Study On Cryopreservation And Homing Of Cord Blood Hematopoietic Cells

Study on cryopreservation and homing of cord blood hematopoietic cellsObjective: The purpose of the present study is to ascertain the effect of cryopreservation procedure on the cell phenotype, biological function and cytoskeleton actin to the homing of cord blood hematopoietic cells, in order to provide theoretical and experimental evidence for umbilical cord blood stem cells banking. Method: The change of phenotype characterization of cell subsets before and after cryopreservation was analyzed by FACS and fluorescent microscope, the expansion capacity and colony forming capacity was measured using 3H-TdR incorboration method and semi-solid colony forming method, as well as the distribution and expression of actin was detected by confocal microscopy and Western blot method. In the ex vivo expansion research , we evaluate the supporting effect of adherent cell from cord blood on the cord blood hematopoietic cells by FACS analysis. Results : No difference between fresh cells and cryopreservation cells was found according to the phnotype analysis. The colony forming cells were 70.56% of fresh cells. There were some changes on distribution and expression of actin after cryopreservation , but it would get right when cultured in combination with cytokines. The combination of cytokines (IL-3, IL-6, GM-CSF) can expand CD34+ cells more effectively in the former period, the proportion of CD34+ cells increased to 3.4% after a week culture, while adherent cells from cord blood supported cord blood hematopoietic cells in the later period, the proportion of CD34+ cells still increased progressively after four weeks. Conclusion: The effect ofcryopreservation on the cord blood hematopoietic cells is negligible, the homing capacity and colony forming capacity get well after short time incubation, and cord blood derived adherent layer support long-term hematopoiesis.