Author(s): Stylianou J, Vowels M, Hadfield K
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Abstract BACKGROUND: Hematopoietic stem cells (HSC) have traditionally been frozen using the cryoprotectant DMSO in dextran-40, saline or albumin. However, the process of freezing and thawing results in loss of HSC numbers and/or function. METHODS: This study investigated the use of CryoStor for the freezing of HSC from cord blood (CB). CB donations (n = 30) were collected under an Institutional Ethics Committee-approved protocol, volume reduced and frozen using three different methods of cryoprotection. Aliquots were frozen with either 10\% DMSO in dextran-40, 10\% DMSO in CryoStor or 5\% DMSO in CryoStor. Prior to freezing samples were separated for nucleated cell (NC) and CD34+ counts and assessment of CD34+ viability. Aliquots were frozen and kept in vapor phase nitrogen for a minimum of 72 h. Vials were rapidly thawed at 37 degrees C and tested for NC and CD34+ counts and CD34+ viability and colony-forming unit (CFU) assay. RESULTS: Cells frozen with CryoStor in 10\% DMSO had significantly improved NC (P < 0.001), CD34+ recovery, viable CD34+ (P < 0.001) and CFU numbers (P < 0.001) compared with dextran in 10\% DMSO. CryoStor in 5\% DMSO resulted in significantly improved NC (P < 0.001) and CFU (P < 0.001). DISCUSSION: These results suggest that improved HSC recovery, viability and functionality can be obtained using CryoStor with 10\% DMSO and that similar if not better numbers can be obtained with 5\% DMSO compared with dextran-40 with 10\% DMSO.
This article was published in Cytotherapy
and referenced in Journal of Stem Cell Research & Therapy