transwellmigration

Transwell migration is an in vitro assay used to quantify the migratory capacity of cells. It employs a two-chamber setup separated by a porous membrane. Cells placed in the upper chamber may move through the pores to the lower chamber in response to chemoattractants or other stimuli, providing a measure of cell motility.

The assay is typically performed with a permeable membrane insert in a multiwell plate. A chemoattractant or serum-containing medium is added to the lower chamber, while cells are placed in the upper chamber in serum-free or low-serum conditions. After an incubation period, which can range from a few hours to about a day, non-migrated cells on the upper surface are removed, and cells that have traversed the membrane and reside on the lower surface are fixed and stained. Migration is quantified by counting migrated cells under a microscope or by measuring dye or fluorescence associated with the stained cells. Some protocols elute the dye for spectrophotometric or fluorometric readouts.

Variations include the invasion assay, which uses a Matrigel or ECM-coated membrane to require degradation of extracellular matrix, providing a measure of invasive capacity. Pore size, coating, and incubation time can influence results and should be chosen to suit the cell type.

Applications of transwell migration include studying cancer cell motility, immune cell trafficking, angiogenesis, wound healing, and screening effects of drugs or genetic perturbations on migration. Limitations include the artificial nature of the setup and potential confounding effects of proliferation; appropriate controls are essential for interpretation.