Cardiac atrial appendage stem cells engraft and differentiate into cardiomyocytes in vivo: A new tool for cardiac repair after MI.

BACKGROUND: This study assessed whether autologous transplantation of cardiac atrial appendage stem cells (CASCs) preserves cardiac function after myocardial infarction (MI) in a minipig model. METHODS AND
RESULTS: CASCs were isolated from right atrial appendages of Göttingen minipigs based on high aldehyde dehydrogenase activity and expanded. MI was induced by a 2h snare ligation of the left anterior descending coronary artery. Upon reperfusion, CASCs were intramyocardially injected under NOGA guidance (MI-CASC, n=10). Non-transplanted pigs (MI, n=8) received sham treatment. 3D electromechanical mapping (EMM) and cardiac MRI were performed to assess left ventricular (LV) function. MI pigs developed LV dilatation at 2 months (2M), while in the MI-CASC group volumes remained stable. Global LV ejection fraction decreased by 16 ± 8% in MI animals vs 3 ± 10% in MI-CASC animals and regional wall thickening in border areas was better preserved in the MI-CASC group. EMM showed decreased viability and wall motion in the LV for both groups POST-MI, whereas at 2M these parameters only improved in the MI-CASC. Substantial cell retention was accompanied by cardiomyogenic differentiation in 98±1% of the transplanted CASCs, which functionally integrated. Second harmonic generation microscopy confirmed the formation of mature sarcomeres in transplanted CASCs. Absence of cardiac arrhythmias indicated the safety of CASC transplantation.
CONCLUSION: CASCs preserve cardiac function by extensive engraftment and cardiomyogenic differentiation. Our data indicate the enormous potential of CASCs in myocardial repair.