| Summary: | The failure rates of drugs once they reach clinical trials are high, with estimates up to nearly 90%. One reason is the lack of biologically relevant models in which potential drug candidates are screened, evaluated and selected during discovery and development phases. Leishmaniasis is a disease that suffers from this problem. Current therapies are weak, toxic and there is a growing problem of drug resistance. The aim of this thesis is to investigate different ways in which the current in vitro model systems could be made more predictive. Three methods of potentially improving reliability and predictability of in vitro models are investigated. Firstly, the differences between the media perfusion and static cell culture systems were studied. Using macrophages and L. major parasites, infections within the media perfusion system were optimised. The activities of standard drugs used for the treatment of leishmaniasis, were determined. A decrease in infection rates and in the activity of standard drugs was seen when using the media perfusion. Secondly, a 3D in vitro infection model was developed and used to determine the activity of standard drugs, compared with 2D cell culture. The model shows that 3D and 2D provide similar results for the activity of the standard drugs tested. Thirdly, a variety of macrophage cell types have been used as Leishmania host cells for intracellular amastigote assays. The use of macrophages differentiated from induced pluripotent stem cells was investigated as a viable and more predictive alternative. The option to use a cell type that is more biologically similar to the human in vivo situation, but can be maintained like cell lines, is a clear benefit to in in vitro assays. It was concluded that macrophages differentiated from induced pluripotent stem cells would be a suitable alternative to currently used cell types.
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