EFFECTS OF ORGANOSILANE MONOLAYER FILMS ON THE GEOMETRICAL GUIDANCE OF CNS NEURONS

This work reports on the alignment of central nerve processes using su rfaces of modified organosilane monolayer films. Two types of organosi lane monolayer films, formed of decyldimethylsiloxane (DDMS) or trimet hylsiloxane (TMS), were covalently formed on glass substrates. The fil ms were pattern modified with a synthetic peptide (P1543) derived from mouse laminin, an extracellular matrix (ECM) protein, via a combinati on of ultraviolet lithography and chemical modification technique. The modification procedure generated a pattern of 10-mu m-wide peptide st ripes that were surrounded by either DDMS films or TMS films. A signif icant difference between the two patterned substrates (DDMS/P1543 and TMS/P1543) was in hydrophobic properties of the surrounding surfaces: whereas the DDMS surrounding surfaces were more hydrophobic compared w ith the peptide surfaces, the TMS surrounding surfaces showed an equiv alent hydrophobic property to that of the peptide surfaces. Effects of the surrounding surfaces on the alignment of central nerve processes were investigated by growing neurons dissociated from embryonic rat hi ppocampi on the patterned DDMS/P1543 and TMS/P1543 substrates at a low density (40 cells/mm(2)) in a chemically defined culture medium. The time-lapse video microscopy revealed that although a similar bipolar m orphology was developed by the hippocampal neurons grown on both patte rned substrates, the growth behaviors of the nerve tips were highly af fected by physicochemical characteristics of the surrounding surfaces. The growing tips advanced straightforward along the peptide stripes w hen the surrounding surfaces were formed of DDMS films, whereas those often explored the surrounding surfaces formed of TMS films. Our work directly shows that although the attachment of neurons on patterned su bstrates is affected by hydrophobic characteristics of surrounding sur faces, the hydrophobicity is not a necessary factor for the neurite gu idance. We presume that localized chemical cues, such as laminin synth etic peptide, are rather crucial constituents that affect the directio nal outgrowth of central nervous system neurons.