A method for direct therapeutic treatment of myocardial tissue in a localized region of a heart having a pathological condition. The method includes identifying at least one target region of the myocardium of the heart to be treated and injecting a keratin-based material that travels to at least one target region to at least one of stiffen, restrain, or constrain the myocardial tissue of the target region. The material applied results in a physical modification of the mechanical properties, including stiffness, of the infarct tissue. Various devices and modes of practicing the method are disclosed for stiffening, restraining and constraining myocardial tissue for the treatment of conditions including myocardial infarction or mitral valve regurgitation.
