as shown in Supplemental Movie 1. For example, some mitochondria were largley static while others moved at high speed, some stopped abruptly before continuing to move, or reversed direction entirely. Overall, the micropatterned neurons cultured for 100 days showed a decrease in mitochondrial motility towards the anterograde direction in comparison with neurons at day 40, while the percentage of stationary mitochondria was greater in neurons at day 100 compared to day 40. Approximately one-half of the mitochondria were stationary in neurites at day 40 and day 70, whereas 70% were stationary at day 100. These results demonstrate the feasibility of quantitating mitochondrial dynamics in human neurons cultured on micropatterned surfaces over long periods. The transport of organelles, e.g. mitochondria, is particularly important in neurons, because their functions are needed throughout the axon. Defects in axonal transport are thus of special interest to degenerative diseases of the nervous system.
