title: Growth cone response to ephrin gradients produced by microfluidic networks.
abstract: A microfluidic network (microFN) etched into a silicon wafer was used to deliver protein solutions containing different concentrations of the axonal guidance molecule ephrinA5 onto a silicone stamp. In a subsequent microcontact printing (microCP) step, the protein was transferred onto a polystyrene culture dish. In this way, stepwise substrate-bound concentration gradients of ephrinA5 were fabricated spanning a total distance of 320 microm. We tested the response of chick retinal ganglion cell (RGC) axons, which are guided in vivo by ephrin gradients, to these in vitro gradients. Temporal, but not nasal axons stop at a distinct zone in the gradient, which is covered with a certain surface density of substrate-bound ephrinA5. Within the temporal RGC population, all axons respond uniformly to the gradients tested. The position of the stop zone depends on the slope of the gradient with axons growing further into the gradient in shallow gradients than in steep gradients. However, axons stop at lower ephrinA5 concentrations in shallow gradients than in steep gradients, indicating that the growth cone can adjust its sensitivity during the detection of a concentration gradient of ephrinA5.
authors.affiliation: Max-Planck-Institut für Entwicklungsbiologie, Spemannstrasse 35, 72076, Tübingen, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Lang
authors.forename: Anne C
authors.initials: AC
authors.lastname: von Philipsborn
authors.forename: André
authors.initials: A
authors.lastname: Bernard
authors.forename: Friedrich
authors.initials: F
authors.lastname: Bonhoeffer
authors.forename: Martin
authors.initials: M
authors.lastname: Bastmeyer
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism; D018929:Cell Culture Techniques / Q000379:methods; D002645:Chickens; D004129:Dimethylpolysiloxanes / Q000737:chemistry; D036386:Ephrin-A5 / Q000737:chemistry; D036342:Ephrins / Q000378:metabolism*; D004867:Equipment Design; D020439:Growth Cones / Q000502:physiology*; D046210:Microfluidic Analytical Techniques; D044085:Microfluidics; D011137:Polystyrenes / Q000737:chemistry; D012165:Retinal Ganglion Cells / Q000166:cytology; D012828:Silicones / Q000737:chemistry; D013997:Time Factors
chemical_list: D004129:Dimethylpolysiloxanes; D036386:Ephrin-A5; D036342:Ephrins; D011137:Polystyrenes; D012828:Silicones; C013830:baysilon