Mesenchymal stromal cell cryopreservation

Abstract

The advent of stem cells and stem cell-based therapies for specific diseases requires particular knowledge of laboratory procedures, which not only guarantee the continuous production of cells, but also provide them an identity and integrity as close as possible to their origin. Their cryopreservation at temperatures below -80°C and typically below -140°C is of paramount importance. This target can be achieved by incorporating high molar concentrations of cryoprotectant mixtures that preserve cells from deleterious ice crystal formation. Usually, dimethyl sulfoxide (DMSO) and animal proteins are used as protectant reagents, but unexpected changes in stem cell fate and downstream toxicity effects have been reported, limiting their wide use in clinical settings. In scientific reviews, there are not much data regarding viability of mesenchymal stromal cells (MSCs) after the freezing/thawing process. During our routine analysis, a poor resistance to cryopreservation of these cells was observed, as well as their weak ability to replicate. This is an important point in the study of MSCs; moreover, it represents a limit for preservation and long-term storage. For this reason, MSCs isolated from equine, ovine, and rodent bone marrow and equine adipose tissue were compared using different cryopreservation solutions for this study of vitality. Our findings showed the best results regarding cell viability using a solution of fetal bovine serum with addition of 10% DMSO. In particular, we noted an increase in survival of equine bone marrow MSCs. This parameter has been evaluated by Trypan blue staining at fixed times (0, 24, and 48 hours post-thaw). This result highlights the fact that equine bone marrow MSCs are the frailest we analyzed. Therefore, it could be useful to delve further into this topic in order to improve the storage possibility for these cells and their potential use in cell-based therapies.