While the quantification of cell movement within defined biochemical gradients is now possible with microfluidic approaches,translating this capability to biologically relevant three-dimensional microenvironments remains a challenge.We introduce an accessible platform,requiring only standard tools {e.g.pipettes),that provides robust soluble factor control within a three-dimensional biological matrix.We demonstrate long-lasting linear and non-linear concentration profiles that were maintained for up to ten days using 34.5 mu L solute volume.We also demonstrate the ability to superimpose local soluble factor pulses onto existing gradients via defined dosing windows.The combination of long-term and transient gradient characteristics within a three-dimensional environment opens the door for signaling studies that investigate the migratory behavior of cells within a biologically representative matrix.To this end,we apply temporally evolving and long-lasting gradients to study the chemotactic responses of human neutrophils and the invasion of metastatic rat mammary adenocarcinoma cells (MtLN3) within three-dimensional collagen matrices.
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