Reply: Adenosine Producing Mesenchymal Stromal Cells.

Adenosine signaling has been described as one of the many immunosuppressive mechanisms of mesenchymal stromal cells (MSCs). Central players in adenosine signaling are the ectonucleotidases CD39 and CD73, which convert ADP/ATP to AMP and AMP to adenosine, respectively. CD73 is one of the three phenotypic markers of MSCs and thus, highly expressed on MSCs. Instead, there has been conflicting results whether MSCs intrinsically express CD39 or not. Stem Cells 2017;35:1649-1650.