The changes of multipotent mesenchymal stromal cells isolated from human adipose tissue during long-term cultivation

Multipotent mesenchymal stromal cells (MMSCs) isolated from human adipose tissue have been subcultured for over 50 population doublings. In three cultures that experienced more than 50 cellular doublings, there appeared cells lacking contact inhibition upon reaching the monolayer. Karyotype analysis (GTG banding) showed a normal diploid karyotype, and aneuploidy and restructurings were not registered. Flow-cytometric analysis of 20 surface antigens on MMSCs in early and late passages revealed changes in the share of cells positively stained with antibodies against CD10 (a zinc depended metalloproteinase); CD34 (sialomucin); CD49 a, d, f, (α1, α4, α6, integrins); and CD71 (a transferrin receptor). Long-term cultivation influenced cell adhesion to proteins of the extracellular matrix (ECM), such as fibronectin and laminin (ligands to α, integrins), as well as the functional abilities of MMSCs to form cells of adipose and bone tissues in vitro. These findings extend our knowledge of cell behavior in culture and allow us to get closer to a deeper understanding of the processes happening to precursor cells in vitro.