Bone Marrow Mesenchymal Stem Cells Enhance the Differentiation of Human Switched Memory B Lymphocytes into Plasma Cells in Serum-Free Medium

Figure 2

Differentiation profile of switched memory B cells under atmospheric and physiologic O₂ in BPFM medium. Switched memory B cells were subjected to a 3-step culture process (a). All cultures were done in BPFM. As illustrated in (a), the first 8 days of expansion were done as described in Figure 1. Afterwards, a transition period of four days was applied to decrease the CD154 interaction to a 1 : 20 ratio and to expose B lymphocytes to IL-6. Finally, cells were maintained in the latter condition for an additional 8 days, except that IL-2 and IL-4 were removed from culture medium. During the differentiation phase, cells were subjected in parallel to 21% and 8% O₂. (b) CD31, CD38, CD39, and CD138 expression were monitored at the end of each phase by gating on viable cells as shown in Figure 3(a). These results are representative of 5 independent experiments. (c) The effect of oxygen levels on cell cycle progression was studied in five additional independent samples cultured as previously mentioned, using the CellVue method. During the last four days of expansion and differentiation phases, cells were subjected to 21% or 8% O₂ in parallel; (c) show the proportion of dividing cells. Statistical analyses were done using the Dunn multiple comparison -test and the values are ≤ 0.05 and ≤ 0.01, as indicated. Data are presented as means ± SEM.

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(b)

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