Duration of in vitro storage affects the key stem cell features of human bone marrow-derived mesenchymal stromal cells for clinical transplantation

Background aims. Mesenchymal stromal cells (MSCs) have the ability to self-renew and differentiate into various cell types. Their plasticity and easy availability make them promising candidates for regenerative medicine. However, for successful clinical application, MSCs need to be expanded under a Good Manufacturing Practices-compliant system to obtain a large quantity of these cells. Although the viability and potency of these in vitro-expanded MSCs need to be maintained during preparation and transportation before transplantation, these characteristics have not thoroughly been examined. Our goal in this study was to standardize MSC preparation and storage before their clinical application to ensure reproducible quality and potency for their clinically intended purpose. Methods. We examined the viability, self-renewal capacity and differentiation capability of MSCs on short-term in vitro storage in saline or dextrose solution at 4 degrees C and room temperature. Results. MSCs harvested and suspended in saline for 1-2 h showed >90% viability regardless of storage temperature. However, when cells were stored for >2 h in saline, their viability decreased gradually over time. The viability of cells in dextrose deteriorated rapidly. MSCs lost colony-forming unit and differentiation capacities rapidly as storage time increased. Collectively, we found that a storage period >2 h resulted in a significant decrease in cell viability, cell proliferation capacity and differentiation potency. Conclusions. Storage of culture-harvested MSCs for >2 h is likely to result in suboptimal MSC-mediated tissue regeneration because of decreased cell viability and differentiation capacity.