No abstract

In this review, we scrutinize the idea of using viral vectors either as cytotoxic agents or gene delivery tools for treatment of glioblastoma multiforme (GBM) in light of the experience that our laboratory has accumulated over ~20 years when using similar vectors in experimental neuroscience. We review molecular strategies and current clinical trials and argue that approaches which are based on targeting a specific biochemical pathway or a characteristic mutation are inherently prone to failure because of the high genomic instability and clonal selection characteristics of GBM. For the same reasons, attempts to develop a viral system which selectively transduces only GBM cells are also unlikely to be universally successful. One of the common gene therapy approaches is to use cytotoxic viruses which replicate and cause preferential lysis of the GBM cells. This strategy, in addition to its reliance on the specific biochemical makeup of the GBM cells, bears a risk of necrotic cell death accompanied by release of large quantities of pro-inflammatory molecules. On the other hand, engaging the immune system in the anti-GBM response seems to be a potential avenue to explore further. We suggest that a plausible strategy is to focus on viral vectors which efficiently transduce brain cells via a non-selective, ubiquitous mechanism and which target (ideally irreversibly) processes that are critical only for dividing tumor cells and are dispensable for quiescent brain cells.

This study reveals that fossil shungite samples exhibit antioxidant activity, can reduce oxidized components, and bind to free radicals. A sample of Sh20 (size fraction—20 μm) (1.30 mg equivalents of ascorbic acid/g of shungite; 3.46 mg equivalents of trolox/g of shungite; 0.99 mg equivalents of quercetin/g of shungite) had the maximal activity according to the amperometric method. The obtained data indicate that shungite has antioxidant properties, but these are approximately 1000 times less pronounced than those of quercetin. A ShT20 sample (size fraction—20 μm + heat treatment) was found to have the highest antioxidant activity against the 2,2-diphenyl-1-picrylhydrazyl radical and cytotoxicity. Further studies, including the optimization of the antioxidant extraction conditions of shungite, and the analysis of the qualitative and quantitative composition of the obtained extracts, are required for a more accurate interpretation of the results. Shungite can be applied as an alternative to activated carbon in water purification, due to its absorption, catalytic, antioxidant, regenerating, and antibacterial properties, as well as its high environmental safety and relatively low cost. It is possible to identify new structural forms of carbon within, and other valuable properties of, shungite substance, which will make it possible to create effective technologies for the practical use of shungite rocks, particularly in the production of fullerenes and other carbon nanoclusters.

Spinocerebellar ataxias are a family of fatal inherited diseases affecting the brain. Although specific mutated proteins are different, they may have a common pathogenetic mechanism, such as insufficient glutamate clearance. This function fails in reactive glia, leading to excitotoxicity and overactivation of NMDA receptors. Therefore, NMDA receptor blockers could be considered for the management of excitotoxicity. One such drug, memantine, currently used for the treatment of Alzheimer’s disease, could potentially be used for the treatment of other forms of neurodegeneration, for example, spinocerebellar ataxias (SCA). We previously demonstrated close parallels between optogenetically induced cerebellar degeneration and SCA1. Here we induced reactive transformation of cerebellar Bergmann glia (BG) using this novel optogenetic approach and tested whether memantine could counteract changes in BG and Purkinje cell (PC) morphology and expression of the main glial glutamate transporter—excitatory amino acid transporter 1 (EAAT1). Reactive BG induced by chronic optogenetic stimulation presented increased GFAP immunoreactivity, increased thickness and decreased length of its processes. Oral memantine (~90 mg/kg/day for 4 days) prevented thickening of the processes (1.57 to 1.81 vs. 1.62 μm) and strongly antagonized light-induced reduction in their average length (186.0 to 150.8 vs. 171.9 μm). Memantine also prevented the loss of the key glial glutamate transporter EAAT1 on BG. Finally, memantine reduced the loss of PC (4.2 ± 0.2 to 3.2 ± 0.2 vs. 4.1 ± 0.3 cells per 100 μm of the PC layer). These results identify memantine as potential neuroprotective therapeutics for cerebellar ataxias.

Spinocerebellar ataxia type 1 (SCA1) is an intractable progressive neurodegenerative disease that leads to a range of movement and motor defects and is eventually lethal. Purkinje cells (PC) are typically the first to show signs of degeneration. SCA1 is caused by an expansion of the polyglutamine tract in the ATXN1 gene and the subsequent buildup of mutant Ataxin-1 protein. In addition to its toxicity, mutant Ataxin-1 protein interferes with gene expression and signal transduction in cells. Recently, it is evident that ATXN1 is not only expressed in neurons but also in glia, however, it is unclear the extent to which either contributes to the overall pathology of SCA1. There are various ways to model SCA1 in mice. Here, functional deficits at cerebellar synapses were investigated in two mouse models of SCA1 in which mutant ATXN1 is either nonspecifically expressed in all cell types of the cerebellum (SCA1 knock-in (KI)), or specifically in Bergmann glia with lentiviral vectors expressing mutant ATXN1 under the control of the astrocyte-specific GFAP promoter. We report impairment of motor performance in both SCA1 models. In both cases, prominent signs of astrocytosis were found using immunohistochemistry. Electrophysiological experiments revealed alteration of presynaptic plasticity at synapses between parallel fibers and PCs, and climbing fibers and PCs in SCA1 KI mice, which is not observed in animals expressing mutant ATXN1 solely in Bergmann glia. In contrast, short- and long-term synaptic plasticity was affected in both SCA1 KI mice and glia-targeted SCA1 mice. Thus, non-neuronal mechanisms may underlie some aspects of SCA1 pathology in the cerebellum. By combining the outcomes of our current work with our previous data from the B05 SCA1 model, we further our understanding of the mechanisms of SCA1.