title: Long-term effects of cryopreservation on clinically prepared hematopoietic progenitor cell products.
abstract: OBJECTIVE
  The question of how long hematopoietic progenitor cells (HPCs) destined for clinical applications withstand long-term cryopreservation remains unanswered. To increase our basic understanding about the stability of HPC products over time, this study focused on characterizing long-term effects of cryopreservation on clinically prepared HPC products.
  
  
  METHODS
  Cryovials (n = 233) frozen for an average of 6.3 ± 14.2 years (range, 0.003-14.6 years) from HPC products (n = 170) representing 75 individual patients were thawed and evaluated for total nucleated cells (TNCs), cell viability, viable CD34+ (vCD34+) cells and colony-forming cells (CFCs). TNCs were determined by use of an automated cell counter, and cell viability was measured with the use of trypan blue exclusion. Viable CD34 analysis was performed by means of flow cytometry and function by a CFC assay.
  
  
  RESULTS
  Significant losses in TNCs, cell viability, vCD34+ cells and CFC occurred on cryopreservation. However, once frozen, viable TNCs, vCD34+ cells and CFC recoveries did not significantly change over time. The only parameter demonstrating a change over time was cell viability, which decreased as the length of time that an HPC product was stored frozen increased. A significant negative correlation (correlation coefficient = -0.165) was determined between pre-freeze percent granulocyte content and post-thaw percent viability (n = 170; P = 0.032). However, a significant positive correlation was observed between percent viability at thaw and pre-freeze lymphocyte concentration.
  
  
  CONCLUSIONS
  Once frozen, HPC products were stable for up to 14.6 years at <-150°C. Post-thaw viability was found to correlate negatively with pre-freeze granulocyte content and positively with pre-freeze lymphocyte content.
authors.affiliation: University of Utah Cell Therapy and Regenerative Medicine Facility, Salt Lake City, Utah, USA.
authors.forename: Jacob M
authors.initials: JM
authors.lastname: Winter
authors.affiliation: University of Utah Cell Therapy and Regenerative Medicine Facility, Salt Lake City, Utah, USA.
authors.forename: Pam
authors.initials: P
authors.lastname: Jacobson
authors.affiliation: University of Utah Cell Therapy and Regenerative Medicine Facility, Salt Lake City, Utah, USA.
authors.forename: Brandon
authors.initials: B
authors.lastname: Bullough
authors.affiliation: University of Utah Cell Therapy and Regenerative Medicine Facility, Salt Lake City, Utah, USA.
authors.forename: Austin P
authors.initials: AP
authors.lastname: Christensen
authors.affiliation: University of Utah Cell Therapy and Regenerative Medicine Facility, Salt Lake City, Utah, USA; University of Utah Division of Hematology & Hematologic Malignancies, Salt Lake City, Utah, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Boyer
authors.affiliation: University of Utah Cell Therapy and Regenerative Medicine Facility, Salt Lake City, Utah, USA; University of Utah Division of Hematology & Hematologic Malignancies, Salt Lake City, Utah, USA. Electronic address: joanna.reems@hsc.utah.edu.
authors.forename: Jo-Anna
authors.initials: JA
authors.lastname: Reems
mesh_terms: D001793:Blood Preservation / Q000379:methods*; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D015925:Cryopreservation / Q000379:methods*; D005434:Flow Cytometry; D005615:Freezing; D018380:Hematopoietic Stem Cell Transplantation / Q000379:methods*; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D013234:Stem Cells
keywords: blood preservation; cell survival; cryopreservation; hematopoietic stem cell transplantation/methods; hematopoietic stem cells