Imaging podosome dynamics and matrix degradation.

Invasive cell migration is critical for leukocyte trafficking into tissues. Podosomes are matrix-degrading adhesive structures that are formed by macrophages and are necessary for macrophage migration and invasion. Here, we describe methods for imaging and quantifying podosomes in primary human macrophages and in THP-1 cells, a monocyte cell line that can be differentiated to a macrophage-like state. Moreover, we outline detailed methods for live imaging of podosomes, which are highly dynamic, and for the quantification of rates of podosome turnover. Finally, we discuss methods for the quantitative analysis of matrix degradation on fluorescent-gelatin-coated cover slips.