A new paper scheduled for publication in the January issue
of Nature Photonics describes the use of spinning microparticles to direct the
growth of nerve fiber, a discovery that could allow for directed growth of
neuronal networks on a chip and improve methods for treating spinal or brain
when a Vaterite particle is rotated anticlockwise and positioned to the
left of the axon defined by the growth direction of the axon (dashed
arrow 1). (From Nature Photonics)
Samarendra Mohanty, an assistant
professor of physics at The
University of Texas at Arlington, is a coauthor of the paper, which is now
The study is based on Mohanty’s hypothesis
that neurons can respond to physical (e.g. fluid flow) cues in addition to
chemical cues. He conducted the seminal work and observed that a laser-driven
spinning calcite microparticle could guide the direction of neuron growth. Its
rotation caused a shearing effect by creating a microfluidic flow.
Mohanty’s work led the University
of California, Irvine team led by Professor Michael Berns to test the vaterite
“micro-motors” in guiding neurons.
Mohanty said: “This is the first
report to demonstrate that neurons can be turned in a controlled manner by
microfluidic flow. With this method, we can direct them to turn right or turn
left and we can quickly insert or remove the rotating beads as needed. But flow can be generated by any means. In the body, for example,
it will be more convenient to use a tube carrying fluids.”
The researchers in the UC Irvine
experiments used a laser tweezers system to trap a birefringent particle
(calcite or vaterite) near axonal growth cones, which are the tips of neurons
where connections are made with other neurons or cells. The same laser causes
rotation of the particle, which creates the flow, Mohanty said.
The paper reports that the new
method successfully turned the growing axon in a new direction up to 42 percent
of the time in lab experiments. The authors noted that the method could also be
used to funnel growth between two rotating particles. The effects also may be
reproducible on a larger scale, they said.
“One can envision large arrays
of these devices that can direct large numbers of axons to different
locations,” the authors wrote. “This may have the potential for use in vivo to
direct regenerating axons to mediate brain and spinal cord repair.”
Mohanty said that
during neurogenesis – the process by which neurons grow and develop in a fetus –
flow of spinal fluid can influence guidance of neurons to their destinations.
His lab at UT Arlington is currently developing a novel optical method
that allows long-range optical guidance of neurons with 100 percent efficacy
without use of any additional external objects.
In addition to UC Irvine and UT
Arlington, other authors on the Nature Photonics study hail from the Quantum
Science Laboratory at The University of Queensland in Australia.
The paper said the experiments
shed valuable light on the effect of shear or lateral forces on neuron growth
and that knowledge may even apply to other forms of cell growth.
Mohanty is one of several
professors conducting breakthrough optics-related research at UT Arlington, a
comprehensive research institution of 33,439 students in the heart of North
Texas. Visit www.uta.edu to