Toxicity of cytostatic drug-loaded nanoparticles: The role of endocytosis
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Poly alkyl cyanoacrylate nanoparticles have caught interest because of its desireable properties, such as biocompatibility and biodegradability. They are relatively easy to make and can entrap molecules which make them great drug carriers. With the expanding field of nanomedicine, understanding the properties of these drug carrier nanoparticles is of high importance if they are to be used in chemotherapy. In this thesis cabazitaxel encapsulated in PIHCA nanospheres were used to study which mechanisms are involved in cellular uptake of the nanoparticle and the cytotoxic responses induced. Cell viability tests were used to study whether or not endocytosis was involved in the toxicity of the drug encapsulated in nanoparticles. MTT and CellTiter-Glo ® assays were utilized to this extent. Confocal fluorescence microscopy was used to investigate cabazitaxel’s effect on the cell cycle at various concentrations, the cells were marked with an fluorescent antibody for the cleaved form of PARP in order to study apoptotic cells. Results from these studies showed a reduction in the number of apoptotic cells and increase in the number of multinucleated cells with increasing concentrations of encapsulated cabazitaxel. The cells showed some protection against the toxicity of drug-loaded nanoparticles using specific inhibitors of endocytic pathways. ATP depletion resulted in a 10-fold increase in protection against the toxicity of the encapsulated drug. Cell viability assays indicated that the drug-loaded nanoparticles are dependent on endocytosis to elicit a toxic effect. The results show that actin-dependent endocytosis might be important in the toxicity caused by encapsulated cabazitaxel.