Hematopoietic Stem Cell Transplantation (HSCT) for Benign Indications Using Plasma Depleted Umbilical Cord Blood Units (UCB) That Were Not Depleted of Red Blood Cells.

UCB is an attractive source for unrelated HSCT of benign indications; however, cell dosage is a critical factor for UCB HSCT. The red cell depletion (RD) and post-thaw wash techniques that are widely used incur significant nucleated cell loss; therefore, two strategies to minimize cell loss are to deplete plasma, but not the red blood cells (PD) during processing and forego post-thaw wash. A retrospective audited analysis was performed on 61 patients with benign disorders who were transplanted with 68 PD UCB units (8 double cords) with 29 thalassemias, 8 AA, 5 WAS, 5 SCID, 2 osteoporosis, 2 sickle cell disease, 2 Hemophagocytic Lymphohistiocytosis, 2 Hurler Syndrome, 1 CGD, 1 Fanconi’s Anemia, 1 Leroy I-Cell Disease, 1 Lymphohistiocytosis, 1 OIMD, and 1 Alpha Mannosidosis. Transplant characteristics: patient median age 4.25 years old (range 0.3–39); median weight 17 kg (range 5–76); male 56%; median # HLA ABDR matches of 5.0 (12–6/6; 19–5/6; 23–4/6; 5–3/6, 1–2/6); median pre-freeze TNC dose 8.1 x 10⁷/kg; median post-thaw TNC dose as reported by TC 7.7 x 10⁷/kg; median pre-freeze CD34 dose 3.1 x 10⁵/kg; transplants outside of U.S.− 32 (52%); non-myeloablative − 9; 44% post-thaw washed (W), 56% infused without post-thaw wash (NW). The Kaplan-Meier estimates of 3-month ANC500 and 6-month platelet 20K and 50K engraftment are 87±5%, 83±6%, and 84±6% respectively. The median time to engraftment for ANC 500, platelet 20K, and 50K are 20 days (range 11–64), 46 days (range 13–153), and 61 days (range 21–171) respectively. No major adverse event was observed in either the W or the NW group, and the median time to engraftment for ANC 500, platelet 20K and 50K for W vs. NW were 21 vs. 19 days, 55 vs. 44.5 days, and 76 vs. 59 days respectively. The incidence of reported grade II–IV acute GVHD was 29%, and 10% had grade III–IV acute GVHD. 33% developed limited chronic GVHD, and 15% developed extensive chronic GVHD. With a median follow-up of 219 days (range 4–1402 days), the Kaplan-Meier estimates of 1-year TRM, OS and disease-free survival were 20±6%, 78±6% and 72±6% respectively. These results demonstrate that HSCT using unrelated PD UCB can be performed safely with outstanding results in patients with benign disorders, and post-thaw washing may delay engraftment of HSCT using PD UCB.