Fig. 3

Contribution of integrins to protein- and peptide- dependent cell attachment. Human bmMSCs (a) or pMSCs (b) were pre-incubated with a function-blocking antibody to CD29 (integrin β1 chain) or remained untreated as indicated (ø). The cells were then incubated on peptide- or fibronectin (FN)-coated spots. Pre-incubation of bmMSCs (a) or pMSCs (b) with anti-CD29 mAb completely blocked the attachment of the cells, whereas untreated MSCs attached well to peptides or proteins. Pre-incubation of bmMSCs with anti-CD90 mAb failed to block attachment of the cells confirming the specificity of the blocking reaction (a, upper right). Incubation of pMSCs on activated bovine serum albumin (aBSA) did not cause unspecific binding of cells to this reagent (b). Human bmMSCs were labeled with PKH26 and attachment of PKH26-loaded cells to FN was confirmed (c, left). Human fibroblasts were labeled with PKH67, mixed 1:1 with PKH26-labeled MSCs and incubated on fibronectin (c, right). DF competed for binding sites and displaced the MSCs (c, right). Human bmMSCs were loaded with Calcein-AM and EthD-1 to discriminate viable cells (green cytoplasm, v) from dead cells (red nuclei, d) and added to LM-111-coated spots (d). The MSCs attached presented a bright green fluorescence indicating a high viability of the population studied (d, v). Only a few dead cells were observed (d, d)