a neuromodulator acting on the GABAergic system, and we extracted the IC50 values (i.e., the effective concentration yielding a reduction in the response by 50%) of the mean firing rate for each configuration. ResultsWe found significant lower values of the IC50 computed for modular cortical-hippocampal ensembles than isolated cortical or hippocampal ones. DiscussionAlthough tested with a specific neuromodulator, this work aims at proving the relevance of ad hoc experimental models to perform neuropharmacological experiments to avoid errors of overestimation/underestimation leading to biased information in the characterization of the effects of a drug on neuronal networks

Experimental Investigation on Spontaneously Active Hippocampal Cultures Recorded by Means of High-Density MEAs: Analysis of the Spatial Resolution Effects

Based on experiments performed with high-resolution Active Pixel Sensor microelectrode arrays (APS-MEAs) coupled with spontaneously active hippocampal cultures, this work investigates the spatial resolution effects of the neuroelectronic interface on the analysis of the recorded electrophysiological signals. The adopted methodology consists, first, in recording the spontaneous activity at the highest spatial resolution (interelectrode separation of 21 μm) from the whole array of 4096 microelectrodes. Then, the full resolution dataset is spatially downsampled in order to evaluate the effects on raster plot representation, array-wide spike rate (AWSR), mean firing rate (MFR) and mean bursting rate (MBR). Furthermore, the effects of the array-to-network relative position are evaluated by shifting a subset of equally spaced electrodes on the entire recorded area. Results highlight that MFR and MBR are particularly influenced by the spatial resolution provided by the neuroelectronic interface. On high-resolution large MEAs, such analysis better represent the time-based parameterization of the network dynamics. Finally, this work suggest interesting capabilities of high-resolution MEAs for spatial-based analysis in dense and low-dense neuronal preparation for investigating signaling at both local and global neuronal circuitries

3F(eature)s model: modularity, heterogeneity and three-dimensionality to design in vitro neuronal model

In this work, we present a novel experimental platform to build in vitro interconnected (i.e., modular) heterogeneous (e.g., cortical-hippocampal) and three-dimensional (3D) neuronal cultures plated on Micro-Electrode Arrays (MEAs) to extracellularly record the electrophysiological activity continuously

Microtubule Dependent Mechano-Transduction Drives Oxidative Stress and Calcium Dysregulation in Dystrophic Skeletal Muscle

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CL316,243, a β3-adrenergic receptor agonist, induces muscle hypertrophy and increased strength.

Studies in vitro have demonstrated that β3-adrenergic receptors (β3-ARs) regulate protein metabolism in skeletal muscle by promoting protein synthesis and inhibiting protein degradation. In this study, we evaluated whether activation of β3-ARs by the selective agonist CL316,243 modifies the functional and structural properties of skeletal muscles of healthy mice. Daily injections of CL316,243 for 15 days resulted in a significant improvement in muscle force production, assessed by grip strength and weight tests, and an increased myofiber cross-sectional area, indicative of muscle hypertrophy. In addition, atomic force microscopy revealed a significant effect of CL316,243 on the transversal stiffness of isolated muscle fibers. Interestingly, the expression level of mammalian target of rapamycin (mTOR) downstream targets and neuronal nitric oxide synthase (NOS) was also found to be enhanced in tibialis anterior and soleus muscles of CL316,243 treated mice, in accordance with previous data linking β3-ARs to mTOR and NOS signaling pathways. In conclusion, our data suggest that CL316,243 systemic administration might be a novel therapeutic strategy worthy of further investigations in conditions of muscle wasting and weakness associated with aging and muscular diseases

Modularity and neuronal heterogeneity: Two properties that influence in vitro neuropharmacological experiments

IntroductionThe goal of this work is to prove the relevance of the experimental model (in vitro neuronal networks in this study) when drug-delivery testing is performed.MethodsWe used dissociated cortical and hippocampal neurons coupled to Micro-Electrode Arrays (MEAs) arranged in different configurations characterized by modularity (i.e., the presence of interconnected sub-networks) and heterogeneity (i.e., the co-existence of neurons coming from brain districts). We delivered increasing concentrations of bicuculline (BIC), a neuromodulator acting on the GABAergic system, and we extracted the IC50 values (i.e., the effective concentration yielding a reduction in the response by 50%) of the mean firing rate for each configuration.ResultsWe found significant lower values of the IC50 computed for modular cortical-hippocampal ensembles than isolated cortical or hippocampal ones.DiscussionAlthough tested with a specific neuromodulator, this work aims at proving the relevance of ad hoc experimental models to perform neuropharmacological experiments to avoid errors of overestimation/underestimation leading to biased information in the characterization of the effects of a drug on neuronal networks

