Post-thaw viability of cryopreserved peripheral blood stem cells (PBSC) does not guarantee functional activity: important implications for quality assurance of stem cell transplant programmes.
Standard quality assurance (QA) of cryopreserved peripheral blood stem cells (PBSC) uses post-thaw viable CD34(+) cell counts. In 2013, concerns arose at Great Ormond Street Hospital (GOSH) about 8 patients with delayed engraftment following myeloablative chemotherapy with cryopreserved cell rescue, despite adequate post-thaw viable cell counts in all cases. Root cause analysis was undertaken; investigations suggested the freeze process itself was a contributing factor to suboptimal engraftment. Experiments were undertaken in which a single PBSC product was divided into three and cryopreserved in parallel using a control-rate freezer (CRF) or passive freezing method (-80°C freezer) at GOSH, or the same passive freezing at another laboratory. Viable CD34(+) counts were equivalent and adequate in each. Granulocyte-monocyte colony-forming unit assays demonstrated colonies from the products cryopreserved using passive freezing (both laboratories), but no colonies from products cryopreserved using the CRF. The CRF was shown to be operating within manufacturer's specifications with freeze-profile within acceptable limits. This experience has important implications for quality assurance for all transplant programmes, particularly those using cryopreserved products. The failure of post-thaw viable CD34(+) counts, the most widely used routine QA test available, to ensure PBSC function is of great concern and should prompt reassessment of protocols and QA procedures.
Department of Paediatric Oncology/Haematology, Great Ormond Street Hospital, London, UK.
Daniel A
DA
Morgenstern
Cell Therapy Laboratory, Great Ormond Street Hospital, London, UK.
Gulrukh
G
Ahsan
Cell Therapy Laboratory, Great Ormond Street Hospital, London, UK.
Margaret
M
Brocklesby
Wolfson Cellular Therapy Unit, University College London Hospitals, London, UK.
Stuart
S
Ings
Wolfson Cellular Therapy Unit, University College London Hospitals, London, UK.
Carmen
C
Balsa
Paediatric Bone Marrow Transplantation, Great Ormond Street Hospital, London, UK.
Paul
P
Veys
Formerly, Department of Paediatric Oncology/Haematology, Great Ormond Street Hospital, London, UK.
Penelope
P
Brock
Department of Paediatric Oncology/Haematology, Great Ormond Street Hospital, London, UK.
John
J
Anderson
Paediatric Bone Marrow Transplantation, Great Ormond Street Hospital, London, UK.
Persis
P
Amrolia
Formerly, Department of Paediatric Oncology/Haematology, Great Ormond Street Hospital, London, UK.
Nicholas
N
Goulden
Cell Therapy Laboratory, Great Ormond Street Hospital, London, UK.
Catherine M
CM
Cale
Wolfson Cellular Therapy Unit, University College London Hospitals, London, UK.
Michael J
MJ
Watts
D018952:Antigens, CD34 / Q000378:metabolism; D015415:Biomarkers; D002470:Cell Survival; D003114:Colony-Forming Units Assay; D015925:Cryopreservation / Q000379:methods; D006085:Graft Survival; D006801:Humans; D007958:Leukocyte Count; D036102:Peripheral Blood Stem Cell Transplantation / Q000379:methods / Q000592:standards; D000072916:Peripheral Blood Stem Cells / Q000166:cytology* / Q000378:metabolism*; D011785:Quality Assurance, Health Care; D013997:Time Factors
D018952:Antigens, CD34; D015415:Biomarkers
cryopreservation; engraftment; potency; stem cell transplantation; viability