The present invention relates to the in vitro production of erythrocytes/granulocytes and to the treatment of myelodysplastic syndrome using a method for inducing hemoblast differentiation. The present invention provides a media composition comprising gelsolin as an active ingredient for inducing the differentiation of hematopoietic precursor cells into erythrocytes/granulocytes, and a pharmaceutical composition comprising gelsolin as an active ingredient for treating myelodysplastic syndrome. Since the composition of the present invention improves the efficiency of differentiation of hematopoietic precursor cells into erythrocytes/granulocytes while maintaining a low rate of occurrence of cell dysplasia and having the effect of improving the enucleation rate and cell survivability, the present invention can be effectively used for producing erythrocytes/granulocytes in vitro and for treating myelodysplastic syndrome.
