Patients and sampling for ex vivo experiments

The study was conducted in accordance with the 1964 Helsinki Declaration and its later amendments and approved by the National Medical Ethics Committee of Slovenia, No. 101/11/14. The study population consisted of 10 patients with bladder cancer who underwent TURB in the Department of Urology, University Medical Centre Ljubljana, Slovenia. Informed consent was obtained from all patients prior to tissue retrieval.

For transmission electron microscopy (TEM), immuno-electron microscopy and lectin analysis of endocytosis ex vivo, a sample of the urothelial tumour was obtained from each patient by cold cup biopsies. For immunolabelling and lectin binding assays, normal urothelium was also taken cystoscopically 2 cm away from the tumour. The biopsies captured the urothelium and lamina propria. For pathological staging and grading of all samples, the pathologist (from the Institute of Pathology, Faculty of Medicine, University of Ljubljana) used the AJCC cancer staging manual (Amin et al. 2017). Urothelial cancers were diagnosed as papilloma (1 sample), non-invasive low-grade urothelial carcinoma-Ta, l. g. (3 samples), invasive low-grade urothelial carcinoma with invasion into the lamina propria-T1, l. g. (2 samples), invasive urothelial carcinoma high-grade with invasion into the lamina propria-T1, h. g. (2 samples) and invasive urothelial carcinoma high-grade with invasion into the muscularis propria-T2, h. g. (2 samples). Of ten cystoscopically normal urothelial specimens, six were classified as normal because histopathological examination revealed that they showed no signs of hyperplasia or dysplasia.