C-2014: Investigation of genetic and epigenetic changes of cryopreserved mesenchymal stem cells

Abstract

Cryopreservation is routinely used to store different types of cells and tissues. It is used for transportation and cell banking. However, the impact of cryopreservation on the genetic and epigenetic profile of frozen cells is still unclear. Here, we try to explore the alterations caused to cryopreserved mesenchymal stem cells and its possible implications. Our freezing protocol showed that the cells frozen with 5% dimethyl sulfoxide (Me2SO) at all passages (early, mid and late) had the best post thaw survivability in terms of MTT assay and adherence capacity. 1% and 15% Me2SO concentrations proved to be sub-optimal after thawing the cells. Adipogenic differentiation of MSCs showed that cells frozen in all concentrations of Me2SO could differentiate to adipocytes. Cells frozen with 5%, 10% and 15% Me2SO showed comparable oil droplet formation. DNA methylation plays a critical role in health and disease. Changes in DNA methylation has been seen in cancer, ageing and auto immune diseases. Alterations in the 5-mC% content of DNA were observed in the frozen samples as compared to control (unfrozen cells, never exposed to Me2SO). Further studies need to be conducted so as to determine the implication of these alterations. In total, cryopreservation seemed to cause changes in the mRNA expressions, global DNA methylation which could alter the cell fate at a later time point. Therefore, there is a need for comprehensive and orderly studies to determine the possible impact of subtle genomic/epigenomic and proteomic changes resulting from cryopreservation.