Transwell migration assay limitations and prevention of possible errors

The transwell migration assay is a commonly used test to study the migratory response of endothelial cells to angiogenic inducers or inhibitors.

To ensure optimal migration, you could try to put something on the transwell to promote and increase cell adhesion such as polylisine, fibronectin, and others. You simply coat the transwel before seeding cells (there are lots of protocols on the internet for this). Some cells are not able to adhere without this "help" and of course not migrate. However before proceeding with this, you must check if it could interfere with the cells that you're testing, and consequently with your experiments. Sometimes cells don't migrate if they're too sensitive and die easily without serum or some growth factor (even in low concentrations).