Cord Blood Storage for ≥ 5 Years Does Not Impact Engraftment

The impact of the years of storage of an umbilical cord blood unit (CBU) on its engraftment potency is not known. We analyzed engraftment kinetics of 15 Old CBUs defined as stored for more than 5 years and compared it to 71 Younger CBUs for end points of time to neutrophil and platelet engraftment. The median duration of storage for the Old CBUs was 5.6 years (5.6-12.2 years). For Old vs. Young CBUs, the average total nucleated count was 0.5 x10⁶ vs. 55x10⁶ (p=0.004), cryopreservation volume of 72ml vs. 70ml (p=0.9), CD34 count of 0.19x10⁶/kg vs. 0.23x10⁶/kg (p=0.7). There were no differences in the processing of the CBUs. The donor characteristics for the Old vs. Young CBUs were Caucasian race: 7% vs. 24% (p<0.0001)and female sex: 43% vs. 49% (p=0.3). The recipient characteristics for the Old vs. Young CBUs were: female sex: 57% vs. 45% (p=0.4), Caucasian race 43% vs. 63% (p<0.0001), recipient weight 30kg vs. 38kg (p=NS), recipient age 14 vs. 16 years (p=NS). The transplant conditioning, GVHD prophylaxis and degree of HLA mismatch was comparable for the two groups. There were no differences in the engraftment kinetics for the Old vs. Young CBUs with time to neutrophil engraftment of 21 vs. 22 days (p=0.5); platelet engraftment of 43 vs. 42 days (p=0.3). Early deaths were comparable 7% vs. 6%, no differences were noted in the duration of hospitalization. We conclude that Old CBUs should remain as a potential source of stem cells.