Double-network theory is extended to include guest-host interactions, enabling injectability and cytcompatibility of tough hydrogels. Noncovalent interactions are used as a sacrificial network to toughen covalently crosslinked hydrogels formed from hyaluronic acid. Shear thinning of supramolecular bonds allows hydrogel injection and rapid self-healing, while gentle reaction conditions permit cell encapsulation with high viability.

Background Injectable, acellular biomaterials hold promise to limit left ventricular (LV) remodeling and heart failure precipitated by infarction through bulking and/or stiffening the infarct region. A material with tunable properties (e.g., mechanics, degradation) that can be delivered percutaneously has not yet been demonstrated. Catheter deliverable soft hydrogels with in vivo stiffening to enhance therapeutic efficacy achieve these requirements. Methods and Results We developed a hyaluronic acid hydrogel that utilizes a tandem crosslinking approach, where the first crosslinking (guest-host, GH) enabled injection and localized retention of a soft (<1kPa) hydrogel. A second crosslinking reaction (dual-crosslinking, DC) stiffened the hydrogel (41.4±4.3kPa) after injection. Posterolateral infarcts were investigated in an ovine model (n≥6 per group), with injection of saline (MI control), GH, or DC. Computational (day 1), histological (1 day, 8 wk), morphological and functional (0, 2, 8 wk) outcomes were evaluated. Finite element modeling projected myofiber stress reduction (>50%, P<0.001) with DC but not GH injection. Remodeling, assessed by infarct thickness and LV volume, was mitigated by hydrogel treatment. Ejection fraction was improved, relative to MI at 8 weeks, with DC (37% improvement, P=0.014) and GH (15% improvement, P=0.058) treatments. Percutaneous delivery via endocardial injection was investigated with fluoroscopic and echocardiographic guidance, with delivery visualized by MRI. Conclusions A percutaneous delivered hydrogel system was developed, and hydrogels with increased stiffness were most effective in ameliorating LV remodeling and preserving function. Ultimately, engineered systems such as these have the potential to provide effective clinical options to limit remodeling in patients after infarction.

No abstract