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Changes of the eExtracellular space diffusion parameters during acute pathological states in the rodent brain and the role of AQP4 channels in cell swelling
Dmytrenko, Lesia ; Vargová, Lýdia (advisor) ; Druga, Rastislav (referee) ; Rokyta, Richard (referee)
1. SUMMARY The diffusion properties of the extracellular space (ECS), which govern the movement of neuroactive substances through its volume and thus extrasynaptic transmission, are profoundly affected in states associated with cell swelling. In this work we compared ECS diffusion parameter changes during acute cell swelling in vivo in models of pilocarpine-induced status epilepticus (SE) and ischemia/anoxia evoked by cardiac arrest. To elucidate mechanisms involving the aquaporin 4 (AQP4) water channel in pathological cell swelling, we used models of hypotonic stress and elevated K+ in coronal slices of genetically modified mice. The ECS diffusion parameters volume fraction ( = ECS volume/total tissue volume), tortuosity factor (2 = apparent diffusion coefficient/free diffusion coefficient) and non-specific uptake (k') were determined by the real-time iontophoretic method, which was the primary method used in my thesis work. Changes in the activity-related extracellular K+ concentration ([K+ ]e) were measured using ion-selective microelectrodes. The apparent diffusion coefficient of water (ADCW) was determined by diffusion-weighted MRI. In both models in vivo, ECS volume fraction and ADCW decreased; these changes were more profound and their time course was faster during terminal ischemia/anoxia in...
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The role of ageing in the changes of the brain extracellular matrix and extracellular space properties
Kamenická, Monika ; Vargová, Lýdia (advisor) ; Růžička, Jiří (referee)
The process of aging causes the major changes in nervous tissue such as changes in the size of brain, architecture of glial cells and extracellular matrix. The size of brain is on the decrease as consequence of aging and there is a change of molecules as well as morphology at all levels. Extracellular space (ECS) is interstitium important especially in communication between cells mediated by diffusion. The limit of diffusion in extracellular space is given by size of ECS, which is discribed by volume fraction and tortuosity, that reflect amount of diffusion barriers. The changes of ECS diffusion parameters during aging were measured by real-time iontophoretic method in four parts of brain (cortex - Cx, hippocampus - Hp, inferior colliculus - IC and corpus trapezoideum - TB). Further, we studied influence of deficiency of Bral2 link protein at differences of ECS diffusion parameters and importance of Bral2 protein at aging and regulation mechanisms of cytotoxic brain edema. Our results show, that aging leads to decreasing of ECS volume v Cx and Hp, but it was not observed in IC and TB, where the intact perineuronal nets act like protecting shield against the degenerative disease induced by aging. However, small differences in composition of perineuronal nets, deficiency of Bral2 link protein, may...
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The use of induced pluripotent stem cells in the treatment of spinal cord injury and ALS.
Gajdoš, Roman ; Jendelová, Pavla (advisor) ; Vargová, Lýdia (referee)
Induced pluripotent stem cells (iPSCs) have become a new phenomenon of regenerative medicine. It is obvious that they share some common characteristics with embryonic stem cells (ESCs) such as stemness potential, self-renewal p., differentiation p. iPSCs retain their epigenetic memory, allowing becoming patient-specific and so it is not necessary to apply immunosuppressants. The use of ESCs is controversial, because their acquisition is associated with embryo destruction. As a cell source for iPSCs derivation we can use any somatic cells, however, fibroblasts are preferably used due to their easy availability. With transcriptional reprogramming cocktail (OCT4, SOX2, KLF4, c- MYC / OCT4, SOX2, NANOG, LIN28) we can obtain required iPSCs line, which is then further differentiated into neural precursors (NPCs). These cells can be grafted into lesion site, where they can facilitate regeneration by several mechanisms (cell replacement, protective effect, facilitation the expression of trophic factors). Nevertheless, here we are still dealing with the risk of tumorogenesis or low cell derivation efficiency that limits the use of iPSCs in clinical practice. In this thesis we will therefore mainly focus on the therapeutic potential of iPSCs in preclinical studies, their use in the treatment of...
