Haptotaxis is Cell Type Specific and Limited by Substrate Adhesiveness
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Motile cells navigate through tissue by relying on tactile cues from gradients provided by extracellular matrix such as ligand density or stiffness. Mesenchymal stem cells (MSCs) and fibroblasts encounter adhesive or ‘haptotactic’ gradients at the interface between healthy and fibrotic tissue as they migrate towards an injury site. Mimicking this phenomenon, we developed tunable RGD and collagen gradients in polyacrylamide hydrogels of physiologically relevant stiffness using density gradient multilayer polymerization to better understand how such ligand gradients regulate migratory behaviors. Independent of ligand composition and fiber deformation, haptotaxis was observed in mouse 3T3 fibroblasts. Human MSCs however, haptotaxed only when cell-substrate adhesion was indirectly reduced via addition of free soluble matrix ligand mimetic peptides. Under basal conditions, MSCs were more contractile than fibroblasts. However, the presence of soluble adhesive peptides reduced MSC-induced substrate deformations; increased contractility may contribute to limited migration, but modulating cytoskeletal assembly was ineffective at promoting MSC haptotaxis. When introduced to gradients of increased absolute ligand concentrations, 3T3s displayed increased contractility and no longer haptotaxed. These data suggest that haptotactic behaviors are limited by adhesion and that although both cell types may home to tissue to aid in repair, fibroblasts may be more responsive to ligand gradients than MSCs.
KeywordsMigration Mesenchymal stem cell Fibroblast Ligand gradient Surface modification Elasticity
This work was supported by grants from the National Institutes of Health (DP2OD006460 to A.J.E.), National Science Foundation (1463689 to A.J.E.), and the National Science Foundation Graduate Research Fellowship Program (to J.H.W. and H.T.-W.). The authors declare no commercial affiliations or conflicts of interest.
Conflict of interest
Jessica H. Wen, Onkiu Choi, Hermes Taylor-Weiner, Alexander Fuhrmann, Jerome V. Karpaik, Adah Almutairi, and Adam J. Engler declare that they have no conflicts of interest related to this work.
No human studies were carried out by the authors for this article. No animal studies were carried out by the authors for this article.
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