Microcarrier bead assay is another technique to conduct studies based on cell model. Due to the extremely high surface area to volume radio of micrraiers, this technique has raised much more attention and interests than conventional monolayer cell culture methods. It has been widely used in cell-based experiments including angiogenesis assays, cell infectivity and cell migration. This technique to research cell migration can be more closely mimicking the tight contact of cells in vivo, since cells can establish close cell-cell interactions on the bead in this assay.