Applying combined optical tweezers and fluorescence microscopy technologies to manipulate cell adhesions for cell-to-cell interaction study.

Cell-to-cell interactions are important for the regulation of various cell activities, such as proliferation, differentiation, and apoptosis. This paper presents an approach to studying cell-to-cell interactions at a single-cell level through manipulating cell adhesions with optical tweezers. Experiments are performed on leukemia cancer cells and stromal cells to demonstrate the feasibility of this method. After the adhesion properties of leukemia cells on stromal cells are characterized, fluorescence intensity is used as a label to study the Wnt signaling pathway of leukemia cells. The activities of the Wnt signaling pathway of K562 cells on M210B4 and HS5 cells are examined based on fluorescence analysis. The reliability of the fluorescence imaging is confirmed through comparison with traditional flow cytometry analysis. The proposed approach will offer new avenues to investigate otherwise inaccessible mechanisms in cell-to-cell interactions.