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Browsing by Subject "light-activated"

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  • Light-activated liposomes as paclitaxel carriers and the optimization of a dynamic cell culture system 
    Mäki-Mikola, Eija (2020)
    Liposomes are nano-sized vesicles, that are composed of a phospholipid bilayer structure. They can be utilized as drug carriers, in which case the drug is incorporated either to their hydrophilic internal cavity, or into their hydrophobic bilayer structure. For anticancer drugs, liposomal formulations have exhibited their capability in reducing adverse effects of anticancer drugs. This is achieved mainly by the enhanced permeability and retention (EPR) effect, in which liposomes accumulate into tumour tissue. However, the conventional liposomes release their drug content passively, and a proportion of drug is distributed to off-target tissues. Therefore, there is a demand to develop liposomes from which the content can be released in a controlled manner, by an external stimulus. The objectives of this master’s thesis project were to determine the potential of light-activated paclitaxel (PTX) liposomes for the treatment of lung cancer, and to optimize a dynamic cell culture system, QuasiVivo® (QV), to study the off-target effects of light-activated PTX liposomes. The hypothesis was that the induction of the light-activated PTX liposomes would increase the efficiency of paclitaxel treatment. For QV experiments, it was expected that the presence of flow would improve the viability of the cells. The encapsulation efficiency of PTX into the liposomes and the effect of the PTX incorporation into the phase transition temperature of the liposomes were determined. The stability of liposomes was determined by monitoring the liposomal size and light sensitizer absorbance during a storage period. The cells of lung cancer cell line A549 were cultured inside QV system, and their viability was monitored with two commercial cell viability assays. Incorporation of PTX decreased the phase transition temperature, but the liposomes remained stable in the studied conditions. The PTX liposome treatments with and without light activation resulted in the similar efficacy as free PTX treatment did. A549 cells failed to display superior viability inside the QV compared to static conditions. Cells cultured under lower flow rate portrayed modestly higher viability. The light-activated PTX liposomes did not improve the efficacy of PTX treatment. Neither of the flow rates were optimal for A549 cells, as the variation between experiments was high. The EPR effect is the main reason for the improved effects of liposomal anticancer drugs, therefore, it is likely that in vivo experiments would elicit the differences between the efficacy of the liposomal and free PTX. The non-existent effects of light activation on the viability are likely caused by the low total concentration of the light sensitizer in the treatment solution.
  • Preparation of light-sensitive ICG-Doxorubicin liposomes and developing of Quasi-Vivo® -based two-cell model for drug efficacy and toxicity testing. 
    Haapalainen, Joonatan (2022)
    Traditional 2D cell cultivating vessels and experimental models cannot often simulate natural chemical and physical environment of different cell types. For example, availability of oxygen, chemical gradients, messaging molecules, fluid pressure, flow and surface topography are factors that may affect significantly in cell differentiation, growth, cellular structure, and metabolism. Modular bioreactors like Quasi-Vivo® -system can be used to simulate these factors. Liposomes are particles of phospholipid bilayer with aqueous space enclosed within. They can be modified in numerous ways, like loading them with hydrophobic and hydrophilic molecules, changing their transition temperature or coating them according to different needs. Doxorubicin is effective and widely used cytostatic agent, but when administered as a free drug it has often severe side-effects, like cardiotoxicity. Goal of this thesis is to determine appropriate manufacturing parameters and verify adequate shelf-life of ICG-Doxorubicin liposomes, that they are applicable for future in vitro experiments. Then survival of HepG2 cell line under flow in Quasi-Vivo®-equipment is determined, after which A549 and HepG2 will be then combined into one two-cell model. Finally, a simple illumination experiment in this cell model with previously made liposomes is conducted, and the effect in whole system is examined. Using protocol presented in this thesis it is possible to produce successfully and repeatedly liposomes with both ICG and doxorubicin encapsulation over 70%. Their shelf-life was at least 14 days when stored in 4°C protected from light. This was determined to be sufficient for in vitro testing. Cultivating A549 and HepG2 cell lines combined in the same system with shared media and fluid flow conditions was successful. Neither of the cell lines show significant difference in viability when compared to static control. When light-activating liposomes are administered to the system and then illuminated, from preliminary results we can see significant difference in drug effect. Both illuminated chambers and off-target chambers connected via Quasi-Vivo® show increased suppression, which shows promise that this in vitro model would be useful for future experiments.

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