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Studying axonal transport in patterned microfluidic devices
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Funding: NSF Nanobiotechnology Center
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Local changes in the neuronal microenvironment that impinge on different parts
of the cell play a key role in neural development and in neural disease.
Axonal specification, axonal guidance, axonal and dendritic branching--all
are regulated by local signaling. In disease states, local stressors like hypoxia or
inflammatory cytokines are thought to impair axonal transport,
ultimately causing synaptic dysfunction and cell death.
At present, there is no experimental model for dynamically controlling the
environment of nerve cells in culture that even remotely matches the spatial
precision of extracellular signaling that occurs in vivo.
Historically, two general strategies have been utilized to
control the neuronal microenvironment; both suffer from
comparatively low spatial resolution and poor reproducibility.
One approach uses “compartmented” cultures, which consist of
two or more chambers whose fluid composition can be independently
controlled; neurons are induced to grow beneath a barrier separating
the compartments. These “Campenot chambers” require axons
to grow several millimeters beneath a grease seal, following scratches
in the substrate made by hand. They are notoriously unreliable, due
both to leaks between chambers and poor axon growth. Moreover, only
neurons from the peripheral nervous system grow long enough axons to
reach the second chamber. Microfabrication has been implemented recently
to address this, but has not to date isolated single axons nor allowed for microfluidic
or laser-enhanced delivery of solutes.
In collaboration with
Gary Banker at Oregon Health and Science
University, our current efforts combine micropatterned surfaces
for single-axonal guidance combined
with microfluidic control of solutes to allow for detailed study of transport in
isolated axons.
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Micropattered pads for control of neuron and axon growth. Thin lines are 2 microns
in size, and facilitate isolation of single axons for study.
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