The present description relates to in vitro methods for culturing hematopoietic stem cells (HSCs) under mild hyperthermia conditions (e.g., between 38° C. and 40° C.) in the presence of a pyrimidoindole derivative agonist of hematopoietic stem cell expansion. The combined use of mild hyperthermia and the pyrimidoindole derivative act synergistically to promote expansion of CD34+ HSCs and/or differentiation into progenitor cells (e.g., megakaryocytic progenitors). The present description also relates to in vitro expanded cell populations of HSCs and/or progenitors, as well as uses thereof in therapy (e.g., transplantation).
