Umbilical cord blood (CB) are cryopreserved as a source of hematopoietic stem cells for allogeneic transplantation in recently established cord blood banks in Japan. However, as the number of cryopreserved CB units increases, the shortage of storage space will become a serious problem. We evaluated the efficacy of the new cryopreservation bag with a small stereocubic shape (F-025, Nipro). The size of F-025 is 87×72×8mm, which is about half of other cryopreservation bags, and the volume is 25ml. This bag consists of two rooms, large (20ml) and small (5ml). The small room is designed for the manipulation of CB cells such as ex-vivo expansion. White blood cells derived from peripheral blood (PB) or cord blood were cryopreserved after concentration in 25ml with 10% dimethylsulfoxide and 1% dextran. After the cryopreservation in liquid nitrogen for 1-4 weeks, these cells were thawed and characterized. Recovery rates of colony-forming cells with PB (n=12) and CB (n=7) were 94.3±18.6% (large room), 95.0±22.2% (small room), and 96.1±13.4% (large room), 87.9±6.9% (small room), respectively, which was comparable to the result of conventional cryopreservation bags. In conclusion, the new cryopreservation bag system is effective for cord blood storing.
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