Filtration of malignant cells: tumour cell depletion in an ex vivo model using a leukocyte adhesion filter.

The clinical use of leukocyte adhesion filters is based on differentiated depletion of blood cells, although most of the mechanisms of filtration are still unclear. There is also evidence that leukocyte adhesion filters can remove disseminated tumour cells from patients' blood. The following proves this observation and consists of three parts: in the first part we analysed the depletion capacity of the LeucotrapWB filter medium (Pall) in an employed small-scale model for the cell line HT29 (colorectal origin) in phosphate-buffered saline (PBS) solution. A depletion rate of more than 99.6% for HT29 cells was seen. In the second part of the study, samples of whole blood were spiked with HT29 cells in a similar setting, showing comparable results. In the last part, defined cell suspensions of various human primary tumours were admixed to whole blood samples and afterwards filtrated in a scale-up model. Again, a nearly complete tumour cell reduction was seen after filtration. Results show a significant tumour cell reduction and, for most cases, a complete depletion of tumour cells independently from quality and origin of the tumour tissue. These experiments and further investigation are supposed to help to reduce the risk of dissemination of tumour cells in patients undergoing oncological surgery.