Exosomes from astrocyte processes: Signaling to neurons

open13It is widely recognized that extracellular vesicles subserve non-classical signal transmission in the central nervous system. Here we assess if the astrocyte processes, that are recognized to play crucial roles in intercellular communication at the synapses and in neuron-astrocyte networks, could convey messages through extracellular vesicles. Our findings indicate, for the first time that freshly isolated astrocyte processes prepared from adult rat cerebral cortex, can indeed participate to signal transmission in central nervous system by releasing exosomes that by volume transmission might target near or longdistance sites. It is noteworthy that the exosomes released from the astrocyte processes proved ability to selectively target neurons. The astrocyte-derived exosomes were proven positive for neuroglobin, a protein functioning as neuroprotectant against cell insult; the possibility that exosomes might transfer neuroglobin to neurons would add a mechanism to the potential astrocytic neuroprotectant activity. Notably, the exosomes released from the processes of astrocytes maintained markers, which prove their parental astrocytic origin. This potentially allows the assessment of the cellular origin of exosomes that might be recovered from body fluids.openVenturini A.; Passalacqua M.; Pelassa S.; Pastorino F.; Tedesco M.; Cortese K.; Gagliani M.C.; Leo G.; Maura G.; Guidolin D.; Agnati L.F.; Marcoli M.; Cervetto C.Venturini, A.; Passalacqua, M.; Pelassa, S.; Pastorino, F.; Tedesco, M.; Cortese, K.; Gagliani, M. C.; Leo, G.; Maura, G.; Guidolin, D.; Agnati, L. F.; Marcoli, M.; Cervetto, C

chitosan biopolymer alternative adhesion factor and scaffold matrix for 2d and 3d neuronal cultures

The increase of different types of cell cultures, which can be used for the in vitro studies of physiological and/or pathological processes, has introduced the need to improve culture techniques through the use of materials and culture media that promote growth, recreating a cellular micro-environment that can be asserted in in vivo condition. The standard methods for the functionalization of supports used for cell cultures are based on the use of synthetic or natural biopolymers, which generally have high costs, such as poly-lysine and polyornithine. The aim of this work is to demonstrate the alternative use of the polysaccharide chitosan as adhesion factor and structural component for 2D/3D neuronal cultures. Thanks to its versatility, it could be easily functionalized for the fabrication of personalized of in vitro model

A Neuromorphic Prosthesis to Restore Communication in Neuronal Networks

Recent advances in bioelectronics and neural engineering allowed the development of brain machine interfaces and neuroprostheses, capable of facilitating or recovering functionality in people with neurological disability. To realize energy-efficient and real-time capable devices, neuromorphic computing systems are envisaged as the core of next-generation systems for brain repair. We demonstrate here a real-time hardware neuromorphic prosthesis to restore bidirectional interactions between two neuronal populations, even when one is damaged or missing. We used in vitro modular cell cultures to mimic the mutual interaction between neuronal assemblies and created a focal lesion to functionally disconnect the two populations. Then, we employed our neuromorphic prosthesis for bidirectional bridging to artificially reconnect two disconnected neuronal modules and for hybrid bidirectional bridging to replace the activity of one module with a real-time hardware neuromorphic Spiking Neural Network. Our neuroprosthetic system opens avenues for the exploitation of neuromorphic-based devices in bioelectrical therapeutics for health care

How 3D scaffolds with different mechanical properties affect the activity of neuronal networks in in vitro models*

Three-dimensionality has been proven extensively to be critical in the development of a reliable model for different anatomical compartments and for many diseases. Currently, we can produce implantable structures that help in the regeneration of different tissues such as bone and heart. Different is the situation when we consider the neuronal compartment. As it is still difficult to understand exactly how the brain computes, to conceive how the complex chain of neuronal events can generate conscious behavior, a comprehensive and workable model of neuronal tissue still has to be found. In this perspective, in the present work, we developed and compared different 3D scaffolds to understand the effects produced by the mechanical and material properties of four different scaffolds on a 3D neuronal network. To help in preclinical testing procedure, the scalability and ease-of-use of the different approaches were also taken into consideration.Clinical Relevance- By comparing different 3D scaffolds for the creation of neuronal constructs, the results in this paper move towards understanding the best strategy to develop functional 3D neuronal units for reliable pre-clinical studies