Liposomal drug carrier systems for inhalation treatment of lung cancer ; Liposomale Arzneistoffträgersysteme für die Inhalationsbehandlung des Lungenkrebses

Goal of this PhD project was the development of a novel anti-cancer therapy by using aerosols of Tf-modified liposomes for a local, thus less problematic, treatment of lung tumours. Since not much published data was available, the first step was to estimate the expression levels of TfR on cells originating from lung cancer, as well as from healthy lung tissues. The data show that TfR expression levels in healthy alveolar epithelial cells in primary culture were significantly lower than in A549 cells, a cell line derived from an adenocarcinoma of the distal lung. TfR expression levels in the continuously growing bronchial epithelial cell lines, Calu-3 and 16HBE14o-, were again significantly higher than those observed for the alveolar cell types. In general, all cell types showed TfR molecules located predominantly at their basolateral membranes, but cells undergoing mitotic proliferation at the time of fixation showed an additional strong signal for TfR on their apical aspect as well, due to the loss in cell polarity. After validating the applicability of TfR as a target molecule for our strategy, in an attempt to produce Tf-modified liposomes, three different linker lipids (DSPE-PEG2000-maleimide, N-glutaryl-PE and DSPE-PEG2000-COOH) were used. Many protocols have been published on the conjugation of proteins to surfaces of liposomes, but (visual) data on the quality and quantity of the claimed modifications are scarce. We successfully used atomic force microscopy (AFM) and transmission electron microscopy (TEM) as novel tools to visualise the actual conjugation of transferrin to the liposomal carrier. In addition, to quantify the conjugation efficiency, BCA-assays were performed and the phospholipid concentration was measured spectrophotometrically according to Stewart's method. The obtained date were then compared to the AFM and TEM results. The third step of the project was to test if the developed Tf-liposomes were actually able to delivery the payload to cancer cells at a higher rate than to their healthy ...