Neuronal Growth and Formation of Neuron Networks on Directional Surfaces

TL;DR

This study combines experimental and theoretical approaches to understand how neuronal axons grow and are guided by substrate geometry, revealing mechanisms that can inform tissue engineering and neural repair strategies.

Contribution

The paper introduces a model of axonal motility incorporating substrate-geometry sensing, supported by experimental data on cytoskeletal influences and contact-guidance mechanisms.

Findings

Axons follow geometrical patterns via contact-guidance.

Cytoskeletal dynamics are crucial for axonal steering.

Geometrical patterns induce high traction forces on growth cones.

Abstract

The formation of neuron networks is a process of fundamental importance for understanding the development of the nervous system and for creating biomimetic devices for tissue engineering and neural repair. The basic process that controls the network formation is the growth of an axon from the cell body and its extension towards target neurons. Axonal growth is directed by environmental stimuli that include intercellular interactions, biochemical cues, and the mechanical and geometrical properties of the growth substrate. Despite significant recent progress, the steering of the growing axon remains poorly understood. In this paper, we develop a model of axonal motility, which incorporates substrate-geometry sensing. We combine experimental data with theoretical analysis to measure the parameters that describe axonal growth on micropatterned surfaces: diffusion (cell motility) coefficients, speed and angular distributions, and cell-substrate interactions. Experiments performed on neurons treated with inhibitors for microtubules (Taxol) and actin filaments (Y-27632) indicate that cytoskeletal dynamics play a critical role in the steering mechanism. Our results demonstrate that axons follow geometrical patterns through a contact-guidance mechanism, in which geometrical patterns impart high traction forces to the growth cone. These results have important implications for bioengineering novel substrates to guide neuronal growth and promote nerve repair.