Dry state preservation of nucleated cells: progress and challenges

Cryopreservation: A Comprehensive Overview, Challenges, and Future Perspectives

Cryopreservation is the most prevalent method of long-term cell preservation. Effective cell cryopreservation depends on freezing, adequate storage, and correct thawing techniques. Recent advances in cryopreservation techniques minimize the cellular damage which occurs while processing samples. This article focuses on the fundamentals of cryopreservation techniques and how they can be implemented in a variety of clinical settings. The article presents a brief description of each of the standard cryopreservation procedures, such as slow freezing and vitrification. Alongside that, the membrane permeating and nonpermeating cryoprotectants are briefly discussed, along with current advancements in the field of cryopreservation and variables influencing the cryopreservation process. The diminution of cryoinjury incurred by the cell via the resuscitation process will also be highlighted. In the end application of cryopreservation techniques in many fields, with a special emphasis on stem cell preservation techniques and current advancements presented. Furthermore, the challenges while implementing cryopreservation and the futuristic scope of the fields are illustrated herein. The content of this review sheds light on various ways to enhance the output of the cell preservation process and minimize cryoinjury while improving cell revival.

Influence of microwave-assisted dehydration on morphological integrity and viability of cat ovarian tissues: First steps toward long-term preservation of complex biomaterials at supra-zero temperatures

Ovarian tissue contains large pools of immature oocytes enclosed in primordial follicles, making it an attractive target for fertility preservation in female cancer patients, livestock and wild species. Compared to cryopreservation, desiccation and long-term storage of samples at supra-zero temperatures (using strategies inspired from small organisms to resist extreme environments) would be more cost-effective and convenient. The objective of the study was to characterize the influence of microwave-assisted dehydration on structural and functional properties of living ovarian tissues. While this method allows preservation of single cells (cat oocytes and sperm cells so far) using trehalose as the xeroprotectant, it has not been developed for multicellular tissues yet. Ovarian cortex biopsies were reversibly permeabilized, exposed to various concentrations of trehalose, and dried for different times using a commercial microwave under thermal control. Effective dehydration of samples along with proper trehalose retention were reached within 30 min of microwave drying. Importantly, the process did not affect morphology and DNA integrity of follicles or stromal cells. Moreover, transcriptional activity and survival of follicles were partially maintained following 10 min of drying, which already was compatible with storage at non-cryogenic temperatures. Present data provide critical foundation to develop dry-preservation techniques for long-term storage of living multicellular tissues.

Methods and practices to diversify cell-based products

Medicinal signaling cell (MSC)-based products represent emerging treatments in various therapeutic areas including cardiometabolic, inflammation, autoimmunity, orthopedics, wound healing and oncology. Exploring innovation beyond minimally manipulated plastic-adherent ex vivo expanded allogeneic MSCs enables product delineation. Product delineation is on the critical path to maximize clinical benefits and market access. An innovation framework is presented here along various innovation dimensions comprising composition-of-matter by means of positive cell surface markers, formulation varying for example the cell dose or the preservation mode and medium, manufacturing to adapt the secretome of MSCs to the condition of interest, the mode of delivery and corresponding delivery devices, as well as molecular engineering and biomarkers. The rationale of the innovation space thus described applies generally to all cell-based therapies.

Dry Preservation of Spermatozoa: Considerations for Different Species

The current gold standard for sperm preservation is storage at cryogenic temperatures. Dry preservation is an attractive alternative, eliminating the need for ultralow temperatures, reducing storage maintenance costs, and providing logistical flexibility for shipping. Many seeds and anhydrobiotic organisms are able to survive extended periods in a dry state through the accumulation of intracellular sugars and other osmolytes and are capable of returning to normal physiology postrehydration. Using techniques inspired by nature's adaptations, attempts have been made to dehydrate and dry preserve spermatozoa from a variety of species. Most of the anhydrous preservation research performed to date has focused on mouse spermatozoa, with only a small number of studies in nonrodent mammalian species. There is a significant difference between sperm function in rodent and nonrodent mammalian species with respect to centrosomal inheritance. Studies focused on reproductive technologies have demonstrated that in nonrodent species, the centrosome must be preserved to maintain sperm function as the spermatozoon centrosome contributes the dominant nucleating seed, consisting of the proximal centriole surrounded by pericentriolar components, onto which the oocyte's centrosomal material is assembled. Preservation techniques used for mouse sperm may therefore not necessarily be applicable to nonrodent spermatozoa. The range of technologies used to dehydrate sperm and the effect of processing and storage conditions on fertilization and embryogenesis using dried sperm are reviewed in the context of reproductive physiology and cellular morphology in different species.

A Raman microspectroscopy study of water and trehalose in spin-dried cells

Long-term storage of desiccated nucleated mammalian cells at ambient temperature may be accomplished in a stable glassy state, which can be achieved by removal of water from the biological sample in the presence of glass-forming agents including trehalose. The stability of the glass may be compromised due to a nonuniform distribution of residual water and trehalose within and around the desiccated cells. Thus, quantification of water and trehalose contents at the single-cell level is critical for predicting the glass formation and stability for dry storage. Using Raman microspectroscopy, we estimated the trehalose and residual water contents in the microenvironment of spin-dried cells. Individual cells with or without intracellular trehalose were embedded in a solid thin layer of extracellular trehalose after spin-drying. We found strong evidence suggesting that the residual water was bound at a 2:1 water/trehalose molar ratio in both the extracellular and intracellular milieus. Other than the water associated with trehalose, we did not find any more residual water in the spin-dried sample, intra- or extracellularly. The extracellular trehalose film exhibited characteristics of an amorphous state with a glass transition temperature of ?22°C. The intracellular milieu also dried to levels suitable for glass formation at room temperature. These findings demonstrate a method for quantification of water and trehalose in desiccated specimens using confocal Raman microspectroscopy. This approach has broad use in desiccation studies to carefully investigate the relationship of water and trehalose content and distribution with the tolerance to drying in mammalian cells.

Using molecular profiled human tissue to accelerate drug discovery

The value of molecular profiled human tissue lies in its potential to improve the efficiency of drug discovery and development. The sequencing and profiling of human biospecimens across multiple omics dimensions provides layers of molecular information that can be used to enhance our knowledge of disease mechanisms to identify and prioritize novel drug targets and provide supportive biological evidence to support a therapeutic hypothesis. It is critical to control pre-analytical variables because the reproducibility and accuracy of molecular data generated by high-throughput technologies is dependent upon biospecimen quality. The scientific knowledge and technology developments gained in tissue banking research are transforming biospecimen collection and biostorage practices. These tissue banking advancements will improve specimen quality and utilization and, at the same time, reduce biobanking costs. Furthermore, well-annotated, high quality biospecimens will provide reliable, consistent gene expression data for target validation for drug discovery. Challenges in understanding the molecular signatures of biospecimens follow the challenges of human tissue acquisition. Sequencing and profiling high-throughput technologies generate heterogeneous, complex data sets that require sophisticated informatics tools for data storage and analysis. As tissue banking and informatics technologies improve and we gain deeper knowledge of the human genome and its functionality, we will see biomarker identification and target therapies brought about by the research performed on high quality biospecimens.