Effects of chorionic mesenchymal stromal cells, their conditioned medium, and membrane particles on neutrophil functionality.

Mesenchymal stromal cells (MSC) are multipotent cells that can modulate immune cells, affecting macrophages, monocytes, and lymphocytes. Neutrophils are circulating leucocytes responsible for the first line of defense and can assume different phenotypes depending on their environment: N0, the naïve form, N1 (inflammatory), N2 (anti-inflammatory). This study explores the potentially protective roles of chorionic membrane MSCs and their products-conditioned medium and pre-conditioned cMSC-derived membrane microparticles (MP-cMSC)-on neutrophils. Conditioned medium treatment reduced the rate of apoptosis and enhanced the immunosuppressive potential consistent with an anti-inflammatory profile. MP-cMSC are a noteworthy cell-free therapy, consisting of artificially generated circular lipid bilayer structures with no cargo and approximately 200 nm in size. When added to neutrophil culture, MPs increased neutral red uptake, suggesting an enhanced phagocytic activity. In the MSC co-culture group, a reduced rate of apoptosis, increased neutral red uptake, and elevated programed death-ligand 1 (PD-L1) expression were observed. These findings suggest that the distinct effects elicited by conditioned media, microparticles, and co-culture are likely influenced by the specific nature of the interactions involved-whether purely paracrine, mediated through direct cell-to-cell contact, or a combination of both.