While Lonza’s Human Aortic Smooth Muscle Cells (AoSMC) are isolated from either the ascending or descending aorta, it is usually the ascending aorta that is used. If the heart comes with the aorta, which happens most of the time, then the AoSMC are most likely isolated from the ascending aorta or the arch of the aorta. If just an aorta comes in, which comes in much less frequently, then the AoSMC are probably isolated from the descending aorta.