In an attempt to repair or regenerate the ischemia-damaged myocardium, there have been different candidates, including feta/neonatal cardiomyocytes, embryonic stem cells, skeletal myoblasts, bone-marrow-derived stem cells, EPCs, peripheral-blood-derived CD34+ cells, cardiac progenitor cells, and fibroblasts, which apparently produced promising results in prior experimental studies on heart failure [91]. Here, CD34 is linked to heart failure.