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Updated: Aug 23, 2026
Cryopreservation and Bioenergetic Evaluation of Human Peripheral Blood Mononuclear Cells
Published on: October 20, 2023
Cryopreservation reduces the concentration of detectable bacteria in contaminated peripheral blood progenitor cell
Frank Kipp1, Elmar Linnemann, Rudolf-Josef Fischer
1Institute of Medical Microbiology, the Institute of Transfusion Medicine/Transplantation Immunology, and the Department of Biometrics, University Hospital Münster, Germany.
Background:
Microbial contamination of PBPC products PBPCPs may cause severe clinical complications. There-fore, we investigated the influence of cryopreservation on the sensitivity to detect bacterial contaminations in PBPCPs.
Study Design And Methods:
Expired PBPCPs (n = 29) were thawed, and defined concentrations of Staphylococcus epidermidis or Escherichia coli were inoculated into each bag. After 60 minutes of intermixing, a representative aliquot was drawn and cultured on Mueller-Hinton agar for 24 hours. Then, the products were cryopreserved for 24 hours, and the procedure was repeated as mentioned above. The total numbers of CFUs were counted before and after cryopreservation.
Results:
A mean concentration of 2529 CFUs per mL of S. epidermidis was determined before cryopreservation versus 2182 CFUs per mL after cryopreservation, demonstrating a decrease of detectable colonies (p < 0.05). For E. coli, the mean numbers were 424 CFUs per mL before cryopreservation and 343 CFUs per mL after cryopreservation, also showing a decrease (p < 0.05).
Conclusion:
The cryopreservation reduces the concentration of detectable bacteria in contaminated PBPCPs. Especially in sterility testing of PBPCPs with low bacterial contamination, this phenomenon could lead to false-negative results with severe clinical consequences.
Insights
Cryopreservation of peripheral blood progenitor cell products (PBPCPs) reduces detectable bacterial contamination. This finding is crucial for accurate sterility testing of PBPCPs to prevent false-negative results and ensure patient safety.
Area of Science:
- Microbiology
- Hematology
- Cell Therapy
Background:
- Microbial contamination of peripheral blood progenitor cell products (PBPCPs) poses significant clinical risks.
- Ensuring the sterility of PBPCPs is critical for patient safety in cell transplantation.
Purpose of the Study:
- To investigate the impact of cryopreservation on the detection sensitivity of bacterial contamination in PBPCPs.
- To assess how cryopreservation affects the recovery of common bacterial contaminants like Staphylococcus epidermidis and Escherichia coli.
Main Methods:
- Expired PBPCPs were artificially contaminated with known concentrations of S. epidermidis or E. coli.
- Bacterial concentrations (CFUs/mL) were quantified before and after a 24-hour cryopreservation period.
- Standard microbiological culture techniques were employed for bacterial enumeration.
Main Results:
- A statistically significant decrease in detectable Staphylococcus epidermidis was observed post-cryopreservation (2529 CFUs/mL vs. 2182 CFUs/mL, p < 0.05).
- Similarly, Escherichia coli counts showed a significant reduction after cryopreservation (424 CFUs/mL vs. 343 CFUs/mL, p < 0.05).
Conclusions:
- Cryopreservation demonstrably reduces the concentration of detectable bacteria in contaminated PBPCPs.
- This reduction may lead to false-negative results in sterility testing, particularly for samples with low bacterial loads.
- Clinical implications include potential risks associated with administering contaminated PBPCPs due to compromised sterility assessment.
