HGF and myocardial infarction: Efforts have been made to improve the ability of BMSCs to treat myocardial infarction through (1) isolation of specific cell types such as CD133 [74], CD271 [75], and CD117 (c-kit)-positive cells; (2) genetically engineered cells overexpressing VEGF [76], hepatocyte growth factor (HGF) [77], and insulin-like growth factor (IGF) [78]; (3) use of exosomes derived from BMCs; (4) using microRNAs such as miR-19a/19b [79] and miR-29a [80]; and (5) using 3D structures of BMCs or engineered BMCs and exosomes.