Axon guidance of rat cortical neurons by microcontact printed gradients

Substrate-bound gradients play a crucial role in the axon guidance mechanism eventually leading to the development of complex neural circuits. In this study, the authors have grown single embryonic rat cortical neurons on a discontinuous substrate-bound gradient primarily comprising of laminin/poly-L-lysine (PLL) or PLL alone and examined the corresponding effects on neurite growth and axon guidance. Though different patterns of the substrate-bound gradient in terms of slope, width, and length had varying outcomes, they allowed neural adhesion, controlled neurite growth and guided up to 84% of the axons. The presence of laminin clearly had additional effects on both neurite growth and axon directionality when compared to PLL alone. The authors have thus mimicked the in vivo protein gradient conditions involved in creating defined neural networks during CNS development and successfully established an optimal model that could be used to guide axons of single multipolar neurons in vitro.