Enforced fucosylation of cord blood hematopoietic cells accelerates neutrophil and platelet engraftment after transplantation

Abstract

Delayed engraftment is a major limitation of cord blood transplantation (CBT), due in part to a defect in the cord blood (CB) cells' ability to home to the bone marrow. Because this defect appears related to low levels of fucosylation of cell surface molecules that are responsible for binding to P- and E-selectins constitutively expressed by the marrow microvasculature, and thus for marrow homing, we conducted a first-in-humans clinical trial to correct this deficiency. Patients with high-risk hematologic malignancies received myeloablative therapy followed by transplantation with 2 CB units, one of which was treated ex vivo for 30 minutes with the enzyme fucosyltransferase-VI and guanosine diphosphate fucose to enhance the interaction of CD34(+) stem and early progenitor cells with microvessels. The results of enforced fucosylation for 22 patients enrolled in the trial were then compared with those for 31 historical controls who had undergone double unmanipulated CBT. The median time to neutrophil engraftment was 17 days (range, 12-34 days) compared with 26 days (range, 11-48 days) for controls (P = .0023). Platelet engraftment was also improved: median was 35 days (range, 18-100 days) compared with 45 days (range, 27-120 days) for controls (P = .0520). These findings support ex vivo fucosylation of multipotent CD34(+) CB cells as a clinically feasible means to improve engraftment efficiency in the double CBT setting. The trial is registered to www.clinicaltrials.gov as #NCT01471067.

Figure 1

Transplantation of unmanipulated and fucosylated CB cells. Patients were admitted on day −8 for intravenous hydration, and the preparative regimen was given from days −7 to −2. On day 0, the CB unit with the highest TNC dose was thawed, washed, and infused without further manipulation. The unit with the smaller TNC dose was then thawed, washed, and treated with 100 mU/mL FT-VI and 1 mM GDP β-fucose (Targazyme) for 30 minutes at room temperature. The fucosylated cells were then washed and infused.

Figure 2

Extent and durability of fucosylation of CB cells. (A) Mean fluorescence intensity of fucosylated (white) and untreated (gray) CB cells. The degree of fucosylation (measured with the HECA antibody) on CB-CD34⁺ cells, megakaryocytes (CD61⁺CD45⁺), NK cells (CD3⁻CD56⁺), and monocytes (CD14⁺) was increased compared with that of the corresponding untreated cells (gray), whereas neither T cells (CD3⁺) nor B cells (CD19⁺) showed increased fucosylation. (B) Stable HECA expression (fucosylation) on (a) CD34⁺ cells, (b) megakaryocytes (CD45⁺CD61⁺), and (c) NK cells (CD3⁻CD56⁺) for up to 24 hours after the fucosylation procedure.

Figure 3

Accelerated engraftment after CB cell fucosylation. (A) Cumulative incidence of neutrophil engraftment at 30 days after transplant was 95.5% (95% CI, 40.8-99.8%) in the study group compared with 81.65% (95% CI, 60.56-91.19%) in controls (P = .0003). (B) Cumulative incidence of platelet engraftment at 65 days was 86.36% (95% CI, 54.54-96.52%) in the study group compared with 58.07% (95% CI, 38.41-73.43%) in controls (P = .0065).

Figure 4

Contributions of fucosylated (blue) and unfucosylated (red) CB units to chimerism on days 15, 30, and 100, analyzed with polymerase chain reaction primer sets that flanked microsatellite repeats. Numbers beneath the graph represent individual patients. (A-C, D-F, and G-I) Results for the peripheral blood (PB), myeloid, and T-cell compartments, respectively.

Figure 5

Times to engraftment by dominant CB unit. Cumulative incidence curves for either (A) neutrophils or (B) platelets did not differ, whether the dominant unit was fucosylated (n = 8) or not (n = 12). See also Figure 4.