title: Sensitive detection of intracellular environment of normal and cancer cells by autofluorescence lifetime imaging.
abstract: Intracellular fluorescence lifetime images of the endogenous fluorophores of nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD), which are well known as autofluorescence chromophores, were obtained from rat normal fibroblast cells (WFB) and H-ras oncogene-transfected cancer cells among WFB (W31). The average lifetime of the NADH and FAD autofluorescence was shorter in cancer cells than in normal cells, indicating that the difference in metabolism between healthy and cancer cells alters the conditions for coenzymes such as NADH and FAD and that the autofluorescence lifetime measurement of NADH and FAD is applicable for the noninvasive diagnosis of cancer cells. The pico- and nano-second time-resolved fluorescence spectra of NADH obtained with different time windows were similar in normal and cancer cells, indicating that every fluorescence decay component gives the same spectrum in both cell types. These results as well as the fluorescence lifetime images of exogenous fluorophores stained with sodium pheophorbide a in normal and cancer cells suggest that the difference in the fluorescence lifetime between normal and cancer cells cannot be attributed to a difference in the intracellular pH or refractive index but to the difference in the bound condition between proteins and NADH or FAD under the different intracellular environments of normal and cancer cells.
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001, Ta-Hsueh Road, Hsinchu 30010, Taiwan.
authors.forename: Kamlesh
authors.initials: K
authors.lastname: Awasthi
authors.affiliation: Department of Bio- and Material Photonics, Chitose Institute of Science and Technology, Chitose 066-8655, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Moriya
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
authors.forename: Takakazu
authors.initials: T
authors.lastname: Nakabayashi
authors.affiliation: Department of Bio- and Material Photonics, Chitose Institute of Science and Technology, Chitose 066-8655, Japan.
authors.forename: Liming
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001, Ta-Hsueh Road, Hsinchu 30010, Taiwan. Electronic address: nohta@nctu.edu.tw.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Ohta
mesh_terms: D000818:Animals; D005453:Fluorescence; D009369:Neoplasms / Q000473:pathology*; D051381:Rats
keywords: Autofluorescence; Cancer cell; FAD; FLIM; NADH; Normal cell