Investigation and characterization of MP derived from media conditioned by various cancer cell lines and their effect on human umbilical vein endothelial cells (HUVECs) under static and flow conditions

Microparticles (MP) are procoagulant due to tissue factor and phospholipid exposure on the surface. MP are tumour-derived and can be a beneficial biomarker of cancer to recognize individuals who are susceptible to venous thrombosis. The aim of the presented work was to develop and validate an in vitro microfluidic system consisting of two distinct microfluidic biochips to enable the investigation of the relationship between tumour MP and endothelial cells in vitro. Firstly, a range of tumour cell lines were assessed for procoagulant activity (PCA) of the cells and also MP released into the media. Pancreatic AsPC-1, human glioma U87 ovarian ES-2 and SKOV-3, were found to have the highest PCA in both cell suspension and cell- free media, while pancreatic MIAPaCa-2 and ovarian A2780 had a lower PCA. Cell lines were then investigated as to whether or not they could form stable spheroids in 3D cell culture U87, AsPC-1 and ES-2 produced the most compact spheroids and had the fastest PCA. In contrast, PANC-1, MIAPaCa-2 and A2780 formed loose shaped spheroids and slower PCA. However, SKOV-3 showed small compact spheroid and slower PCA. Following the application of media flow, ES-2 and U87 were selected and transferred into the developed dual microfluidic biochips model. Labelled MP were quantified via flow cytometry and this showed MP concentration reduced over time suggesting attachment of tumour MP to HUVECs. This reduction in MP was further reflected with a loss of PCA associated with the media. The effect of Doxorubicin on tumour spheroids resulted in an increased PCA of an endothelial cell layer under flow condition. In conclusion, in this study a microfluidic two-chip dynamic model mimics the interstitial fluid flow showed that tumour MPs released from tumour spheroids attach to endothelial cells and potentially could be a mechanism of clot formation in cancer patients