Time-lapse imaging of contact dynamics between mesenchymal stem cells and T cells (THER5P.913)

Mesenchymal stem cells (MSC) ameliorate the pathogenesis of systemic lupus erythematosus through inhibiting T cell functions via soluble mediators and direct cell-cell contact. However, little is known about the contact dynamics at the single cell level. Using time-lapse imaging, we show that their contact is dependent on CCL2, but not CCL3, CCL4, CXCL10, and CXCL12, which are produced by MSCs. First, we analyzed contact dynamics of MSCs. Each WT MSC contacted 11 T cells and each contact lasted 107 min. In the same condition, each CCL2-/- MSC contacted 10 T cells and each contact continues 34 min. Subsequently, CCL2-/- MSCs did not inhibit T cell functions. Next, we analyzed migration dynamics of only T cells, since MSCs did not move well. When calculating the percentage of T cells contacting MSCs more than one time for 6 h, 68% T cells contacted MSCs and 59% T cells contacted CCL2-/- MSCs. T cells moved at average speeds of 7 um/min without contact and did not move well during the contact period, which was similar in cultures with either WT or CCL2-/- MSCs. Together, our data demonstrate that MSC-derived CCL2 might increase T cell migration, prolong contact duration with T cells, and finally inhibit T cell functions.