Pre‐freeze and post‐thaw characteristics on chimerism patterns in double‐unit cord blood transplantation

We analyzed the pre‐freeze and post‐thaw characteristics on chimerism patterns in 20 cases of double‐unit cord blood transplantation. The cord blood units (CBUs) were a 4/6 HLA match or better with recipients and achieved a minimum combined precryopreservation cell dose of 3.7 × 10 7 total nucleated cell (TNC)/kg. The unit with a higher cell dose was infused first. All evaluable patients engrafted at a median of 18 days. By day 42, neutrophil engraftment was derived from both donors in 63% of cases and a single donor in 37% of patients. By day 100, one unit predominated in 80% of the patients. Higher pre‐freeze TNC and CD34+ cell doses were associated with cord predominance in 67% of patients. Pediatr Blood Cancer 2009;52:547–550. © 2008 Wiley‐Liss, Inc.