Graphene glial-interfaces: challenges and perspectives

Graphene nanosheets are mechanically strong but flexible, electrically conductive and bio-compatible. Thus, due to these unique properties, they are being intensively studied as materials for the next generation of neural interfaces. Most of the literature focused on optimizing the interface between these materials and neurons. However, one of the most common causes of implant failure is the adverse inflammatory reaction of glial cells. These cells are not, as previously considered, just passive and supportive cells, but play a crucial role in the physiology and pathology of the nervous system, and in the interaction with implanted electrodes. Besides providing structural support to neurons, glia are responsible for the modulation of synaptic transmission and control of central and peripheral homeostasis. Accordingly, knowledge on the interaction between glia and biomaterials is essential to develop new implant-based therapies for the treatment of neurological disorders, such as epilepsy, brain tumours, and Alzheimer's and Parkinson's disease. This work provides an overview of the emerging literature on the interaction of graphene-based materials with glial cells, together with a complete description of the different types of glial cells and problems associated with them. We believe that this description will be important for researchers working in materials science and nanotechnology to develop new active materials to interface, measure and stimulate these cells

LRRC8A is essential for swelling-activated chloride current and for regulatory volume decrease in astrocytes

Consolidated evidence indicates that astroglial cells are critical in the homeostatic regulation of cellular volume by means of ion channels and aquaporin-4. Volume-regulated anion channel (VRAC) is the chloride channel that is activated upon cell swelling and critically contributes to cell volume regulation in astrocytes. The molecular identity of VRAC has been recently defined, revealing that it belongs to the leucine-rich repeat-containing 8 (LRRC8) protein family. However, there is a lack of evidence demonstrating that LRRC8A underpins VRAC currents in astrocyte. Nonetheless, direct evidence of the role of LRRC8A in astrocytic regulatory volume decrease remains to be proved. Here, we aim to bridge this gap in knowledge by combining RNA interference specific for LRRC8A with patch-clamp analyses and a water-permeability assay. We demonstrated that LRRC8A molecular expression is essential for swelling-activated chloride current via VRAC in primary-cultured cortical astrocytes. The knockdown of LRRC8A with a specific short interference RNA abolished the recovery of the cell volume after swelling induced by hypotonic challenge. In addition, immunoblotting, immunofluorescence, confocal imaging, and immunogold electron microscopy demonstrated that LRRC8A is expressed in the plasma membrane of primary cortical astrocytes and in situ in astrocytes at the perivascular interface with endothelial cells. Collectively, our results suggest that LRRC8A is an essential subunit of VRAC and a key factor for astroglial volume homeostasis.-Formaggio, F., Saracino, E., Mola, M. G., Rao, S. B., Amiry-Moghaddam, M., Muccini, M., Zamboni, R., Nicchia, G. P., Caprini, M., Benfenati, V. LRRC8A is essential for swelling-activated chloride current and for regulatory volume decrease in astrocytes

AQP4-independent TRPV4 modulation of plasma membrane water permeability

: Despite of the major role of aquaporin (AQP) water channels in controlling transmembrane water fluxes, alternative ways for modulating water permeation have been proposed. In the Central Nervous System (CNS), Aquaporin-4 (AQP4) is reported to be functionally coupled with the calcium-channel Transient-Receptor Potential Vanilloid member-4 (TRPV4), which is controversially involved in cell volume regulation mechanisms and water transport dynamics. The present work aims to investigate the selective role of TRPV4 in regulating plasma membrane water permeability in an AQP4-independent way. Fluorescence-quenching water transport experiments in Aqp4-/- astrocytes revealed that cell swelling rate is significantly increased upon TRPV4 activation and in the absence of AQP4. The biophysical properties of TRPV4-dependent water transport were therefore assessed using the HEK-293 cell model. Calcein quenching experiments showed that chemical and thermal activation of TRPV4 overexpressed in HEK-293 cells leads to faster swelling kinetics. Stopped-flow light scattering water transport assay was used to measure the osmotic permeability coefficient (Pf, cm/s) and activation energy (Ea, kcal/mol) conferred by TRPV4. Results provided evidence that although the Pf measured upon TRPV4 activation is lower than the one obtained in AQP4-overexpressing cells (Pf of AQP4 = 0.01667 ± 0.0007; Pf of TRPV4 = 0.002261 ± 0.0004; Pf of TRPV4 + 4αPDD = 0.007985 ± 0.0006; Pf of WT = 0.002249 ± 0.0002), along with activation energy values (Ea of AQP4 = 0.86 ± 0.0006; Ea of TRPV4 + 4αPDD = 2.73 ± 1.9; Ea of WT = 8.532 ± 0.4), these parameters were compatible with a facilitated pathway for water movement rather than simple diffusion. The possibility to tune plasma membrane water permeability more finely through TRPV4 might represent a protective mechanism in cells constantly facing severe osmotic challenges to avoid the potential deleterious effects of the rapid cell swelling occurring via AQP channels

