Browsing by Subject "veri-aivoeste"

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  • Viljakainen, Tuulikki (Helsingfors universitet, 2019)
    Parkinson’s disease is a progressive neurodegenerative disease, in which dopamine neurons are dying in the nigrostriatal dopaminergic pathway. This causes motor symptoms such as slowness of movement, tremor, and rigidity. In addition, various non-motor symptoms appear. All currently used medicines are symptomatic, and there are no disease modifying treatment available for Parkinson’s disease. Several neurotrophic factors have shown promise in animal models of Parkinson’s disease. One of those is cerebral dopamine neurotrophic factor (CDNF) which has been studied in different animal models, including rodents and non-human primates. CDNF is a secreted protein but it is also localized in endoplasmic reticulum (ER). CDNF has two domains, N-terminal and C-terminal, which may have distinct functions. CDNF can be retained in the ER by the ER retention sequence at the end of the C-terminal domain. The C-terminal domain also has an evolutionarily conserved disulfide bridge which is crucial for the biological activity of CDNF. The exact mechanism of CDNF is still unknown. However, it has been shown that CDNF affects the unfolded protein response (UPR) in the presence of ER stress. Neurotrophic factors do not penetrate blood-brain barrier (BBB), for this reason, they need to be injected directly to the brain. Penetration of the BBB is also a problem in the treatment of many other diseases. Various methods for enhancing the BBB penetration of drugs have been studied. For example, permeability of the BBB can be temporarily increased by focused ultrasound combined with microbubbles. Another possibility is the use of a carrier molecule, which can be transported through BBB via specific transport mechanisms. Furthermore, molecule modification offers many applications to achieve enhanced BBB penetration. In view of peripheral administration, a next generation variant of CDNF (ngCDNF) has been developed. The efficacy of this novel variant after intrastriatal injection is equal to that of CDNF in a 6-hydroxydopamine (6-OHDA) rat model of Parkinson’s disease. Systemic administration could also enable treatment of non-motor symptoms of Parkinson’s disease. The aim of this experiment was to study the effects of subcutaneously injected ngCDNF on rotation behaviour, and nigrostriatal TH-positive cells in rats with 6-OHDA lesions. 6-OHDA was injected unilaterally to three different sites in the striatum. Two weeks later, the lesion size was estimated, via amphetamine- induced rotation test. ngCDNF, at two dose levels, was injected twice weekly for three weeks. Amphetamine-induced rotation test was assessed every other week, until week 12. At the end, optical density of tyrosine hydroxylase (TH) was measured from sections of the striatum, and TH positive cells in the substantia nigra were counted. In addition, the effect of ngCDNF on anxiety and depression like behaviour, learning, and locomotor activity were studied at three different levels in naïve mice. Behaviour was analyzed by open field test, forced swim test, and fear conditioning test. The ngCDNF did not seem to have clear effect on rats’ behaviour or TH positive cells and fibers compared to the control group, but positive tendency was found in the group with lower dose. The reduced efficacy of ngCDNF,via subcutaneous administration, is likely due to rapid metabolism and insufficient entry of the active form to the brain. In naïve mice, ngCDNF did not reduce anxiety-like behaviour and did not affect locomotor activity after subcutaneous injections. This result supports previous findings, which suggest that the effects of CDNF are specific to the toxin treated cells and CDNF has no effect in naïve animals.
