Short & Long-term Repopulating Capacity of Cord Blood Cells That Are Stored Overnight before Cryopreservation

Jung, Yun Seok; Kim, Sook Ja; Kim, Kyung Ha; Kim, Han Jo; Kim, Se Hyung; Kim, Hyun Jung; Lee, Sang Chul; Bae, Sang Byung; Kim, Chan Kyu; Lee, Nam Su; Lee, Kyu Taek; Park, Sung Kyu; Hong, Dae Sik; Park, Hee Sook; Won, Jong Ho

Abstract

BACKGROUND
Umbilical cord blood (UCB) is generally stored overnight and it undergoes a CD34 positive selection process the next day for reducing the cost and due to the convenience. We intended to determine whether overnight storage of cord blood cells affects the short and long-term repopulating capacity.
METHODS
Five individuals' UCB samples were analyzed by colony assay, apoptotic cell counts and long term bone marrow culture. All the samples were divided to four groups, which were the fresh group (immediate use of harvest), the overnight storage group (overnight storage at room temperature after harvest), the immediate cryopreservation group (immediate cryopreservation after harvest) and the overnight cryo group (cryopreservaton after overnight storage at room temperature after harvest).
RESULTS
The number of colony forming units-granulocyte macrophage (CFU-GM) was 116.2+/-20.1 in the fresh group and 90.8+/-15.8 in the overnight storage group (P=0.07). The number of CFUs-GM was similar between the immediate and overnight cryo groups (P=0.79). The immediate cryo group showed a significantly lower number of CFUs-GM as compared to that of the fresh group (P=0.03). The apoptotic cells were detected at 21+/-6.8% in the fresh group and this was 24.2+/-2.4% in the overnight storage group (P=0.32), and this was similar between immediate and overnight cryo groups (P=0.80). The fresh group had a significantly lower number of apoptotic cells compared to that of the immediate cryo group (P=0.02). After long term stromal-based culture, the mean production of CFU-GM colonies was similar between all the groups (P>0.05).
CONCLUSION
These results support the continue use of overnight storage of UCB before cryopreservation as a convenient, cost reducing measure.