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Improved Engraftment in an NOD-SCID IL-2Rγnull Mouse Model Following Transplantation of Fucosylated Cord Blood Mononuclear Cells

Year: 2009

Type: article

Abstract: Cord blood (CB) provides a readily available, ethnically-diverse source of hematopoietic tissue for transplantation, however, low cell dose delays engraftment and increases risk of graft failure. In addition, it has also been suggested that CB hematopoietic stem cells (HSC) home less efficiently to the hematopoietic microenvironment after transplantation when compared to bone marrow or peripheral blood HSC. Homing mechanisms may rely, at least in part, on the interaction between fucosylated glycoproteins on the surface of HSC and P- and E-selectins expressed by the microvasculature of the hematopoietic system. Glycoproteins expressed on the surface of CB HSC appear to be poorly fucosylated. It has been proposed that the use of a fucosyltransferase (FT) to increase levels of surface glycoprotein fucosylation may improve homing to the bone marrow and thereby improve engraftment. In an initial series of experiments, levels of fucosylation of surface glycoproteins expressed on CB CD34+ cells were increased using FT-VI (Engraftin™, America Stem Cell). When subsequently injected into an NOD-SCID IL-2Rγnull mouse model, the rate and magnitude of human engraftment was greater than in mice receiving a similar dose of untreated CB CD34+ cells. Since CB recipients receive mononuclear cells (MNC) rather than selected CD34+ cells, the efficacy of a fucosylation strategy using CB MNC was investigated. Methods: MNC were obtained from a frozen CB unit. Half was untreated and half fucosylated: incubation for 30 minutes at room temperature with 1 mM GDP β-Fucose, 1 mM MnCl2 and FT-VI. Fucosylated and untreated MNC were washed and each transplanted into sublethally-irradiated (270 cGy) NOD-SCID IL-2Rγnull mice (5 mice/gp). Mice each received 6 × 106 CB MNC (containing 2.5 × 104 CD34+ cells) by tail vein injection. Engraftment was followed at weekly intervals by flow cytometric measurement of human CD45+ cells in the peripheral blood. Results: 6 weeks after transplantation, recipients of fucosylated MNC showed a maximal 14% human engraftment, as compared to 1% in recipients of untreated MNC. Conclusion: Consistent with preliminary data following transplantation of fucosylated, or untreated CB CD34+ cells, fucosylation of CB MNC appears to improve both the rate and magnitude of engraftment. The efficacy of this technology will be explored in both the single and double CB transplant settings and a clinical trial evaluating this approach will be designed and executed.

Source: Transplantation and Cellular Therapy

DOI: 10.1016/j.bbmt.2008.12.046