Efficient Expansion of SALL4–Transduced Umbilical Cord Blood Derived CD133+Hematopoietic Stem Cells

Abstract

Hematopoietic stem cells (HSCs) were characterized by self-renewal and multilineage potential. Umbilical cord blood-derived (UCB) as an alternative source of HSCs is widely used especially in children for stem cells transplant (SCT). The main limitation in using UCB for transplantation especially in adults is low cell dose. To overcome this limitation besides using double dose UCB, ex vivo expansion is the most important way to increase cell number for transplantation. HSCs are mainly isolated using CD133 or CD34. CD133, as the most primitive marker, shows important physiological role in maintenance and expansion of HSCs. SALL4 plays crucial role in the development and maintaining the pluripotency and self-renewal ability of embryonic stem cells (ESCs) as well as HSCs. Moreover, SALL4 act as a regulator of HSCs expansion, normal hematopoiesis, and hematological malignancies. In the present study, CD133⁺ cells positively selected and ex vivo expanded in SALL-4 and GFP-transduced group. CD133 expression assessed using flow cytometry at day 0, 7 and 10. Moreover, multilineage differentiation and proliferation potential of expanded cells in both groups evaluated using colony forming unit (CFU) assay, and cells count assay. Karyotyping analysis was performed to assess any chromosomal instability after 7 days of expansion. Obtained results demonstrated that SALL-4 transduced cells showed significant increase in cell number compared to control group. Moreover, immunophenotyping results showed higher expression level of CD133 at day 7 and 10 following expansion in SALL-4 transduced (62 % and 42%) compared to control group (51% and 20.6%). Our results illustrated that SALL4 could act as a positive factor for the expansion of CD133⁺ derived UCB cells besides maintaining self-renewal and differentiation ability of expanded cell without any numerical and structural chromosomal aberrations.