Towards Clinically Meaningful Expansion of Human HSCs

Improved strategies for ex vivo expansion of human hemato-poietic stem cells(HSCs)are necessary to supply the large demand of cells required for certain clinical applications such as gene therapy/editing and cord blood(CB)transplantation.In a recent paper published in Nature,Sakurai et al.reported that the combination of three small molecules,namely a phosphoi-nositide 3-kinase activator peptide,a thrombopoietin receptor agonist and the pyrimidoindole derivative UM171,was sufficient to stimulate the expansion of umbilical CB HSCs,providing the first chemically defined cytokine-free expansion medium for human HSCs.