Characterization of mesenchymal stem cells under the stimulation of Toll‐like receptor agonists

Infective factors cause the perpetuation of inflammation as a result of the permanent exposure of the immune system to exogenous or endogenous products of virus or bacteria. Mesenchymal stem cells ( MSC s) can be exposed to this infective environment, which may change the characteristics and therapeutic potency of these MSC s. MSC s have the ability to repair damaged and inflamed tissues and regulate immune responses. In this study, we demonstrated that MSC s express functional Toll‐like receptors ( TLR ) 3 and 4, the Toll‐like receptor families that recognize the signals of viral and bacterial mimics, respectively. The specific stimulations did not affect the self‐renewal and apoptosis capabilities of MSC s but instead promoted their differentiation into the adipocytes and osteoblasts with the TLR 3 ligand. The reverse of these results were obtained with the TLR 4 ligand. The migration of the MSC s to stimulate either of the two specific ligands was inhibited at different times, whereas the immunogenicity and immunosuppressive properties of the MSC s were not weakened unlike in the MSC s group. These results suggest that TLR 3 and TLR 4 stimulation affect the characterization of MSC s.