Fucosylation with fucosyltransferase VI or fucosyltransferase VII improves cord blood engraftment.

BACKGROUND AIMS: Advantages associated with the use of cord blood (CB) transplantation include the availability of cryopreserved units, ethnic diversity and lower incidence of graft-versus-host disease compared with bone marrow or mobilized peripheral blood. However, poor engraftment remains a major obstacle. We and others have found that ex vivo fucosylation can enhance engraftment in murine models, and now ex vivo treatment of CB with fucosyltransferase (FT) VI before transplantation is under clinical evaluation (NCT01471067). However, FTVII appears to be more relevant to hematopoietic cells and may alter acceptor substrate diversity. The present study compared the ability of FTVI and FTVII to improve the rapidity, magnitude, multi-lineage and multi-tissue engraftment of human CB hematopoietic stem and progenitor cells (HSPCs) in vivo. METHODS: CD34-selected CB HSPCs were treated with recombinant FTVI, FTVII or mock control and then injected into immunodeficient mice and monitored for multi-lineage and multi-tissue engraftment. RESULTS: Both FTVI and FTVII fucosylated CB CD34⁺ cells in vitro, and both led to enhanced rates and magnitudes of engraftment compared with untreated CB CD34⁺ cells in vivo. Engraftment after treatment with either FT was robust at multiple time points and in multiple tissues with similar multi-lineage potential. In contrast, only FTVII was able to fucosylate T and B lymphocytes. CONCLUSIONS: Although FTVI and FTVII were found to be similarly able to fucosylate and enhance the engraftment of CB CD34⁺ cells, differences in their ability to fucosylate lymphocytes may modulate graft-versus-tumor or graft-versus-host effects and may allow further optimization of CB transplantation.

Fucosyltransferase VII improves the function of selectin ligands on cord blood hematopoietic stem cells.

Selectins and their carbohydrate ligands mediate the homing of hematopoietic stem/progenitor cells (HSPCs) to the bone marrow. We have previously shown that ex vivo fucosylation of selectin ligands on HSPCs by α1,3 fucosyltransferase VI (FUT6) leads to improved human cord blood (CB)-HSPC engraftment in non-obese diabetic (NOD)/severe combined immune deficient (SCID) mice. In the present study, we determined whether surface fucosylation with α1,3 fucosyltransferase VII (FUT7), which is primarily expressed by hematopoietic cells, improves the function of selectin ligands on CB-HSPCs in comparison with FUT6. A saturating amount of either FUT6 or FUT7, which generates comparable levels of expression of fucosylated epitopes on CB CD34(+) cells, was used for these experiments. In vitro, FUT7-treated CB CD34(+) cells exhibited greater binding to P- or E-selectin than that of FUT6-treated CB CD34(+) cells under static or physiological flow conditions. In vivo, FUT7 treatment, like FUT6, improved the early engraftment of CB CD34(+) cells in the bone marrow of sublethally irradiated NOD/SCID interleukin (IL)-2Rγ(null) (NSG) mice. FUT7 also exhibited marginally-yet statistically significant-increased engraftment at 4 and 6 weeks after transplantation. In addition, FUT7-treated CB CD34(+) cells exhibited increased homing to the bone marrow of irradiated NSG mice relative to sham-treated cells. These data indicate that FUT7 is effective at improving the function of selectin ligands on CB-HSPCs in vitro and enhancing early engraftment of treated CB-HSPCs in the bone marrow of recipients.

Fucosylation Enhances the Efficacy of Adoptively Transferred Antigen-Specific Cytotoxic T Lymphocytes.

PURPOSE: Inefficient homing of adoptively transferred cytotoxic T lymphocytes (CTLs) to tumors is a major limitation to the efficacy of adoptive cellular therapy (ACT) for cancer. However, through fucosylation, a process whereby fucosyltransferases (FT) add fucose groups to cell surface glycoproteins, this challenge may be overcome. Endogenously fucosylated CTLs and ex vivo fucosylated cord blood stem cells and regulatory T cells were shown to preferentially home to inflamed tissues and marrow. Here, we show a novel approach to enhance CTL homing to leukemic marrow and tumor tissue. EXPERIMENTAL DESIGN: Using the enzyme FT-VII, we fucosylated CTLs that target the HLA-A2-restricted leukemia antigens CG1 and PR1, the HER2-derived breast cancer antigen E75, and the melanoma antigen gp-100. We performed in vitro homing assays to study the effects of fucosylation on CTL homing and target killing. We used in vivo mouse models to demonstrate the effects of ex vivo fucosylation on CTL antitumor activities against leukemia, breast cancer, and melanoma. RESULTS: Our data show that fucosylation increases in vitro homing and cytotoxicity of antigen-specific CTLs. Furthermore, fucosylation enhances in vivo CTL homing to leukemic bone marrow, breast cancer, and melanoma tissue in NOD/SCID gamma (NSG) and immunocompetent mice, ultimately boosting the antitumor activity of the antigen-specific CTLs. Importantly, our work demonstrates that fucosylation does not interfere with CTL specificity. CONCLUSIONS: Together, our data establish ex vivo CTL fucosylation as a novel approach to improving the efficacy of ACT, which may be of great value for the future of ACT for cancer.

Circulating mononuclear progenitor cells: differential roles for subpopulations in repair of retinal vascular injury.

PURPOSE: We examined effect on retinal vascular homing of exogenous CD34(+) and CD14(+) progenitor cells using mouse models of chronic (streptozotocin [STZ]-induced diabetes) and acute (ischemia-reperfusion [I/R]) ocular vascular injury. METHODS: STZ-treated mice of short or long duration (≤4, ≥11 months) diabetes, along with age- and sex-matched controls, were given intravitreous injections of human CD34(+) and CD14(+) cells isolated from healthy or diabetic donors alone or in combination. I/R injured mice were given diabetic or nondiabetic CD34(+) cells with mesenchymal stem cells (MSCs) or diabetic CD34(+) cells manipulated by ex vivo fucosylation with ASC-101. Injected cells were localized by fluorescent immunocytochemistry, and the degree of retinal vascular colocalization quantified morphometrically. Permeability was assessed by fluorescent albumin leakage. RESULTS: Diabetic CD14(+) cells associated with vessels to a greater degree than diabetic CD34(+) cells. Vascular permeability was reduced only by nondiabetic cells and only at the highest number of cells tested. Diabetic CD34(+) cells consistently demonstrated reduced migration. There was a 2-fold or 4-fold increase over control in the specific localization of diabetic CD34(+) cells within the vasculature when these cells were co-administered with MSCs or ex vivo fucosylated prior to injection, respectively. CONCLUSIONS: Diabetic CD14(+) cells, unlike diabetic CD34(+) cells, retain robust homing characteristics. CD34(+) or CD14(+) subsets rather than whole bone marrow or peripheral blood cells may prove more beneficial in autologous cell therapy for diabetics. Co-administration with MSCs or ex vivo fucosylation may enhance utility of CD34(+) cells in cell therapy for diabetic ocular conditions like macular ischemia and retinal nonperfusion.