Effect of substrate stiffness on pulmonary fibroblast activation by TGF-β

• Published in: Acta biomaterialia Vol. 8; no. 7; pp. 2602 - 2611
• Main Authors: Chia, H.N., Vigen, M., Kasko, A.M.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.07.2012
• Subjects: actin; Actins - metabolism; adhesion; Adsorption - drug effects; Amino Acid Sequence; Cell adhesion; Cell Adhesion - drug effects; Cell Communication - drug effects; Cell Count; Cell Differentiation - drug effects; cytoskeleton; ethylene glycol; etiology; Extracellular matrix; fibroblasts; Fibroblasts - cytology; Fibroblasts - drug effects; Fibroblasts - metabolism; gels; Humans; hydrocolloids; Hydrogel; Hydrogel, Polyethylene Glycol Dimethacrylate - chemistry; Hydrogel, Polyethylene Glycol Dimethacrylate - pharmacology; Integrin; Lung - cytology; mechanical properties; Molecular Sequence Data; muscles; peptides; Peptides - chemistry; Phenotype; Polyethylene Glycols - pharmacology; Pulmonary fibrosis; Stress, Mechanical; transforming growth factor beta 1; Transforming Growth Factor beta1 - pharmacology; Extracellular matrix; Integrin; Pulmonary fibrosis; Hydrogel; Cell adhesion
• ISSN: 1742-7061; 1878-7568
• DOI: 10.1016/j.actbio.2012.03.027

Peptide crosslinkers containing the sequence C-X-CG (X represents various adhesive peptides) were incorporated into poly(ethylene glycol) (PEG) hydrogel networks with different mechanical properties. Pulmonary fibroblasts (PFs) exhibit increased adhesion to rigid hydrogels modified with X=RGDS, DGEA and IKVAV (0.5 and/or 5mM) compared with a scrambled control (X=HRPNS). PFs exhibit increased adhesion to softer hydrogels when X=DGEA at low (0.5mM) peptide concentration. PFs seeded onto hydrogels modified with X=RGDS produce alpha-smooth muscle actin (α-SMA), a myofibroblast marker, and form an extensive cytoskeleton with focal adhesions. Decreasing substrate stiffness (achieved through hydrolytic degradation) results in down-regulation of α-SMA expression by PFs. Substrate stiffness increases the sensitivity of PFs to exogenously applied transforming growth factor beta (TGF-β1); PFs on the most rigid gels (E=900kPa) express α-SMA when treated with low concentrations of TGF-β1 (1ngml−1), while those on less rigid gels (E=20–60kPa) do not. These results demonstrate the importance of both mechanical and chemical cues in studying pulmonary fibroblast activation, and establish PEG hydrogels as a viable material for further study of IPF etiology.