Pregnancy-specific glycoproteins as molecular links between mesenchymal stromal cells and M2 macrophages in tissue repair: implications for cancer progression

After some decades of research on mesenchymal stromal cells (MSCs), they are not yet routinely used in clinical protocols. Even though various lines of investigation have pointed out that MSCs are therapeutic mainly owing to their secreted molecules, and a number of such molecules have been described, it is apparent that further understanding of MSC biology is still required to make them effective tools to treat diseases. This mini-review brings the perspective that MSCs do not act alone, but rather in concert with other cell types such as macrophages, to bring about tissue regeneration or, in some instances, unwanted consequences. In this context, the possible effects of pregnancy-specific glycoproteins produced by MSCs on macrophages, and consequences of this for tissue repair, cancer progression, and chimeric antigen receptor T cell therapy in solid tumors will be discussed.