Fig. 6

Effects and mechanisms of sequential transplantation of exosomes and the combinatorially pretreated MSCs in the treatment of AMI. Delivery of exosomes into infarcted myocardium 30 min after infarction markedly elevated myocardial SDF-1 levels, decreased inflammatory cytokines levels including TNF-α and IL-6 and reduced apoptosis at Day 3 post-AMI, ameliorating the harsh microenvironment which was beneficial for the recruitment and survival of the sequentially transplanted MSCs. In addition, combinatorial pretreatment of hypoxia and TXL augmented the CXCR4 level and increased the recruitment of transplanted MSCs to the infarcted myocardium. These effects ultimately led to significantly enhanced cardiac function, angiogenesis and reduced infarct size