Current description is related to in-vitro method, candidate stem cell (HSCs) is cultivated under mild hyperthermia situation (for example, between 38 degrees Celsius and 40 degrees Celsius) under the conditions of it is used for existing for the pyrimidoindole derivative excitant of hematopoietic stem cell expansion. The combined use of mild hyperthermia and pyrimidoindole derivatives synergistic effect is to promote CD34+ HSCs and/or difference to be extended to the cell (for example, megakaryocytic progenitor) of progenitor cells. Current description is also related to the ex vivo cell population of HSCs and/or predecessor, and its use in therapy (for example, transplanting).
