Effective Cryopreservation and Recovery of Living Cells Encapsulated in Multiple Emulsions

Quality Assessment of Long-Term Cryopreserved Human Bone-Derived Marrow Mesenchymal Stromal Cell Samples: Experience from the Texas Heart Institute Biorepository and Biospecimen Profiling Core

In biomedical research, biorepositories are pivotal resources that safeguard and supply clinical samples for scientific investigators. Proper long-term cryopreservation conditions are essential to maintain biospecimen quality. In this study, we analyzed the efficacy of sample cryopreservation at the Texas Heart Institute Biorepository and Biospecimen Profiling Core (THI-BRC). Our assessments included a thorough review of internal processes, quality reports, and both internal and external audit outcomes. We examined the integrity of human bone marrow-derived multipotent mesenchymal stromal cells (BM-MSCs) that were cryopreserved for over 5 years. These samples originated from randomly selected clinical trial participants or commercially sourced cell lines. Parameters such as cell viability, DNA and RNA integrity, population doubling time, sterility, and BM-MSC-specific attributes such as surface antigen expression and differentiation potential were studied. BM-MSC samples cryopreserved for ∼6 months served as our control. Our results demonstrated that the 5-year cryopreserved samples maintained their integrity compared with the shorter-term stored control samples. Moreover, THI-BRC has met accreditation agency standards and has not received any repeated deficiencies over 7 years. Collectively, our findings affirm that THI-BRC's biospecimen storage protocols align with accepted standards as confirmed by the quality assessment of long-term stored clinical samples.

Comparison of cell viability methods for human mesenchymal/stromal stem cells and human A549 lung carcinoma cells after freeze-thaw stress

For the safety and efficacy of frozen cell therapy products, determination of cellular viability is key. However, results of cell viability measurements do not only depend on the cell line or on the inflicted stress, but also on the assay used, making inter-experimental comparisons difficult. The aim of this study was thus to assess commonly used viability assays in clinically relevant human mesenchymal/stromal stem cells and human A549 lung carcinoma cells. Post freeze-thaw stress viability and proliferation were evaluated under different conditions using trypan blue, acridine orange/DAPI stain, alamarBlue, ATP, and neutral red assays. Significant differences in cell viability between metabolic assays were observed, likely due to their distinct intrinsic detection mechanisms. Membrane-integrity based assays generally overestimated cell viabilities in this study. Furthermore, noticeable differences in inter-assay sensitivities were observed. These differences highlight that cell viability methods should be meticulously selected and their associated results carefully interpreted in a relevant context to ensure reliable conclusions. Indeed, although cell membrane integrity based assays are a popular choice to determine cellular quality attributes after freezing and thawing, we demonstrate that metabolic assays may be more suitable in this context.

Morphological, Ultrastructural, and Immunocytochemical Characterization and Assessment of Puma (Puma concolor Linnaeus, 1771) Cell Lines After Extended Culture and Cryopreservation

Cell lines are valuable tools to safeguard genetic material from species threatened with extinction that is mainly due to human action. In this scenario, the puma constitutes a species whose population is being rapidly reduced in the ecosystems it inhabits. For the first time, we characterized puma skin-derived cell lines and assessed these cells after extended culture (experiment 1) and cryopreservation (experiment 2). Initially, we identified and characterized four dermal fibroblast lines using morphology, ultrastructure, and immunofluorescence assays. Moreover, we evaluated the effects of culture time (1st, 3rd, and 10th passages) and cryopreservation on their morphology, ultrastructure, viability, metabolism, proliferative activity, reactive oxygen species (ROS) levels, mitochondrial membrane potential (ΔΨm), and apoptosis. The cells showed a typical spindle-shaped morphology with centrally located oval nuclei. The cells were identified as fibroblasts by staining for vimentin. In vitro culture after the 1st, 3rd, and 10th passages did not alter most of the evaluated parameters. Cells in the 3rd and 10th passages showed a reduction in ROS levels (p < 0.05). The ultrastructure revealed morphological damage in the prolongments, and nuclei of cells derived from the 3rd and 10th passages. Moreover, cryopreservation resulted in a reduction in ΔΨm compared with that of noncryopreserved cells, suggesting that the optimization of cryopreservation methods for puma fibroblasts is essential. In conclusion, we found that viable fibroblasts could be obtained from puma skin, with slight changes after the 10th passage in in vitro culture and cryopreservation. This is the first report on the development of cell lines derived from pumas.

