Fluorescence spectroscopy of mouse organs using ultraviolet excitation: towards assessment of organ viability for transplantation

摘要

Identifying diseases and evaluating tissue function and viability can be performed by subjective or objective methods.However, subjective techniques may be inaccurate and non-optical objective techniques may be relatively expensive andtime-consuming. Then, these techniques may not be suitable for clinical applications that require immediate assessmentand intervention. Fluorescence spectroscopy (FS) is one of the optical techniques with great potential for medicaldiagnostics and surgical guidance. This potential is associated to the possibility of label-free techniques biochemicalsensitivity without contrast agents. For clinical applications, fluorescence can be used to assess biomolecular content ofrespiratory metabolism involving NAD(P)H and FAD. In addition, changes in collagen, elastin, porphyrin, pyridoxine,and tryptophan content can potentially be detected. One way to collect epifluorescence signals from superficial tissuelayers is using ultraviolet (UV) excitation. In this study, we used UV excitation FS to investigate the effect oftemperature variation (from 0 to 25 degrees Celsius) on tissue autofluorescence. The measurements reproducibility wasassessed by variations of the spectral shape accounted by the calculation of the Pearson correlation coefficient for eachpair of measurements. Overall, fluorescence measurements were more reproducible at 25 ℃ compared to 0 ℃. Livershowed lowest fluorescence variability (most homogeneous organ) regarding results from both 300 nm and 340 nmexcitations. We report temperature and wavelength-dependent spectral changes due to the tissue thawing by calculatingthe difference between normalized UVEFS measurements at 0℃ and 25℃. Observed differences may be attributed toblood absorption and NADH fluorescence emission. Our results can be used to increase the database of tissuefluorescence spectra using UV excitation for future reference to choose targeted wavelengths in fluorescenceinstrumentation. Furthermore, our study illustrates expected fluorescence variations during the assessment of organsviability for transplantation, especially due to cold preservation.