Abstract: Objective To study the effect of temperature difference caused by different storage location ingas phase liquid nitrogen tank on the cryopreservation quality of umbilical cord blood（UCB）derived hematopoietic stem cells. Methods Twenty units of UCB hematopoietic cells in liquid nitrogen were selected as control group A, twenty units of samples preserved at the lowest temperature in the gas phase liquid nitrogen tank as experimental group B, and twenty units preserved at the highest temperature in the tank as experimental group C. After thawing and resuscitation, nucleated cell count, cell activity, CD34⁺% and CFU-GM were detected and one-way ANOVA was performed. Results There was no significant difference in the recovery rate of nucleated cells, the change rate of activity of nucleated cells, the recovery rate of CFU-GM and the recovery rate of CD34⁺ cells among the three groups.（P>0.05）Conclusion The temperature difference caused by storage position has no effect on the cryopreservation quality of UCB hematopoietic stem cells in the temperature range of no more than -188℃.

Key words: Umbilicalcord blood hematopoietic stem cells, Cryopreservation, Gas phase liquid nitrogen tank