深低温冻存不同时间对脐血细胞质量的影响

本研究旨在探讨不同冻存时间的脐血干细胞复苏后的回收率，并分析冷冻复苏的细胞对患者植入速度的影响。20份经-196℃液氮低温保存1-10年的脐血干细胞标本，比较冻存前（脐血库提供资料）和复苏后的细胞活率、总有核细胞数（TNC）、CD34＋细胞和粒-巨噬细胞集落形成单位（CFU-GM）的数量，并分析复苏后的细胞回收对移植受者植入速度的影响。结果表明，不同冻存时间对复苏后干细胞的回收率没有影响。经冻存复苏后，细胞活存率为（92．75±2．55）％，TNC、CD34＋细胞数和CFU-GM的回收率分别为89．9％、84．8％和84．3％，与冻存前相比明显减少（P=0．000），但细胞数量的下降对移植患者中性粒细胞和血小板的植入时间均无影响。冻存后TNC和CD34＋细胞数量与冻存前数量有很大的相关性（r=0．954；r=0．931，P=0．000），而CFU-GM的相关性弱（r=0．285，P=0．223）。结论：冻存和复温过程会-定程度上损伤脐血干细胞，导致细胞丢失，但不会影响移植的效果。

Effect of Different Cryopreservation Time on Quality of Umbilical Cord Blood Cells

This study was aimed to explore the effect of different cryopreservation time on recovery rate of cord blood stem cells, and analyze the influence of cord blood cells after thawing on the engraftment speed of cord blood ceils in patients. 20 cord blood units were stored at - 196℃ for 1 - 10 years. The cell viability, content of total nucleated cell （TNC）, CD34＋ cells and the colony forming units of granulocyte/macrophage （CFU-GM） were assessed after thawing, the impact of cell recovery on engraftment speed in patients was analyzed. The results showed that as compared with data provided by Umbilical Cord Blood Bark, the different cryopreservation time had no effect on yield of cord blood stem cells after thawing. The cell viability was （92.75 ±2.55 ） % after thawing, the yields of TNC, CD34 ＋ cells and CFU-GM were 89.9% ,84.8% and 84.3%, compared with that of pre-freezing, their differences were statistically significant （P = 0.000）, however, loss of cells had no effect on the time of neutrophils and platelets engraftment. The TNC and CD34 ＋ cell count after thawing correlated closly with that of pre-freezing （ r = 0. 954 and r = 0. 931, P = 0.000）, but CFU-GM content poorly correlated with that （ r = 0. 285, P = 0.223 ）. It is concluded that cryopreservation and thawing process can damage the cord blood stem cells, leading to cell loss, but not affect transplant results.