Poly(acrylic acid)-Coated Iron Oxide Nanoparticles interact with mononuclear phagocytes and decrease platelet aggregation

•PAC-IONs did not compromise the viability of mononuclear.•PAC-IONs did not affect the platelet activation but antagonized their aggregation.•MDMS differentiated in the presence of PAC-IONs did not affect their functions.•PAC-IONs affected LPS-induced cytokines. Poly(acrylic acid)-Coated Iron Oxide Nanoparticles (PAC-IONs) did not compromise the viability of mononuclear cells and potentially interact with cells through scavenger receptors. This study evaluated: 1) The capacity of the PAC-IONs to induce platelet activation and aggregation, and 2) The effect of the PAC-IONs in two functions of Monocyte-Derived Macrophages (MDMs) when differentiated in their presence; that is, the removal of apoptotic cells (ACs) and the levels of cytokines induced by Lipopolysaccharide (LPS) and the ACs. The PAC-IONs did not affect the platelet activation but antagonized their aggregation. On the other hand, the differentiation of MDMS in the presence of PAC-IONs did not inhibit the ability of these cells to phagocytose latex beads but decreased the number of apoptotic bodies internalized by them. MDMs differentiated in the presence of PAC-IONs and stimulated with LPS or ACs exhibited an overall decrease of the cytokine levels. The altered synthesis of cytokines could be attributed to a high production of Reactive Oxygen Species (ROS) caused by the increase in the intracellular iron content. The effect of the PAC-IONs on the cell cycle of U937 and Jurkat cells was also studied; there was not either cell accumulation in any phase of the cell cycle or changes in the DNA content. It is clear that PAC-IONs affect neither the viability nor compromise some cellular functions. However, they could alter the functioning of the immune system; therefore, in the case of being used as a diagnostic tool, their permanence in the body should be considered.