Specific fragments of vasostatin are disclosed. Also disclosed is a method of stimulating the proliferation or survival of a hematopoietic cell exposed to a chemotherapeutic agent or irradiation using these fragments. A method of stimulating the proliferation or survival of a hematopoietic cell is also disclosed. In one embodiment, the method is disclosed for stimulating the growth or survival of a hematopoietic stem cell with a fragment of vasostatin, in the presence of a growth factor.