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Astrocyte volume changes in alpha-syntrophin deficient mice
Mikešová, Michaela ; Anděrová, Miroslava (advisor) ; Vargová, Lýdia (referee)
(EN) The formation of brain oedema, which accompanies ischemic or traumatic brain injuries, originates from a disruption of ionic/neurotransmitter homeostasis that leads to extracellular K+ elevation and neurotransmitter accumulation in the extracellular space. An increased uptake of these osmotically active substances, predominantly provided by astrocytes, is accompanied by intracellular water accumulation via aquaporin-4 (AQP4). Since it has been shown that the removal of perivascular AQP4 via the deletion of α- syntrophin, which is the protein responsible for anchoring AQP4 on the astrocytic membrane (Neely et al. 2001), delays oedema formation and K+ clearance (Amiry-Moghaddam et al. 2003), we aimed to elucidate how the alpha-syntrophin deletion affects astrocyte volume changes in the cortex during pathological states, such as hypoosmotic stress or oxygen- glucose deprivation (OGD), using three-dimensional (3D) confocal morphometry in situ. In order to visualize individual astrocytes that lack alpha-syntrophin, double transgenic mice (GFAP/EGFP/α-Syn-/- ) were generated by crossbreeding GFAP-EGFP mice with α- syntrophin knockout mice. 3D-confocal morphometry revealed that alpha-syntrophin deletion did not alter astrocyte swelling during hypoosmotic stress or their recovery in isotonic solution;...
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Neurogenesis and gliogenesis after ischemic brain injury in EGFP/GFAP mice
Dlouhá, Veronika ; Anděrová, Miroslava (advisor) ; Vargová, Lýdia (referee)
Focal ischemia induces enhancement of neurogenesis/gliogenesis in the subventricular zone (SVZ) of the lateral ventricle and it also leads to glial scar formation in the vicinity of the ischemic lesion. The gliotic scar is mainly formed by reactive astrocytes that express glial fibrilarly acidic protein (GFAP), nevertheless this protein is also expressed in adult multipotent neural stem cells (NSCs). Therefore, we have used the strain of transgenic mice (GFAP/EGFP mice), in which the enhanced green fluorescent protein (EGFP) is expressed under human GFAP promoter in astrocytes as well as in NSCs, thus allowing us an immediate vizualization of these cells, and to estimate the effect of ischemic injury on their fate during proliferation and differentiation in vitro. Focal ischemia was induced by the occlusion of the middle cerebral artery (MCAO) and 3 days post injury, an immunohistochemical analysis was carried out. Furthermore, the cell isolation from SVZ and the region of gliotic scar was performed, followed by their cultivation under proliferative conditions (as neurospheres) and their differentiation for 7-10 days. The differentiation potential of these cells was studied using immunocytochemical analyses and patch clamp technique was employed to estimate their membrane properties. Based on increased...
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Astrocyte volume regulation during aging
Eliášová, Barbora ; Anděrová, Miroslava (advisor) ; Vargová, Lýdia (referee)
Astrocytes, as one of the glial cell types, have many important functions in healthy functioning of the central nervous system (CNS) but also in its pathology. Since they play a key role in maintenance of ionic, neurotransmitter and water homeostasis in CNS, they possess the ability to regulate their volume. Hypo- or hyperosmotic stress can trigger regulatory volume decrease or increase in astrocytes in order to stabilize their volume. During aging, astrocytes undergo many changes together with the rest of the brain. In order to determine whether these alterations involve also regulatory volume mechanisms, we employed three dimensional morphometry, which comprises confocal microscope scanning of fluorescently labelled astrocytes in brain slices of EGFP/GFAP mice and quantification of astrocyte volume during different pathological stimuli. Time-dependent volume changes of hippocampal astrocytes were recorded while applying either hypoosmotic solution or solution with high extracellular potassium concentration. In the four different age groups studied in the experiment, several differences in volume changes were discovered together with some sex-dependent alterations in astrocyte volume. Additionally, in accordance with previous studies, two subpopulation of astrocytes were identified using...
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The role of ageing in the changes of the brain extracellular matrix and extracellular space properties
Kamenická, Monika ; Vargová, Lýdia (advisor) ; Růžička, Jiří (referee)
The process of aging causes the major changes in nervous tissue such as changes in the size of brain, architecture of glial cells and extracellular matrix. The size of brain is on the decrease as consequence of aging and there is a change of molecules as well as morphology at all levels. Extracellular space (ECS) is interstitium important especially in communication between cells mediated by diffusion. The limit of diffusion in extracellular space is given by size of ECS, which is discribed by volume fraction and tortuosity, that reflect amount of diffusion barriers. The changes of ECS diffusion parameters during aging were measured by real-time iontophoretic method in four parts of brain (cortex - Cx, hippocampus - Hp, inferior colliculus - IC and corpus trapezoideum - TB). Further, we studied influence of deficiency of Bral2 link protein at differences of ECS diffusion parameters and importance of Bral2 protein at aging and regulation mechanisms of cytotoxic brain edema. Our results show, that aging leads to decreasing of ECS volume v Cx and Hp, but it was not observed in IC and TB, where the intact perineuronal nets act like protecting shield against the degenerative disease induced by aging. However, small differences in composition of perineuronal nets, deficiency of Bral2 link protein, may...
