Abstract: An injectable elastin-like recombinamer (ELR) hydrogel for use in a method of treating a mammal that has suffered a myocardial infarction to modulate the response of cardiac muscle damaged by the infarct is described. The hydrogel is injected into the cardiac muscle damaged by the infarct at least two days after the myocardial infarction, and results in clinically significant repair of cardiac muscle evidenced by at least one or more of reduced scarring, positive remodelling of the damaged muscle, restoring cardiac muscle function to a clinically significant extent after infarction an improvement in angiogenesis, or a decreased pro-inflammatory response in the infarct zone, and typically within 10, 20 or 30 days of administration.