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Characterization of Cardiac Stem Cells Derived from Right Atrial Myocardium in Young Patients

The adult human heart contains cardiac stem cells (CSCs) that can repair myocardial damage. We examined CSCs in young patients (age 13 days‐9 years) with congenital heart defects (CHD pts) to determine if CHD pts have similar CSCs with respect to CSC markers or regenerative potential. Right atrial appendage biopsy samples were obtained, with parental consent, at routine CHD surgery procedures. Tissues were characterized by immunohistochemistry for expression of CSC markers, minced, and serially plated to obtain an efficient and reproducible CSC isolation method. All heart tissue samples, mean weight 61.3 mgs, generated CSCs despite different patient ages and CHD. We generated 65419.7±502.6 cells/mg of tissue maintained up to passage 4. Flow cytometry analysis demonstrated CSCs were hematopoietic lineage (Lin1), and were positive for c‐kit+ (48±25.5%), representing higher c‐kit+ percentage than reported for adult patients (~20%). No age‐related difference was observed when comparing c‐kit+ cell percentage between patients <1 versus >1 year of age. Immunocytochemical staining showed CSCs expressed alpha‐sarcomeric actin, sarcoplasmic reticulum Ca2+ ATPase‐2 and connexin 43. Despite small tissue samples, CSCs are reproducibly attainable from CHD pts, regardless of age or diagnosis. In future these cells may be used to treat CHD pts to improve myocardial function or engineer cardiovascular structures.