Human ischemic cardiomyopathy specimens.

Cardiac tissue specimens were obtained from the explanted hearts of adult patients with ischemic cardiomyopathy undergoing cardiac transplantation at Northwestern Memorial Hospital. Explanted hearts were immediately immersed and rinsed with cold cardioplegia solution. Tissue specimens from infarct-scar or viable remote (absence of fibrosis) myocardium were obtained from the lateral wall of the left ventricle. Specimens were maintained in cold cardioplegia solution to preserve tissue integrity. Within 1 hour of procurement, specimens were digested with collagenase type II (600 U/mL, Worthington) and DNase I (0.1 mg/mL; Sigma-Aldrich) in HBSS at 37°C for 30 minutes with agitation. Specimens were subsequently triturated through a 40-μm cell strainer to prepare a single-cell suspension for analyses by flow cytometry.