05). In contrast, both ligands increased the VEGF levels (Fig. 3D). Previous studies have suggested 5-Fluoracil price the possible involvement of Gal-3 in diverse physiological and pathological processes, including pre-mRNA splicing, neoplastic transformation and immune response [18]. Gal-3 is also reported to play a negative role in T-cell activation, a process that requires clustering of a threshold number of T-cell receptor at the site of antigen presentation [19, 20]. Based on these early findings, we investigated the potential effect of Gal-3 gene silencing in MSC on T-cell proliferation to alloantigens. To identify

effective siRNA against Gal-3, we visually examined the sequence of Gal-3 mRNA and selected 3 targeting sites. The silencing potency of the designed siRNA was tested in freshly isolated human monocytes (Fig. 4A). All the 3 siRNA inhibited Gal-3 expression with siRNA-3 being the most effective. At a concentration of 2 μg, the silencing efficiency was around 99% when compared to control cells. Having demonstrated that siRNA-3 is effective in human monocytes, next we assessed its silencing potency in MSC (Fig. 4B and C). The designed siRNA resulted in nearly 94% (±3%) reduction in intracellular protein levels, and around 95% (±4%) reduction in the secreted protein when compared to cells transfected with control siRNA. In contrast, depletion of Gal-3 has no

significant Bortezomib heptaminol effect on either β actin or VEGF expression, thus confirming the specificity of the designed siRNA-3. To uncover the potential effects of Gal-3 knockdown on MSC function, we asked whether MSC-expressing Gal-3 could have an effect on the proliferation of lymphocytes in response to alloantigens. To this end, we first determined the cell concentration that gave a significant inhibition and found that suppression can be achieved after the addition of approximately 10–50 000 MSC to mixed lymphocyte cultures. Second, we tested lymphocyte response in the presence of 30 000 allogeneic MSC that have been transfected with either siRNA-3 against Gal-3

or control siRNA. In these experiments, peripheral blood mononuclear cells from donor 1 (PBMC1) were incubated with PBMC from a responder donor 2 (PBMC2) in the absence or presence of irradiated “third-party” MSC. In contrast to Gal-3 expressing MSC, knockdown of Gal-3 resulted in less immunosuppressive effect on T-cell proliferation (Fig. 4D, P < 0.05, as a representative example). In addition to the expression of certain TLR, this study shows that MSC also express NOD-1. Unlike TLR, NLR consist of soluble proteins that survey the cytoplasm for signs that advertise the presence of intracellular invaders [15]. By screening the expression profiles in response to NOD-1 and TLR-2 synthetic ligands, we have identified a set of genes that were altered subsequent to overnight activation of MSC.