The cell cycle is extensively characterized, yet there is much to learn about the decision-making process involved in cell division. Here, the optical redox ratio (ratio of NADH to FAD fluorescence intensity) of MCF10A cells was imaged every 20 minutes over 12 hours using multiphoton microscopy. Cell tracking was used to monitor individual cells over time. We found a positive correlation in the variations of the optical redox ratio with the phases of the entire cell cycle. This study reveals the novel role of redox signaling in the progression the cell cycle.
Macrophages adopt a variety of phenotypes that are a reflection of the many functions they perform as part of the immune system. In particular, metabolism is a phenotypic trait that differs between classically activated, proinflammatory macrophages, and alternatively activated, prohealing macrophages. Inflammatory macrophages have a metabolism based on glycolysis while alternatively activated macrophages generally rely on oxidative phosphorylation to generate chemical energy. We employ this shift in metabolism as an endogenous marker to identify the phenotype of individual macrophages via live-cell fluorescence lifetime imaging microscopy (FLIM). We demonstrate that polarized macrophages can be readily discriminated with the aid of a phasor approach to FLIM, which provides a fast and model-free method for analyzing fluorescence lifetime images.