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 precryo-preservation cell dose of 3.7 x 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.