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

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.

The Effect of Overnight Storage of Cord Bloods on Cell Viability, Live CD34 Cell Fraction, and Clonogenic Potential under Different Storage Conditions / 대한소아혈액종양학회지

PURPOSE: In children, at least two or more stem cell mobilization processes are needed in autologous peripheral blood stem cell transplantation to prevent delayed engraftment. And to decrease the risk of tumor cell contaminations, the use of CD34 positive cell selcetion is in increasing tendency. The first leukapheresis product is stored overnight and undergoes CD34 positive selection process mixed with the next day leukapheresis product to save the costs. We intended to find out the optimal overnight storage condition that might minimize the loss of stem cell components. METHODS: RBC (red blood cell)- depleted human umbilical cord bloods (UCB) were used as the source of stem cells because of their easy availability. UCB were processed by isolating the mononuclear cell (MNC) layer using Ficoll-Paque to make the nature similar to leukapheresis products. Fifteen individual UCB were analyzed by several parameters (MNC count and viability, live CD34 positive cell fraction, clonogenic potential) at fresh conditions and under four different overnight storage conditions (room temperatiure (RT), room temperature with autoplasma (AP), 4degrees C, 4degrees C with autoplasma). Analysis of variance, Kruskal-Wallis test, and Wilcoxon signed rank test were used for statistical analyses. RESULTS: Though MNC counts were statistically not different between each conditions (P=0.07), the best recovery (mean 86.9%) was observed at 4degrees C with AP but without statistical significance. MNC viability decreased at RT with or without AP (P 0.05). Live CD34 positive cell fractions were significantly decreased under all four different storage conditions compared with fresh ones. However, the samples stored at 4degrees C showed less prominent decreases in live CD34 positive cell fractions than those of RT conditions irrespective of the presence of AP (P=0.0001). CONCLUSION: It seems that 4degrees C condition is superior to RT when short term storage of stem cell products is mandatory. The addition of AP seemed to be advantageous but without statistical significance. The overnight storage of stem cell products at 4degrees C seems to be mandatory because it offers relatively high recovery and less loss of stem cell components. Although the effect of AP was statistically not significant, the role of AP should be studied further because there was a tendency of higher recovery of stem cells in the presence of AP.