Compliance of hippocampal neurons to patterned substrate networks

Neuronal growth can be controlled in vitro by plating cells at low density and by differential adhesion between the cell and substrate. Primary cultures of rat hippocampal neurons were grown in serum-free culture on polylysine-coated glass coverslips patterned by selective laser ablation so as to leave grids of polylysine with varying linewidths (3, 5, and 10 microns), intersection distance (80, 120, and 160 microns), and nodal (intersection) diameter (5, 10, and 20 microns). Not only did somae strongly prefer the unablated polylysine areas, but they also migrated to loci where the local area of unablated polylysine was higher. These loci were the nodes, as opposed to the narrow connecting paths, and larger nodes, as compared with smaller nodes. Maximum migration to nodes of 88% occurred for a combination of 5-microns path width, 20-microns node diameter, and 80-microns path length. Daily observations indicated active migration to larger adhesive areas, which explains the differential compliance.