Experimental Study Of The Effect Of Mesenchymal Stem Cells On The Treatment Of Acute Liver Failure By Promoting Macrophage To Type M2 Polarization

BackgroundWhen acute liver failure (acute liver failure, ALF) occurs, the imbalance between immune system activation and inhibition leads to the serious disorders of liver cells immune microenvironment, resulting in massive necrosis of liver cells, even leading to the deterioration of liver function in rapid short-term. The polarization state as well as plasticity of liver macrophages is involved in maintaining homeostasis of liver immune microenvironment. Soluble cytokines secreted by Mesenchymal stem cells can improve liver immune microenvironment by immune regulation when ALF occurs.AimsIt aims at improving liver immune microenvironment by means of exogenous transplanted MSCs in the experimental animals model when ALF occurs. Furthermore, it evaluates the effect of MCs transplantation therapy on ALF, and then detects the changes of infiltration and polarization of macrophages in the liver tissues. In addition, it pinpoints not only the MSCs internal molecular mechanism in transplantation therapy of ALF but also the effect of macrophages in maintaining the homeostasis of liver immune microenvironment, thus probing further into the relationship between the MCs transplantation therapy and the infiltration and polarization of macrophages.Methods:It is carried out by drug-induced ALF mouse model, exogenous transplanted mouse MSCs cells, biochemical analyzer test in mice liver function (ALT, AST, PT, NH3) after cell transplantation treatment, using protein microarray to detect the changes of inflammation mediators in peripheral blood and HE staining to detect the histopathologic changes. On one hand, it chooses the larger differences in expressions of inflammation mediators before and after cell transplantation in the treatment of ALF by protein chip technology screening. On the other hand, it analyzes the infiltration and polarization of macrophages in the liver tissues before and after cell transplantation by immunohistochemistry and flow cytometry, therefore further detecting its correlation with the liver function of experimental animals. Moreover, it observes the changes of macrophages in the liver tissue of mice through inhibit differential expression of the inflammatory mediators after treatment of MSCs cell transplantation. In addition, it delves into not only the relationship between MSCs transplantation therapy and infiltration degree and polarization state of macrophages but also the corresponding changes in the signal transduction pathway using Western blot detection. Finally, it verifies the clinical relevance of polarization state and infiltration degree of liver macrophages combined with the partial observations of clinical specimens.ResultsFirst, it is found that MSCs transplantation therapy can significantly improve ALF mice liver function, thus enhancing coagulation and reducing tissue damage and apoptosis of liver cells and IL-1, IL-6, and TNF-a and other inflammatory mediators infiltration. Secondly, the results of protein chips suggest that many anti-inflammatory cytokine expressions are increased significantly after the MSCs transplantation in the ALF treatment, in which IL-10 is increased even more particularly. Thirdly, the results of flow cytometry indicate that, M1 type macrophages infiltration is mainly within ALF mice liver tissue before MSCs transplantation, but M2 type macrophages infiltration is given priority after MSCs transplantation, and the proportion of M2/M1 is significantly increased after transplantation. Moreover, the degree of infiltration of macrophages in the liver tissue is also reduced significantly after MSCs cell transplantation therapy. When AS 101 (an inhibitor of IL-10 biosynthesis) is combined with MSCs transplantation in the treatment group, liver protective effects of MSCs are antagonistic, and macrophage phenotype restore to the M1 type. Finally, compared the mice western blot test results of MSCs transplantation of liver failure of the original generation of macrophage with those of before transplantation treatment, STAT3, p-STAT3 and Arg expressions are increased obviously, and iNOS expression is decreased. After combined with AS101, STAT3, p-STAT3 and Arg expression is significantly decreased and iNOS expression is increased. After the cell supernatants combined with Static, the content of IL-10 secreted by macrophage though autocrine way significantly reduced.ConclusionsMSCs can activate STAT3 signal channels by secreting IL-10 though paracrine way to promote liver tissue macrophages to M2 type polarization thereby maintaining homeostasis within the microenvironment of liver inflammation to play a protective role. The infiltration and polarization state of macrophage are closely related to liver function in patients with acute liver failure, which may be expected to become an important means to treat patients with acute liver failure.