Figure 3.

CD44-expressing extracellular vesicles (EVs) from human mesenchymal stromal cells (MSCs) are partially responsible for their modulatory effects. (A) Flow cytometry demonstrates that MSC-derived EVs are (Ai) smaller in diameter than latex beads of 4-μm diameter and (Aii) positive for CD44 expression on their surface. (B) Preincubation of MSC conditioned medium (CM) with anti-CD44 neutralizing antibody partially reversed MSC suppression of tumor necrosis factor (TNF)-α secretion by human monocyte–derived macrophages (MDMs; n = 4 for all groups) and completely prevented MSC enhancement of (Ci) the proportion of phagocytic MDMs as well as (Cii) their phagocytic index (Phago; n = 5 for all groups). One-way analysis of variance with Bonferroni’s post hoc test was used. Data are presented as mean ± SD. *P < 0.05; **P < 0.01. APC = allophycocyanin; Cy = cyanine; FITC = fluorescein isothiocyanate; FSC = forward scatter; MFI = median fluorescence intensity; PE = phycoerythrin; PerCP = peridinin-chlorophyll-protein complex; SSC = side scatter.