Microfluidic isolation and characterisation of bladder cancer cells from urine for early and non-invasive diagnosis of bladder cancer

Bladder cancer has one of the highest recurrence rates among cancers and requires lifelong surveillance. Cystoscopy and urine cytology are the “gold standard” for bladder cancer detection but have well-known limitations. Thus, new methodologies to early identify and characterise various bladder cancers and their true biological potential are urgently needed. In this work, rare tumour-associated cells from body fluids of bladder cancer patients were isolated and characterised, using a microfluidic device. Importantly, cell capture was based on deformability and size, so that all cancer cells were trapped, regardless of their phenotype. Results show that in spiking experiments of HT1376 bladder cancer cells with peripheral blood mononuclear cells, the microfluidic platform reached an isolation efficiency of around 50% and an enrichment ratio of 22. Additionally, bladder wash and urine samples collected from bladder cancer patients subjected to transurethral resection were immunostained in situ with the following identifying markers: pan-cytokeratin (epithelial), vimentin (mesenchymal), survivin (malignancy), DAPI (nucleus) and CD45 (leukocyte). Notably, survivin, pan-cytokeratin and vimentin positive cells were found both in bladder wash and urine samples of a patient diagnosed with high-grade non-invasive papillary urothelial carcinoma (stage Ta). In contrast, for another patient diagnosed with low-grade carcinoma, survivin could not be detected in any sample, and vimentin positive cells were only present in the bladder wash. Overall, our findings revealed the phenotypic diversity of cancer cells in body fluids, likely relevant for patient treatment and follow up and pave the way for the realisation of a liquid biopsy for bladder cancer.