Cell migration, via chemotaxis, is important to many fundamental biological processes including embryogenesis, cancer metastasis, immune response, and wound healing. In these scenarios, cells respond to a gradient in signaling molecules to migrate and perform necessary functions. Platforms for in vitro identification and characterization of these gradients in signaling cues, in space and time, are necessary to determine the underlying mechanisms involved. Gradient temporal evolution, in addition to concentration range, and gradient steepness, are important key features of the signal.
In this work, we present finite element models and scaling arguments for characterization of concentration profiles and gradients in a few common commercialized chemotaxis chambers and microfluidic platforms. We found that the experimental system properties have profound effects on the gradient persistence, evolution, and uniformity across the cell population. This variable signaling environment can alter a multitude of cellular responses. A number of critical parameters (molecular size of the signaling molecule and system geometry) in each experimental platform affect the quality of the gradient and hence the signals that initiate and sustain the chemotactic behavior. These effects are quantified as they relate to time of signal persistence and uniformity of signal across the cell population. This work suggests it is crucial to understand each experimental setup and carefully design the time course of the experiments. Moreover, when extracting data and drawing conclusions through comparison between experiments, it is important to take into account the effect of differences in the experimental platforms and the molecules of interest.