DMSO-Free Cryopreservation of Human Umbilical Cord Tissue

Cryostorage of Mesenchymal Stem Cells and Biomedical Cell-Based Products

Mesenchymal stem cells (MSCs) manifest vast opportunities for clinical use due both to their ability for self-renewal and for effecting paracrine therapeutic benefits. At the same time, difficulties with non-recurrent generation of large numbers of cells due to the necessity for long-term MSC expansion ex vivo, or the requirement for repeated sampling of biological material from a patient significantly limits the current use of MSCs in clinical practice. One solution to these problems entails the creation of a biobank using cell cryopreservation technology. This review is aimed at analyzing and classifying literature data related to the development of protocols for the cryopreservation of various types of MSCs and tissue-engineered structures. The materials in the review show that the existing techniques and protocols for MSC cryopreservation are very diverse, which significantly complicates standardization of the entire process. Here, the selection of cryoprotectors and of cryoprotective media shows the greatest variability. Currently, it is the cryopreservation of cell suspensions that has been studied most extensively, whereas there are very few studies in the literature on the freezing of intact tissues or of tissue-engineered structures. However, even now it is possible to develop general recommendations to optimize the cryopreservation process, making it less traumatic for cells.

Enhanced Cellular Cryopreservation by Biopolymer-Associated Suppression of RhoA/ROCK Signaling Pathway

With increasing demands on long-term storage of cells, cryopreservation of cells is gaining more importance in cell-based research and applications. Dimethyl sulfoxide (DMSO) is a commonly used chemical cryoprotectant, providing increased cell survival during the freezing process. However, its use is limited in clinical applications due to its low biocompatibility above cryogenic temperatures. Herein, we present a new approach for reducing the use of DMSO in cryopreservation by using biodegradable hyaluronic acids (HAs). By adding HAs into cryoprotectant media containing a low concentration of DMSO, higher cell viability and cell proliferation rate were observed upon thawing after cryopreservation. The HA-supplemented cryopreservation media did not reduce the size of the ice crystal, which significantly influenced cell viability during cell freezing, but decreased the Ras homolog family member A (RhoA)/Rho-associated protein kinase (ROCK) signaling pathway related to apoptosis. The cell-interactive cryoprotectants containing HA can be applied to the development of a new cryoprotectant that reduces the adverse effect of DMSO.

Influence of Sucrose on the Efficiency of Cryopreservation of Human Umbilical Cord-Derived Multipotent Stromal Cells with the Use of Various Penetrating Cryoprotectants

We studied the influence of sucrose applied in combination with different concentrations of penetrating cryoprotectants (DMSO, ethylene glycol, and glycerol) on the efficiency of cryopreservation of umbilical cord-derived multipotent stromal cells (MSC). The results indicate that these cells can be cryopreserved with the use of 5-10% DMSO or ethylene glycol with equal efficiency; addition of 0.2 M sucrose does not affect cell survival after thawing. The efficiency of glycerol as a cryoprotectant increases with increasing its concentration from 5 to 10%, but remains significantly lower than the efficiency of DMSO or ethylene glycol. Addition of sucrose to a final concentration of 0.2 M increases the efficiency of glycerol. The efficiency of combination of 10% glycerol and sucrose was comparable with that of combinations of DMSO and ethylene glycol with sucrose. The mechanism of the observed enhancement is apparently related to the influence of sucrose on the dynamic properties of the lipid membranes and facilitation of glycerol diffusion into the cells.

Towards Reduction or Substitution of Cytotoxic DMSO in Biobanking of Functional Bioengineered Megakaryocytes

Donor platelet transfusion is currently the only efficient treatment of life-threatening thrombocytopenia, but it is highly challenged by immunological, quality, and contamination issues, as well as short shelf life of the donor material. Ex vivo produced megakaryocytes and platelets represent a promising alternative strategy to the conventional platelet transfusion. However, practical implementation of such strategy demands availability of reliable biobanking techniques, which would permit eliminating continuous cell culture maintenance, ensure time for quality testing, enable stock management and logistics, as well as availability in a ready-to-use manner. At the same time, protocols applying DMSO-based cryopreservation media were associated with increased risks of adverse long-term side effects after patient use. Here, we show the possibility to develop cryopreservation techniques for iPSC-derived megakaryocytes under defined xeno-free conditions with significant reduction or complete elimination of DMSO. Comprehensive phenotypic and functional in vitro characterization of megakaryocytes has been performed before and after cryopreservation. Megakaryocytes cryopreserved DMSO-free, or using low DMSO concentrations, showed the capability to produce platelets in vivo after transfusion in a mouse model. These findings propose biobanking approaches essential for development of megakaryocyte-based replacement and regenerative therapies.

Dimethyl sulfoxide: a central player since the dawn of cryobiology, is efficacy balanced by toxicity?

Dimethyl sulfoxide (DMSO) is the cryoprotectant of choice for most animal cell systems since the early history of cryopreservation. It has been used for decades in many thousands of cell transplants. These treatments would not have taken place without suitable sources of DMSO that enabled stable and safe storage of bone marrow and blood cells until needed for transfusion. Nevertheless, its effects on cell biology and apparent toxicity in patients have been an ongoing topic of debate, driving the search for less cytotoxic cryoprotectants. This review seeks to place the toxicity of DMSO in context of its effectiveness. It will also consider means of reducing its toxic effects, the alternatives to its use and their readiness for active use in clinical settings.