Evaluation of Cleaning Methods for Change-over After the Processing of Cell Products to Avoid Cross-contamination Risk

Introduction: Cell-processing facilities face the risk of environmental bacteria contaminating biosafety cabinets during processing, and manual handling of autologous cell products can result in contamination. We propose a risk- and evidence-based cleaning method for cross-contamination, emphasizing proteins and DNA.

Methods: The transition and residual risks of the culture medium were assessed by measuring both wet and dried media using fluorescence intensity. Residual proteins and DNA in dried culture medium containing HT-1080 cells were analyzed following ultraviolet (UV) irradiation, wiping, and disinfectant treatment.

Results: Wet conditions showed a higher transition to distilled water (DW), whereas dry conditions led to higher residual amounts on SUS304 plates. Various cleaning methods for residual culture medium were examined, including benzalkonium chloride with a corrosion inhibitor (BKC + I) and DW wiping, which demonstrated significantly lower residual protein and DNA compared to other methods. Furthermore, these cleaning methods were tested for residual medium containing cells, with BKC + I and DW wiping resulting in an undetectable number of cells. However, in some instances, proteins and DNA remained.

Conclusions: The study compared cleaning methods for proteins and DNA in cell products, revealing their advantages and disadvantages. Peracetic acid (PAA) proved effective for nucleic acids but not proteins, while UV irradiation was ineffective against both proteins and DNA. Wiping emerged as the most effective method, even though traceability remained challenging. However, wiping with ETH was not effective as it caused protein immobilization. Understanding the characteristics of these cleaning methods is crucial for developing effective contamination control strategies.