ICAM1 and abortion: Li Y. et al. (2019) found that the direct interaction between M1 macrophages and MSCs is essential for the treatment of LPS-induced abortion by MSCs. Using an abortion model, they demonstrated that MSCs induce immune tolerance based on a TSG-6-dependent paracrine effect and by cell-to-cell contact between MSCs and proinflammatory macrophages (Li Y. et al., 2019). Espagnolle reported that the inhibitory effect of MSCs on T cell proliferation was increased due to the upregulation of CD54 in hMSCs in contact with M1 macrophages (Espagnolle et al., 2017).