Evaluation of the damage caused by in vitro culture and cryopreservation to dermal fibroblasts derived from jaguars: An approach to conservation through biobanks

Ex-situ conservation strategies such as the formation of somatic cell banks are valuable tools for the conservation of jaguars, whose population has been declining in recent years. Once properly established, these cells can be successfully leveraged for future applications. We aimed to assess the effects of in vitro culture and cryopreservation on the establishment of fibroblasts derived from jaguars. Initially, we identified five dermal fibroblastic lines using morphology and immunophenotyping assays; these lines were then subjected to two experiments. In the first experiment, the viability, metabolism, and proliferative activity of cells at different passages (first, third, and tenth) were evaluated. In the second experiment, the cells were cryopreserved and the levels of reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm) and apoptosis were evaluated after one, three, and ten passages. Noncryopreserved cells were used as controls. The in vitro culture after first, third, and tenth passages and cryopreservation conditions did not affect the proliferative activity and viability. However, cells cultured until tenth passage and frozen/thawed cells showed reduced metabolism. In addition, cryopreserved cells showed higher levels of intracellular ROS and altered ΔΨm when compared with those of noncryopreserved cells. Finally, frozen/thawed cells cultured after ten passages showed reduced proliferative activity and number of viable cells than did frozen/thawed cells cultured after one and three passages. In summary, we have shown that viable fibroblasts can be established from jaguar skin and that although these cells do not show altered viability and proliferative activity, they do undergo damage during extended culture and cryopreservation.

Actual approaches to the transportation of biological samples at low temperatures

Taking into account the impact of shipment method of biosamples is necessary for obtaining high-quality biological samples in biobanking and laboratory research. The impact of liquid nitrogen, dry ice and cold accumulators on the quality of biological markers was considered, as well as recommendations to reduce the impact of these methods of shipment. The liquid nitrogen provides the best preservation of samples, however, dry ice is used much more often during their transportation. When transporting certain types of cells using dry ice, there is the way to use CryoStor CS1 and Cell Banker 1 cryoprotectors. The dry ice has a significant effect on both the pH of liquid biological samples and the coagulological parameters of plasma samples. The penetration of CO2 into the sample leads to changes in the parameters of PTT and APPT, as well as to decrease the protein C and fibrinogen level under certain conditions. Serum and plasma samples exposed to dry ice for more than 16 hours should be thawed open at room temperature, or instead of it should be kept at -80 °C for 24 hours to avoid changes in coagulation parameters, The use of cold accumulators is unacceptable for long-term shipment of serum and plasma containing unstable biomarkers because of insufficiently low temperature (increase over time to -25 °C and above). Besides, metal pellets can be used as cold storage batteries at low temperatures (up to -80 ° C), but they are not as effective as dry ice, since it is able to hold the required temperature for much longer.

Dimethyl sulfoxide-free cryopreservation for cell therapy: A review

Cell-based therapeutics promise to transform the treatment of a wide range of diseases including cancer, genetic and degenerative disorders, or severe injuries. Many of the commercial and clinical development of cell therapy products require cryopreservation and storage of cellular starting materials, intermediates and/or final products at cryogenic temperature. Dimethyl sulfoxide (Me₂SO) has been the cryoprotectant of choice in most biobanking situations due to its exceptional performance in mitigating freezing-related damages. However, there is concern over the toxicity of Me₂SO and its potential side effects after administration to patients. Therefore, there has been growing demand for robust Me₂SO-free cryopreservation methods that can improve product safety and maintain potency and efficacy. This article provides an overview of the recent advances in Me₂SO-free cryopreservation of cells having therapeutic potentials and discusses a number of key challenges and opportunities to motivate the continued innovation of cryopreservation for cell therapy.

DNA damage, repair and the improvement of cancer therapy - A tribute to the life and research of Barbara Tudek

Professor Barbara Tudek received the Frits Sobels Award in 2019 from the European Environmental Mutagenesis and Genomics Society (EEMGS). This article presents her outstanding character and most important lines of research. The focus of her studies covered alkylative and oxidative damage to DNA bases, in particular mutagenic and carcinogenic properties of purines with an open imidazole ring and 8-oxo-7,8-dihydroguanine (8-oxoGua). They also included analysis of mutagenic properties and pathways for the repair of DNA adducts of lipid peroxidation (LPO) products arising in large quantities during inflammation. Professor Tudek did all of this in the hope of deciphering the mechanisms of DNA damage removal, in particular by the base excision repair (BER) pathway. Some lines of research aimed at discovering factors that can modulate the activity of DNA damage repair in hope to enhance existing anti-cancer therapies. The group's ongoing research aims at deciphering the resistance mechanisms of cancer cell lines acquired following prolonged exposure to photodynamic therapy (PDT) and the possibility of re-sensitizing cells to PDT in order to increase the application of this minimally invasive therapeutic method.