Modulated expression of adhesion molecules and galectin-1: role during mesenchymal stromal cell immunoregulatory functions.

OBJECTIVE: As mesenchymal stromal cells (MSCs) have been proposed as a tool for management or prevention of graft-vs-host disease, we investigated their immunoregulatory properties, their expression of adhesion molecules and galectin-1, and the impact of environment context on these functions.
MATERIALS AND METHODS: The effects of MSCs on T-cell proliferation were analyzed using carboxyfluorescein diacetate N-succinimidyl ester labeling. We evaluated the expression of adhesion molecules and galectin-1 by MSCs and the impact of an inflammatory or infectious environment on these expressions. Using neutralizing antibodies against adhesion molecules and a galectin-1 inhibitor, we assessed the role of these molecules in MSC functions.
RESULTS: MSCs inhibition of T-cell proliferation depended on MSC concentrations, cell contact, and culture environment. Expression of adhesion molecules and secretion of galectin-1 by MSCs are tightly regulated. Coculture with activated T cells upregulated expression of CD54 (intercellular adhesion molecule 1) and CD58 (lymphocyte function-associated antigen 3) and secretion of galectin-1 by MSCs. Interestingly, in an inflammatory or infectious environment, expression of adhesion molecules and galectin-1 by MSCs was differentially modulated. Furthermore, blocking galectin-1 activity prevented the suppressive potential of MSCs. Neutralization of adhesion molecule activity had no effect on MSC inhibition.
CONCLUSION: Galectin-1 plays an important role in MSC immunoregulatory functions, which are depending on cell environment. The present study provides new insights concerning MSC physiology and will increase the safety and efficiency of MSCs in clinical settings.