Alteration of the immune status of umbilical cord mesenchymal stem cells stimulated by TLR1/2 agonist, Pam3Csk.

Mesenchymal stem cells (MSCs) have been widely used in clinical trials due to their multiple differentiation ability, low immunogenicity and immunosuppressant effects on immune response. However, accumulating evidence has indicated that MSCs may stimulate in vivo immune responses and result in the disappearance of MSCs following engrafting. Toll­like receptors (TLRs) are important in immune response induction against invaded pathogens, however, the function of TLRs in regulating the immune status of MSCs has been seldom reported. The present stimulated umbilical cord (UC) MSCs by treatment with the TLR1/2 agonist, Pam3Csk, the to determine whether activation of TLR1/2 signaling alters the immune status of UCMSCs. The results indicated that activation of TLR1/2 increased the proliferation of peripheral blood mononuclear cells (PBMCs) and the production of lactate dehydrogenase in a PBMC­MSC co­culture system. The study also demonstrated that Pam3Csk induced the secretion of pro­inflammatory molecules, and increased the expression levels of cytokine and chemokines in UCMSCs. Flow cytometry analysis indicated that the levels of surface co­stimulators, CD80 and CD86, were increased on UCMSCs in the presence of Pam3Csk, whereas activation of TLR1/2 exerted no observable effect on the differentiation abilities of UCMSCs. The results of the current study indicated that activation of TLR1/2 signaling may alter the immune status of UCMSCs, however, further mechanistic research is required in future studies.