title: [Effect of cryopreservation on umbilical blood cells and its mechanism].
abstract: OBJECTIVE
  To evaluate the effect of cryopreservation on clonogenic ability and apoptosis rate of mono-nuclear cells and CD34+ cells in umbilical blood (UB), and to choose the index to present the freezing injury and optimize the cryopreservation of UB.
  
  
  METHODS
  The mono-nuclear cells (MNC) and CD34+ cells were separated from UB and frozen.After 30 days, they were thawed in warm water. Clonogenic capacity and clonogenic recovery before and after the cryopreservation was compared. We also used Annexin V-FITC-PI to investigate the apoptosis rate of the cells before and after the cryopreservation of these 2 types of cells.
  
  
  RESULTS
  The number of colony forming unit-granulocyte/monocyte (CFU-GMs) was not changed after freezing and thawing in both MNCs and CD34+ cells, while the number of colony forming unit-granulocyte, erythrocyte, monocyte and megakaryocyte (CFU-GEMM) was obviously reduced after freezing in CD34+ cells. The 2 types of cryopreserved cells had certain degree of apoptosis before the cryopreservation. MNC-type cryopreservation increased the cells apoptosis a little, while CD34+-type cryopreservation increased more.
  
  
  CONCLUSIONS
  The cells have certain degree of apoptosis before the cryopreservation. The freezing and thawing procedure does affect the early stage progenitor cells-CFU-GEMM in the CD34+- type cryopreserved cells in UB. The damage may be induced by the cell apoptosis.
authors.affiliation: Department of Hematology, THird Xiangya Hospital, Central South University, Changsha 410013, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Li
authors.forename: Fangping
authors.initials: F
authors.lastname: Chen
authors.forename: Tiebin
authors.initials: T
authors.lastname: Jiang
authors.forename: Erhua
authors.initials: E
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
mesh_terms: D018952:Antigens, CD34; D017209:Apoptosis / Q000502:physiology; D001773:Blood Cells / Q000166:cytology; D001793:Blood Preservation / Q000379:methods*; D002470:Cell Survival; D003114:Colony-Forming Units Assay; D015925:Cryopreservation / Q000379:methods*; D005312:Fetal Blood / Q000166:cytology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000166:cytology*
chemical_list: D018952:Antigens, CD34