Central neuronal synapse formation on micropatterned surfaces

Controlling synapse formation is a key to patterning of neurons into functi onal circuits and networks in vitro. However, the process of synapse format ion among neurons grown on artificial surfaces is relatively unstudied. We cultured embryonic hippocampal cells on trimethoxysilylpropyl-diethylenetri amine (DETA) and tridecafluoro-1,1,2,2-tetrahydrooctyl-1-dimethylchlorosila ne (13F), and on patterns composed of DETA lines separated by 13F spaces. F or comparison, neurons were concurrently plated on surfaces coated with uni form poly-D-lysine (PDL). Pre- and postsynaptic specializations were identi fied by immunostaining for synapsin I and microtubule-associated protein-2 (MAP-2). Spontaneous (SPCs) and evoked (EPCs) postsynaptic currents were re corded using dual patch-clamp techniques. We found that DETA promoted synap se formation, whereas evidence for synapse formation on 13F was barely dete cted. MAP-2(+) neuronal soma and rapidly growing dendrites were co-localize d with synapsin I puncta faithfully along DETA lines. The expression of syn apsin I puncta, and MAP-2(+) soma and dendrites correlated well with the ap pearance of SPCs. Synapsin I, MAP-2 and SPCs emerged together at days 3-4 a nd increased at day 7, when EPCs appeared. Synaptic signals occurring durin g 4-7 days in culture were all GABAergic. These results indicate that fully functional synapses are formed on silane surfaces, demonstrating the suita bility of patterned silane surfaces for organizing synapse formation in vit ro. (C) 1998 Published by Elsevier Science B.V. All rights reserved.