  • Sipola, Kirsi (Helsingin yliopisto, 2021)
    Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder caused by degeneration of motor neurons in brain and spinal cord. The degeneration of motor neurons leads to muscle atrophy and paralysis. Currently there is no cure for ALS. Available drugs for ALS can lengthen the survival time by a couple of months. Several factors involve the pathophysiology of ALS, such as endoplasmic reticulum stress and neuroinflammation. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a protein which has shown neuroprotective effects on animal models of Parkinson disease and brain ischemia. C-terminal fragment of MANF can cross the blood-brain barrier, allowing it to be administered subcutaneously instead of injected directly into the brain. The experimental part consists of two parts. The aim of the first part was to study the pharmacokinetic properties of next generation MANF (C-MANF). The aim of the second part was to elucidate the effect of twice a week administered subcutaneous injection of C-MANF in genetic SOD1-G93A mouse model and its neuroprotective effects by assessing protection of lumbar motor neurons. Pharmacokinetic properties of C-MANF were determined in wild type mice after a single subcutaneous injection of C-MANF at different time points by using indirect ELISA assay. The effects of C-MANF in SOD1-G93A mouse model were assessed by subcutaneous injection of either C-MANF or PBS twice a week and by monitoring clinical score and motor behavior of mice from 10 weeks of age to clinical endpoint. Hematoxylin eosin staining was used to study neuroprotective effects of C-MANF. C-MANF administered subcutaneously is absorbed into the blood circulation and the highest serum concentration of C-MANF is after 60 minutes of dosing. Subcutaneously injected C-MANF also crosses the blood-brain barrier and reach the brain in 120 minutes. C-MANF did not preserve motor function or ameliorated ALS symptoms in SOD1-G93A mouse model. In this study C-MANF did not increase the survival of SOD1-G93A mice. C-MANF did not significantly protect motor neurons from degeneration even though there was a slight trend between the groups. No beneficial effects were observed with C-MANF in SOD1-G93A mouse model and therefore the dose and frequency of administration of C-MANF were not optimal. Subcutaneously injected C-MANF provides a safer dosing option for neurodegenerative disorders.
  • Sjöstedt, Noora (Helsingfors universitet, 2011)
    The blood-brain barrier (BBB) is a unique barrier that strictly regulates the entry of endogenous substrates and xenobiotics into the brain. This is due to its tight junctions and the array of transporters and metabolic enzymes that are expressed. The determination of brain concentrations in vivo is difficult, laborious and expensive which means that there is interest in developing predictive tools of brain distribution. Predicting brain concentrations is important even in early drug development to ensure efficacy of central nervous system (CNS) targeted drugs and safety of non-CNS drugs. The literature review covers the most common current in vitro, in vivo and in silico methods of studying transport into the brain, concentrating on transporter effects. The consequences of efflux mediated by p-glycoprotein, the most widely characterized transporter expressed at the BBB, is also discussed. The aim of the experimental study was to build a pharmacokinetic (PK) model to describe p-glycoprotein substrate drug concentrations in the brain using commonly measured in vivo parameters of brain distribution. The possibility of replacing in vivo parameter values with their in vitro counterparts was also studied. All data for the study was taken from the literature. A simple 2-compartment PK model was built using the Stella™ software. Brain concentrations of morphine, loperamide and quinidine were simulated and compared with published studies. Correlation of in vitro measured efflux ratio (ER) from different studies was evaluated in addition to studying correlation between in vitro and in vivo measured ER. A Stella™ model was also constructed to simulate an in vitro transcellular monolayer experiment, to study the sensitivity of measured ER to changes in passive permeability and Michaelis-Menten kinetic parameter values. Interspecies differences in rats and mice were investigated with regards to brain permeability and drug binding in brain tissue. Although the PK brain model was able to capture the concentration-time profiles for all 3 compounds in both brain and plasma and performed fairly well for morphine, for quinidine it underestimated and for loperamide it overestimated brain concentrations. Because the ratio of concentrations in brain and blood is dependent on the ER, it is suggested that the variable values cited for this parameter and its inaccuracy could be one explanation for the failure of predictions. Validation of the model with more compounds is needed to draw further conclusions. In vitro ER showed variable correlation between studies, indicating variability due to experimental factors such as test concentration, but overall differences were small. Good correlation between in vitro and in vivo ER at low concentrations supports the possibility of using of in vitro ER in the PK model. The in vitro simulation illustrated that in the simulation setting, efflux is significant only with low passive permeability, which highlights the fact that the cell model used to measure ER must have low enough paracellular permeability to correctly mimic the in vivo situation.
