title: Effect of dimethyl sulfoxide on post-thaw viability assessment of CD45+ and CD34+ cells of umbilical cord blood and mobilized peripheral blood.
abstract: BACKGROUND
  The effect of dimethyl sulfoxide (Me2SO) on enumeration of post-thaw CD45+ and CD34+ cells of umbilical cord blood (HPC-C) and mobilized peripheral blood (HPC-A) has not been systematically studied.
  
  
  METHODS
  Cells from leukapheresis products from multiple myeloma patients and umbilical cord blood cells were suspended in 1, 2, 5, or 10% Me2SO for 20 min at 22 degrees C. Cells suspended in Me2SO were then immediately assessed or assessed following removal of Me2SO. In other samples, cells were suspended in 10% Me2SO, cooled slowly to -60 degrees C, stored at -150 degrees C for 48 h, then thawed. The thawed cells in 10% Me2SO were diluted to 1, 2, 5, or 10% Me2SO, held for 20 min at 22 degrees C and then immediately assessed or assessed after the removal of Me2SO. CD34+ cell viability was determined using a single platform flow cytometric absolute CD34+ cell count technique incorporating 7-AAD.
  
  
  RESULTS
  The results indicate that after cryopreservation neither recovery of CD34+ cells nor viability of CD45+ and CD34+ cells from both post-thaw HPC-A and HPC-C were a function of the concentration of Me2SO. Without cryopreservation, when Me2SO is present recovery and viability of HPC-C CD34+ cells exposed to 10% Me2SO but not CD45+ cells were significantly decreased. Removing Me2SO by centrifugation significantly decreased the viability and recovery of CD34+ cells in both HPC-A and HPC-C before and after cryopreservation.
  
  
  CONCLUSIONS
  To reflect the actual number of CD45+ cells and CD34+ cells infused into a patient, these results indicate that removal of Me2SO for assessment of CD34+ cell viability should only be performed if the HPC are infused after washing to remove Me2SO.
authors.affiliation: Canadian Blood Services, Edmonton, Alta., Canada. ycryoscientific@yahoo.ca
authors.forename: H
authors.initials: H
authors.lastname: Yang
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: J P
authors.initials: JP
authors.lastname: Acker
authors.forename: J Z
authors.initials: JZ
authors.lastname: Liu
authors.forename: J
authors.initials: J
authors.lastname: Akabutu
authors.forename: L E
authors.initials: LE
authors.lastname: McGann
mesh_terms: D018952:Antigens, CD34 / Q000097:blood; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology; D003627:Data Interpretation, Statistical; D004121:Dimethyl Sulfoxide / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005260:Female; D005312:Fetal Blood / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D005434:Flow Cytometry; D006412:Hematopoietic Stem Cells / Q000187:drug effects* / Q000276:immunology / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D017493:Leukocyte Common Antigens / Q000097:blood; D009101:Multiple Myeloma / Q000097:blood; D011247:Pregnancy
chemical_list: D018952:Antigens, CD34; D003451:Cryoprotective Agents; D017493:Leukocyte Common Antigens; D004121:Dimethyl Sulfoxide