A dual compartment diffusion chamber for studying axonal chemotaxis in 3D collagen

During nervous system development growing axons are often guided by diffusible chemical gradients. An important contribution to our understanding of the mechanisms involved in this process has been made by in vitro assays. However, an inexpensive and simple assay which allows the establishment of stable and reproducible gradients in a 3D collagen environment has been lacking. Here we present a simple two-compartment diffusion chamber for this purpose. We show that gradient steepnesses of up to 2% are achieved within 1. h post setup, and a gradient persists for at least 2 days. We demonstrate the assay by showing robust chemoattraction of dorsal root ganglion neurites by gradients of nerve growth factor (NGF), and chemorepulsion of olfactory bulb neurites by gradients of Slit2