Controlled outgrowth of dissociated neurons on patterned substrates

Abstract

The cytoarchitecture of nervous tissue is lost during the dissociation procedures used to form primary cell cultures. As a first step toward reestablishing an ordered arrangement of these cells in vitro, we developed a set of procedures for patterning the outgrowth of cells cultured on 2-dimensional substrates. These procedures used a combination of surface chemistry and photolithographic techniques. The adhesive properties of either silicon or silicon dioxide (quartz) surfaces were controlled by covalently binding small organic molecules to the surface with silane coupling agents. The attachment and growth of either embryonic mouse spinal cells or perinatal rat cerebellar cells were found to be promoted by binding certain amine derivatives to the surface. In particular, cells grown on surfaces bound with diamines and triamines, but not with monoamines, formed cultures whose morphology was similar to that of cells cultured on conventional substrates, i.e., glass coated with poly(D-lysine). The attachment of cells to a substrate was inhibited by binding alkane chains (e.g., n-tetradecane) to the surface and plating the cells in media containing 5-10% (vol/vol) serum. Patterns of selected adhesivity were formed using photochemical resist materials and lithographic masking techniques compatible with the silane chemistry. Cultures of either spinal cord cells or cerebellar cells could be confined to square regions on the scale of 50 micron. Cerebellar cells could be confined to grow on lines with widths less than 10 micron. This width is comparable to the diameter of granule cell somata. The patterned growth of cerebellar cells was maintained up to 12 d in vitro. Over this time period the granule cells were observed to develop electrical excitability and immunoreactivity for neuron-specific enolase. Purkinje neurons also developed electrical excitability when grown on the chemically modified surfaces. Immunochemical reactivity of the patterned cultures for glial fibrillary acid protein (GFAP) showed that glia are patterned along with the associated granule cells. Interestingly, the GFAP-positive glia that proliferated on surfaces bound with amine derivatives attained primarily a tile-shaped, fibroblast-like morphology, while those proliferating on glass coated with poly(D-lysine) developed primarily a spindle-shaped, process-bearing morphology. Granule cells preferentially associated with the spindle-shaped glia.