P65 National Blood Service Directed Sibling Cord Blood Banking for Transplantation

Umbilical cord blood (UCB) is an important source of stem cells for transplantation and may cause less GvHD than non-T-depleted bone marrow (BM). Only 25% of paediatric patients have an HLA matched sibling and for the remainder an unrelated BM or UCB donation may also not be available. A directed UCB (DCB) collection from a newborn sibling may be the only opportunity for a transplant until the sibling can donate BM. Matched DCB donations have been shown to give better long-term results than matched unrelated UCB or BM but DCB collection is not as easy to control as unrelated banking in hospitals established as collection sites. In the context of mandatory licensing under the European Union Tissues and Cells Directive introduced in April 2006, we have reviewed NBS DCB banking. Over ten years, 268 DCB collections were made, 233 (87%) for an existing sibling with a disease treatable by transplantation, and the remainder for families with a history of an inherited high risk disease. Diagnoses included 114 haematological malignancies, 68 hereditary anaemias and 53 immune or metabolic deficiencies. Collections were cryopreserved within 24 h without volume reduction.   Volume mL Total TNC ×108 Total CD34 ×106 TNC Viability % Median 73 8.8 2.3 99.0 Mean ± S.D. 76 ± 32 9.9 ± 5.5 3.3 ± 3.4 98.2 +3.7 Range 14–173 1.0–31.0 0.13–26.7 73.0–100.0 88% of collections exceeded 40 ml UCB, the cut-off used by some banks including NHS-CBB. Despite the logistical difficulties in organising collections from many hospitals the cell counts and viabilities of DCB collections compare favourably with collections for UCB banks. The decision to continue storage was made once the cell counts and tissue typing results were also known. Of units collected for existing siblings, 67 (28%) were a 10:10 match for HLA -A, -B, -Cw, -DRB1 and -DQB1. Of these, 13 units were transplanted, with 10 for non-malignant disorders, including one collected following pre-implantation tissue typing for a sibling affected by DBA. Median time to neutrophil engraftment was 18 days (range 14–28) and 30 days (range 11–59) for platelets. DCB collection provides the option of immediate transplant with the potential of future sibling donation of stem cells or lymphocytes. DCB banking for high-risk families is therefore a useful service to provide and complements the work of unrelated UCB banks.