Fibronectin fn

The hiPSC line was derived from cardiac fibroblasts and kindly provided by Dr. Jianyi Zhang (University of Alabama at Birmingham, Birmingham, UK). The cells were mycoplasma-free and were maintained in mTesR™1 and passaged with ReLeSR™ every 3–5 days. Only cells with passages <70 were used in this study. To prepare for the bioprinting of centimeter-scale cardiac tissues, an ECM-based bioink optimized for hiPSC proliferation and cardiac differentiation was used as previously described. hiPSCs were dissociated for 8 min with Accutase^® (cat#AT-104, Innovative Cell Technologies, Inc., San Diego, CA, USA) and resuspended in mTesR™1 with 187.5 μg/mL fibronectin (FN, cat# 356008, Corning Life Science, Tewksbury, MA, USA), 187.5 μg/mL laminin (LN, cat# 354259, Corning Life Science, Tewksbury, MA, USA), and 10 μM ROCK inhibitor to a concentration of 30 million cells/mL. The cell suspension was subsequently mixed 1:1 with gelatin methacrylate (GelMA, kindly provided by the Bioprinting Facility, UMN)/collagen methacrylate (ColMA, cat#5198, Advanced BioMatrix, Carlsbad, CA, USA)/lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP, cat#900889, Sigma-Aldrich, St. Louis, MO) precursor solution to produce the final cell-laden bioink containing 15 million cells/mL with 10% GelMA, 0.25% ColMA, 93.75 μg/mL LN and FN, 0.5% LAP, and 5 μM ROCK inhibitor.

High molecular weight hyaluronic acid (HMW HA) was a kind gift from Professor Ivan Donati (Department of Life Sciences, University of Trieste, Italy). Fibronectin (FN) was purchased from Corning (Milan, Italy).
The following antibodies were used: mouse mAb anti-vimentin and mouse mAb anti-CD44, purchased from Sigma-Aldrich (St. Louis, MO, USA); rabbit anti-human vWF, rabbit anti-human CK8/18, rabbit anti-human FN and goat anti-mouse FITC-conjugated F(ab)’ from Dako (Milan, Italy); mouse mAb anti-human CD45-PE was bought from Immunotools (Friesoythe, Germany); rabbit anti-human MUC1 from Invitrogen (Monza, Italy); mouse anti-human CD44 was bought from Thermo Fisher Scientific (Milan, Italy); mouse anti-human β1-integrin from Merck Millipore (Darmstadt, Germania); mouse anti-human gC1qR was a kind gift from Professor Berhane Ghebrehiwet (Department of Medicine, State University of New York, Stony Brook, NY, USA); and FITC-conjugated goat anti-rabbit and Cy3-conjugated goat anti-rabbit were purchased from Jackson ImmunoResearch (Milan, Italy). All chemicals were purchased from Sigma-Aldrich.