Simultaneous
Generation of Gradients with Gradually
Changed Slope in a Microfluidic Device for Quantifying Axon Response
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Abstract
Over
the past decades, various microfluidic devices have been developed
to investigate the role of the molecular gradient in axonal development;
however, there are very few devices providing quantitative information
about the response of axons to molecular gradients with different
slopes. Here, we propose a novel laminar-based microfluidic device
enabling simultaneous generation of multiple gradients with gradually
changed slope on a single chip. This device, with two asymmetrically
designed peripheral channels and opposite flow direction, could generate
gradients with gradually changed slope in the center channel, enabling
us to investigate simultaneously the response of axons to multiple
slope gradients with the same batch of neurons. We quantitatively
investigated the response of axon growth rate and growth direction
to substrate-bound laminin gradients with different slopes using this
single-layer chip. Furthermore, we compartmented this gradient generation
chip and a cell culture chip by a porous membrane to investigate quantitatively
the response of axon growth rate to the gradient of soluble factor
netrin-1. The results suggested that contacting with a molecular gradient
would effectively accelerate neurites growth and enhance axonal formation,
and the axon guidance ratio obviously increased with the increase
of gradient slope in a proper range. The capability of generating
a molecular gradient with continuously variable slopes on a single
chip would open up opportunities for obtaining quantitative information
about the sensitivity of axons and other types of cells in response
to gradients of various proteins