The Immunomodulatory Properties of Mesenchymal Stem Cells Play a Critical Role in Inducing Immune Tolerance after Liver Transplantation

Figure 2

The mechanism of immune tolerance induced by mesenchymal stem cells (MSCs). (a) MSCs regulate the maturation, proliferation, differentiation, and apoptosis of immune cells to generate a tolerogenic microenvironment via cell-cell interactions and diverse cytokines and signal pathways. (b) Preconditionings to induce immune tolerance. The capacity of immune regulation of MSCs might be influenced by the pretreatment with cytokines, genetic modification, and culture method (three-dimensional (3D) culture or 2D culture). (c) Paracrine mechanisms and extracellular vesicles derived from MSCs to induce immune tolerance after liver transplantation. TGF-β: transforming growth factor-beta; PGE2: prostaglandin E2; IDO: indoleamine 2,3-dioxygenase; PD-L1: programmed cell death-ligand 1; CCL-2: chemokine ligand-2; EBI3: Epstein-Barr virus-induced 3; IL-10: interlukin-10; FoxP3: forkhead box P3; NK: natural killer; DCs: dendritic cells; CTLs: cytotoxic T lymphocytes; Tregs: regulatory T cells; Bregs: regulatory B cells; Th1: T helper 1.