The effects of confinement on neuronal growth cone morphology and velocity

Abstract

Optimizing growth cone guidance through the use of patterned substrates is important for designing regenerative substrates to aid in recovery from neuronal injury. Using laser ablation, we designed micron-scale patterns capable of confining dissociated mouse cerebellar granule neuron growth cones to channels of different widths ranging from 1.5 to 12 μm. Growth cone dynamics in these channels were observed using time lapse microscopy. Growth cone area was decreased in channels between 1.5 and 6 μm as compared to that in 12 μm and unpatterned substrates. Growth cone aspect ratio was also affected as narrower channels forced growth cones into a narrow, elongated shape. There was no difference in the overall rate of growth cone advance in uniform channels between 1.5 and 12 μm as compared to growth on unpatterned substrates. The percentage of time growth cones advanced, paused, and retracted was also similar. However, growth cones did respond to changes in confinement: growth cones in narrow lanes rapidly sped up when encountering a wide region and then slowed down as they entered another narrow region. Our results suggest that the rate of neurite extension is not affected by the degree of confinement, but does respond to changes in confinement.

Modulation of Early Stage Neuronal Outgrowth through Out-of-Plane Graphene

“…Our results emphasize the key role played by protruding substrate features on GC morphology occurrence and size, as reported elsewhere. , We have found that small GCs are more frequent in NT-3DFGc and NT-3DFGnc. Furthermore, the size of large, branching and re-extending GCs is significantly reduced on such substrates.…”

Spatial confinement: A spur for axonal growth

“…This competition triggers a wealth of adaptive behaviors, described in a body of work using e.g., laminin spots deposited on a PLL background [35], PLL discs surrounded by IK [36] or semaphorin 3F [37] (figure 1b-c). Smirnov et al [38] and Liu et al [39] observed a similar phenomenon when GCs confined into narrow adhesive stripes enter a node or a larger surface of spreading, respectively. Both Zhao et al [36] and Ryu et al [37], using adhesive PLL disks of increasing diameters, reported that the spreading surface of the GC tend to match those of the discs.…”

“…Beyond these systematic studies, among the fastest neurite average growth were reported for 2 µm wide stripes (i.e., 0.6 µm/min [40] as compared to the ~0.03 µm/min reported for the longest neurite on 2D PLL substrates [58 Sun, 59 Santos]). A discordant note comes however from the work of Smirnov et al, which reports no difference in the overall rate of GC advance on adhesive stripes in the range 1.5-12 µm for postnatal mice cerebellar granule neurons [38].…”

LIM and SH3 protein 1 localizes to the leading edge of protruding lamellipodia and regulates axon development

“…In support of this hypothesis, LASP1 knockdown substantially impaired the axon outgrowth and branch formation of cultured hippocampal neurons over several days. Axonal outgrowth is achieved by rapid forward movement of the growth cone interspersed with pauses and retractions ( Smirnov et al. , 2014 ).…”