The Potential Role of Quorum Sensing in Clonal Growth and Subsequent Expansion of Bone Marrow Stromal Cell Strains in Culture

Figure 5

Clonal expansion is a biological property of MSC acquired in a social context. (a) Five individual colonies ( cells/colony) formed at cloning dilution in 96-well plates in FBS-supplemented culture medium (A) were trypsinized and split in half (B), and each half was replated either alone (C) or pooled with all other half clones (D). Individual pools were subdivided into 5 samples, each containing the same number of cells and replated in 6-well plates. Pure half colonies underwent senescence after 5 PD, whereas expansion of mixed strains, including the same number of cells as pure half colonies, continued for >10 PD (E). Culture images (F, G) shown are representative results. These experiments showed that promiscuous strains resumed the ability for efficient expansion, whereas pure clonal strains remained growth impaired (). (b) Assay for secondary CFE and growth potential of BM-MSC strains. 100 BM-MSCs transduced with GFP-lentiviral vectors were plated at clonal density either alone or together with 100 nontransduced BM-MSCs (A, B). After 14 days in culture, CFE was identical, but a 3-fold higher cell number was determined by FACS analysis (C), and a 2-fold higher PD was observed for GFP-BM-MSCs in the mixed cultures compared to the “pure” GFP-BM-MSCs (). Scale bars represent 40 μm, 60 μm, 70 μm, and 100 μm as indicated.

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