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The role of link proteins in the stabilization of the brain extracellular matrix and in formation and maintaining of the perineuronal nets
Suchá, Petra ; Vargová, Lýdia (advisor) ; Jendelová, Pavla (referee)
The brain extracellular space (ECS) contains specified macromolecules forming the extracellular matrix (ECM), containing a high amount of negative charges that could bind water or other soluble ions and molecules diffusing within the ECS. In specific brain areas, the ECM molecules form a condensed, reticular-like structure of perineuronal nets (PNNs). It has been found that PNNs appear at the end of the critical period, when they stabilize the synapses and terminate their plasticity and may have also neuroprotective function. To study the role of brain link protein 2 (Bral2) in stabilizing the ECM complexes, we employed the real-time iontophoretic method and immunohistochemical analysis to show the difference in the ECS diffusion parameters and level of expression of the ECM molecules between the wild type and Bral2-deficient mice. We also compared changes in the ECS diffusion parameters induced by Bral2 deficiency with those appeared after enzymatic destruction of the ECM by the chondroitinase ABC (chABC). In the Bral2-deficient mice, we discovered significantly decreased values of tortuosity in the trapezoid body. This difference was age related and did not manifest itself in young mice. Immunohistochemical analysis showed that inferior colliculus does not contain Bral2-brevican based...
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The use of induced pluripotent stem cells in the treatment of spinal cord injury and ALS.
Gajdoš, Roman ; Jendelová, Pavla (advisor) ; Vargová, Lýdia (referee)
Induced pluripotent stem cells (iPSCs) have become a new phenomenon of regenerative medicine. It is obvious that they share some common characteristics with embryonic stem cells (ESCs) such as stemness potential, self-renewal p., differentiation p. iPSCs retain their epigenetic memory, allowing becoming patient-specific and so it is not necessary to apply immunosuppressants. The use of ESCs is controversial, because their acquisition is associated with embryo destruction. As a cell source for iPSCs derivation we can use any somatic cells, however, fibroblasts are preferably used due to their easy availability. With transcriptional reprogramming cocktail (OCT4, SOX2, KLF4, c- MYC / OCT4, SOX2, NANOG, LIN28) we can obtain required iPSCs line, which is then further differentiated into neural precursors (NPCs). These cells can be grafted into lesion site, where they can facilitate regeneration by several mechanisms (cell replacement, protective effect, facilitation the expression of trophic factors). Nevertheless, here we are still dealing with the risk of tumorogenesis or low cell derivation efficiency that limits the use of iPSCs in clinical practice. In this thesis we will therefore mainly focus on the therapeutic potential of iPSCs in preclinical studies, their use in the treatment of...
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Changes of the eExtracellular space diffusion parameters during acute pathological states in the rodent brain and the role of AQP4 channels in cell swelling
Dmytrenko, Lesia ; Vargová, Lýdia (advisor) ; Druga, Rastislav (referee) ; Rokyta, Richard (referee)
1. SUMMARY The diffusion properties of the extracellular space (ECS), which govern the movement of neuroactive substances through its volume and thus extrasynaptic transmission, are profoundly affected in states associated with cell swelling. In this work we compared ECS diffusion parameter changes during acute cell swelling in vivo in models of pilocarpine-induced status epilepticus (SE) and ischemia/anoxia evoked by cardiac arrest. To elucidate mechanisms involving the aquaporin 4 (AQP4) water channel in pathological cell swelling, we used models of hypotonic stress and elevated K+ in coronal slices of genetically modified mice. The ECS diffusion parameters volume fraction ( = ECS volume/total tissue volume), tortuosity factor (2 = apparent diffusion coefficient/free diffusion coefficient) and non-specific uptake (k') were determined by the real-time iontophoretic method, which was the primary method used in my thesis work. Changes in the activity-related extracellular K+ concentration ([K+ ]e) were measured using ion-selective microelectrodes. The apparent diffusion coefficient of water (ADCW) was determined by diffusion-weighted MRI. In both models in vivo, ECS volume fraction and ADCW decreased; these changes were more profound and their time course was faster during terminal ischemia/anoxia in...
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