‘SCF + TPO + FL + IGFBP1 + IGFBP2 + ANGPTL3’ is the optimal cytokine combination to enhance ex vivo expansion of CD34+CD38−CD90+primitive progenitor cells. Post-thaw umbilical cord blood cells (4 × 105 cells/ml) were suspended in serum-free Stemspan® media (Stemcell technologies, vancouver, BC, Canada) supplied with different cytokine combinations with optimal doses and standard cytokine combinations of 100 ng/ml stem cell factor (S), 50 ng/ml FLT3 ligand (F) and 100 ng/ml thrombopoietin (T), inoculated on a passage 3 to 5 bone marrow-derived mesenchymal stromal cell layer in a 24-well plate and cultured for 12 days. Here, the optimal dose of IGFBP1 (A), IGFBP2 (B), IGF2 (C) and ANGPTL3 (D) was 15 ng/ml, 20 ng/ml, 10 ng/ml and 20 ng/ml respectively. (A) Expansion of viable total nucleated cells (TNCs). (B) Expansion of CD34+ cells. (C) Expansion of granulocyte–macrophage colony-forming units (CFU-GM). (D) Expansion of CD34+CD38−CD90+ cells. Results expressed as mean ± standard error (cord blood unit number, n = 6). ANGPTL, angiopoietin-like protein; IGF, insulin-like growth factor; IGFBP, insulin-like growth factor binding protein.