Modifications to the Transwell Migration/Invasion Assay Method That Eases Assay Performance and Improves the Accuracy

Migration is a key property of live cells and critical for normal development, immune response, and disease processes such as cancer metastasis and inflammation. Methods to examine cell migration are especially useful and important for a wide range of biomedical research such as cancer biology, immunology, vascular biology, cell biology, and developmental biology. In vitro assays are excellent approaches to extrapolate to in vivo situations and study live cells behavior. The aim of this article is to discuss the existing methods for transwell migration/invasion studies, the problems associated with this assay, and proposed modifications to this methodological approach that makes it simple to perform and improve the assay accuracy. Results of our studies demonstrated that the count of cells that had grown on top of the membrane is important to accurately evaluate the percentage of migrated/invaded cells. The results also showed that the transparent transwell insert with 4',6-diamidino-2-phenylindole (DAPI) stained cells is the best approach to ease the analysis of cell numbers on top of the membranes. In addition, the overlay of bright light (representing membrane pores) and DAPI images can further improve the accuracy of cell count. All these modifications in combination simplify the assay performance and improve the accuracy of the transwell migration assay method.