title: Hyaluronic acid matrices show matrix stiffness in 2D and 3D dictates cytoskeletal order and myosin-II phosphorylation within stem cells.
abstract: Physical features of microenvironments such as matrix elasticity E can clearly influence cell morphology and cell phenotype, but many differences between model matrices raise questions as to whether a standard biological scale for E exists, especially in 3D as well as in 2D. An E-series of two distinct types of hydrogels are ligand-functionalized here with non-fibrous collagen and used to elucidate wide-ranging cell and cytoskeletal responses to E in both 2D and 3D matrix geometries. Cross-linked hyaluronic acid (HA) based matrices as well as standard polyacrylamide (PA) hydrogels show that, within hours of initial plating, the adhesion, asymmetric shape, and cytoskeletal order within mesenchymal stem cells generally depend on E nonmonotonically over a broad range of physiologically relevant E. In particular, with overlays of a second matrix the stiffer of the upper or lower matrix dominates key cell responses to 3D: the cell invariably takes an elongated shape that couples to E in driving cytoplasmic stress fiber assembly. In contrast, embedding cells in homogeneous HA matrices constrains cells to spherically symmetric shapes in which E drives the assembly of a predominantly cortical cytoskeleton. Non-muscle myosin II generates the forces required for key cell responses and is a target of a phospho-Tyrosine signaling pathway that likely regulates contractile assemblies and also depends nonmonotonically on E. The results can be understood in part from a theory for stress fiber polarization that couples to matrix elasticity as well as cell shape and accurately predicts cytoskeletal order in 2D and 3D, regardless of polymer system.
authors.affiliation: Biophysical Eng'g. Lab, University of Pennsylvania, Philadelphia, PA 19104, USA. rehfeldt@physik3.gwdg.de
authors.forename: Florian
authors.initials: F
authors.lastname: Rehfeldt
authors.forename: André E X
authors.initials: AE
authors.lastname: Brown
authors.forename: Matthew
authors.initials: M
authors.lastname: Raab
authors.forename: Shenshen
authors.initials: S
authors.lastname: Cai
authors.forename: Allison L
authors.initials: AL
authors.lastname: Zajac
authors.forename: Assaf
authors.initials: A
authors.lastname: Zemel
authors.forename: Dennis E
authors.initials: DE
authors.lastname: Discher
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects / Q000502:physiology; D002470:Cell Survival / Q000187:drug effects; D024042:Collagen Type I / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D055119:Elastic Modulus / Q000502:physiology; D004548:Elasticity / Q000502:physiology*; D005109:Extracellular Matrix / Q000737:chemistry / Q000502:physiology*; D005780:Gelatin / Q000737:chemistry / Q000494:pharmacology; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology; D006801:Humans; D006820:Hyaluronic Acid / Q000737:chemistry* / Q000494:pharmacology; D020100:Hydrogels / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D018995:Myosin Heavy Chains / Q000378:metabolism; D024507:Nonmuscle Myosin Type IIA / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects*; D019000:Phosphotyrosine / Q000378:metabolism; D022502:Stress Fibers / Q000187:drug effects / Q000502:physiology*; D016596:Vinculin / Q000378:metabolism; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D000199:Actins; D024042:Collagen Type I; D005780:Gelatin; D006576:Heterocyclic Compounds, 4 or More Rings; D006820:Hyaluronic Acid; D020100:Hydrogels; D018995:Myosin Heavy Chains; D024507:Nonmuscle Myosin Type IIA; D019000:Phosphotyrosine; D016596:Vinculin; D000099166:Polyacrylamides; C488955:VCL protein, human; C472645:blebbistatin