No abstract

Astrocytes are actively involved in brain development, in mature CNS regulation, and in brain plasticity. They play a critical role in response to cerebral injuries and toxicants through a reaction known as "reactive gliosis," which is characterized by specific structural and functional features. A large amount of literature highlights the central role of astrocytes in mediating methylmercury (MeHg) neurotoxicity. In fact, mercury is the major neurotoxic pollutant that continues to arouse interest in research because of the severe risk it poses to human health. In this article, we focus on the action of MeHg on human astrocyte (HA) reactivity. We clearly demonstrate that MeHg induces a state of cellular suffering by promoting delayed and atypical astrocyte reactivity mediated by impairment of the proliferative and trophic component of the astrocyte together with an inflammatory state. This condition is generated by negative modulation of the major proteins of the filamentous network, which is manifested by the destabilization of astrocytic cytoarchitecture. Our data confirms the toxic effects of MeHg on HA reactivity and allows us to hypothesize that the establishment of this state of suffering and the delayed onset of a typical astrocytic reactivity compromise the main protective function of HA.

Extracellular matrix (ECM) represents an essential component of the cellular niche. In this conditioned microenvironment, the proliferation rates and differentiation states of stem cells are regulated by several factors. In contrast, in in vitro experimental models, cell growth, or induction procedures toward specific cell lines usually occur in contact with plastic, glass, or biogel supports. In this study, we evaluated the effect of a decellularized ECM, derived from bone marrow stem cells, on the neuronal differentiation of mesenchymal stem cells (MSCs) extracted from dental pulp (Dental Pulp Stem Cells -DPSCs). Since DPSCs derive from neuroectodermal embryonic precursors, they are thought to have a greater propensity toward neuronal differentiation than MSCs isolated from other sources. We hypothesized that the presence of a decellularized ECM scaffold could act positively on neuronal-DPSC differentiation through reproduction of an in vivo-like microenvironment. Results from scanning electron microscopy, immunofluorescence, and gene expression assays showed that ECM is able to positively influence the morphology of cells and their distribution and the expression of specific neuronal markers (i.e., NF-L, NF-M, NF-H, PAX6, MAP2).

Brain and other nervous system cancers are the 10th leading cause of death worldwide. Genome instability, cell cycle deregulation, epigenetic mechanisms, cytoarchitecture disassembly, redox homeostasis as well as apoptosis are involved in carcinogenesis. A diet rich in fruits and vegetables is inversely related with the risk of developing cancer. Several studies report that cruciferous vegetables exhibited antiproliferative effects due to the multi-pharmacological functions of their secondary metabolites such as isothiocyanate sulforaphane deriving from the enzymatic hydrolysis of glucosinolates. We treated human astrocytoma 1321N1 cells for 24 h with different concentrations (0.5, 1.25 and 2.5% v/v) of sulforaphane plus active myrosinase (Rapha Myr®) aqueous extract (10 mg/mL). Cell viability, DNA fragmentation, PARP-1 and γH2AX expression were examined to evaluate genotoxic effects of the treatment. Cell cycle progression, p53 and p21 expression, apoptosis, cytoskeleton morphology and cell migration were also investigated. In addition, global DNA methylation, DNMT1 mRNA levels and nuclear/mitochondrial sirtuins were studied as epigenetic biomarkers. Rapha Myr® exhibited low antioxidant capability and exerted antiproliferative and genotoxic effects on 1321N1 cells by blocking the cell cycle, disarranging cytoskeleton structure and focal adhesions, decreasing the integrin α5 expression, renewing anoikis and modulating some important epigenetic pathways independently of the cellular p53 status. In addition, Rapha Myr® suppresses the expression of the oncogenic p53 mutant protein. These findings promote Rapha Myr® as a promising chemotherapeutic agent for integrated cancer therapy of human astrocytoma.

Conventional approaches to human intracellular optical sensing, generally, require dedicated laboratories with bulky detection systems. They are performed by cell labeling procedures based on the use of fluorophores that are, mostly, phototoxic, invasive, bleached in case of prolonged light exposures, which require carriers and/or structural modifications for the cellular uptake. These issues, together with the sensitivity of the eukaryotic cell model, could be problematic towards the development of a robust sensing system suitable for biomedical screening. In this work, we studied a sensing system resulting from the combination of the commercial tris(2,2’bipyridyl)ruthenium(II) fluorophore, for cell labeling, with a potentially miniaturizable optical system composed by a laser source and a photomultiplier tube, for the fluorescence analysis.