Paracrine mechanisms of stem cell reparative and regenerative actions in the heart

► Stem cell secreted soluble factors improve overall cardiac function in the damaged myocardium. ► Healing processes include protection, neovascularization, differentiation, and remodeling. ► Adult stem cells that mediate cytoprotective effects include MSCs, BM-MNCs, EPCs and CPCs. ► Stem cell mediated paracrine effects can be enhanced by ex vivo and genetic modification. ► Though challenges remain, paracrine factor remains a promising therapy for cardiac repair.