Other ligands included Clu (Clusterin), which has also been identified in exosomes originated from pericardial fluid and could facilitate arteriogenesis during heart regeneration after MI [14], and Hspg2, a kind of heparan sulfate proteoglycan, which served as an essential determinant of angiogenesis following hind-limb ischemia [41]. Here, CD44 is linked to myocardial infarction.