The Immunomodulatory Effect of Bone-Marrow Mesenchymal Stem Cells on Expression of TLR3 and TLR9 in Mice Dendritic Cells

Background: Mesenchymal stem cells (MSCs) are multipotent cells with immunomodulatory effect on immune cells including dendritic cells (DCs). DCs are the most potent antigen-presenting cells (APC). MSCs have been found to modulate both differentiation and function of DCs. DCs express a broad range of Tolllike receptors (TLR), which play a critical role in DCs maturation and function. Objective: To evaluate expression level of TLR3 and TLR9 transcripts in DCs following treatment with MSCs supernatant. Methods: MSCs and DCs were derived from adult BALB/c mice bone marrow and spleen, respectively. MSCs supernatant was harvested following 24, 48, and 72 hours. Isolated DCs were treated with MSCs supernatant and incubated for 24 and 48 hours. TLR3 and TLR9 transcript levels were evaluated using real-time PCR. Results: The results showed that 48 and 72 hours MSCs supernatant significantly decreased the expression of TLR3 in DCs following 24 and 48 hours incubation in comparison with untreated cells (p<0.01). Moreover, 48 hours of treatment with 24, 48 and 72 hours MSCs supernatant significantly decreased TLR9 transcript level (p<0.05). Conclusion: TLR3 and TLR9 mRNA expression decreases in DCs after incubation with MSCs culture supernatant. This confirms the immunomodulatory role of MSCs in cell-base therapy.