Authors:
Simon N. Robinson, Hong Yang, William K. Decker, Dongxia Xing, David Steiner, Jingjing Ng, Michael W. Thomas, Richard E. Champlin, Paul J. Simmons, Nathalie Brouard, Shannon Kidd, Leonard P. Miller, Lijun Xia, Laurence J.N. Cooper, Elizabeth J. Shpall, and Patrick A.
Zweidler-McKay
Summary:
Background - The use of cord blood (CB) as a stem cell source for transplant is limited by cell dose and delayed engraftment. Beyond cell dose, it has been shown that on a cell-for-cell level, cord blood-derived hematopoietic stem cells (HSCs) are deficit in homing compared to adult bone marrow-derived HSCs. Although cord blood HSCs express P-selectin glycoprotein ligand-1 (PSGL1), they lack the terminal fucosylation which is necessary for P and E-selectin binding. These selectins are expressed by the microvasculature of the hematopoietic microenvironment, and appear to play a role in HSC homing.
Objective - To determine if increasing the level of fucosylation of surface ligands on CB HSCs will improve the rate and magnitude of engraftment.
Design/Methods - Freshly collected human cord blood cells were CD34- selected, then exposed to recombinant fucosyltransferase VI (FTVI, kindly provided by OMRF and ASC) in the presence of the substrate GDP-fucose for 30 minutes prior to injection into sublethally-irradiated NOD/SCID/IL- 2Rgamma mice. Levels of fucosylation pre- and post-treatment were determined by flow cytometry using the anti-sialyl Lewis X antibody. Each mouse received _4.5_104 CD34þ cells by tail vein injection. The rate of human engraftment was measured by the appearance of human CD45þ cells in peripheral blood (PB) samples. Multi-lineage reconstitution was measured with human-specific lineage markers.
Results - Following fucosylation, 95% of CD34þ cells had high Lewis X antigen levels, compared to 1% in non-fucosylated samples, confirming significant fucosyltransferase activity. In mice, peripheral human engraftment could be detected in FTVI-treated HSC mice within 2 weeks post-transplant, compared to >3 weeks in control HSC mice. In addition, engraftment percentages after 3 weeks remained greater than 4- fold higher in FTVI-treated HSC mice. Importantly, no loss of engraftment was seen and no significant differences were observed in multi-lineage engraftment.
Conclusions - These data demonstrate that ex vivo fucosylation of CB HSCs dramatically improves the rate of engraftment, provides long-term multi-lineage reconstitution and is clinically feasible. These preliminary data support ex-vivo fucosylation as a novel method of improving cord blood transplantation.
Source:
The American Society of Pediatric Hematology/Oncology (ASPHO) 21st Annual Meeting, May 14-17, 2008, Duke Energy Center & Hyatt Regency, Cincinnati, OH, Poster 101/PLATFORM SESSION 304