Non-Destructive Microfluidic Cell-Based Assay for Determining Cell Deformability as a Function of Epithelial-to-Mesenchymal Transition
Peyman Tavassoli, Lin Wang, Sunyoung Park, Hongshen Ma, Peter Black. University of British Columbia, Vancouver, BC, Canada
Background: The routine identification of circulating tumor cells (CTC) is based on cell surface expression of epithelial markers in the cancer cells. It is likely, however, that a subset of the most invasive CTC has lost expression of these epithelial markers in the process of epithelial-to-mesenchymal transition (EMT), a critical process that enables cells to detach from their primary site of growth, to invade and to metastasize. We have therefore developed a microfluidic device for the identification of CTC based on cell deformability. Here we aim to demonstrate that cell deformability depends on EMT status in bladder cancer cells.
Design: We have established a microfluidic technique for measuring the deformability of single cells. Cells are infused into a microfluidic channel and through a narrowing that requires cell deformation for passage. Using precisely controlled pressure, the cortical tension is determined by the liquid-drop model.
Zeb-1, a mediator of mesenchymal differentiation, was silenced in the highly invasive and mesenchymal cell line UC-13, while E-cadherin, the maker of epithelial differentiation, was silenced in UC-1. Differences in cortical tension and in invasive ability (matrigel invasion assay) were compared between these cells and the controls.
Results: UC-13 cells were less invasive after silencing of zeb1, and the mean cortical tension increased from 490 pN/µm to 837 pN/µm, representing a 1.7-fold increase in stiffness. Similarly, UC-1 cells were more invasive after silencing of E-cadherin, and the mean cortical tension decreased from 1198 pN/µm to 774 pN/µm, representing a 1.5-fold decrease in stiffness.
Conclusions: The non-destructive microfluidic cell-based assay enables us to measure the cortical tension of a variety of cells. We were able to demonstrate that cortical tension was inversely related to invasiveness of a bladder cancer cells, and both were dependent on EMT status. We therefore believe that EMT status will influence passage of CTC through our microfluidic cell sorting device, and aim to demonstrate this in ongoing work. This could be also potentially be used as a complementary test in for clinical cytology, especially in difficult samples such as urine cytology.
Monday, March 4, 2013 9:30 AM
Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 283, Monday Morning