Label-free sensing of cells with fluorescence lifetime imaging: The quest for metabolic heterogeneity

Significance Tumors are complex systems characterized by spatial heterogeneity at the genetic, molecular, and cellular levels. Tumor heterogeneity is the critical phenomenon determining the difference in therapeutic outcomes for patients with similar histological diagnosis. Metabolic heterogeneity, i.e., the difference in cancer cell metabolism within a tumor and between tumors, is considered to be a negative prognostic factor and is accompanied by an increased probability of recurrence and higher mortality. Detection and quantification of metabolic heterogeneity can help in diagnosing cancer, assessing tumor progression, and optimizing cancer treatment. Here, we demonstrate that fluorescence lifetime imaging with the advanced detection and signal analysis system may allow rapid, sensitive, and noninvasive assessment of cellular metabolic heterogeneity in living cells.