Novel chemical attempts at ex vivo hematopoietic stem cell expansion.

Hematopoietic stem cells (HSCs) are the most extensively studied stem cell type in adults, and the only stem cell type with proof of clinical utility. However, the greatest challenge for the broader use of HSCs remains the true expansion of the stem cells ex vivo. The development of researches on small-molecule compounds that support the safe and efficient ex vivo expansion of HSCs would help to promote the clinical application of HSCs. In recent years, several novel small-molecule compounds have been reported to improve ex vivo HSC expansion by promoting self-renewal, delaying differentiation, increasing homing, and inhibiting apoptosis. Here, we review recent chemical developments in stem cell research and the mechanisms underlying these compounds' effects.