[Engraftment of ex vivo expanded mononuclear cells from human umbilical cord blood in NOD/SCID mice]

Abstract

This study was purpose to explore the effect of combination of SCF, FL, TPO without serum and stroma on the ex vivo expansion of the mononuclear cells derived from umbilical cord blood (CB) and to evaluate the proper infused time and implantation of expanded cells. Mononuclear cells derived from CB were cultured with the combination of SCF, FL and TPO for 14 days. At 0, 7, 10 and 14 days, the total mononuclear cells in culture were counted, CD34+ cells and CD34+CXCR4+, CD34+CD49d+ cells were assayed by flow cytometry, and CFU were determined. Mononuclear cells from CB cultured for 7 days ex vivo in serum- and stroma-free medium containing FL+SCF+TPO were infused into sublethally irradiated NOD/SCID mice. Six weeks after transplantation, the human cells were assessed by flow cytometry and PCR. The results showed that after culturing ex vivo in the presence of SCF+FL+TPO for 14 days, the total number of nuclear cells significantly increased in the early stage of culture, CD34+, CD34+CD49d+ cells reached a peak level at 7 days and then decreased, while the peak level of CFU, CD34+CXCR4+ cells was at 10 days, then decreased. Human hematopoietic cells could be detected in the marrow of the recipients at 6 weeks after infusion and the rate of success of NOD/SCID mice implanted with the expanded cells was higher than mice transplanted with fresh sample and control (p<0.05). It is concluded that day 7-10 may be an optimal harvest time for transplantation. The expanded cells with FL+SCF+TPO can be engrafted into the bone marrow of sublethally irradiated NOD/SCID mice. The engrafting potential of cord blood may be enhanced via up-regulating CXCR4 and CD49d expression on the CD34+ cells.