Chemical Stimulation of Adherent Cells by Localized Application of Acetylcholine from a Microfluidic System

Abstract

Chemical stimulation of cells is inherently cell type selective in contrast to electro-stimulation. The availability of a system for localized application of minute amounts of chemical stimulants could be useful for dose related response studies to test new compounds. It could also bring forward the development of a novel type of neuroprostheses. In an experimental setup microdroplets of an acetylcholine solution were ejected from a fluidic microsystem and applied to the bottom of a nanoporous membrane. The solution traveled through the pores to the top of the membrane on which TE671 cells were cultivated. Calcium imaging was used to visualize cellular response with temporal and spatial resolution. Experimental demonstration of chemical stimulation for both threshold gated stimulation as well as accumulated dose–response was achieved by either employing acetylcholine as chemical stimulant or applying calcein uptake, respectively. Numerical modeling and simulation of transport mechanisms involved were employed to gain a theoretical understanding of the influence of pore size, concentration of stimulant and droplet volume on the spatial-temporal distribution of stimulant and on the cellular response. Diffusion, pressure driven flow and evaporation effects were taken into account. Fast stimulation kinetic is achieved with pores of 0.82 μm diameter, whereas sustained substance delivery is obtained with nanoporous membranes. In all cases threshold concentrations ranging from 0.01 to 0.015 μM acetylcholine independent of pore size were determined.

Can Nanofluidic Chemical Release Enable Fast, High Resolution Neurotransmitter-Based Neurostimulation?

“…Solid barriers have been electrochemically opened but are not reversible (Chung et al, 2008 ). Air has been used to interrupt diffusion, but required a macroscopic gap which cannot be miniaturized or implanted (Zibek et al, 2010 ).…”

Microfabricated polymer-metal biosensors for multifarious data collection from electrogenic cellular models

“…Chemical stimulation in a localized setting, such as that modeled here, is vital, for instance, in studying the effects of localized dopamine stimulation and the effects of such stimulation on cellular populations using localized field potential measurements additionally enabled by the device 47 . Furthermore, such chemical stimulations can be tuned through optimization studies for individual uptake and diffusion characteristics of desired compounds 48 . The forthcoming application of microfluidic integration for localized perfusion and controlled spheroidal manipulation is ongoing as a continuation of our existing work 5 .…”

Rapid photothermal actuation of light-addressable, arrayed hydrogel columns in a macroporous silicon membrane

“…This may allow novel light-directed drug release systems based on unique deswelling property of the thermo responsive hydrogel. Such systems can benefit applications in the area of chemical stimulations of neuronal networks [29][30][31][32] that require high spatiotemporal resolution of drug release.…”