Due to the low number of collectable stem cells from single umbilical cord blood (UCB) unit, their initial uses were limited to pediatric therapies. Clinical applications of UCB hematopoietic stem and progenitor cells (HSPCs) would become feasible if there were a culture method that can effectively expand HSPCs while maintaining their self-renewal capacity. In recent years, numerous attempts have been made to expand human UCB HSPCs in vitro. In this study, we report that caffeic acid phenethyl ester (CAPE), a small molecule from honeybee extract, can promote in vitro expansion of HSPCs. Treatment with CAPE increased the percentage of HSPCs in cultured mononuclear cells. Importantly, culture of CD34 + HSPCs with CAPE resulted in a significant increase in total colony-forming units and high proliferative potential colony-forming units. Burst-forming unit-erythroid was the mostly affected colony type, which increased more than 3.7-fold in 1 μg mL 1 CAPE treatment group when compared to the controls. CAPE appears to induce HSPC expansion by upregulating the expression of SCF and HIF1-α. Our data suggest that CAPE may become a potent medium supplement for in vitro HSPC expansion.hematopoietic stem and progenitor cells, caffeic acid phenethyl ester, expansion Citation:Liu YM, Zhang BW, Zhang J, Wang SH, Yao HL, He LJ, Chen L, Yue W, Li YH, Pei XT. CAPE promotes the expansion of human umbilical cord blood-derived hematopoietic stem and progenitor cells in vitro.