  • Salovuori, Noora (Helsingfors universitet, 2019)
    Background and objectives: Cells secrete extracellular vesicles (EV) and it has been found that cells communicate via EVs. EVs are liposome-like vesicles. Membrane is consisting of a lipid bilayer and hydrophilic moiety is inside the vesicle. It has been found that EVs carry e.g. nucleic acids, lipids and proteins. The aim of this master thesis was to determine whether EVs can transport non-coding RNA (siRNA) into the central nervous system through the blood-brain barrier. In the literature review, investigated methods which has been used to load siRNA into the EVs and how EVs are transported through the blood-brain barrier. The aim of the experimental part was to produce and isolate EVs and to load FAM-labeled dsDNA and siRNA into EVs by physical methods such as sonication and electroporation. Fluorescence measurements were taken to demonstrate FAM-labeled DNA loading into EVs and the functionality of the siRNA-loaded EVs was measured by measuring the expression level of the gapdh gene. Methods: Extracellular vesicles were produced in ARPE-19 and PC-3 cells. EVs were isolated from the cell culture medium by two-step differential centrifugation (DC) and further purified by gradient centrifugation (GC) by using the OptiPrep™-reagent. OptiPrep™-reagent was purified by Amicon 10kDa filtration tubes. The average particle size and size distribution of the isolated EVs were determined by NTA analysis, protein concentration was measured by colorimetric BCA method and EVs were characterized by Western blot method using HSP70 and CD9 antibodies. EVs were loaded with 21 bp length FAM-labeled dsDNA or siRNA by sonication or electroporation. Free nucleic acid and OptiPrep™-reagent were purified from EVs by the size-exclusion chromatography with Sephacryl (S-300) column. Loading efficient of the EVs were studied by measuring the fluorescence (ex 485 nm, em 520 nm) and qPCR method was used to demonstrate the functionality of the siRNA loaded EVs. In qPCR, the expression level of the gapdh gene was measured in dividing ARPE-19 cells. Results: DC and GC purified ARPE-19 and PC-3 EVs had an average particle size of about 140 nm and were successfully characterized by Western blot method. PC-3 EVs were produced in the bioreactor and the yields were enough for loading experiments. ARPE-19 cells produced only small amounts of EVs in culture flasks. The size-exclusion chromatography was a good method to purification free nucleic acids from EVs. The sonication method did not cause EVs to be degradation under the conditions used. Based on fluorescence measurement, FAM-labeled dsDNA could not be loaded into EVs. The functionality of siRNA-loaded EVs could not be demonstrated in ARPE-19 cell experiments. After electroporation large number of EVs were lost and this method of loading siRNA into EVs did not proved to be suitable. Conclusions: ARPE-19 EVs must be produced in the bioreactor to produce enough EVs for loading experiments. The EV purification protocol should be further optimized since the recovery-% of EVs were low after several purification steps. The size-exclusion chromatography is suitable for the purification of the free siRNA from EVs, but the chromatography method needs further optimization and miniaturization. Loaded EVs should be produced by aseptically or alternatively sterilized prior to ARPE-19 cell assay. Physical loading method, such as sonication, can be scaled to larger scale. Sonication method should be optimized e.g. by experimenting with higher temperatures and longer sonication times. The probe sonicator should be tested instead of the water bath sonicator. According to the literature review, the use of extracellular vesicles as carriers for biomolecule delivery into the central nervous system seems to be promising.
  • Juuti, Hanne (Helsingfors universitet, 2010)
    The blood-brain barrier protects brain from xenobiotics that are in blood. Different in vivo and in vitro methods have been developed for studying blood brain barrier and those can be found in the literature. There are only few computational models pharmacokinetics of compounds in the brain. In this study permeability factors, which were measured in vitro or in vivo, were collected from literature. Additionally two different pharmacokinetic computer models of blood-brain barrier were described. One of which is called microdialysis model and the other efflux model. Microdialysis model is a very simple two compartmental model, the compartments being the blood and the brain. Five substances were simulated according to the values measured in vivo in rat. The model did not correlate well with the in vivo results, because of the simplicity of the model as the model missed the compartment of brain tissue and the kinetics of transporters. Efflux model has three compartments, blood, blood brain barrier endothelial cells and brain. The model was used to study the impact of the of efflux transporter at the luminal barrier of endothelial cells and passive permeability to the steady-state concentration of a compound in the brain extracellular fluid with theoretical simulations. The relation between free drug concentrations in blood and brain extracellular fluid (Kp,uu) was studied. The impact of Michaelis-Menten kinetics of efflux transporter to the concentration of compound was shown in the results. The efflux model is suitable for theoretical simulations. It is possible to add new active transporters. With theoretical simulations the results from in vitro and in vivo studies can be combined and the different factors can be studied in one simulation.