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Meeting the COVID challenge: Optimizing vCD34+ in cryopreserved HPC samples for implementation of an external QA
Annabella Chang1, Scott J Ragg2, David D Ma3
1Blood, Stem Cell and Cancer Research Program, St Vincent's Applied Medical Research Centre, and Department of Haematology and BM Transplant, St Vincent's Hospital Sydney, NSW, Australia.
Insights
A new method using dry ice and liquid nitrogen storage ensures reproducible counting of viable CD34+ cells for hematopoietic progenitor cell transplantation quality assurance. This cost-effective approach improves global cell procurement during pandemics.
Area of Science:
- Hematology
- Transplantation Immunology
- Biotechnology
Background:
- The COVID-19 pandemic disrupted global procurement of allogeneic hematopoietic progenitor cells (HPCs).
- Current External Quality Assurance (EQA) programs are inadequate for viable CD34+ cell (vCD34+) enumeration in cryopreserved HPCs.
- Standardized, cost-effective distribution of cryopreserved reference samples (CRSs) is crucial for vCD34+ EQA.
Purpose of the Study:
- To evaluate optimal conditions for transporting cryopreserved HPC samples for vCD34+ EQA.
- To establish a reproducible and harmonized method for vCD34+ HPC enumeration during pandemics.
Main Methods:
- Cryopreserved HPC samples were stored on dry ice or a combination of dry ice and liquid nitrogen (LN).
- Viable CD34+ HPC enumeration was performed using flow cytometry with 7-AAD viability dye exclusion.
- Optimal transport conditions were validated in pilot and multicenter national studies.
Main Results:
- A transport method combining 1 day on dry ice followed by LN storage maintained cell viability better than continuous dry ice storage.
- Dispatch of CRSs within 26 hours over distances up to 4000 km, followed by LN storage, yielded reproducible intercenter vCD34+ enumeration.
- This dry ice and LN method is over 20-fold cheaper than LN-only transport.
Conclusions:
- The developed transport strategy provides a reproducible and cost-effective method for distributing CRSs for vCD34+ EQA.
- This approach supports economically and scientifically sound distribution of reference materials for quality assurance in HPC transplantation.
Background:
The COVID-19 pandemic has forced a fundamental change in the global procurement of allogeneic hematopoietic progenitor cells (HPCs) for transplantation. To better meet the emergent challenges of transporting cryopreserved allogeneic HPC during pandemics, there is an urgent need for External Quality Assurance (EQA) programs to evaluate reproducibility and harmonization of viable CD34+ cell (vCD34+) HPC enumeration, as the current EQA programs are unsuitable for analysis of vCD34+. The cost-effective distribution of HPC cryopreserved reference samples (CRSs) with acceptable reproducibility and specificity is key to the success of a vCD34+ EQA program.
Methods:
Cryopreserved HPC samples (n = 11) were either stored on dry ice for 1 to 4 days or for 1 day followed by liquid nitrogen (LN) storage for 1 to 3 days to assess optimal conditions for vCD34+ EQA. Flow cytometric enumeration of vCD34+ HPCs was performed using a single platform assay combined with 7-AAD viability dye exclusion. The optimum transportation condition was validated in pilot and multicenter national studies (n = 12).
Results:
A combination of 1 day on dry ice followed by LN storage stabilized viability compared with continuous storage on dry ice. This study demonstrates that dispatch of CRSs on dry ice to recipient centers across a distance of ≤4000 km within 26 h, followed by LN storage, resulted in reproducible intercenter vCD34+ enumeration. The estimated cost of safer and more convenient dry ice delivery is >20-fold lower than that of LN.
Conclusion:
This approach can form the basis for economically and scientifically acceptable distribution of CRSs for external vCD34+ EQA.
