EFFECT OF PEPTIDOGLYCAN-LIPOPOLYSACCHARIDE ON NITRIC OXIDE PRODUCTION BY RAT MESENCHYMAL STEM CELL (MSC) AND INDUCTION OF APOPTOSIS IN ACTIVATED T CELL WITH MSC

Mesenchymal stem cells (MSCs) are adult cells which are identified as non-hematopoietic and pluripotent stem cells. Specific stimulation of toll like receptors on the surface of mesenchymal stem cells could change immune responses of these cells into the pre or anti-inflammation phenotype. The aim of this study was to evaluate the effect of peptidoglycan-lipopolysaccharide on the polarization of stem cells into the anti inflammation phenotype and apoptosis induction in T cells. MSCs were isolated from the femoral and tibial bone marrow and re-suspended in DMEM media, and kept in 5% CO2 incubator at 37 ° C for 24 hours. After that the cell concentration reached to 70 % treated with toll like receptor’s agonist with high (10 ng/ml) and low (5 ng/ml) doses for 1 and 12 hours. Then supernatant of cell culture flask were collected for nitric oxide measurement. Apoptosis percentage in T cells was assayed by flowcytometry in the presence of Acridine orange/ propidium iodide (AO/PI). The percentage of apoptosis in activated T cells significantly (P<0.05) was higher in long term (12 h) and low dose (5 ngr/ml) treatment with TLR4 agonist than the control. Also, the finding indicated that the nitric oxide production significantly (P<0.05) was higher at short term (1 h) and high dose (10 ngr/ml) of TLR agonist in comparison to the control. It should be concluded that the amount of agonist and duration of treatment in stem cells can affect the apoptosis activity and nitric oxide production in MSCs.