Cryopreservation in Closed Bag Systems as an Alternative to Clean Rooms for Preparations of Peripheral Blood Stem Cells

Application-Oriented Bulk Cryopreservation of Human iPSCs in Cryo Bags Followed by Direct Inoculation in Scalable Suspension Bioreactors for Expansion and Neural Differentiation

Stem cell-based therapies are promising tools for regenerative medicine and require bulk numbers of high-quality cells. Currently, cells are produced on demand and have a limited shelf-life as conventional cryopreservation is primarily designed for stock keeping. We present a study on bulk cryopreservation of the human iPSC lines UKKi011-A and BIONi010-C-41. By increasing cell concentration and volume, compared to conventional cryopreservation routines in cryo vials, one billion cells were frozen in 50 mL cryo bags. Upon thawing, the cells were immediately seeded in scalable suspension-based bioreactors for expansion to assess the stemness maintenance and for neural differentiation to assess their differentiation potential on the gene and protein levels. Both the conventional and bulk cryo approach show comparative results regarding viability and aggregation upon thawing and bioreactor inoculation. Reduced performance compared to the non-frozen control was compensated within 3 days regarding biomass yield. Stemness was maintained upon thawing in expansion. In neural differentiation, a delay of the neural marker expression on day 4 was compensated at day 9. We conclude that cryopreservation in cryo bags, using high cell concentrations and volumes, does not alter the cells' fate and is a suitable technology to avoid pre-cultivation and enable time- and cost-efficient therapeutic approaches with bulk cell numbers.

Cryopreservation as a Key Element in the Successful Delivery of Cell-Based Therapies-A Review

Cryopreservation is a key enabling technology in regenerative medicine that provides stable and secure extended cell storage for primary tissue isolates and constructs and prepared cell preparations. The essential detail of the process as it can be applied to cell-based therapies is set out in this review, covering tissue and cell isolation, cryoprotection, cooling and freezing, frozen storage and transport, thawing, and recovery. The aim is to provide clinical scientists with an overview of the benefits and difficulties associated with cryopreservation to assist them with problem resolution in their routine work, or to enable them to consider future involvement in cryopreservative procedures. It is also intended to facilitate networking between clinicians and cryo-researchers to review difficulties and problems to advance protocol optimization and innovative design.

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.

Microbial contamination risk in hematopoietic stem cell products: retrospective analysis of 1996–2016 data

Quality assurance and safety of hematopoietic stem cells (HSC) with special emphasis on bacterial and fungal contamination is the prerequisite for any transplantation procedure. The aim was to determine the incidence rate of such contamination during processing of transplantation material with regard to HSC source: peripheral blood stem cell (PBSC), bone marrow (BM), or cord blood (CB). Analysis involved autologous and allogenic products dedicated for patients and comprised in all 4135 donations, including 112 BM (2.70%), 3787 PBSC (91.60%), and 236 CB (5.70%) processed in cell bank over the period 1996–2016. Aerobic and anaerobic contamination was determined.

Analysis of the 20-year data revealed 42 contaminated products: 25 PBSC (0.66% of tested units) and 17 CB (7.20% of tested units). No microbial contamination of BM products was detected. Overall percentage of contaminated products was 1.01%, mostly with Staphylococcus epidermidis (61.36%). Bacterial contamination rate at cell bank is relatively low and processing in a closed system does not seem as crucial as might be expected. This is particularly true for BM components. Equally important are evaluation of donor’s medical status and condition of the puncture site for collection of source material. Implementation of appropriate sample collection procedures should help minimize the risk of false-positive results due to environmental contamination.

Technical Considerations in the Freezing, Low-Temperature Storage and Thawing of Stem Cells for Cellular Therapies

The commercial and clinical development of cellular therapy products will invariably require cryopreservation and frozen storage of cellular starting materials, intermediates and/or final product. Optimising cryopreservation is as important as optimisation of the cell culture process in obtaining maximum yield and a consistent end-product. Suboptimal cryopreservation can lead not only to batch-to-batch variation, lowered cellular functionality and reduced cell yield, but also to the potential selection of subpopulations with genetic or epigenetic characteristics divergent from the original cell line. Regulatory requirements also impact on cryopreservation as these will require a robust and reproducible approach to the freezing, storage and thawing of the product. This requires attention to all aspects of the application of low temperatures: from the choice of freezing container and cryoprotectant, the cooling rate employed and its mode of de-livery, the correct handling of the frozen material during storage and transportation, to the eventual thawing of the product by the end-user. Each of these influences all of the others to a greater or lesser extent and none should be ignored. This paper seeks to provide practical insights and alternative solutions to the technical challenges faced during cryopreservation of cells for use in cellular therapies.

Hurdles Associated with the Translational Use of Genetically Modified Cells

Purpose of Review

Recent advancements in the use of genetically modified hematopoietic stem cells (HSCs) and the emergent use of chimeric antigen receptor (CAR) T-cell immunotherapy has highlighted issues associated with the use of genetically engineered cellular products. This review explores some of the challenges linked with translating the use of genetically modified cells.

Recent Findings

The use of genetically modified HSCs for ADA-SCID now has European approval and the U.S. Food and Drug Administration recently approved the use of CAR-T cells for relapsed/refractory B-cell acute lymphoblastic leukemia. Current good manufacturing processes have now been developed for the collection, expansion, storage, modification, and administration of genetically modified cells.

Summary

Genetically engineered cells can be used for several therapeutic purposes. However, significant challenges remain in making these cellular therapeutics readily available. A better understanding of this technology along with improvements in the manufacturing process is allowing the translation process to become more standardized.