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Browsing by Subject "retina"

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  • Kosma, Oona (2016)
    The leading causes of vision loss in developed countries are related to the impairment of the posterior segment of the eye. The drug delivery to the posterior segment with topical or systemic methods is challenging due to the protective barriers of the eye. The conventional and effective technique to deliver therapeutic concentrations of drugs to the posterior segment is intravitreal injection. Since naked molecules usually have a rapid vitreal clearance, the invasive injections need repeated administration in chronic conditions, resulting to increased risk of complications and poor patient compliance. The growing field of research of drug delivery systems, such as implants, nano- and microparticles and liposomes emphasizes to answer these challenges by enhancing time-controlled and targeted drug release to retinal and choroidal tissues, enabling less frequent administration and reduced off-target side effects. Liposomal drug delivery systems have potential in delivering therapeutics to posterior eye tissues in sustained and targeted manner. The experimental part of the thesis focused on studying the cell uptake, content release and cytotoxicity of light triggered pH-sensitive gold nanoparticle liposomes in human retinal pigment epithelial (ARPE-19), human umbilical vein endothelial (HUVEC) and monkey choroidal endothelial (RF/6A) cell lines. To enhance the cell differentiation to resemble the in vivo morphology, ARPE-19 cells were also used as a filter-cultured model. HUVEC cells were cultured on an artificial basement membrane matrix and induced with vascular endothelial growth factor (VEGF) to form capillary like tube structures. The liposomes were not cytotoxic during 24-hour incubation. All cells internalized liposomes to some extent, but in HUVEC capillary tubes the uptake seemed to be negligible. The light induced calcein release was variable between the experiments, possibly due to the study setting related factors, such as difficulties in temperature control. The liposomal carrier system has promising attributes to posterior eye drug delivery. Liposome-encapsulation prolongs the half-live of a drug. Light triggered release and pH-sensitivity enables highly targeted intracellular drug release decreasing the off-target side effects. Optimization of the study arrangement and liposome production procedure is needed in order to get more reliable results and further assess the future potential of these liposomes in the treatment of posterior eye diseases.