Validation of an automated quality control method to test sterility of two advanced therapy medicinal products: Mesenchymal stromal cells and their extracellular vesicles

Mesenchymal stromal cells are multipotent cells present in various tissues that are widely studied for relevant therapeutic potential due to their paracrine immunomodulatory and tissue regenerating properties. Many mesenchymal stromal cell-based products are under investigation for the treatment of different clinical conditions. Recently, the therapeutic potential of the extracellular vesicles released by these cells has been under focus, with emphasis on clinical translation. Sterility testing during manufacture and before the final release of the advanced therapy medicinal products to markets is a critical quality control measure. Therefore, analytical methods for sterility testing in addition to complying with pharmacopeial standards must validate the adequacy of each product and evaluate matrix interference. Here, an automated system for sterility control of reagents used in the bioprocessing of mesenchymal stromal cells and their extracellular vesicles was validated. Reagents (culture media, antibiotics, and excipients in the final product) were inoculated with 10 or 50 colony forming units of microorganisms in BACTEC™ Peds Plus™ T/F aerobic/anaerobic bottles. Under aerobic conditions (BACTEC™ Peds Plus™ T/F aerobic bottles), microbial growth was detected within an acceptable incubation time according to regulatory guidelines. The results of this study corroborate other studies that use automated sterility testing as an alternative to the manual USP<71> compendial method to detect microorganisms close to the limit of detection within an acceptable incubation time.