ABSTRACT: Ex vivo expansion of Bone Marrow Stromal Cells (BMSC) is required to obtain clinical dose for cellular therapy, and different labs use different confluence in their practice, however, the impacts of 100% confluence on the biological properties of BMSC remain controversial. In this study, we detected the changes occurred to BMSCs when they reached 100% confluence, including viability, population doubling time (PDT), apoptosis, colony formation, immunosuppression, proteins in the culture supernatant, and surface markers; we also performed gene expression profiling and microRNA profiling on 50%, 80% and 100% confluent BMSCs. Our results showed that 100% confluent BMSCs had similar level of immunosuppression to 80% confluent BMSCs; they increased the expression of CD10, CD54, CD106, CD200, TLR4, but decreased CD49f and PODXL; we detected of 39 proteins in the culture supernatant, which displayed different patterns and an increase on the PEDF/VEGF ratio was observed with higher confluence. We identified 26 differentially expressed microRNAs, which were reported to be involved in the proliferation and differentiation of BMSC; and 2708 genes that were involved in extracellular matrix, cell adhesion, immune response and inflammatory response; particularly, angiogenesis inhibitor PEDF, and Wnt Singling inhibitors DKK1, DKK2, and DKK3 were up-regulated by 100% confluent BMSCs. These data suggest that 100% confluent BMSC may retain immunosuppressive activities but have comprised pro-angiogenesis effects.
