The Immunomodulatory Effects of Mesenchymal Stem Cell Polarization within the Tumor Microenvironment Niche

Figure 5

MSC immune suppression or promotion of adaptive immune cells. MSCs inhibit several aspects of B cell activity, including activation, proliferation, chemokine receptor expression, and differentiation to becoming antibody-secreting plasma cells. Unknown soluble factors and PD-1/PD-L1 ligation mediate these effects of MSCs on B cells. MSC can induce NO in response to inflammatory cytokine detection to suppress CD8⁺ T cell proliferation, cytokine production, and cytotoxicity. In response to activation by certain cytokines, CD4⁺ T cells can differentiate into numerous effector populations. MSCs produce soluble factors (NO, TGFβ, HGF, PGE2, truncated CCL-2, and IL-10) and membrane-bound molecules (PD-1 ligation) to achieve suppression of CD4⁺ T cell proliferation and the polarization of CD4⁺ T cells towards TH1 and TH17 cells. MSCs also favor the development of TH2 and anti-inflammatory Treg populations. Effects of MSC: + indicates promotion and − indicates suppression.