Human mesenchymal stromal cells preserve their stem features better when cultured in the Dulbecco's modified Eagle medium

The human mesenchymal stromal cell (hMSC), a type of adult stem cell with a fibroblast-like appearance, has the potential to differentiate along the mesenchymal lineage and also along other cell lineages. These abilities make hMSC a promising candidate for use in regenerative medicine. As the hMSC represents a very rare population in vivo, in vitro expansion is necessary for any clinical use. hMSC characterization is commonly carried out through the expression of specific markers and by the capability of differentiating toward at least adipo-, osteo- and chondrocytic lineages. Commitment processes also result in significant changes in the ultrastructure in order to acquire new functional abilities; however, few studies have dealt with the ultrastructural characteristics of hMSC according to the time of incubation and type of media.The immunophenotype, functional characteristics and ultrastructural features of bone marrow (BM) hMSC cultured in two different media were investigated. The media chosen were Iscove's modified Dulbecco's medium (IMDM) and the Dulbecco's modified Eagle medium (DMEM). The latter has been recommended recently by two international transplantation and cytotherapy societies, the International Society of Cellular Therapy (ISCT) and European Group for Blood and Bone Marrow Transplantation (EBMT), for hMSC expansion for clinical applications.The present results indicate that culture conditions greatly influence hMSC ultrastructural features, proliferation, growth and differentiation. In particular, our findings demonstrate that DMEM preserves the hMSC stem features better. Furthermore, the results obtained in IMDM suggest that a small size does not always correlate with conditions of cell immaturity and a greater proliferative potential.