An injectable hydrogen-producing bacteria hydrogel for cardiac repair in rodent and porcine models

Cardioprotective effects of current therapies for mitigating ischaemia/reperfusion (I/R) injury have had limited success. The major challenge is to effectively control oxidative stress while preserving mitochondrial function in a timely manner. Hydrogen (H₂) selectively reduces cytotoxic oxygen radicals, aiding in the regulation of physiological and pathological functions. However, the efficacy of H₂ therapy is highly dependent on the amount and rate of H₂ release, making it critically important to develop rapid, simple and efficient techniques for evolving therapeutic H₂. Here we encapsulate H₂-producing photosynthetic bacteria (PSB) in an injectable porcine dermal extracellular matrix (ECM) hydrogel to facilitate cardiac I/R injury repair. Upon light exposure, sustained and high H₂ production from PSB hydrogel preserves mitochondrial homeostasis and essential functions. In a porcine model of cardiac I/R injury, PSB hydrogel treatment effectively mitigates myocardial damage and salvages jeopardized myocardium. We anticipate that this bacterial therapy for photosynthetic H₂ production could provide an improved treatment for I/R-related diseases.