Pathfinding by neuroblastoma cells in culture is directed by preferential adhesion to positively charged surfaces

Pathfinding is a fundamental behavior of migrating neuroblasts and advancing growth cones. We have analyzed this behavior in culture using mouse neuroblastoma (N1E-115) cells grown on a chemically patterned surface. The patterned surface was defined photolithographically and consisted of intersection 10-micron-wide pathways. The pathways were coated with positively charged amines and separated by regions bound with uncharged alkanes. Cells and growth cones were guided along the pathways and made choices at intersections. Whereas migrating cells made random choices at intersections, growth cones displayed a preference for advancing straight ahead. Interference reflection microscopy (IRM) revealed that pathfinding by cells and growth cones was correlated with greater overall attachment to aminated regions, although cell bodies and appendages also attached to adjacent alkanated regions. Thus guidance was not simply due to contact inhibition by alkanes; rather, it was due to "preferential" adhesion to aminated surfaces. Gray level analysis of IRM images demonstrated that focal and close contacts were made on both surfaces, indicating that preferential adhesion was not the result of tighter attachment to aminated surfaces. Fluorescent labeling of F-actin and microtubules indicated that preferential adhesion was not due to compartmentalization of these cytoskeletal structures on aminated regions. We propose that preferential adhesion involved a signal transduction mechanism that discriminated between positively charged and uncharged molecules. Such a mechanism could contribute to pathfinding by neuroblasts and growth cones along extracellular matrix proteins in vivo.