Fig. 6. (A ) Effects of human placental multipotent mesenchymal stromal cells (hPMSCs) on regulating endotoxin binding to RAW264.7 cells assayed by flow cytometry. (B ) Effects of hPMSCs on regulating toll-like receptor 4/myeloid differential-2 complex activation in RAW264.7 cells assayed by flow cytometry. Human placental MSCs (cell numbers: hPMSCs vs.  RAW264.7 cells = 1:10²) were added to RAW264.7 cells at 4 h before lipopolysaccharide (LPS, 100 ng/ml) administration. NS-398 (1 μM) was added at 30 min before hPMSCs. In addition, fluorescein-labeled lipopolysaccharide (100 ng/ml) was employed to facilitate endotoxin binding assay. LPS+R is the RAW264.7 cells plus LPS group; LPS+R+S is the RAW264.7 cells plus hPMSCs plus LPS group; LPS+R+S+N is the RAW264.7 cells plus hPMSCs plus NS-398 plus LPS group. RAW264.7 cells plus phosphate buffered saline (i.e. , the PBS+R group) served as the negative control. All data were derived from three independent experiments performed in duplicates (n = 6) and analyzed with one-way ANOVA with the Tukey test for post hoc  comparisons. Data were mean ± standard deviations. *P < 0.05 versus  the PBS+R group. FITC = fluorescein-labeled; LPS = lipopolysaccharide; MD-2 = myeloid differential-2; MFI = mean fluorescence intensity; N = NS-398; PBS = phosphate buffered saline; R = RAW264.7; S = human placental multipotent mesenchymal stromal cells, or hPMSCs; TLR4 = toll-like receptor 4.