Bio-orthogonally double cross-linked alginate-gelatin hydrogels with tunable viscoelasticity for cardiac tissue engineering

Introduction Myocardial infarction is a major cause of death worldwide. Cardiac tissue engineering (CTE) offers biomaterial-based strategies to restore cardiac function and develop in vitro models for drug discovery. Biomimetic 3D hydrogels reproducing ECM-like viscoelasticity are crucial for cell regulation [1]. Furthermore, bio-orthogonal hydrogels are attracting increased interest in cell-encapsulation. Herein bio-orthogonal double-crosslinked alginate-gelatin hydrogels with tunable viscoelasticity were designed for CTE. Experimental methods Alginate-azide (ALG-Az) and gelatin-azide (GEL-Az) were first produced. Mixing ALG-Az and GEL-Az with 4-arm-PEG-DBCO formed spontaneous hydrogels via bio-orthogonal SPAAC chemistry. Double-crosslinked hydrogels were then formed by additional ionic crosslinking. Viscoelastic and physicochemical properties of hydrogels were investigated. In vitro tests with human cardiac fibroblasts (HCFs) were performed in 2D and 3D settings. Results and discussion Bio-orthogonal double-crosslinked alginate-gelatin hydrogels were produced and their properties modulated by varying the azide:DBCO molar ratio. Increase in azide:DBCO ratios resulted in higher elastic response mimicking healthy cardiac tissue. Hydrogels exhibited physiological stress relaxation rates with tunable viscoelasticity. In 2D cultures, hydrogels supported cell viability and adhesion; viscoelastic properties influenced cell spreading. HCFs embedded in 3D hydrogels showed high viability. Conclusion Bio-orthogonal double-crosslinked alginate-gelatin hydrogels were designed as promising biomimetic substrates for cardiac tissue engineering applications. References 1. Chaudhuri, O. et al., Nat. Mater. 15(3), 326-334 (2016) AcKnowledgments This work was supported from: European Research Council (ERC) under European Union's Horizon 2020 Research and Innovation Programme (GA: 772168); DESIRE project – funded by European Union – Next Generation EU within the PRIN 2022 program (D.D. 104 - 02/02/2022 Ministero dell’Università e della Ricerca). This abstract reflects only the authors’ views and opinions and the Ministry cannot be considered responsible for them