Autofluorescence of transplantable hepatoma A22 (MH-A22): Prospects of tumor tissue optical biopsy

Aim: Autofluorescence of experimental tumor (hepatoma A22 (MH-A22)) was employed to discriminate the optical differences between necrotic and non-necrotic tumor, hemorrhagic tumor and healthy tissue. Methods: The experiment was performed ex vivo using the transplantable tumor from the right haunch of hybrid mice (C57B1/CBA). Blue LED light (λ_em = 405 nm) was applied for autofluorescence excitation and fibre optics based spectrofluorimeter was used for spectra detection. Results: We observed that necrotic tumor tissue is characterized by the absence of endogenous porphyrins fluorescence, and registered spectra do not possess differences in the red spectral region (600-710 nm) in comparison with normalized autofluorescence spectra of muscle. Moreover, only certain segments of non-necrotic tumor bear the fluorescence of endogenous porphyrins. Conclusions: Based on the experimental results, we suggest that the absence of long-waved fluorescence differences between necrotic tumor tissue and healthy tissue, e.g. muscle can impede the demarcation between healthy and tumor tissue. The uneven distribution of endogenous porphyrins in non-necrotic tumor tissue as well as the absence of endogenous porphyrins fluorescence in the small experimental tumors complicates the localization of cancerous tissue based on the autofluorescence registration.