Gelatin-based hydrogel patch by promoting M2 macrophage polarization to reduce inflammation and fibrosis alleviate post-myocardial infarction ventricular remodeling.

More than 50 % of the myocardial infarction (MI) survivors will develop into progressive heart failure within five years due to post-infarction myocardial contractile dysfunction. Therapeutic strategies that promote the polarization of M2 macrophages during the acute phase of MI may represent a promising approach. A hydrogel patch was developed by combining Gelatin methacryloyl (GelMA) with nitrobenzyl-modified gelatin (GelNB). The precursor solution of this hydrogel can be crosslinked on the cardiac surface after brief ultraviolet (UV) irradiation for 5 s. The GelMA/GelNB hydrogel patch exhibits customizable mechanical properties and rapid photocross-linking with strong tissue adhesion. Moreover, this hydrogel exhibits preliminary multi-organ safety profile, can effectively promote the polarization of M2 macrophages independent of cells/exogenous factors, and in the MI model of Sprague-Dawley (SD) rats, it can alleviate inflammation, reduce fibrosis, and improve cardiac function. GelMA/GelNB demonstrates promising preclinical potential as a cell-free hydrogel platform for post-MI repair.