Comparative characteristics of mesenchymal stem cells derived from human various sources and optimization of in vitro storage conditions for clinical transplantation

Abstract

Mesenchymal stem cells (MSCs), which are multipotent stromal cells, have the ability to self-renew and differentiate into various cell types. Their plasticity and availability make them promising candidates for regenerative medicine. Since bone marrow-derived MSCs were first discovered, MSCs have been isolated from various tissues of the body, each of which has demonstrated slightly different properties. These differences may be due to different isolation protocols or the heterogeneity of MSCs. In this study, we undertook a comparative analysis of the characteristics of MSCs derived from various human tissues to define their differences and find effective cell sources for cell therapy. Our results showed that the morphology of MSCs, including human dermal fibroblasts, did not differ. Immunophenotyping and analysis of pluripotency markers revealed similar expression patterns in all cell types, but the multilineage differentiation potential of the cells in vitro was different depending on cell origin. All MSCs other than fibroblasts had tri-lineage differentiation capacity. Further, we attempted to identify specific markers to distinguish one type of MSC from the others. We also compared expression profiles of neurotrophic and anti-inflammatory factors, but there were no significant differences in our experiments, despite utilizing a variety of approaches. These results demonstrated that all MSCs with features of stem cells, such as differentiation capacity, from a variety of tissues are promising tools for cell-based therapies.For successful clinical application, the viability and potency of in vitro-expanded MSCs need to be maintained during preparation and transportation prior to transplantation. However, the stability and potency of MSCs under these conditions have not been thoroughly examined. Another goal of this study was to standardize MSC preparation and storage prior to clinical application to ensure reproducible quality and potency for the intended clinical purpose. We examined the viability and potency of MSCs after short-term in vitro storage in saline or dextrose solution at 4°C and room temperature (RT). We then analyzed cell viability, proliferation capacity, and differentiation potential. MSCs harvested and suspended in saline for 1~2 h showed greater than 90% viability regardless of storage temperature. When cells were stored for longer than 2 h in saline, however, their viability decreased gradually over time, whereas the viability of cells stored in dextrose deteriorated rapidly. MSCs lost their colony-forming unit (CFU) and differentiation capacities rapidly as storage time increased. Altogether, we found that a storage period greater than 2 h resulted in a significant decrease in cell viability, proliferation capacity, and differentiation potency. Therefore, storage of culture-harvested MSCs for longer than 2 h is likely to result in suboptimal MSC-mediated tissue regeneration due to decreased cell viability and differentiation capacity.