Cell Volume Regulation Mechanisms in Differentiated Astrocytes

The ability of astrocytes to control extracellular volume homeostasis is critical for brain function and pathology. Uncovering the mechanisms of cell volume regulation by astrocytes will be important for identifying novel therapeutic targets for neurological conditions, such as those characterized by imbalances to hydro saline challenges (as in edema) or by altered cell volume regulation (as in glioma). One major challenge in studying the astroglial membrane channels involved in volume homeostasis in cell culture model systems is that the expression patterns of these membrane channels do not resemble those observed in vivo. In our previous study, we demonstrated that rat primary astrocytes grown on nanostructured interfaces based on hydrotalcite-like compounds (HTlc) in vitro are differentiated and display molecular and functional properties of in vivo astrocytes, such as the functional expression of inwardly rectifying K+ channel (Kir 4.1) and Aquaporin-4 (AQP4) at the astrocytic microdomain. Here, we take advantage of the properties of differentiated primary astrocytes in vitro to provide an insight into the mechanism underpinning astrocytic cell volume regulation and its correlation with the expression and function of AQP4, Transient Receptor Potential Vanilloid 4 (TRPV4), and Volume Regulated Anion Channel (VRAC)

Biomimetic graphene for enhanced interaction with the external membrane of astrocytes

Graphene and graphene substrates display huge potential as material interfaces for devices and biomedical tools targeting the modulation or recovery of brain functionality. However, to be considered reliable neural interfaces, graphene-derived substrates should properly interact with astrocytes, favoring their growth and avoiding adverse gliotic reactions. Indeed, astrocytes are the most abundant cells in the human brain and they have a crucial physiological role to maintain its homeostasis and modulate synaptic transmission. In this work, we describe a new strategy based on the chemical modification of graphene oxide (GO) with a synthetic phospholipid (PL) to improve interaction of GO with brain astroglial cells. The PL moieties were grafted on GO sheets through polymeric brushes obtained by atom-transfer radical-polymerization (ATRP) between acryloyl-modified PL and GO nanosheets modified with a bromide initiator. The adhesion of primary rat cortical astrocytes on GO–PL substrates increased by about three times with respect to that on glass substrates coated with standard adhesion agents (i.e. poly-D-lysine, PDL) as well as with respect to that on non-functionalized GO. Moreover, we show that astrocytes seeded on GO–PL did not display significant gliotic reactivity, indicating that the material interface did not cause a detrimental inflammatory reaction when interacting with astroglial cells. Our results indicate that the reported biomimetic approach could be applied to neural prosthesis to improve cell colonization and avoid glial scar formation in brain implants. Additionally, improved adhesion could be extremely relevant in devices targeting neural cell sensing/modulation of physiological activity

Malaria, HIV and Malnutrition among Internally Displaced People in Mozambique During COVID-19 Pandemic: Results from a Community-Based Intervention

Background: The spread of COVID-19 poses an unprecedented challenge to care delivery in post-disaster and conflict situations. In Mozambique, the 2019 cyclone Idai and the violence by Non-State-Armed-Groups devastated the province of Sofala and Cabo Delgado respectively and led to the displacement of thousands of people living in poor and overcrowded conditions. The pandemic has further aggravated the situation. Doctors with Africa CUAMM (University college for aspiring missionary doctors) implemented surveillance activities in these regions between October 2020 and September 2021. The aim of this study is to give an overview of the prevalence of malaria, malnutrition, COVID-19 related symptoms and access to HIV testing. Methods: Data were collected in targeted internally displaced people (IDP) sites in Sofala and Cabo Delgado province between 31st January and 25th September 2021. The tool used enabled to assess COVID-19 symptoms, risk of HIV infection, malaria cases and malnutrition in children under five. Results: The project reached 93 503 people. During the study period, 13.6% people reported at least one symptom suggestive of COVID-19 infection. Malaria Rapid Diagnostic Tests (RDT) were administered to 86% of the recruited people (n = ?), with a positive diagnosis in the 4.5% of them (n = ?). Among the recruited Internally Displaced Persons (IDP), 23.1% were considered eligible for HIV screening, but only 1.4% were referred for testing. Acute malnutrition was found in 6.3% of children screened and, among these, a higher prevalence of concurrent COVID-19 symptoms was reported. Discussion: Our study highlights the importance of mass clinical screening for COVID-19 infection in this target population to enact prevention behavior, although this may not be enough, due to the pivotal role played by asymptomatic transmissions. Considering the overlap of the symptoms of COVID-19 and malaria, a combined diagnostic algorithm is urgently needed to avoid underdiagnosing malaria. Moreover, the high prevalence of respiratory symptoms in malnourished children confirmed the known correlation between malnutrition and respiratory infection. Finally, access to HIV screening needs to be implemented, given the high prevalence of people with HIV risk factors to avoid diagnostic delay. Conclusions: Population-specific needs make necessary to develop new screening methods that respond to the specific characteristics of the target population

