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Dissertation/Thesis Abstract

Probing biological systems using a microfluidic chemical signal generator: An investigation into the dynamics of ionophore stimulation in NIH-3T3 fibroblasts
by Kuczenski, Brandon, Ph.D., Carnegie Mellon University, 2008, 137; 3305825
Abstract (Summary)

The complex signal transduction systems that regulate intracellular calcium are a subject of extensive research in biology. Observations of cellular behavior in response to time-varying stimuli can aid in the modeling and analysis of this and other cell signaling processes. I present an experimental technique to probe the dynamic characteristics of living cells using the phenomenon of parallel laminar flow in a microfluidic channel. Under laminar flow conditions, distinct fluids can flow alongside one another in parallel streams without convective mixing. The resulting concentration gradient will relax into a diffusion boundary layer that grows with downstream distance. If the relative flow rates of the streams are adjusted, the diffusion region will move laterally across the channel's width. As a result, cells adherent to the channel surface will be exposed to a chemical environment that varies continuously in time, a "chemical signal" which can be used to study a cell's dynamic behavior.

I employed this technique to perturb intracellular calcium concentration in NIH-3T3 fibroblasts with ionophores while observing their response with fluorescence microscopy. Using feedback control of reservoir pressure to modulate fluid flow rates in a microfluidic device, I stimulated target cells with approximate impulse functions and oscillatory signals. Cells were observed to release and then re-sequester calcium from an internal store after a short exposure. The observed cellular response can be closely modeled as a low-order linear dynamic system whose parameters are roughly consistent across the population studied. Physical measurements of the calcium regulatory system can be extracted from the model.

Indexing (document details)
Advisor: LeDuc, Philip R.
School: Carnegie Mellon University
School Location: United States -- Pennsylvania
Source: DAI-B 69/03, Dissertation Abstracts International
Subjects: Cellular biology, Mechanical engineering
Keywords: Calcium signaling, Chemical signal generator, Dynamic systems, Ionophores, NIH-3T3 fibroblasts, Parallel laminar streams
Publication Number: 3305825
ISBN: 978-0-549-52563-9
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