Autofluorescence microscopy of fresh cervical-tissue sections reveals alterations in tissue biochemistry with dysplasia

Fluorescence spectroscopy offers an effective, noninvasive approach to the detection of precancers in multiple organ sites. Clinical studies have demo nstrated that fluorescence spectroscopy can provide highly sensitive, speci fic and cost-effective diagnosis of cervical precancers. However, the under lying biochemical mechanisms responsible for differences in the fluorescenc e spectra of normal and dysplastic tissue are not fully understood. We desi gned a study to assess the differences in autofluorescence of normal and dy splastic cervical tissue. Transverse, fresh tissue sections were prepared f rom colposcopically normal and abnormal biopsies in a 34-patient study. Aut ofluorescence images were acquired at 380 and 460 nm excitation, Results sh owed statistically significant increases in epithelial fluorescence intensi ty (arbitrary units) at 380 nm excitation in dysplastic tissue (106 +/- 39) relative to normal tissue (85 +/- 30). The fluorophore responsible for thi s increase is possibly reduced nicotinamide adenine dinucleotide, Stromal f luorescence intensities in the dysplastic samples decreased at both 380 nm (102 +/- 34 [dysplasia] vs 151 +/- 44 [normal]) and 460 nm excitation (93 /- 35 [dysplasia] vs 137 +/- 49 [normal]), wavelengths at which collagen is excited. Decreased redox ratio (17-40% reduction) in dysplastic tissue sec tions, indicative of increased metabolic activity, was observed in one-thir d of the paired samples. These results provide valuable insight into the bi ological basis of the differences in fluorescence of normal and precancerou s cervical tissue.