Cell cycle phases and genetic profile of bone marrow-derived mesenchymal stromal cells expanded in vitro from healthy donors.

Human mesenchymal stromal cells (MSCs) expanded in vitro for cell therapy approaches need to be carefully investigated for genetic stability, by employing both molecular and conventional karyotyping. Reliability of cytogenetic analysis may be hampered in some MSC samples by the difficulty of obtaining an adequate number of metaphases. In an attempt to overcome this problem, a methodology apt to evaluate the cell-cycle structure on synchronous MSCs was optimised. Results obtained in five independent experiments by comparing cell-cycle analysis of synchronous and asynchronous MSC populations evaluated at early and late culture passages documented that in synchronous MSCs, 30% of cells entered G2/M phase after about 27-28 h of culture, while in asynchronous MSCs only 8% of cells in G2/M phase could be observed at the same time point. Cytogenetic analysis on synchronous MSCs allowed us to obtain 20-25 valuable metaphases/slide, whereas only 0-4 metaphases/slide were detectable in asynchronous preparations.