Assay for Neuronal Cell Migration

Chemoattractant-induced neuronal migration can be directly and quantitatively evaluated in vitro, using a microchemotaxis assay. This assay has been used to quantitate the chemotropic responses of several migratory cell types, including neutrophils (Harvath et al., 1980 ; Geiser et al., 1993 ), monocytes (Reinisch et al., 1993 ), melanoma cells (Stracke et al., 1989 ), and smooth muscle cells (Higashiyama et al., 1993 ). In general, relatively low concentrations of attractants (nM -fM ) typically stimulate migratory responses in the greatest number of cells (Stracke et al., 1989 ; Yao et al., 1990 ; Grant et al., 1992 ; Hendey et al., 1992 ; Rot et al., 1992 ; Shure et al., 1992 ; Geiser et al., 1993 ; Higashiyama et al., 1993 ; Reinisch et al., 1993 ). In this assay, cells are acutely dissociated from the developing nervous system, and resuspended in buffer. The suspension of dissociated cells is placed in the upper half of a microchemotaxis chamber, soluble chemoattractants are placed in the bottom half of the chamber, and the cells are separated from the chemoattractants by a membrane containing 8-�m pores. Cells induced to migrate squeeze through the pores, then adhere to the underside of the membrane, which is precoated with substrates to promote cell adhesion.