The influence of freezing and storage on the characteristics and functions of human mesenchymal stromal cells isolated for clinical use

Background Studies have shown that stem cell therapy could be a novel option for improving neovascularization and cardiac function in patients with ischemic heart disease. Human mesenchymal stromal cells (MSC) have generated wide interest in the clinical setting because of their ability to regenerate tissue. The aim of the study was to test whether freezing and storage of human BM mononuclear cells (BM-MNC) and ex vivo-expanded MSC influenced their phenotypic and functional characteristics as well as proliferation capacity. Methods MNC were isolated from BM and divided into two portions: one part was immediately cultured (MSC PO) whereas the second part was frozen for a week before cultivation and analysis (F-MSC PI). Confluent MSC (PO) were harvested and divided: one was analyzed as MSC P1 and the other was frozen for a week before further cultivation and analysis as F-MSC P2. Results MSC P1, F-MSC P1 and F-MSC P2 bad similar proliferation capacities and demonstrated almost identical expression levels of markers characteristic for MSC The capacity to form endothelial vascular structures was independent of freezing. Discussion The proliferation and differentiation capacity as well as the cellular characteristics were identical in cultivated MSC derived from freshly isolated BM-MNC and MSC derived after freezing and storage of either freshly isolated BM-MNC or ex vivo-cultivated MSC. This highlights the potential clinical use of MSC in patients with cardiac and degenerative diseases, as it would be possible to inject MSC obtained from the same BM aspiration at different time points.