Novel cryoprotectant significantly improves the post-thaw recovery and quality of HSC from CB.
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).


CONCLUSIONS
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.
Stylianou
J
J
Sydney Cord Blood Bank, Sydney Children's Hospital, NSW, Australia.
Vowels
M
M
Hadfield
K
K
D018952:Antigens, CD34 / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D003114:Colony-Forming Units Assay; D015925:Cryopreservation / Q000379:methods*; D003451:Cryoprotective Agents / Q000494:pharmacology*; D005312:Fetal Blood / Q000166:cytology*; D005615:Freezing; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000187:drug effects*; D006801:Humans
D018952:Antigens, CD34; D003451:Cryoprotective Agents