Real-time ATP quantification reveals inherent and acquired metabolic plasticity in hematopoietic stem cells

Understanding how young and old hematopoietic stem cells (HSCs) maintain tissue homeostasis and adapt to intrinsic and extrinsic stress requires defining their metabolic regulation. Here, we quantify adenosine triphosphate (ATP) concentration in thousands of living HSCs and progenitors at the single-cell level with high temporal resolution and identify distinct metabolic adaptation strategies used by HSCs in response to proliferative signals, nutrient perturbation, exposure to reactive oxygen species, and physiological aging. Combining this approach with 13C-glucose tracer analysis, we show that HSCs have higher glycolytic plasticity than progenitors in meeting ATP demands and that upon aging they acquire robust plasticity in mitochondrial ATP production. Mechanistically, we show that AMPK/PFKFB3 signaling likely enables demand-driven ATP production, whereas fatty acid oxidation is required for steady state ATP homeostasis and age-related mitochondrial plasticity. This study demonstrates that real-time ATP quantification can reveal metabolic programs used by stem cells to adapt to stresses