ABSTRACT
OBJECTIVE: Mesenchymal stem cells (MSCs) are precursors of tissue of mesenchymal origin, but they also have the capacity to regulate the immune response by suppressing T and B lymphocyte proliferation in a non-major histocompatibility complex-restricted manner. Use of MSCs as immunosuppressant agents in autoimmune diseases has been proposed and successfully tested in animal models. We explored the feasibility of using allogeneic MSCs as therapy for collagen-induced arthritis, a mouse model for human rheumatoid arthritis. METHODS: DBA/1 mice were immunized with type II collagen in Freund's complete adjuvant, and some of the animals received an intraperitoneal injection of allogeneic MSCs. RESULTS: A single injection of MSCs prevented the occurrence of severe, irreversible damage to bone and cartilage. MSCs induced hyporesponsiveness of T lymphocytes as evidenced by a reduction in active proliferation, and modulated the expression of inflammatory cytokines. In particular, the serum concentration of tumor necrosis factor alpha was significantly decreased. MSCs exerted their immunomodulatory function by educating antigen-specific Tregs. CONCLUSION: Our results suggest an effective new therapeutic approach to target the pathogenic mechanism of autoimmune arthritis using allogeneic MSCs. However, further studies are required before these results can be translated to clinical settings.
Subject(s)
Arthritis, Experimental/therapy , Bone and Bones/drug effects , Cartilage, Articular/drug effects , Joints/drug effects , Mesenchymal Stem Cell Transplantation , Animals , Arthritis, Experimental/pathology , Arthritis, Experimental/physiopathology , Bone Marrow Cells , Bone and Bones/pathology , Cartilage, Articular/pathology , Cell Proliferation/drug effects , Cytokines/blood , Female , Joints/pathology , Male , Mesenchymal Stem Cells/immunology , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Mice, Transgenic , T-Lymphocytes, Regulatory/drug effects , T-Lymphocytes, Regulatory/metabolism , T-Lymphocytes, Regulatory/pathology , Transplantation, HomologousABSTRACT
Bone marrow mesenchymal progenitor cells (BMSC) are used for regenerating tissues of mesodermal origin, as well as tissues of different embryological derivation. Experimental evidence shows that BMSC are able to suppress the activation of the immune response by mechanisms that are still not completely understood. Thus far, in vitro studies carried using human or mouse cells indicate that autologous or allogeneic BMSC strongly suppress proliferation of T lymphocytes, triggered by cellular stimuli, nonspecific mitogenic stimuli, or antigenic peptides. Using cell proliferation and blocking assays, we demonstrated that BMSC inhibited the activation of murine splenocytes, T, and B lymphocytes. Direct contact of BMSC and target cells in a cognate fashion determined the inhibition of cell proliferation via engagement of the inhibitory molecule programmed death 1 (PD-1) to its ligands PD-L1 and PD-L2, leading the target cells to modulate the expression of different cytokine receptors and transduction molecules for cytokine signaling. Soluble factors present on supernatants of BMSC cultures were effective in suppressing proliferation of B cells to a mitogenic stimulus. Taken together, these results highlight the complexity of the role of BMSC in regulating the immune response, asserting the possibility of their therapeutic application in transplantation and autoimmune diseases.
