Transplantation with Two Units of HLA-Mismatched Unrelated Umbilical Cord Blood in Treatment of an Adult Patient with Acute Myeloid Leukemia.

Objective To explore the feasibility, long-term hematopoiesis and complication of transplantation with two units of HLA-mismatched unrelated umbilical cord blood in treatment of adult acute myeloid leukemia.

Methods A 32 years old, 50kg male with acute myeloid leukemia in complete remission received transplantation with two units of HLA-mismatched unrelated umbilical cord blood.The conditioning regimen were modified(BU/CY)+ATG. The prophylaxis regimen for graft versus-host disease(GVHD) consisted of cyclosporine(CSA) and mycophenolate mofetil(MMF). The umbilical cord blood obtained from two different donors, both with mismatched HLA B/DRB locus from the recipient and mismatched HLA- B locus between the two donors. The umbilical cord blood was preserved in liquid nitrogen, recovered in a 40o C water bath immediately, infused via a catheter from the femoral artery to the arc of aorta, The doses of nucleated cells infusion were 4.4×10⁷/kg (from donor 1) and 2.8×10⁷/kg (from donor 2).

Results An absolute neutrophil count of more than 0.5×109/L at day 26,and a platelet count of more than 20×109/L at day 42. Septicemia with MRSA and pseudomomanas occurred at day 9 and day 14 because of agranulocytosis. The infection was controlled by Vancomycin, Tienam and HD-dose Gama immunoglobulin. Neither acute nor chronic GVHD developed in a follow-up period of 90 days. DNA-STR and HLA distinct analysis assay revealed a complete implant of cells from only one donor(donor2).

Conclusions 1.No donor with matched HLA bone marrow stem cell was available for the adult patient at the time of his relapse. HLA mismatched umbilical cord blood was obtained from two donors. Although cell counts for transplantation are much lower than the requirement of routine bone marrow transplantation, the speed of blood cell regeneration in the recipient is compatible with routine bone marrow transplantation. 2.Furthermore, Although DNA-STR and HLA analysis indicate complete implant of cells from only one donor, the result indicates transplantation with umbilical cord blood cells obtained from two different donors is promising in the situation where the cell number obtained from one donor is not enough.3.HLA- B/DRB locus was mismatched in the two donors. GVHD did not develop even after tapered off immunosuppresents 3 months post transplantation. No cross rejection observed by clinical presentation and blood cell analysis. The results indicate the incidence of GVHD is low after umbilical cord blood transplantation.