title: The mechanical memory of lung myofibroblasts.
abstract: Fibroblasts differentiate into the highly synthetic and contractile myofibroblast phenotype when exposed to substrates with an elastic modulus corresponding to pathologically stiff fibrotic tissue. Cellular responses to changes in substrate stiffness are typically analyzed after hours or days, which does not enable the monitoring of myofibroblast persistence, a hallmark of fibrosis. To determine long-lasting effects on the fibrotic behavior of lung fibroblasts, we followed a novel approach of explanting and repeatedly passaging fibroblasts on silicone substrates with stiffness representing various states of lung health. Fibrotic activity was determined by assaying for myofibroblast proliferation, cell contractility, expression of α-smooth muscle actin, extracellular matrix and active TGFβ1. As predicted, myofibroblast activity was low on healthy soft substrates and increased with increasing substrate stiffness. However, explanting and mechanically priming lung fibroblasts for 3 weeks on pathologically stiff substrates resulted in sustained myofibroblast activity even after the cells were returned to healthy soft cultures for 2 weeks. Such primed cells retained higher fibrotic activity than cells that had been exclusively cultured on soft substrates, and were not statistically different from cells continuously passaged on stiff surfaces. Inversely, priming lung fibroblasts for 3 weeks on soft substrates partially protected from myofibroblast activation after the shift to stiff substrates. Hence, mechano-sensed information relating to physical conditions of the local cellular environment could permanently induce fibrotic behavior of lung fibroblasts. This priming effect has important implications for the progression and persistence of aggressive fibrotic diseases such as idiopathic pulmonary fibrosis.
authors.affiliation: Laboratory of Tissue Repair and Regeneration, Matrix Dynamics Group, Faculty of Dentistry, University of Toronto, Fitzgerald Building, Room 234, 150 College Street, Toronto, ON M5S3E2, Canada.
authors.forename: Jenna L
authors.initials: JL
authors.lastname: Balestrini
authors.forename: Sidharth
authors.initials: S
authors.lastname: Chaudhry
authors.forename: Vincent
authors.initials: V
authors.lastname: Sarrazy
authors.forename: Anne
authors.initials: A
authors.lastname: Koehler
authors.forename: Boris
authors.initials: B
authors.lastname: Hinz
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D001696:Biomechanical Phenomena; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000737:chemistry; D017077:Culture Media, Conditioned / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004548:Elasticity; D005109:Extracellular Matrix / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006244:Hardness; D019394:Ki-67 Antigen / Q000378:metabolism; D008168:Lung / Q000166:cytology*; D008297:Male; D058628:Myofibroblasts / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012828:Silicones / Q000737:chemistry / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000199:Actins; D024042:Collagen Type I; D017077:Culture Media, Conditioned; D019394:Ki-67 Antigen; D012828:Silicones; D053773:Transforming Growth Factor beta1; C498862:Acta2 protein, rat