Long-term maintenance of patterns of hippocampal pyramidal cells on substrates of polyethylene glycol and microstamped polylysine

For neurons to attach and remain in precise micropatterns for weeks in culture, background molecules that remain nonpermissive for extended culture durations need to be identified. Nonpermissive background molecules of either polyethylene glycol (PEG) or the amino acid serine (C ₃H ₇NO ₃) were evaluated. The foreground regions were microstamped with 3-, 5-, or 10-μm lines of poly-D-lysine (PDL), which promotes neural attachment and growth. After 29 days in culture the foreground compliance, or the fraction of all live somata which rested on the desired PDL surface, averaged 86% for serine and 90% for PEG, with only a small decline. The background compliance, or the fraction of square areas in the pattern background which were free of neurite extension, declined from highs of 40% and 55% (midculture) to 5.5% and 12% (29 days) for serine and PEG, respectively. Images of the cultures suggest that PEG is significantly more effective as a nonpermissive substrate. The authors conclude that these materials, especially PEG, are adequate for the maintenance of long-term patterned cultures of neurons. They believe that this is the first report of high-quality long-term patterning of cultured neurons.