Intracellular delivery of trehalose renders mesenchymal stromal cells viable and immunomodulatory competent after cryopreservation

Trehalose Cryopreservation of Human Mesenchymal Stem Cells from Cord Tissue

Adequate hypothermic storage of human mesenchymal stem cells (hMSCs) is of fundamental importance since they have been explored in several regenerative medicine initiatives. However, the actual clinical application of hMSCs necessitates hypothermic storage for long periods, a process that requires the use of non-toxic and efficient cryo-reagents capable of maintaining high viability and differentiating properties after thawing. Current cryopreservation methods are based on cryoprotectant agents (CPAs) containing dimethylsulphoxide (DMSO), which have been shown to be toxic for clinical applications. In this study, we describe a simple and effective trehalose (TRE)-based solution to cryo-store human umbilical cord-derived MSCs (UC-MSCs) in liquid nitrogen. Cells viability, identity, chromosomal stability, proliferative and migration capacity, and stress response were assessed after cryopreservation in TRE as CPA, testing different concentrations by itself or in combination with ethylene glycol (EG). Here we show that TRE-stored UC-MSCs provided lower cell recovery rates compared with DMSO-based solution, but maintained good functional properties, stability, and differentiating potential. The best cell recovery was obtained using 0.5 M TRE with 10% EG showing no differences in the osteogenic, adipogenic, and chondrogenic differentiation capacity. A second cycle of cryopreservation in this TRE-based solution had no additional impact on the viability and morphology, although slightly affected cell migration. Furthermore, the expression of the stress-related genes, HSPA1A, SOD2, TP53, BCL-2, and BAX, did not show a higher response in UC-MSCs cryopreserved in 0.5 M TRE + 10% EG compared with DMSO. Together these results, in addition to ascertained therapeutic properties of TRE, provide sufficient evidence to consider TRE-based medium as a low-cost and efficient solution for the storage of human UC-MSCs cells and potentially substitute DMSO-based cryo-reagents.

Mesenchymal stem cell cryopreservation with cavitation-mediated trehalose treatment

Dimethylsulfoxide (DMSO) has conventionally been used for cell cryopreservation both in research and in clinical applications, but has long-term cytotoxic effects. Trehalose, a natural disaccharide, has been proposed as a non-toxic cryoprotectant. However, the lack of specific cell membrane transporter receptors inhibits transmembrane transport and severely limits its cryoprotective capability. This research presents a method to successfully deliver trehalose into mesenchymal stem cells (MSCs) using ultrasound in the presence of microbubbles. The optimised trehalose concentration was shown to be able to not only preserve membrane integrity and cell viability but also the multipotency of MSCs, which are essential for stem cell therapy. Confocal imaging revealed that rhodamine-labelled trehalose was transported into cells rather than simply attached to the membrane. Additionally, the membranes were successfully preserved in lyophilised cells. This study demonstrates that ultrasonication with microbubbles facilitated trehalose delivery, offering promising cryoprotective capability without the cytotoxicity associated with DMSO-based methods.

Mesenchymal stromal cells derived from various tissues: Biological, clinical and cryopreservation aspects: Update from 2015 review

Mesenchymal stromal cells (MSCs) have become one of the most investigated and applied cells for cellular therapy and regenerative medicine. In this update of our review published in 2015, we show that studies continue to abound regarding the characterization of MSCs to distinguish them from other similar cell types, the discovery of new tissue sources of MSCs, and the confirmation of their properties and functions that render them suitable as a therapeutic. Because cryopreservation is widely recognized as the only technology that would enable the on-demand availability of MSCs, here we show that although the traditional method of cryopreserving cells by slow cooling in the presence of 10% dimethyl sulfoxide (Me2SO) continues to be used by many, several novel MSC cryopreservation approaches have emerged. As in our previous review, we conclude from these recent reports that viable and functional MSCs from diverse tissues can be recovered after cryopreservation using a variety of cryoprotectants, freezing protocols, storage temperatures, and periods of storage. We also show that for logistical reasons there are now more studies devoted to the cryopreservation of tissues from which MSCs are derived. A new topic included in this review covers the application in COVID-19 of MSCs arising from their immunomodulatory and antiviral properties. Due to the inherent heterogeneity in MSC populations from different sources there is still no standardized procedure for their isolation, identification, functional characterization, cryopreservation, and route of administration, and not likely to be a "one-size-fits-all" approach in their applications in cell-based therapy and regenerative medicine.

On the universality of viscosity in supersaturated binary aqueous sugar solutions: Cryopreservation by vitrification

Nowadays, the physical nature of supersaturated binary aqueous sugar solutions in the vicinity of the glass transition represents a very important issue due to their biological applications in cryopreservation of cells and tissues, food science and stabilization and storage of nano genetic drugs. We present the construction of the Supplemented Phase Diagram and the non-equilibrium nature of the undersaturated-supersaturated kinetic transition. The description of its thermodynamic nature is achieved through the study of behavior of their viscosity as temperature is lowered and concentration increased. In this work, we find a universal character for the viscosities of several sugar water solutions.

Long-term and short-term preservation strategies for tissue engineering and regenerative medicine products: state of the art and emerging trends

There is an ever-growing need of human tissues and organs for transplantation. However, the availability of such tissues and organs is insufficient by a large margin, which is a huge medical and societal problem. Tissue engineering and regenerative medicine (TERM) represent potential solutions to this issue and have therefore been attracting increased interest from researchers and clinicians alike. But the successful large-scale clinical deployment of TERM products critically depends on the development of efficient preservation methodologies. The existing preservation approaches such as slow freezing, vitrification, dry state preservation, and hypothermic and normothermic storage all have issues that somehow limit the biomedical applications of TERM products. In this review, the principles and application of these approaches will be summarized, highlighting their advantages and limitations in the context of TERM products preservation.