Sterility testing of apheresis hematopoietic progenitor cell products using an automated blood culture system

Comparison of CryoMACS Freezing Bags with Maco Biotech Freezing-Ethinyl Vinyl Acetate Bags for Hematopoietic Progenitor Cells Cryopreservation Using a CD34+-Enriched Product

Background: Hematopoietic progenitor cells (HPCs) cryopreservation have applications, especially in the autologous setting, allowing therapeutic use several years after collection. Cryopreservation aims to preserve the therapeutic properties of HPCs, and successful cryopreservation depends on several factors such as preservation procedures, biopreservation media, freezing rates, and thawing procedures. In this context, the choice of the freezing bag is critical as it provides mechanical protection during the freezing process. Since Maco Biotech Freezing-ethinyl vinyl acetate (EVA) Bags^® are no longer available in our country, a comparative study was developed to verify bioequivalence with the Miltenyi CryoMACS^® freezing bag. Methods: In this study, a CD34⁺-enriched product was used to better reproduce HPC apheresis. Freezing bags were filled with the same volume, cryopreserved with controlled rate freezing, and stored in the vapor phase of liquid nitrogen for at least 6 months. After thawing, all bags were tested for integrity and sterility using a microbial challenge. In addition, a comparison was developed by evaluating recovery of white blood cells, mononuclear cells, lymphocytes, and CD34⁺ cells. Results: No significant differences between the two manufacturers' bags have been observed in terms of the evaluated parameters. Data were confirmed, even comparing bags according to filling volume. Data presented in this study support the conclusion that CryoMACS freezing bags are bioequivalent to Maco Biotech Freezing-EVA Bags for HPC cryopreservation.

Bacterial safety of cell-based therapeutic preparations, focusing on haematopoietic progenitor cells

Bacterial safety of cellular preparations, especially haematopoietic progenitor cells (HPCs), as well as advanced therapy medicinal products (ATMPs) derived from stem cells of various origins, present a challenge for physicians, manufacturers and regulators. The article describes the background and practical issues in this area and illustrates why sterility of these products cannot currently be guaranteed. Advantages and limitations of approaches both for classical sterility testing and for microbiological control using automated culture systems are discussed. The review considers novel approaches for growth-based rapid microbiological control with high sensitivity and faster availability of results, as well as new methods for rapid bacterial detection in cellular preparations enabling meaningful information about product contamination within one to two hours. Generally, however, these direct rapid methods are less sensitive and have greater sampling error compared with the growth-based methods. Opportunities for pyrogen testing of cell therapeutics are also discussed. There is an urgent need for development of novel principles and methods applicable to bacterial safety of cellular therapeutics. We also need a major shift in approach from the traditional view of sterility evaluation (identify anything and everything) to a new thinking about how to find what is clinically relevant within the time frame available for the special clinical circumstances in which these products are used. The review concludes with recommendations for optimization of microbiological control of cellular preparations, focusing on HPCs.