Quantum sensing to monitor changes in free radical generation by intracellular vesicles of polarized macrophages

Macrophages are immune cells crucial in clearing our tissues from bacteria, viruses, dying cells, cell debris and other waste products. They also regulate inflammation by differentiating from non-activated (M0) cells into macrophages that initiate inflammation (pro-inflammatory macrophages, M1), or resolve inflammation (anti-inflammatory macrophages, M2). One of their key functions is to ingest pathogens within vesicles where they are degraded. The production of free radical (FR) plays an important role in this degradation process but also in macrophage differentiation and signaling. Here we used diamond-based quantum sensing to track free radical changes in vesicles with nanoscale resolution. We further followed the oxidative stress status, through free radical measurement during the macrophage activation process. We found that the three macrophage subtypes differed significantly in free radical generation in their vesicles. Additionally, we showed that the FR generation evolves over time in the different subtypes. We observed a 50 % increase in radical production in M0 after 24 h compared to the T1 values measured after 4 h of cell culture, a decrease in M1 and constant radical levels in M2 macrophages.