Background: Lithium chloride (LiCl) has been linked to an increase in bone mass when used as a treatment for mental disorders. Bone healing that is delayed due to acute or prolonged inflammation is a serious issue. In the early stages of the healing process, some chemokines and cytokines are released such as IL-6, causing an increase in immune cell migration and pro- inflammatory behavior in the injured area. To be able to proceed with the healing process however, it might be preferred if inflammation is attenuated. In terms of regenerative medicine, mesenchymal stem cells (MSCs) are an ideal cell source due to their differentiation capacity and also their immunomodulatory properties. We conducted this study in order to investigate whether incubation of bone marrow (BM)-derived MSCs with LiCl would affect the expression of several immunomodulatory genes. Methods: BM-MSCs were obtained from the bone marrow aspirate of patients after obtaining their informed consent and the characteristics of the BM-MSCs were examined using flow cytometry as well as evaluating their differentiation potential using specific differentiation media. Afterwards, the samples were treated with LiCl (20 mM, for 24 h), and following RNA extraction and cDNA synthesis, the samples were evaluated for the expression of several immunomodulatory genes by real time PCR. Results: Our experiment proved the identity of BM-MSCs through the overexpression of several cell surface markers, such as CD44, CD73, CD90, and CD105, which confirmed the identity of BM-MSCs. As a result of staining fat vacuoles and calcium deposits of differentiated cells, we were also able to confirm their multipotency. In BM-MSCs treated with LiCl, the expressions of immunomodulatory related genes including TDO-2, COX-2 and TSG-6 significantly increased (p <0.01) compared to the control group. A decrease (p <0.01) in the expression of IL-6, one of the pro-inflammatory cytokines, was also observed following the treatment of BM-MSCs with LiCl. Conclusion: BM-MSCs treated with lithium chloride, were observed to exhibit profound up- and down-regulatory effects on the expression of immunomodulatory and pro-inflammatory genes, respectively, the phenomena associated with the anti-inflammatory phenotype of MSCs.

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