Scratch assays are a well-established, convenient and cost-effective in vitro method to analyze cell migration. This approach is particularly useful for studying the effects of cell-matrix and cell-cell interactions on cell migration, and for mimicking cell migration during wound healing or the formation of new blood vessels (angiogenesis) in vivo. Scratch assays can also be used for live-cell imaging during migration to monitor intracellular events, including the migration of both homogeneous cell populations and individual cells. The cell types typically cultured for use in scratch assays include fibroblasts, keratinocytes, epithelial or endothelial cells.
In vitro scratch assays involve introducing a ‘scratch’ (a gap) in the cell culture monolayer using one of three procedures:
- Manually scraping a tool through the culture
- Growing the culture in specifically designed culture wells
- Using a silicone insert to create a gap
After the scratch has been introduced, cell migration to close the gap occurs. Images are captured at the beginning and at regular intervals during the cell migration period, which are then compared to quantify the migration rate of the cells.