An agarose spot assay for chemotactic invasion

The directed motility of cells toward the source of a soluble chemical (chemotaxis) plays a role in events ranging from immune function to cancer progression. Numerous chemotaxis assays are commonly employed, yet none provides an optimal combination of the relevant parameters. The ideal chemotaxis assay for use in the analysis of cells crawling across a planar surface should be cost-effective, simple to perform, and suitable for high-throughput multiplexing, as well as permit alteration of experimental conditions during cell motility. Here we describe a novel chemotaxis assay based upon the invasion of cells into agarose spots into which chemoattractants are suspended. Our studies demonstrate that this system assays chemotaxis and not chemokinesis, and provide proof-of-principle for drug screening studies as well as analysis through high-resolution cellular imaging.