A microfluidic culture platform for CNS axonal injury, regeneration and transport

Nature Methods - 2, 599 - 605 (2005)Published online: 21 July 2005; | doi:10.1038/nmeth777

Many memorable journal articles are those that present a new method to the science community. For this week’s TBT I’m posting about an article that literally made the experiments in my own thesis possible. Anne Taylor and colleagues published a novel way to compartmentalize cultured neurons in Nature Methods, 10 years ago (yikes!). One of the fundamental properties of neurons is that they consist of molecularly and functionally distinct compartments. Axons, cell bodies, and dendrites all have their unique roles to ensure proper growth and maintenance of the neuron, as well as for completing the neuron’s mission to transmit information from one neuron to another. The complexity of this compartmentalization is really quite beautiful; and can really be quite difficult to understand. This article presents a microfluidic chamber as a way to isolate (and thus study) separate parts of the cell, in vitro.  

 

microfluidic chamber

The paper describes their fabrication of the microfluidic device; essentially, the device is made up of two narrow chambers that are separated by tiny microgrooves. It is a simple design that takes advantage of the properties of diffusion—when there is a volume difference between the chambers the high fluidic resistance of the microgrooves (given by their “micro” size) produces a small but sustained flow from one chamber to the other. Importantly, this unidirectional flow will counteract any diffusion of small molecules (or drugs or growth factors, etc.) from the lower volume chamber. The establishment of flow allows for manipulation of one compartment and one compartment only. For example, one can ask if the action of a neuronal survival factor is necessary in axons or in cell bodies. The especially novel advantage of this method is that the chamber is made of a clear plastic polymer (PDMS) and is affixed to a glass coverslip, which allows for immunocytochemistry  and live cell imaging in a compartmentalized culture system. In this paper specifically, they used the chamber as a model for studying axonal injury and regeneration. The authors showed that cutting the axons (axotomy) resulted in a host of proteins being upregulated in the cell body (despite the cell body being protected from injury), thus illustrating the axonal environment of a cell does have important effects on the biochemistry of the cell body.

The fun of a TBT is that we can look back and see which publications ended up being impactful in our field. This paper is an example of a methods paper that has really helped the field advance. This microfluidic system has been shown to be quite adaptable; many different versions of these chambers now exist for asking unique questions not only about injury and regeneration but also about synapses. And one day soon my own paper will be adding to the scientific conversation of how neuronal compartments compare, thanks to this novel method!

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