AbstractIn 2008, using a model of compression brain ischemia, we presented the first evidence that mitochondria-targeted antioxidants of the SkQ family, i.e. SkQR1 [10-(6′-plastoquinonyl)decylrhodamine], have a neuroprotective action. It was shown that intraperitoneal injections of SkQR1 (0.5–1 μmol/kg) 1 day before ischemia significantly decreased the damaged brain area. Later, we studied in more detail the anti-ischemic action of this antioxidant in a model of experimental focal ischemia provoked by unilateral intravascular occlusion of the middle cerebral artery. The neuroprotective action of SkQ family compounds (SkQR1, SkQ1, SkQTR1, SkQT1) was manifested through the decrease in trauma-induced neurological deficit in animals and prevention of amyloid-β-induced impairment of long-term potentiation in rat hippocampal slices. At present, most neurophysiologists suppose that long-term potentiation underlies cellular mechanisms of memory and learning. They consider inhibition of this process by amyloid-β1-42 as an in vitro model of memory disturbance in Alzheimer’s disease. Further development of the above studies revealed that mitochondria-targeted antioxidants could retard accumulation of hyperphosphorylated τ-protein, as well as amyloid-β1-42, and its precursor APP in the brain, which are involved in developing neurodegenerative processes in Alzheimer’s disease.

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Recently, we showed that tetrasaccharide selectin ligand SiaLeX provided targeted delivery of liposomes loaded in the bilayer with melphalan lipophilic prodrug to tumour endothelium followed by severe injury of tumour vessels in a Lewis lung carcinoma model. Here, we study the impact of SiaLeX ligand on the interactions of liposomes with human umbilical vein endothelial cells (HUVEC) using flow cytometry, spectrofluorimetry and confocal microscopy. Liposomes composed of egg phosphatidylcholine/yeast phosphatidylinositol/1,2-dioleoyl glycerol ester of melphalan, 8:1:1, by mol, and varying percentages of lipophilic SiaLeX conjugate were labelled with BODIPY-phosphatidylcholine. The increase in SiaLeX content in liposomes led to a proportional increase in their uptake by cytokine-activated cells as opposed to non-activated HUVEC: for 10% SiaLeX liposomes, binding avidity and overall accumulation increased 14- and 6-fold, respectively. The early stages of intracellular traffic of targeted liposomes in the activated cells were monitored by co-localisation with the trackers of organelles. Endocytosis of SiaLeX liposomes occurred mostly via clathrin-independent pathways, which does not contradict the available literature data on E-selectin localisation in the plasma membrane. Using dual fluorescence labelling, with rhodamine-labelled phospholipid and calcein encapsulated at self-quenching concentrations, we found that SiaLeX liposomes undergo rapid (within minutes) internalisation by activated HUVEC accompanied by the disruption of liposomes; non-activated cells consumed a negligible dose of liposomes during at least 1.5h. Our data evidence the selective effect of SiaLeX formulations on activated endothelial cells and indicate their potential for intracellular delivery of melphalan lipophilic prodrug.

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Alzheimer's disease is characterized by progressive memory loss and cognitive decline accompanied by degeneration of neuronal synapses, massive loss of neurons in the brain, eventually resulting in complete degradation of personality and death. Currently, the cause of the disease is not fully understood, but it is believed that the person's age is the major risk factor for development of Alzheimer's disease. People who have survived after cerebral stroke or traumatic brain injury have substantially increased risk of developing Alzheimer's disease. Social exclusion, low social activity, physical inactivity, poor mental performance, and low level of education are among risk factors for development of this neurodegenerative disease, which is consistent with the concept of phenoptosis (Skulachev, V. P., et al. (1999) Biochemistry (Moscow), 64, 1418-1426; Skulachev, M. V., and Skulachev, V. P. (2014) Biochemistry (Moscow), 79, 977-993) stating that rate of aging is related to psychological and social aspects in human behavior. Here we assumed that Alzheimer's disease might be considered as an exacerbation of senile phenoptosis. If so, then development of this disease could be slowed using mitochondria-targeted antioxidants due to the accumulated data demonstrating a link between mitochondrial dysfunction and oxidative stress both with normal aging and Alzheimer's disease.

Neurogenesis is a key mechanism of brain development and plasticity, which is impaired in chronic neurodegeneration, including Parkinson’s disease. The accumulation of aberrant α-synuclein is one of the features of PD. Being secreted, this protein produces a prominent neurotoxic effect, alters synaptic plasticity, deregulates intercellular communication, and supports the development of neuroinflammation, thereby providing propagation of pathological events leading to the establishment of a PD-specific phenotype. Multidirectional and ambiguous effects of α-synuclein on adult neurogenesis suggest that impaired neurogenesis should be considered as a target for the prevention of cell loss and restoration of neurological functions. Thus, stimulation of endogenous neurogenesis or cell-replacement therapy with stem cell-derived differentiated neurons raises new hopes for the development of effective and safe technologies for treating PD neurodegeneration. Given the rapid development of optogenetics, it is not surprising that this method has already been repeatedly tested in manipulating neurogenesis in vivo and in vitro via targeting stem or progenitor cells. However, niche astrocytes could also serve as promising candidates for controlling neuronal differentiation and improving the functional integration of newly formed neurons within the brain tissue. In this review, we mainly focus on current approaches to assess neurogenesis and prospects in the application of optogenetic protocols to restore the neurogenesis in Parkinson’s disease.

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