Acute Delta Hepatitis in Italy spanning three decades (1991–2019): Evidence for the effectiveness of the hepatitis B vaccination campaign

Updated incidence data of acute Delta virus hepatitis (HDV) are lacking worldwide. Our aim was to evaluate incidence of and risk factors for acute HDV in Italy after the introduction of the compulsory vaccination against hepatitis B virus (HBV) in 1991. Data were obtained from the National Surveillance System of acute viral hepatitis (SEIEVA). Independent predictors of HDV were assessed by logistic-regression analysis. The incidence of acute HDV per 1-million population declined from 3.2 cases in 1987 to 0.04 in 2019, parallel to that of acute HBV per 100,000 from 10.0 to 0.39 cases during the same period. The median age of cases increased from 27 years in the decade 1991-1999 to 44 years in the decade 2010-2019 (p < .001). Over the same period, the male/female ratio decreased from 3.8 to 2.1, the proportion of coinfections increased from 55% to 75% (p = .003) and that of HBsAg positive acute hepatitis tested for by IgM anti-HDV linearly decreased from 50.1% to 34.1% (p < .001). People born abroad accounted for 24.6% of cases in 2004-2010 and 32.1% in 2011-2019. In the period 2010-2019, risky sexual behaviour (O.R. 4.2; 95%CI: 1.4-12.8) was the sole independent predictor of acute HDV; conversely intravenous drug use was no longer associated (O.R. 1.25; 95%CI: 0.15-10.22) with this. In conclusion, HBV vaccination was an effective measure to control acute HDV. Intravenous drug use is no longer an efficient mode of HDV spread. Testing for IgM-anti HDV is a grey area requiring alert. Acute HDV in foreigners should be monitored in the years to come

“Nanoglial interfaces: nanostructured materials, interfaces and devices to unveil the role of astrocytes in brain function and dysfunction”

The role of non-neuronal brain cells, called astrocytes, is emerging as crucial in brain function and dysfunction, encompassing the neurocentric concept that was envisioning glia as passive components. Ion and water channels and calcium signalling, expressed in functional micro and nano domains, underpin astrocytes’ homeostatic function, synaptic transmission, neurovascular coupling acting either locally and globally. In this respect, a major issue arises on the mechanism through which astrocytes can control processes across scales. Finally, astrocytes can sense and react to extracellular stimuli such as chemical, physical, mechanical, electrical, photonic ones at the nanoscale. Given their emerging importance and their sensing properties, my PhD research program had the general goal to validate nanomaterials, interfaces and devices approaches that were developed ad-hoc to study astrocytes. The results achieved are reported in the form of collection of papers. Specifically, we demonstrated that i) electrospun nanofibers made of polycaprolactone and polyaniline conductive composites can shape primary astrocytes’ morphology, without affecting their function ii) gold coated silicon nanowires devices enable extracellular recording of unprecedented slow wave in primary differentiated astrocytes iii) colloidal hydrotalcites films allow to get insight in cell volume regulation process in differentiated astrocytes and to describe novel cytoskeletal actin dynamics iv) gold nanoclusters represent nanoprobe to trigger astrocytes structure and function v) nanopillars of photoexcitable organic polymer are potential tool to achieve nanoscale photostimulation of astrocytes. The results were achieved by a multidisciplinary team working with national and international collaborators that are listed and acknowledged in the text. Collectively, the results showed that astrocytes represent a novel opportunity and target for Nanoscience, and that Nanoglial interface might help to unveil clues on brain function or represent novel therapeutic approach to treat brain dysfunctions

Caff\ue8 e camomilla: "solo" bevande? Valutazione e confronto del loro potere antiossidante

