title: The effects of x-irradiation on ex vivo expansion of cryopreserved human hematopoietic stem/progenitor cells.
abstract: In our previous study (Life Sciences 84: 598, 2009), we demonstrated that placental/umbilical cord blood-derived mesenchymal stem cell-like stromal cells have the effect to support the regeneration of freshly prepared X-irradiated hematopoietic stem/progenitor cells (HSPCs). Generally, HSPCs are supplied from companies, institutions, and cell banks that cryopreserve them for clinical and experimental use. In this study, the influence of cryopreservation on the responses of HSPCs to irradiation and co-culture with stromal cells is assessed. After cryopreservation with the optimal procedure, 2 Gy-irradiated HSPCs were cultured with or without stromal cells supplemented with combination of interleukin-3, stem cell factor, and thrombopoietin. The population of relatively immature CD34(+)/CD38(-) cells in cryopreserved cells was significantly higher than in fresh cells prior to cryopreservation; furthermore, the hematopoietic progenitor populations of CD34(+)/CD45RA(+) cells and CD34(+)/CD117(+) cells in cryopreserved cells were significantly lower than that in fresh cells. However, the rate of expansion in the cryopreserved HSPCs was lower than in the fresh HSPCs. In the culture of cryopreserved cells irradiated with 2 Gy, the growth rates of CD34(+) cells, CD34(+)/CD38(-) cells, and hematopoietic progenitors were greater than growth rates of their counterparts in the culture of fresh cells. Surprisingly, the effect to support the hematopoiesis in co-culture with stromal cells was never observed in the X-irradiated HSPCs after cryopreservation. The present results demonstrated that cryopreserving process increased the rate of immature and radio-resistant HSPCs but decreased the effects to support the hematopoiesis by stromal cells, thus suggesting that cryopreservation changes the character of HSPCs.
authors.affiliation: Department of Radiological Life Sciences, Hirosaki University Graduate School of Health Sciences.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Ikuo
authors.initials: I
authors.lastname: Kashiwakura
mesh_terms: D018952:Antigens, CD34 / Q000032:analysis; D002454:Cell Differentiation / Q000187:drug effects / Q000528:radiation effects; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured / Q000187:drug effects / Q000528:radiation effects; D018920:Coculture Techniques; D015925:Cryopreservation; D005312:Fetal Blood / Q000166:cytology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D006410:Hematopoiesis / Q000187:drug effects / Q000528:radiation effects*; D016298:Hematopoietic Cell Growth Factors / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects*; D006801:Humans; D017493:Leukocyte Common Antigens / Q000032:analysis; D008533:Megakaryocytes / Q000166:cytology; D059630:Mesenchymal Stem Cells / Q000166:cytology; D019009:Proto-Oncogene Proteins c-kit / Q000032:analysis; D011836:Radiation Tolerance; D011994:Recombinant Proteins / Q000494:pharmacology; D017154:Stromal Cells / Q000166:cytology; D014021:Tissue Preservation / Q000379:methods*
chemical_list: D018952:Antigens, CD34; D016298:Hematopoietic Cell Growth Factors; D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D019009:Proto-Oncogene Proteins c-kit; D017493:Leukocyte Common Antigens