|
Nerve cells decide which direction to grow by sensing both the
chemical cues flowing through their environment as well as those
attached to the surfaces that surround them. The chip, which is made
of a plastic-like substance and covered with a glass lid, features a
system of channels and wells that allow researchers to control the
flow of specific chemical cocktails around single nerve cells.
�It is difficult to establish ideal experimental conditions to study
how neurons react to growth signals because so much is happening at
once that sorting out nerve cell connections is hard, but the chip,
designed by experts in both brain chemistry and engineering, offers a
sophisticated way to sort things out,� says Guo-li Ming, M.D., Ph.D.,
associate professor of neurology at the Johns Hopkins School of
Medicine and Institute for Cell Engineering.
In experiments with their chip, the researchers put single nerve cells,
or neurons, onto the chip then introduced specific growth signals (in
the form of chemicals). They found that the growing neurons turned and
grew toward higher concentrations of certain chemical cues attached to
the chip�s surfaces, as well as to signaling molecules free-flowing in
solution.
When researchers subjected the neurons to conflicting signals (both
surface bound and cues in solution), they found that the cells turned
randomly, suggesting that cells do not choose one signal over the
other. This, according to Levchenko, supports the prevailing theory
that one cue can elicit different responses depending on a cell�s
surroundings.
�The ability to combine several different stimuli in the chip
resembles a more realistic environment that nerve cells will encounter
in the living animal,� Ming says. This in turn will make future
studies on the role of neuronal cells in development and regeneration
more accurate and complete.
|
