Evaluation of activity of peritoneal macrophages in mouseC57BL/6 after phagocytosis of apoptosis of WJ MSC

Macrophages are one of the most important immune cells. Macrophages can be divided into two main subgroups of classical or inflammatory macrophages(M1) and alternative or non -inflammatory macrophages or (M2), due to different stimuli. One of the factors that causes the macrophage to orient towards M2, is the phagocytosis of apoptosis cells (efferocytosis). The phagocytosis of mesenchymal stem cells, can be very important in cell therapy due to immunomedulatory properties and their ability to modulate macrophage function. Mesenchymal stem cells were isolated from Wharton's jelly and characterized by flow cytometry as well as differentiation to Osteoblasts and adipocytes. MSCs in the passage 2 exposed to UV light for induction of apoptosis for thirty minutes and followed by incubation for two hours. The cells were then isolated and added to macrophages in a ratio of 4 to 1. After that cells were incubated for 48 hours, after incubation time the production of TNFα and IL10 cytokines was measured by ELISA and nitric oxide production was measured. Macrophages phagocytosis ability was also measured by yeast and apoptotic thymocytes phagocytosis in different groups. The phagocytosis of Wharton's jelly–Mesenchymal stem cells (WJ–MSCs) by macrophages reduces the production of inflammatory cytokine TNFα and increases the production of inhibitory cytokine IL-10. Nitric oxide production has decreased in these macrophages. Also, after phagocytosis of apoptotic WJ–MSCs, the ability of yeast phagocytosis in these macrophages was reduced and phagocytosis of apoptotic thymocyte was increased. The phagocytosis of apoptotic WJ–MSCs, induce non-inflammatory phenotype in macrophages. So, injected WJ–MSCs maintain their immunomodulatory properties even if they get apoptosed in the body.