Guiding neuronal growth with light

Author :A. Ehrlicher, T. Betz, B. Stuhrmann, D. Koch, V. Milner, M. G. Raizen, and J. Kas
Publication :PNAS
Volume :99
Number :25
Pages :16024-16028
Year :2002

Control over neuronal growth is a fundamental objective in neuroscience,
cell biology, developmental biology, biophysics, and
biomedicine and is particularly important for the formation of
neural circuits in vitro, as well as nerve regeneration in vivo [Zeck,
G. & Fromherz, P. (2001) Proc. Natl. Acad. Sci. USA 98, 10457’10462].
We have shown experimentally that we can use weak optical
forces to guide the direction taken by the leading edge, or growth
cone, of a nerve cell. In actively extending growth cones, a laser
spot is placed in front of a specific area of the nerve’s leading edge,
enhancing growth into the beam focus and resulting in guided
neuronal turns as well as enhanced growth. The power of our laser
is chosen so that the resulting gradient forces are sufficiently
powerful to bias the actin polymerization-driven lamellipodia
extension, but too weak to hold and move the growth cone.We are
therefore using light to control a natural biological process, in
sharp contrast to the established technique of optical tweezers
[Ashkin, A. (1970) Phys. Rev. Lett. 24, 156’159; Ashkin, A. &
Dziedzic, J. M. (1987) Science 235, 1517’1520], which uses large
optical forces to manipulate entire structures. Our results therefore
open an avenue to controlling neuronal growth in vitro and in vivo
with a simple, noncontact technique.