Engineering Hybrid-Hydrogels Comprised of Healthy or Diseased Decellularized Extracellular Matrix to Study Pulmonary Fibrosis

• Published in: Cellular and molecular bioengineering 2022-10, Vol.15 (5), p.505-519
• Main Authors: Saleh, Kamiel S., Hewawasam, Rukshika, Šerbedžija, Predrag, Blomberg, Rachel, Noreldeen, Saif E., Edelman, Benjamin, Smith, Bradford J., Riches, David W. H., Magin, Chelsea M.
• Format: Article
• Language: English
• Subjects: 2022 CMBE Young Innovators; Biochemical composition; Biological and Medical Physics; Biomaterials; Biomedical Engineering and Bioengineering; Biomedical Engineering/Biotechnology; Biomedical materials; Biophysics; Bleomycin; Cell Biology; Collagen (type I); Composition; Engineering; Extracellular matrix; Fibroblasts; Fibrosis; Gas exchange; Hydrogels; Lung diseases; Lungs; Mechanical properties; Modulus of elasticity; Ninhydrin; Polyethylene glycol; Pulmonary fibrosis; Rheological properties; Rheology; Stiffening; Stoichiometry
• ISSN: 1865-5025; 1865-5033
• DOI: 10.1007/s12195-022-00726-y

Idiopathic pulmonary fibrosis is a chronic disease characterized by progressive lung scarring that inhibits gas exchange. Evidence suggests fibroblast-matrix interactions are a prominent driver of disease. However, available preclinical models limit our ability to study these interactions. We present a technique for synthesizing phototunable poly(ethylene glycol) (PEG)-based hybrid-hydrogels comprising healthy or fibrotic decellularized extracellular matrix (dECM) to decouple mechanical properties from composition and elucidate their roles in fibroblast activation. Here, we engineered and characterized phototunable hybrid-hydrogels using molecular techniques such as ninhydrin and Ellman’s assays to assess dECM functionalization, and parallel-plate rheology to measure hydrogel mechanical properties. These biomaterials were employed to investigate the activation of fibroblasts from dual-transgenic Col1a1-GFP and αSMA-RFP reporter mice in response to changes in composition and mechanical properties. We show that reacting functionalized dECM from healthy or bleomycin-injured mouse lungs with PEG alpha-methacrylate (αMA) in an off-stoichiometry Michael-addition reaction created soft hydrogels mimicking a healthy lung elastic modulus (4.99 ± 0.98 kPa). Photoinitiated stiffening increased the material modulus to fibrotic values (11.48 ± 1.80 kPa). Percent activation of primary murine fibroblasts expressing Col1a1 and αSMA increased by approximately 40% following dynamic stiffening of both healthy and bleomycin hybrid-hydrogels. There were no significant differences between fibroblast activation on stiffened healthy versus stiffened bleomycin-injured hybrid-hydrogels. Phototunable hybrid-hydrogels provide an important platform for probing cell-matrix interactions and developing a deeper understanding of fibrotic activation in pulmonary fibrosis. Our results suggest that mechanical properties are a more significant contributor to fibroblast activation than biochemical composition within the scope of the hybrid-hydrogel platform evaluated in this study.