Caff\ue8 e camomilla, insieme al t\ue8, rappresentano alcune delle bevande pi\uf9 comuni e consumate in tutto il mondo. Aldil\ue0 delle loro propriet\ue0 dissetanti, molte altre attivit\ue0 benefiche per la salute dell\u2019uomo sono ad esse riconosciute, non solo dalla tradizione popolare ma recentemente anche dalla comunit\ue0 scientifica. Infatti, alcuni studi sono a favore degli effetti benefici del caff\ue8 e del suo principale composto attivo, la caffeina, poich\ue9 possono concorrere all\u2019azione preventiva di alcune importanti patologie (diabete di tipo 2, morbo di Alzheimer e morbo di Parkinson). Altre sostanze presenti nel caff\ue8, oltre la caffeina, come il cafestolo ed il kahweolo sarebbero responsabili di effetti epatoprotettivi, antiossidanti e chemiopreventivi, anche se il meccanismo preciso cos\uec come il coinvolgimento di queste molecole nell\u2019azione benefica sono ancora tutti da chiarire. Il contenuto di tali sostanze nel caff\ue8 varia in base ai metodi di preparazione e in base alla qualit\ue0 della materia prima. Per quanto riguarda la camomilla (Matricaria recutita) la propriet\ue0 pi\uf9 nota da sempre \ue8 quella calmante; considerare la camomilla solo un sedativo naturale \ue8 per\uf2 riduttivo in quanto studi recenti hanno dimostrato numerose propriet\ue0 benefiche sull'organismo. Grazie al camazulene (sostanza da cui derivano l'odore caratteristico e il sapore amarognolo) e al bisabololo, la camomilla ha azione antinfiammatoria, mentre le apigenine sono responsabili dell'attivit\ue0 antispasmodica. Oltre ad alleviare i disturbi gastrointestinali, i capolini hanno azione sedativa sul sistema nervoso centrale, cicatrizzante, antimicotica e antimicrobica. Inoltre i ricercatori ritengono che la camomilla possa agire anche come antiossidante, ma gli studi clinici sull\u2019uomo sono ancora scarsi. Per questo motivo nel Laboratorio di Analisi Farmaco-Tossicologica si sta valutando in vitro il potere antiossidante di vari estratti acquosi di caff\ue8 e camomilla. I test che verranno utilizzati per misurare il potere antiossidante sono diversi e individuati sulla base del meccanismo della reazioni coinvolte: - test ORAC (Oxygen Radical Absorbance Capacity) basato sul trasferimento di un atomo di idrogeno; - test TEAC (Trolox Equivalence Antioxidant Capacity) basato sia sul trasferimento di un singolo elettrone sia di un atomo di idrogeno; - test della reazione oscillante di Briggs-Rauscher (metodo BR), basato sugli effetti inibitori del regime oscillatorio provocati dall\u2019aggiunta di antiossidanti sottrattori di radicali liberi per trasferimento di un atomo di idrogeno. Per ciascuna metodica i risultati ottenuti del potere antiossidante saranno confrontati e valutati anche in base al tipo di estrazione effettuata e al tipo di cultivar utilizzato sia per il caff\ue8 che per la camomilla

Polyaniline nano-needles into electrospun bio active fibres support in vitro astrocyte response

none9noRRecent studies have proposed that the bioelectrical response of glial cells, called astrocytes, currently represents a key target for neuroregenerative purposes. Here, we propose the fabrication of electrospun nanofibres containing gelatin and polyaniline (PANi) synthesized in the form of nano-needles (PnNs) as electrically conductive scaffolds to support the growth and functionalities of primary astrocytes. We report a fine control of the morphological features in terms of fibre size and spatial distribution and fibre patterning, i.e. random or aligned fibre organization, as revealed by SEM- and TEM-supported image analysis. We demonstrate that the peculiar morphological properties of fibres – i.e., the fibre size scale and alignment – drive the adhesion, proliferation, and functional properties of primary cortical astrocytes. In addition, the gradual transmission of biochemical and biophysical signals due to the presence of PnNs combined with the presence of gelatin results in a permissive and guiding environment for astrocytes. Accordingly, the functional properties of astrocytes measured via cell patch-clamp experiments reveal that PnNs do not alter the bioelectrical properties of resting astrocytes, thus setting the scene for the use of PnN-loaded nanofibres as bioconductive platforms for interfacing astrocytes and controlling their bioelectrical properties.noneEMANUELA Saracino, VINCENZO Cirillo, MARICA Marrese, SERENA Zuppolini, VINCENZO Guarino, VALENTINA Benfenati, ANNA Borriello, ROBERTO Zamboni, LUIGI AmbrosioEMANUELA Saracino, VINCENZO Cirillo, MARICA Marrese, SERENA Zuppolini, VINCENZO Guarino, VALENTINA Benfenati, ANNA Borriello, ROBERTO Zamboni, LUIGI Ambrosi